Aus dem Institut für Tierzucht und Tierhaltung

der Agrar- und Ernährungswissenschaftlichen Fakultät

der Christian-Albrechts-Universität zu Kiel

__________________________________________________________________________

GENETIC EVALUATION OF INDICATOR TRAITS FOR CLAW AND LEG

DISEASES AND ESTIMATION OF BACKFAT THICKNESS USING NEW

TRAITS FROM AN AUTOMATIC 3D OPTICAL SYSTEM

Dissertation

zur Erlangung des Doktorgrades

der Agrar- und Ernährungswissenschaftlichen Fakultät

der Christian-Albrechts-Universität zu Kiel

vorgelegt von

Dipl.-Ing. agr.

ASTRID WEBER

aus Düren, Nordrhein-Westfalen

Dekan: Prof. Dr. R. Horn

Erster Berichterstatter: Prof. Dr. G. Thaller

Zweiter Berichterstatter: Prof. Dr. H. H. Swalve

Tag der mündlichen Prüfung: 24. April 2013

___________________________________________________________________________

Die Dissertation wurde mit dankenswerter finanzieller Unterstützung aus Mitteln des

Bundesministeriums für Ernährung, Landwirtschaft und Verbraucherschutz (BMELV) über die

Bundesanstalt für Landwirtschaft und Ernährung (BLE) im Rahmen des Programms zur

Innovationsförderung angefertigt.

http://www.agrar.uni-kiel.de/de/fakultaet/dekanat-1/dekane/prof.-dr.-rainer-horn-1

Meinen Eltern

Table of Contents

General Introduction 1

Chapter 1

Genetic parameters for lameness and claw and leg diseases

in dairy cows 4

Chapter 2

Genetic correlations between claw and leg diseases, lameness,

foot and leg conformation traits, stature and body weight in

German Holstein-Friesian heifers 27

Chapter 3

Estimation of backfat thickness using extracted traits from an

automatic 3D optical system in lactating Holstein-Friesian cows 47

General Discussion 69

General Summary 79

Zusammenfassung 81

1

General Introduction

During the last decades, dairy cattle selection has mainly focused on increasing milk

production per cow. However, the increase in milk yield was accompanied by detrimental

effects on functional traits. The reason for this problem is the unfavorable genetic correlation

among the two characteristics (e.g. Simianer et al., 1991). Functional traits are defined as

those characteristics of an animal, which increase efficiency not by higher output of products

but through reduced costs of input (Groen et al., 1997). The complexes health, fertility,

calving ease, efficiency of feed utilization, milkability, and conformation are identified as

functional traits (Groen et al., 1997; Koenig and Swalve, 2006). Since the early 2000s, more

emphasis has been put on broadening selection indices by including functional traits (Miglior

et al., 2005). With regard to the economic aspects of dairy production, the main reasons for

this change was the introduction of milk quotas which have restricted the returns for

increasing yield, price limitations as well as the stronger increase of labor costs in comparison

to the milk price (Boettcher, 2005). In addition to the direct impact of functional traits on the

economic efficiency of dairy cattle farming, increasing producer and consumer concerns

regarding animal welfare are evident (Miglior et al., 2005). Some properties of functional

traits complicate their inclusion in a selection index. These imply lower heritability in

comparison to production traits as well as the difficulty to properly define, record and analyze

such traits. The use of indicator traits, which indicating the genetic merit of an animal for the

target trait, is gaining importance (Loker et al., 2012). Generally, the measurement takes place

earlier in life and the recording of indicator traits is easier (Berry et al., 2003), but the genetic

correlation between the indicator trait and the trait of interest has to be high.

There is a large interest in the improvement of recording methods for functional traits as well

as in the development of new traits which might be used as predictor traits. A further

approach might be the application of new technologies which simplify the measurement of the

traits and increase the amount of data.

As the direct selection on claw disorders is challenging due to the low heritability of these

traits and the expensive and time-intensive recording of specific diseases, selection is

performed indirectly using foot and leg conformation traits (Boettcher and Dekkers, 1997).

An indicator of the overall energy status of the dairy cow is body condition scoring (BCS) as

a subjective measure of the tissue reserves available on an animal (Roche et al., 2009; Loker

et al., 2012). Furthermore, because of the moderate to high genetic correlations, BCS is a

useful predictor trait for health and fertility status in dairy cattle (Pryce et al., 2001; Dechow

2

et al., 2004). Several countries have already included BCS in their national genetic evaluation

(Interbull, 2012).

Within the project “Innovative methods of trait recording in dairy cattle as a basis of the

modern breeding program of the Nord-Ost-Genetic”, at the research farm Karkendamm of the

Institute of Animal Breeding and Husbandry, Christian-Albrechts-University Kiel (Germany),

the StepMetrix system for automatic recording of lameness in dairy cows was implemented.

To evaluate its practicability and properties, locomotion scores of all lactating cows were

collected on a weekly basis. Despite promising features of the StepMetrix system assure by

the company BouMatic, no reliable data were available for statistical or genetic analyses.

Therefore the project concentrated to use locomotion scores as binary trait (lame vs. not

lame). In Chapter 1 of the present study, lameness was investigated as indicator trait of claw

and leg diseases. First, the impact of the environmental factors parity and stage of lactation on

lameness and claw and leg diseases in primiparous and multiparous dairy cows was assessed.

Next, genetic parameters for both traits using linear and threshold models were estimated. As

the selection on claw and leg disorders is primarily performed indirectly using foot and leg

conformation traits, in Chapter 2 the relationships were analyzed. Furthermore, the

correlation between lameness and the conformation traits were estimated in order to describe

a possible accordance between the traits. Although phenotypic association among claw and

leg diseases and body weight or stature were reported in literature (Schöpke et al., 2013),

nothing is known about their genetic relationship. Therefore, the genetic correlation among

the traits was estimated.

The automation of the routine assessment of the cows’ body condition offers numerous

benefits, especially against the background of the increasing herd sizes. Thus, the main

objective in Chapter 3 was to assess whether traits of the animals rear area developed using

images of a Time-of-Flight camera might be useful indicators of the backfat thickness of dairy

cows.

References

Berry, D. P., F. Buckley, P. Dillon, R. D. Evans, M. Rath, and R. F. Veerkamp. 2003. Genetic

relationships among body condition score, body weight, milk yield, and fertility in dairy

cows. J. Dairy Sci. 86:2193-2204.

Boettcher, P. 2005. Breeding for improvement of functional traits in dairy cattle. Ital. J. Anim.

Sci. Suppl. 4:7-16.

3

Boettcher, P. J. and J. C. M. Dekkers. 1997. Indirect selection for resistance to locomotive

disorders in dairy cattle. Interbull Bull. 15:123-129.

Dechow, C. D., G. W. Rogers, U. Sander-Nielsen, L. Klei, T. J. Lawlor, J. S. Clay, A. E.

Freeman, G. Abdel-Azim, A. Kuck, and S. Schnell. 2004. Correlations among body

condition scores from various sources, dairy form, and cow health from the United States

and Denmark. J. Dairy Sci. 87:3526-3533.

Groen, A. F., T. Steine, J.-J. Colleau, J. r. Pedersen, J. Pribyl, and N. Reinsch. 1997.

Economic values in dairy cattle breeding, with special reference to functional traits.

Report of an EAAP-working group. Livest. Prod. Sci. 49:1-21.

Interbull. 2012. Description of National Genetic Evaluation Systems for dairy cattle traits as

applied in different Interbull member countries. Accessed February 16, 2013. http://www-

interbull.slu.se/national_ges_info2/framesida-ges.htm.

Koenig, S. and H. H. Swalve. 2006. Modellkalkulationen zu züchterischen Möglichkeiten auf

Klauengesundheit beim Milchrind. Zuechtungskunde 78:345-356.

Loker, S., F. Miglior, A. Koeck, T. F. O. Neuenschwander, C. Bastin, J. Jamrozik, L. R.

Schaeffer, and D. Kelton. 2012. Relationship between body condition score and health

traits in first-lactation Canadian Holsteins. J. Dairy Sci. 95:6770-6780.

Miglior, F., B. L. Muir, and B. J. Van Doormaal. 2005. Selection indices in Holstein cattle of

various countries. J. Dairy Sci. 88:1255-1263.

Pryce, J. E., M. P. Coffey, and G. Simm. 2001. The relationship between body condition score

and reproductive performance. J. Dairy Sci. 84:1508-1515.

Roche, J. R., N. C. Friggens, J. K. Kay, M. W. Fisher, K. J. Stafford, and D. P. Berry. 2009.

Invited review: Body condition score and its association with dairy cow productivity,

health, and welfare. J. Dairy Sci. 92:5769-5801.

Schöpke, K., S. Weidling, R. Pijl, and H. H. Swalve. 2013. Relationships between bovine

hoof disorders, body condition traits, and test-day yields. J. Dairy Sci. 96:679-689.

Simianer, H., H. Solbu, and L. R. Schaeffer. 1991. Estimated genetic correlations between

disease and yield traits in Dairy cattle. J. Dairy Sci. 74:4358-4365.

4

5

Chapter 1

Genetic parameters for lameness and claw and leg diseases in

dairy cows

A. Weber1, E. Stamer

2, W. Junge

1, G. Thaller

1

1Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, D-24098 Kiel,

Germany

2TiDa Tier und Daten GmbH, D-24259 Westensee, Germany

Published in Journal of Dairy Science 96: 3310-3318

6

Abstract

Lameness in dairy cows is a serious welfare and economic problem in dairy production. The

majority of all lameness cases seem to stem from claw and leg diseases. Indirect selection on

claw health potentially might be feasible with lameness as indicator trait. Therefore, the

genetic parameters for the 2 traits were estimated by applying both linear and threshold

models. In addition, the impact of environmental effects, parity and stage of lactation was

analyzed. In total, 8,299 locomotion scores (1-5) of 326 dairy cows and 708 claw and leg

disease diagnoses or treatments of 335 dairy cows from the dairy research farm Karkendamm

(Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, Kiel, Germany)

were analyzed. Lameness was defined by a locomotion score of ≥ 3. Days in milk were

limited to the range of 10 to 350 d. To quantify the effect of the claw disease digital

dermatitis, a second data set without this disease was built; 52.8 and 36.4% (without digital

dermatitis) of the cows were treated at least once; 47.2% of the cows were clinically lame at

least at one time. Genetic parameters were estimated bivariately using the average information

restricted maximum likelihood procedure as implemented in the DMU software package. The

heritability estimates derived from the threshold model were about twice as large as the values

based on the linear model. For lameness, the threshold heritability increased from 0.15 to 0.22

and decreased for the diseases from 0.24 to 0.22 after exclusion of digital dermatitis. The

genetic correlations were high and even increased from 0.60 to 0.72 after the exclusion of

digital dermatitis, which suggests that lameness (locomotion score) seems to be a good

indicator for claw and leg diseases. Digital dermatitis seems to affect the mobility of the dairy

cow less strongly than other claw and leg diseases.

Key words: dairy cow, locomotion score, lameness, claw and leg diseases

Introduction

Lameness in dairy cows is one of the major animal welfare issues in dairy production. It is a

painful condition and causes economic losses through decreased milk production, impaired

reproductive performance and involuntary culling (Kossaibati and Esslemont, 1997). In

German herds, lameness (claw and leg lesions) is the third main reason for early culling after

mastitis and infertility problems. Annual statistics published by the German Cattle Breeders

Federation (Bonn, Germany) show that the percentage of cullings because of feet and leg

disorders among all cullings increased from 4.40 (1980) to 10.40% (2009) in the last 30 yr

(ADR, 1980-2009). The majority of all lameness cases seemed to be caused by claw and leg

lesions; Murray et al. (1996) quantified this amount at about 90%.

7

Much of the variability in foot diseases is associated with environmental factors, such as

management and housing. Nevertheless, a few studies have found a genetic effect on such a

trait (Koenig et al., 2005; Swalve et al., 2008; van der Linde et al., 2010). Therefore, apart

from improvement of the environmental effects, claw health may be improved through

selection. Direct selection on claw diseases is difficult because detailed inspection of the

claws can be expensive and time intensive. Successful indirect selection demands a high

genetic correlation between the indicator trait and claw health and the trait has to be heritable.

Such a trait could be lameness recorded as an indicator trait for claw diseases. Controlling and

examination of lameness at a herd level is potentially possible with a well-established

locomotion scoring system. Several approaches were developed in the last 23 yr (Manson and

Leaver, 1989; Sprecher et al., 1997). Thus, this trait might be more easily and inexpensively

assessed than specific claw lesions (Boettcher et al., 1998). A few studies have reported

heritabilities for locomotion, which is being used as an additional conformation trait in the

type classification of Holstein-Friesian heifers (van der Waaij et al., 2005; Laursen et al.,

2009; van der Linde et al., 2010). In contrast to the genetic parameters for claw health and

locomotion, the parameters for lameness have not been well investigated.

Thus, the first objective of this study was to examine the impact of the environmental effects,

such as parity or stage of lactation, on lameness and claw and leg diseases. Then, taking the

relevant fixed effects into consideration, the genetic parameters were estimated applying both

linear and threshold models.

Materials and Methods

Data

Locomotion scores were recorded between September 2010 and February 2012 on the dairy

research farm Karkendamm of the Institute of Animal Breeding and Husbandry, Christian-

Albrechts-University Kiel (Germany). According to the system of Sprecher et al. (1997), 326

lactating Holstein Friesian cows (primiparous and multiparous) were examined weekly for

lameness (locomotion score) by one classifier. This system emphasizes the leg placement and

back posture of the dairy cows and is expressed by 5 possible scores (1 = normal gait, 2 =

mildly lame, 3 = moderately lame, 4 = lame, and 5 = severely lame). Locomotion was scored

while the cows were standing or walking on the concrete slatted passageways at the feeding

bunk or between the cubicles on 1 of the 2 concrete slatted floor systems. Cows in straw and

the selection yard were not assessed. Before the start of the study period, all animals were

examined weekly for 2 mo to train the judge in the procedure of scoring locomotion. As the

8

emphasis of this study was mainly on the investigation of lameness in dairy cows and due to

the low number of the more extreme scores (scores 4 and 5), the locomotion scores were

dichotomized, using 3 as the cut-off. As shown in Figure 1, in almost 16% of the locomotion

scores (3 to 5) cows were classified as lame. For further analysis, clinically lame cows were

coded as 1 (score ≥ 3). If the locomotion was normal (scores 1 and 2), the value was set to 0.

Figure 1. Frequencies of locomotion scores

In the same observation period as scoring locomotion, all claw and leg diagnoses and

treatments were recorded by a veterinarian or farm staff. On the research farm, the claws of

the animals were trimmed routinely until 100 d postpartum and before the dry period by one

claw trimmer (farm staff). In addition to this routine, cows recognized as lame by locomotion

scoring or farm staff were examined. All in all, 8 different claw and leg disorders were

diagnosed and treated (Table 1). The main claw disease was sole ulcer with a frequency of

24%, followed by digital dermatitis with a frequency of about 22%. The frequency of leg

disease was small (slightly less than 7%).

45.17

39.06

13.35

2.34 0.08

0

10

20

30

40

50

1 2 3 4 5

Fre

qu

ency

(%

)

Locomotion Score

9

Table 1. Frequencies (%) of the recorded claw and leg diseases

Diagnosis Absolute frequency Relative frequency

Sole ulcer 183 24

Digital dermatitis 167 22

Interdigital hyperplasia 148 19

Interdigital necrobacillosis 127 17

White line disease 61 8

Leg lesions (e.g., hock swelling) 51 7

Double sole 27 4

Undefined injuries 7 1

Total 771

The number of claw and leg diseases decreased from 771 to 708 in the final data set due to the

restriction of being within 10 and 350 DIM. For definition of the trait claw and leg diseases,

each day with at least 1 treatment was coded as 1. Additionally, the following 8 DIM were

also coded as 1. The 8-d period was chosen because claw and leg diseases seemed to affect

the cows for at least 1 wk (Buttchereit et al., 2012). All other days were classified as healthy

(coded as 0). Days in milk were limited to the range of 10 to 350 d because of the small

number of cows in the first days postpartum and above 350 lactation days. To quantify the

effect of the claw disease digital dermatitis, a second data set without this disease was built.

Table 2. Frequencies of claw and leg diseases (with and without digital dermatitis) and

lameness (score ≥ 3)

Trait Cow days

Cows (lactations)

Lactation

period (d) Total Affected (%)

Total Affected (%)

Claw and leg diseases 10 to 350 73,433 6.7

335 (420) 52.8 (60.0)

Claw and leg diseases

without digital dermatitis 10 to 350 73,433 5.0

335 (420) 36.4 (32.9)

Lameness (score ≥ 3) 10 to 350 8,299 15.4

326 (404) 47.2 (43.3)

Table 2 summarizes the number of affected cows and the number of days coded as 1 for claw

and leg diseases and lameness (score ≥ 3). In total, 52.8 and 36.4% (without digital dermatitis)

of the 335 examined cows were treated at least once because of one or more claw and leg

diseases, and 47.2% of the 326 rated cows were clinically lame at least at one time in the

observation period.

10

Statistical Analysis

The model fitting was done with PROC GENMOD using the probit link function of the SAS

package (SAS Institute, 2008). For all model runs, fixed effects with only one value (0 or 1)

were added to neighboring classes to avoid extreme categories (Hoeschele and Tier, 1995;

Luo et al., 2001). A model with the fixed effects test day and 21 different combinations of

lactation stage and lactation number as well as their interactions were tested. Evaluation of

goodness of fit of different models for locomotion score and claw and leg diseases was carried

out using the corrected Akaike information criterion (AICC; Burnham and Anderson, 1998)

and the Bayesian information criterion (BIC; Schwarz, 1978). The model that minimizes

AICC or BIC is superior, but if AICC or BIC are close, the simpler model is generally

considered preferable (Littell et al., 2006). Based on the results of the model fitting, the

following threshold was used for the 3 traits claw and leg diseases, claw and leg diseases

without digital dermatitis, and lameness (score ≥ 3) to test and to describe the fixed effects:

E [πijkl] = Φ (TDi + LNOj + LSjk + cowl),

where E [πijkl] = expected probability for occurrence of claw and leg diseases or lameness

(score ≥ 3); Φ = cumulative probability of standard normal distribution; TDi = fixed effect of

ith test day (i = 1 to 507 for claw and leg diseases, i = 1 to 504 for claw and leg diseases

without digital dermatitis, and i = 1 to 69 for lameness); LNOj = fixed effect of the jth

lactation number (j = 1, 2, ≥ 3); LSjk = fixed effect of the kth lactation stage (10-50, 51-100,

101-150, 151-200, 201-250, 251-300, or 301-350) within the jth lactation number; and cowl =

random effect of the lth cow (l = 1 to 335 for claw and leg diseases, l = 1 to 335 for claw and

leg diseases without digital dermatitis, and l = 1 to 326 for lameness).

The models were analyzed using PROC GLIMMIX in SAS with the residual marginal

pseudo-likelihood (RMPL) method. The significance of differences between least squared

means was adjusted with the Bonferroni correction (SAS Institute, 2008).

Genetic parameters for claw and leg diseases (with and without digital dermatitis) and

lameness were estimated using the average information (AI) restricted maximum likelihood

procedure as implemented in the DMU software package (version 6, release 5.0; Madsen and

Jensen, 2010). For these estimations, the above described threshold model included the

random permanent environmental effect of the cow and the additive genetic effect of the

animal instead of the random effect of the cow. Pedigree information contained sires and

dams 3 generations back, so in total, 1,649 animals were in the pedigree file. Heritabilities and

11

genetic correlations between claw and leg diseases (with and without digital dermatitis) and

lameness were estimated bivariately with threshold models as well as with the following

linear model:

Yijklmn = μ +TDi + LNOj + LSjk + pl + am + eijklmn,

where Yijklmn = observation of claw and leg diseases or lameness; μ = overall mean; pl =

random permanent environmental effect of the lth cow (l = 1 to 335 for claw and leg diseases,

l = 1 to 335 for claw and leg diseases without digital dermatitis, and l = 1 to 326 for

lameness); am = random additive genetic effect of the mth animal (m = 1 to 1,649); eijklmn =

random residual effect.

Results

Figure 2 shows the prevalence of claw and leg diseases and lameness (score ≥ 3) during 10 to

350 DIM. The trajectory of the claw and leg diseases showed a peak at the beginning of the

lactation, whereas the frequency of lameness remained at a constant low level during the same

time period. After the first 2 lactation months the prevalence of both traits persisted at a

constant height.

Figure 2. Prevalence of claw and leg diseases and lameness (score ≥ 3) during 10 to 350 DIM

In the first analysis, a generalized linear model was used to investigate the fixed

(environmental) effects on lameness and claw and leg diseases. According to the results of the

F-tests, all fixed effects [test day and lactation number (1, 2, and ≥ 3)] included in the final

0

10

20

30

2 10 18 26 34 42 50

Pre

val

ence

(%

)

Lactation Week

claw and leg diseases lameness (score ≥ 3)

12

model and the interaction between lactation number and lactation stage had a highly

significant effect (P < 0.0001) on the probability of incidence of lameness and claw and leg

diseases.

The covariance parameter of the random effect cow and the scale parameter for claw and leg

diseases (with and without digital dermatitis) and lameness (score ≥ 3) are given in Table 3.

The covariance parameter estimate for claw and leg diseases increased from 0.4985 to 0.6719

with almost constant scale parameter after the claw disease digital dermatitis was excluded

from the data set. This result indicates that the frequency of digital dermatitis was largely

influenced by environmental effects such as farm management. For lameness, the covariance

parameter was quite high compared with the parameters for the claw and leg diseases.

Table 3. Covariance parameter estimates of the random effect cow (σc2), with standard errors

in parentheses and estimates of the scale parameter (Ø) for claw and leg diseases (with and

without digital dermatitis) and lameness (score ≥ 3)

Trait σc2 Ø1

Claw and leg diseases 0.4985 (0.043) 0.95

Claw and leg diseases without digital dermatitis 0.6719 (0.056) 0.96

Lameness (score ≥ 3) 0.9054 (0.096) 0.59 1Ratio of the generalized χ2 statistic and its degrees of freedom.

The probability of lameness (score ≥ 3) increased clearly with increasing lactation number

(parity; Figure 3). For the diseases, the pattern was not so clear. The probability of claw and

leg diseases decreased slightly from the first to the second lactation. After the exclusion of

digital dermatitis the likelihood for the occurrence of claw and leg diseases declined for the

first 2 parities, whereas the probability for older cows increased slightly. For cows with at

least 3 lactations, lameness and claw and leg diseases were more common.

13

Figure 3. Probability of lameness (score ≥ 3) and claw and leg diseases with and without

digital dermatitis depending on lactation number (F-test; P < 0.0001; LSM)

In the course of lactation, the probability of lameness increased until 150 DIM and decreased

shortly after for both primiparous cows and cows with at least 3 lactations (Figure 4). In

contrast, in second-parity cows’ risk of lameness seemed to be highest around 250 DIM.

Cows in the third or higher parities were more susceptible for lameness than younger cows

(Figure 4).

Figure 4. Probability of lameness (locomotion score ≥ 3) depending on lactation number

within lactation stage (F-test; P < 0.0001; LSM)

In contrast to lameness, the probability for claw and leg diseases was highest in early lactation

(Figure 5). For first-parity cows, the trajectory declined gradually with increasing stage of

lactation. The probability for cows with at least 3 lactations also indicated a declining trend

0.11 0.15

0.28

0.05 0.04 0.07

0.03 0.03

0.08

0.00

0.10

0.20

0.30

0.40

1 2 ≥ 3

Pro

bab

ilit

y (

%)

Lactation Number

lameness (score ≥ 3) claw and leg diseases

claw and leg diseases without digital dermatitis

14

but with an increasing probability around 250 DIM. For second-parity cows, the probability of

the occurrence of claw and leg diseases did not show a clear pattern. But the trajectory

indicated rather an increasing than a decreasing trend. At the end of lactation, all observed

parities were on the same level. Older cows seemed to be more vulnerable to claw and leg

diseases.

Figure 5. Probability of claw and leg diseases (with and without digital dermatitis) depending

on lactation number within lactation stage (F-test; P < 0.0001; LSM)

In the case of claw and leg diseases without digital dermatitis, the trajectory for second-parity

and older cows was similar to that with digital dermatitis (Figure 5). Just the height changed;

for cows in the second lactation, the means were marginally lower and for the older cows

marginally higher. The figure reflects the fact that the effect of the exclusion of the claw

disease digital dermatitis was highest for primiparous cows. The trajectory for this group of

cows did not show a strong peak at the beginning of lactation and the course remained on a

constant level during lactation.

Heritability estimates for lameness (h2 = 0.08) were higher than for claw and leg diseases (h

2

= 0.02; Table 4). The estimates for the heritabilities based on the linear model did not change

15

after the exclusion of the claw disease digital dermatitis. In the threshold model analysis,

compared with the estimates of the linear model, the heritabilities were about twice as large

for lameness and even higher for claw and leg diseases. After omitting digital dermatitis, the

threshold heritability for lameness increased from 0.15 to 0.22 and decreased from 0.24 to

0.22 for the diseases.

The genetic correlations between lameness and claw and leg diseases derived from the linear

model were higher than from the threshold model. The estimates ranged from 0.60 to 0.72

(threshold model) and from 0.94 to 0.95 (linear model).

Table 4. Additive genetic variance (σ2

a), permanent environmental variance (σ2

pe), residual

variance (σ2

e), heritability estimates (h2) for lameness (score ≥ 3) and claw and leg diseases

(with and without digital dermatitis) and genetic correlations (rg) from different models1

Traits in bivaritate model2 σ

2a σ

2pe σ

2e h

2 rg

Linear

Lameness (score ≥ 3) 0.011 0.052 0.074 0.081

0.939

Claw and leg diseases 0.001 0.007 0.055 0.019

Lameness (score ≥ 3) 0.011 0.048 0.074 0.085

0.951

Claw and leg diseases without digital dermatitis 0.001 0.005 0.041 0.021

Threshold

Lameness (score ≥ 3) 0.432 1.799 0.610 0.152

0.597

Claw and leg diseases 0.419 0.652 0.681 0.239

Lameness (score ≥ 3) 0.550 1.401 0.604 0.215

0.716

Claw and leg diseases without digital dermatitis 0.398 0.923 0.510 0.218 1Standard errors for heritabilities: 0.02 to 0.15; standard errors for genetic correlations: 0.27 to 0.31. 2For each model (linear and threshold), 2 separate bivariate analyses were conducted. First, lameness and claw

and leg diseases and second, lameness and claw and leg diseases without digital dermatitis. Lameness was the

same trait in each of both analyses but the results for lameness are different because they depend also on the

second trait, which was here analyzed simultaneously.

Discussion

Frequencies of Lameness (Score ≥ 3) and Claw and Leg Diseases

In our study, the lameness rate (ca. 15%) agrees to a reasonable extent with the result of

Frankena et al. (2009; ca. 23%). Of the 326 examined cows, 47.2% were lame (score ≥ 3) at

least once. This figure is in accordance with the prevalence in the study of Frankena et al.

(2009); those authors found that almost 37% of the observed animals were lame at least once

during their examination. In contrast, Sogstad et al. (2005b, 2012) and Manske et al. (2002)

16

reported obviously lower values, which may have resulted from different examination

environments. Further reasons for the large variability in reported lameness occurrence might

be different scoring methods and different sources of lameness data. Lower lameness

incidence could also be associated with breed, small herd sizes, and low milk yield (Sogstad

et al., 2012).

In this study, we found that 52.8 and 36.4% (without digital dermatitis) of the 335 examined

cows were affected at least once by one or more claw or leg diseases. Our findings are quite

low compared with the results from other studies. In a Dutch study, 69% of the animals from

different lactations suffered from at least one claw disease (van der Linde et al., 2010).

Although their analysis was also based on cows that could have repeated observations within

lactation as well as across lactations, the study period is clearly different, which makes the

comparison of the results difficult. A rather low rate of affected animals (40%) was reported

by Buch et al. (2011). In this Swedish study, only claw and leg diseases from the first claw

trimming after first calving were taken into account. The authors suggested that claw diseases

such as laminitis, sole hemorrhages, and sole ulcers would not occur at that time because they

are of metabolic origin (Buch et al., 2011). Besides the disagreement in the number of

recordings, their study also is distinguished by the time of claw trimming.

The decreased rate of affected cows after nonconsideration of digital dermatitis cases as well

as the high frequency of the disease indicates that digital dermatitis seems to be a herd

problem. Several animals were only affected by digital dermatitis (Table 2), which was the

second-most-frequent disease (22%) after sole ulcer with a frequency of 24%. The frequency

of leg diseases was small (almost 7%). Compared with the frequencies of claw and leg

diseases published by other authors, the disease pattern presented in our study was rather

specific. As shown in several studies, sole hemorrhage was the most prominent claw disease,

whereas laminitis or sole hemorrhages were not mentioned in our investigation (Sogstad et al.,

2005a,b; van der Waaji, 2005; von der Linde et al., 2010). Individual cases of mild forms of

hemorrhages in the horn of the sole were measured but these cases were attached to the

disease sole ulcer. As Bergsten (2003) indicated, minor hemorrhages in the horn of the sole

reflect the early phase of laminitis and most commonly occur in regions that are the rear part

of the claw bone and are recognized as the typical sole ulcer site.

The comparison of the frequencies of claw and leg diseases is also difficult because

categorizing and diagnosing of claw and leg lesions, methods of data recording, observation

period, and data sources often differ among the published studies, which might cause

differences in frequencies (Sogstad et al., 2005b).

17

The trajectory of the frequencies of claw and leg diseases showed a peak at the beginning of

the lactation, which might be a result of the routine hoof trimming at that time (Figure 2). The

lower constant level in the frequency of lameness could result from the fact that only a small

number of early lactation cows could be examined at that time. To ensure particular

supervision, early lactation cows were housed in a separated barn area. Due to the

constructional circumstances of this barn, the lameness status of the cows could not classified.

Probability of Lameness (Score ≥ 3) and Claw and Leg Diseases (Without Digital

Dermatitis) Depending on Lactation Number

The incidence of lameness increased with increasing parity (Figure 3) as also shown by

Rowlands et al. (1985), Groehn et al. (1992), and Boettcher et al. (1998). In a prospective

cohort study by Groehn et al. (1992) more than a 30% risk of becoming lame exists for 1-yr

increase in age. Alban (1995) found the highest risk for lameness in Danish dairy heifers and

fourth-parity cows. The high hazard in first-parity cows might originate from the rapid

environmental and metabolic shifts that are associated with first calving (Alban, 1995).

The probability of claw and leg diseases did not show a clear increasing trend but the highest

probability was found in cows with at least 3 parities. After omission of digital dermatitis, the

probability for the first 2 parity classes decreased and increased slightly for cows in higher

parities. The occurrence of claw and leg diseases related to the parity is strongly dependent on

the specific disease. Rowlands et al. (1985) have shown that the incidence of white line

disease and sole ulcer and, to a lesser degree, underrun heel increased with age. The incidence

for foul in the foot and leg lesions only showed marginal change with parity. Koenig et al.

(2005) reported significant influences of parity on wall disorders and sole ulcers, but no effect

was observed on digital dermatitis and interdigital hyperplasia. Furthermore, the authors

indicated that the susceptibility to digital dermatitis was slightly higher for primiparous cows

than for cows in higher parities (13.9 vs. 12.5%), which is comparable with our observations.

In addition, several authors have shown that the probability for occurrence of digital

dermatitis generally decreased with increasing parity. A cause for the susceptibility of first-

parity cows to digital dermatitis could be the changes in nutrition, metabolism, and

environment before and after calving. The decreased risk of digital dermatitis with increasing

age might be result from the rising immunity of older cows (Somers et al., 2005; Holzhauer et

al., 2006).

A reason for the higher risk of claw and leg diseases and lameness in older cows could be the

fact that cows in higher parities have been subject to greater effects of age, wear, and stress

18

than younger cows (Boettcher et al., 1998). Boelling and Pollot (1998a) noted that the

impairment of mobility in older cows resulted from an alteration in body conformation (i.e.,

bulgy udder and sickled rear leg). The authors found that a high locomotion score was

associated phenotypically with a big udder and sickled legs. Mature cows with bulgy udder

develop a splay-legged gait and this has been attributed to the fact that the rear leg had to

elude the udder by describing a circle, which results in uneven wear of the claws and could

cause lameness. Sogstad et al. (2005a) indicated that the increasing risk of lameness with age

might be to the effect of aging and cumulative damages of claw tissue. The quality of cows’

claws declines progressively with age, based on the impairment in shape and (or) softening of

the horn and internal structures (Rowlands et al., 1985).

Probability of Lameness (Score ≥ 3) and Claw and Leg Diseases (Without Digital

Dermatitis) Depending on Lactation Stage Within Lactation Number

Lameness probability differed between lactation stages within and between the 3 parity

groups (Figure 4). Our findings regarding the probability of lameness (score ≥ 3) are not

directly comparable with the results in literature because of the separate definition of parity

classes as well as the definition of the lactation stage classes within parity. In the literature,

lameness was most common during the earliest stage of lactation or within the first month of

lactation (Rowlands et al., 1985; Boettcher et al., 1998; Van Dorp et al., 2004). These findings

indicate that the environmental, feeding, and metabolic change before and after calving might

result in more lameness cases in the early stage of lactation. High-energy nutrition with a

relative low roughage-to-concentrate ratio provokes metabolic diseases, such as ruminal

acidosis, which often implicates laminitis and lameness (Boettcher et al., 1998). In contrast,

Espejo et al. (2006) could not find any relationship between lameness and lactation stage.

The probability of occurrence of claw and leg diseases is highest at early lactation, which

might be a result of the routine claw trimming at that time. Several authors have shown that

sole ulcer, which is the most frequent disease in our study, mostly occurs in the first part of

lactation. This could be a second reason for the strong peak. Sole ulcer as a feed-related claw

disease can be caused by the rapid nutrition change from low energy prepartum to high energy

postpartum (Huang et al., 1995; Holzhauer et al., 2006; Buch et al., 2011). The peaks at the

end of the lactation might also be caused by the routine claw trimming. The exclusion of

digital dermatitis affected the trajectory of the primiparous cows most. The strong peak at the

beginning of lactation disappeared and the course remained on a constant low level during

lactation. These results emphasize the assumption that first-parity cows are more susceptible

19

to digital dermatitis (Somers et al., 2003, 2005; Holzhauer et al., 2006). The strong peak at the

beginning of lactation in first-parity cows might also originate from purchased heifers as well

as in-house heifers that are already affected with the disease.

The exclusion of digital dermatitis also affected the trajectory of claw and leg diseases in

cows with at least 3 parities. Omission of the disease resulted in a higher probability for this

group of cows because of the altered ratio of diseases in all 3 parity classes. Older cows are

more susceptible for claw diseases such as sole ulcer and white line disease but show less

frequently signs of digital dermatitis, whereas cows in first parity are more vulnerable to

digital dermatitis (Somers et al., 2003, 2005; Holzhauer et al., 2006). Therefore, for first-

parity cows, the probability of claw and leg diseases decreases and increases for older cows

after omission of digital dermatitis.

Genetic Parameters

Heritability estimates for lameness are in accordance with the results of Boettcher et al.

(1998). Using a linear as well as a threshold model, they reported estimates of 0.10 and 0.22,

respectively, for clinical lameness. Boelling et al. (2007) estimated a similar value (0.10)

using a linear animal model after converting the locomotion scores from the type trait scale

(notes 1-9) into 2 categories [lame (class 1) vs. not lame (classes 2-9)]. A former study

(Boelling and Pollott, 1998b) found a distinctly lower value of 0.01 for lameness as binary

trait [not lame (class 1-4) vs. lame (class 5-9)] after transforming heritability from the

binomial scale to the continuous underlying scale. Besides the estimates for lameness as a

binary trait, heritabilities for locomotion on the original type classification scale [1 (obvious

lameness) to 9 (walks with even gait)] ranged between 0.03 and 0.22 (van der Waaij et al.,

2005; Onyiro and Brotherstone, 2008; Laursen et al., 2009; van der Linde et al., 2010; Zink et

al., 2011). The trait locomotion as additional conformation trait in the type classification of

Holstein-Friesian heifers and lameness as a binary trait examined in our study cannot be

compared directly with one another. The 2 traits were recorded with different locomotion

scoring systems (1-9 vs. 1-5/0-1) and the objectives were clearly different. Our aim was to

examine lameness in primiparous as well as multiparous Holstein-Friesian dairy cows in one

herd over a long period of time. The linear trait locomotion is used to describe the stride of

Holstein-Friesian cows in first parity at one date and should only be scored if the cow does

not show any signs of lameness (ICAR, 2012).

Heritabilities for claw and leg diseases were in agreement with the estimates of different claw

diseases from the threshold model reported by Swalve et al. (2008). van der Waaij et al.

20

(2005) have shown that the heritability estimates using the threshold model and linear model

were very similar and ranged from 0.01 (sole ulcer and clinical laminitis) to 0.10 (digital

dermatitis and interdigital hyperplasia). Laursen et al. (2009) analyzed claw health data

recorded by veterinarians and found a heritability of 0.06 for claw health, which was

transformed to the underlying continuous scale with the formula of Dempster and Lerner

(1950). The low estimate might stem from the fact that the diseases were scored by

veterinarians and not by claw trimmers as in the other studies. Therefore, it could be that only

the most severe cases of claw and leg diseases were registered.

Our moderate heritability for lameness estimated with a threshold model as well as the results

of Boettcher et al. (1998) indicated that direct selection for reduced lameness could be

moderately successful. The results of claw and leg diseases also show that substantial genetic

variation does exist.

Genetic correlations between lameness and claw and leg diseases using threshold models

were positive and quite large [0.60 vs. 0.72 (without digital dermatitis)], but it should be noted

that the estimates were associated with relatively high standard errors. Estimates from linear

models were rather higher. According to Gianola (1982) and Vinson et al. (1976), estimates

for additive genetic correlations should not be affected by violation of assumption of

normality when using linear models for analysis of binary data. However, Stock et al. (2007)

showed considerable variation of bias. The genetic correlation between 2 binary traits were

overestimated by 13 to 38% as well as biased downward. To the best of our knowledge,

genetic correlations between lameness as a binary trait and claw and leg diseases have not

been estimated so far. A few authors have estimated genetic correlations between claw and

leg lesions and the conformation trait locomotion. For recorded health data by veterinarian the

genetic correlation was 0.46 (Boelling et al., 2008; Laursen et al., 2009). Boelling et al.

(2008) found a genetic correlation of 0.79 between claw diseases recorded by claw trimmers

and locomotion. All correlations were estimated using linear models.

Based on the genetic correlations, lameness seems to be a good indicator of susceptibility to

claw and leg diseases. The increase in the genetic correlation after exclusion of digital

dermatitis demonstrates that this disease affects the mobility of the animals less strongly than

other claw and leg diseases. With regard to the underlying specific pattern of claw diseases in

the trait claw and leg diseases in our study, it should be noted that the relationship might

change with a different disease structure. This was already demonstrated by the omission of

digital dermatitis. Due to the limited data set, especially for the lameness cases, the genetic

parameters were associated with large standard errors. However, the results indicate that

21

genetic selection for improved health of feet and legs will be feasible. Further research is still

needed to confirm the results.

Conclusions

The estimated genetic parameters presented in this study suggest that lameness might be a

useful indicator for claw and leg health. As the parameters are associated with large standard

errors, the study should be repeated with a larger data set to confirm the values. Furthermore,

the examination of the relationship between the trait lameness, recorded by locomotion score,

and the type classification trait locomotion should be analyzed to exclude the possibility that

they are the same trait and avoid double recording.

Acknowledgements

We gratefully acknowledge the Federal Office for Agriculture and Food (Bonn-Mehlem,

Germany), and the Federal Ministry of Food, Agriculture and Consumer Protection (Bonn,

Germany) for financial support of the project “Innovative methods of trait recording in dairy

cattle as a basis of the modern breeding program of the Nord-Ost-Genetic”. Furthermore,

gratitude is expressed to our cooperation partners Nord-Ost-Genetic GmbH & Co. KG

(Verden an der Aller, Germany); Martin Luther University Halle-Wittenberg (Germany);

Landesforschungsanstalt für Landwirtschaft und Fischerei MV (Mecklenburg-Vorpommern,

Germany); Sächsisches Landesamt für Umwelt, Landwirtschaft und Geologie (Dresden,

Germany); and Leibniz Institute for Farm Animal Biology (Dummerstorf, Germany).

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25

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26

27

Chapter 2

Genetic correlations between claw and leg diseases, lameness, foot

and leg conformation traits, stature and body weight in German

Holstein-Friesian heifers

A. Weber1, E. Stamer

2, W. Junge

1, G. Thaller

1

1Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, D-24098 Kiel,

Germany

2TiDa Tier und Daten GmbH, D-24259 Westensee, Germany

28

Abstract

Diseases of claws and legs are a serious welfare and economic problem in dairy production.

Both environmental and genetic factors influence these disorders. Indirect selection on claw

and leg health potentially might be feasible with foot and leg related conformation traits or

lameness as indicator traits. The body associated type trait stature and the body weight of the

dairy cows could be genetically correlated with diseases of the claws and legs. Therefore, the

heritability of claw and leg diseases, lameness, foot and leg related conformation traits, stature

and body weight as well as the genetic relationship among the traits were estimated using the

average information restricted maximum likelihood procedure as implemented in the DMU

software package. Heritabilities were estimated univariately and genetic correlations between

all traits were obtained from bivariate analyses. Heritability estimates from threshold models

were 0.18 for claw and leg diseases and 0.28 for lameness. The heritability of the

conformation traits associated with foot and leg were estimated with linear models and ranged

from 0.01 (locomotion) to 0.21 (rear leg side view). Body weight had a heritability of 0.39

and the body related trait stature of 0.40. Genetic correlations among all traits studied were

associated in some instances with large standard errors. However, the results suggest that a

selection on claw and leg diseases is indirectly possible using foot and leg conformation traits

and the trait lameness. The positive genetic correlations among the traits body weight and

stature with claw and leg diseases indicate that taller and heavier cows are more prone to claw

and leg diseases.

Key words: claw and leg diseases, lameness, conformation traits, body weight

Introduction

Claw and leg diseases are a persistent, nondecreasing problem in high-producing dairy herds.

Lameness due to diseases of the claws and legs is a painful condition for the cow and thus one

of the most serious animal welfare issues. In addition, lameness causes economic losses for

the dairy producers through decreased milk production, impaired reproductive performance

and involuntary culling (Kossaibati and Esslemont, 1997). In German herds, claw and leg

diseases are the most frequent reason for early culling along with mastitis and infertility

problems. The percentage of cullings because of feet and leg diseases among all cullings has

even increased in the last thirty years from 4.40 (1980) to 10.40% (2009) (ADR, 1980-2009).

Many of the factors that are responsible for the variability in claw and leg diseases are of

environmental origin such as diet, housing, and management (Boettcher and Dekkers, 1997).

The body weight and the stature of the dairy cow might also have an influence on the

29

development of claw and leg diseases and lameness. Boettcher et al. (1998) showed that cows

that were relatively heavy in relation to their frame size were more susceptible to clinical

lameness. Wells et al. (1993) reported that lame cows were significantly heavier. A

relationship between large body size and feet and leg problems in cows was found by Hansen

et al. (1999). To the best of our knowledge, the genetic relationships between body weight

measured automatically on a daily basis or stature as a body related conformation trait with

claw and leg diseases or lameness have not been evaluated so far.

Besides the environmental impact, several studies have shown that genetic factors also play a

role in predisposition of cows to claw and leg diseases (Koenig et al., 2005; Swalve et al.,

2008; van der Linde et al., 2010). In the Nordic countries (Finland, Denmark and Sweden)

and the Netherlands a routine genetic evaluation of claw health has been established (Laursen

et al., 2009; van der Linde et al., 2010). However, due to the limited amount of disease data

recorded routinely from claw trimmers in most other countries, selection for decreased claw

and leg diseases (claw health) is carried out indirectly using foot and leg related conformation

traits. Several studies reported considerable genetic correlations among foot and leg

conformation traits and claw health (van der Waaij et al., 2005; Laursen et al., 2009; van der

Linde et al., 2010), whereas other studies (Swalve et al., 2008; Uggla et al., 2008) showed that

the genetic correlations were not that high. A new indicator trait for claw and leg health might

be lameness. The lameness status of dairy cows can be controlled and assessed with a well-

established locomotion scoring system. Thus, the evaluation of this trait might be easier and

less expensive than the direct examination of specific claw diseases (Boettcher et al., 1998).

Additionally, the relationship between lameness and the conformation trait locomotion should

be analyzed in order to describe the possible accordance between the traits.

Therefore, the objective of the study was to evaluate genetic parameters of claw and leg

diseases, lameness, foot and leg related conformation traits, stature, and body weight in

primiparous Holstein-Friesian heifers.

Materials and Methods

Data

Data were collected from Holstein-Friesian primiparous dairy cows during the period of June

2001 to June 2012 at the dairy research farm Karkendamm of the Institute of Animal Breeding

and Husbandry, Christian-Albrechts-University Kiel (Germany). On the research farm a bull

dam performance test ran from April 2001 to March 2012. All bull dam candidates were

tested under commercial conditions until 180 DIM. Nonqualified cows left the herd after the

30

test period, whereas the qualified animals were tested until the end of the lactation. Besides

these selected primiparous cows, data were also obtained from the in-house heifers throughout

the lactation.

All claw and leg diagnoses and treatments from 1,850 primiparous cows were recorded by

veterinarian or farm staff. The claws of the animals were trimmed routinely until 100 days

postpartum and before dry period by one claw trimmer (farm staff). Beside this routine, cows

recognized as lame by locomotion scoring (see below) or farm staff were also examined. In

the beginning of the data recording period only cases of lameness were included but not the

causative disease. Since 2006, 8 different claw and leg diseases were registered. The main

disease is sole ulcer with a frequency of 31%, followed by digital dermatitis with about 16%

(Table 1). Leg lesions were less frequently observed with 8%. For definition of the trait claw

and leg diseases each day with at least one treatment and the following 8 days were coded as

1. The 8-day period was chosen because claw and leg diseases seemed to affect the cows for

at least one week (Buttchereit et al., 2012). All other days were classified as healthy (0).

Table 1. Frequencies of the recorded claw and leg diseases

Diagnosis Absolute frequency Relative frequency

Sole ulcer 771 31.28

Lame (unspecific disease) 506 20.53

Digital dermatitis 403 16.35

Interdigital necrobacillosis 286 11.60

Interdigital hyperplasia 214 8.68

Leg lesions (e.g., hock swelling) 205 8.32

White line disease 38 1.54

Double Sole 26 1.05

Undefined injuries of the claw 16 0.65

2,465 100.00

Lameness (locomotion score) data recorded accordingly to the 5-point scoring system of

Sprecher et al. (1997) were available from September 2010 to June 2012. 300 first-lactating

cows were examined weekly for lameness by one classifier. Locomotion was assessed while

the cows were standing or walking on the concrete slatted passageways at the feeding bunk or

between the cubicles on one of the two concrete slatted floor systems. Cows in the separated

barn area were not scored. In nearly 10% of the locomotion scores (3 to 5) cows were

classified as lame (Figure 1). For further analysis lameness was also defined as a binary trait.

31

Clinically lame cows were coded as 1 (score ≥ 3) and cows with normal locomotion (scores 1

and 2) were set to 0.

Figure 1. Frequencies of locomotion scores

Due to the small number of cows in the first days postpartum and above 350 lactation days,

DIM were restricted to the range of 10 to 350 days. In the final dataset, 36.4% of the 1,802

examined cows were treated at least once due to one or more claw and leg diseases and nearly

the same frequency of the 293 rated cows were lame at least at one time in the observation

period (Table 2). Of all cow days, 3.9 and 9.8% were defined as disease or lameness days,

respectively.

Table 2. Frequencies of claw and leg diseases and lameness (score ≥ 3)

Trait

Cow days

Cows

Lactation

period(d) Total Affected (%)

Total Affected (%)

Claw and leg diseases 10 to 350 396,107 3.9

1,802 36.4

Lameness (score ≥ 3) 10 to 350 6,068 9.8

293 36.5

Conformation data were recorded from July 2001 to June 2012 by 2 trained classifiers from

the local herdbook association. With respect to feet and leg traits, the 8 individual type traits

involved in the analysis were rear leg side view (RLs), rear leg rear view (RLr), foot angle

54.53

35.12

8.58

1.73 0.05 0

10

20

30

40

50

60

1 2 3 4 5

Fre

quen

cy (

%)

Locomotion score

32

(FA), foot height (FH), locomotion (LOC), hock quality (HQ) and the overall index for feet

and legs (FUN). Additionally, the body related trait stature (STA) was considered in the

evaluation. This trait was measured in centimeters from top of the spine in between hips to

ground. Locomotion has been recorded as linear conformation trait since 2006. About 60% of

all 1,275 scored dairy cows have a value for this characteristic. In 2006, the foot height, which

represents the height of the rear hoofs has been replaced by foot angle, the angle at the front

of the rear hoofs. Of the scored cows, 95 and 61% have a value for foot height and foot angle,

respectively. Hock quality is an additional conformation trait in the official German

classification system. The linear traits were scored on a scale of 1 to 9, which illustrates the

expected biological extremes, whereas the overall index for feet and legs represents a

aggregation of the traits rated on a scale from 65 to 88 (WHFF, 2008; DHV, 2012). As stated

in the official classification system, most cows were judged in the first half of lactation. In the

present study, the mean stage of lactation was 104 DIM with a range of 11 to 251 days. Table

3 summarizes the definition of the recorded conformation traits, whereas the descriptive

statistics of the traits are given in Table 4.

Table 3. Description of the German scoring scale for conformation traits

Trait1 Description

2

STA 1 = short (130 cm), …, 9 = tall (154 cm)

RLs 1 = straight, …, 9 = sickle

RLr 1 = extreme toe-out, …, 9 = parallel feet

HQ 1 = with cartilage, …, 9 = dry

FH 1 = very low, …, 9 = very high

FA 1 = very low angle, …, 9 = very steep

LOC 1 = severe abduction – short stride, …, 9 = no abduction – long stride

FUN 65 = poor, …, 88 = very good 1STA = stature; RLs = rear leg side view; RLr = rear leg rear view; HQ = hock quality; FH = foot height; FA =

foot angle; LOC = locomotion; FUN = overall index for feet and legs. 2according to WHFF (2008) and DHV (2012).

33

Table 4. Descriptive statistics of the conformation traits and body weight

Trait1 Observation period N Mean SD Minimum Maximum

STA 30.07.01 – 28.06.12 1,275 148.84 2.55 140 160

RLs 30.07.01 – 28.06.12 1,275 5.10 0.87 1 8

RLr 30.07.01 – 28.06.12 1,275 5.19 1.21 2 9

HQ 30.07.01 – 28.06.12 1,275 5.05 1.15 1 9

FH until 17.06.11 1,209 5.25 1.03 1 9

FA from 31.03.06 780 5.21 1.21 2 9

LOC from 31.03.06 779 4.77 1.17 1 8

FUN 30.07.01 – 28.06.12 1,275 82.82 2.82 65 87

BW 01.06.01 – 30.06.12 244,312 609.67 59.40 426 795 1STA = stature; RLs = rear leg side view; RLr = rear leg rear view; HQ = hock quality; FH = foot height; FA =

foot angle; LOC = locomotion; FUN = overall index for feet and legs; BW = body weight.

The daily body weight of 1,815 first lactation dairy cows was available from June 2001 to

June 2012. After each milking the cows were weighed automatically on the weighing platform

of a continuous scale. Morning and evening body weights (BW) were averaged to get a daily

value. Until March 2006, the continuous scale was installed in the back driving aisle of the

milking robot and since March 2006 the cows were weighed after leaving the rotary milking

parlor. Records of BW were adjusted for outliers by rejecting observations with a residual

beyond ±3 SD and observation days with exceptionally high or low means of daily body

weight (e.g., frost periods). After the adjustment and the restriction to 341 (10 to 350) DIM,

the final dataset consists of 244,312 daily body weights from 1,528 primiparous cows. Mean

value for BW was nearly 610 kg with a standard deviation of ±59.4 kg (Table 4).

Statistical Analysis

Because of the binary nature of the diseases and the lameness data, a threshold model was

used for the analysis of the fixed effects as well as for the estimation of the genetic

parameters. The model fitting was done with the GENMOD procedure using the probit link

function of the SAS package (SAS Institute, 2008). Evaluation of goodness of fit of different

models was carried out with the corrected Akaike information criterion (AICC; Burnham and

Anderson, 1998) and the Bayesian information criterion (BIC; Schwarz, 1978). Year-season

classes and test-days with all responses equal to ‘0’ were added to neighboring classes in

order to avoid the extreme category problem (Hoeschele and Tier, 1995). The testing of the

fixed effects was done using the SAS procedure GLIMMIX with the residual subject-specific

pseudo-likelihood (RSPL) method (SAS Institute, 2008).

34

Model fitting as well as testing of the fixed environmental effects of the linear conformation

traits and the body weight data were carried out with the SAS procedure MIXED (SAS

Institute, 2008).

Genetic parameters for the binary and linear traits were estimated using the average

information (AI) restricted maximum likelihood procedure as implemented in the DMU

software package (version 6, release 5.0; Madsen and Jensen, 2010). For these estimations,

the models included the random permanent environmental effect of the cow and the additive

genetic effect of the animal. In the case of the conformation traits the permanent

environmental effect of the cow was omitted. Statistical models:

claw and leg diseases: E [πijklm] = Φ (YMi + AFCj + LSk + pl + am),

lameness (score ≥ 3): E [πijklm] = Φ (TDi + AFCj + LSk + pl + am),

conformation traits: Yijkmn

= μ + TDi + AFCj + LSk + am

+ eijkmn,

body weight: Yijklmn

= μ + TDi + AFCj + LWk

+ pl

+ am

+ eijklmn,

where E [πijklm]= expected probability for occurrence of claw and leg diseases or lameness

(score ≥ 3); Yijkmn = observation of each conformation trait; Yijklmn

= observation of body

weight; Φ = cumulative probability of standard normal distribution; μ = overall mean; YMi =

fixed effect of ith year-month (i = 1 to 130); TDi = fixed effect of ith test day (i = 1 to 74 for

lameness (score ≥ 3); i = 1 to 109 for STA, RLs, RLr, HQ, FUN; i = 1 to 106 for FH; i = 1 to

61 for FA, LOC; i = 1 to 2,875 for body weight); AFCj = fixed effect of the jth age at first

calving (21 to 25, 26, 27, 28, and 29 to 41 month for claw and leg diseases, lameness (score ≥

3), and body weight; 22 to 25, 26, 27, 28, and 29 to 41 month for each conformation trait);

LSk = fixed effect of the kth lactation stage (10-50, 51-100, 101-150, 151-200, 201-250, 251-

300, 301-350 for claw and leg diseases, and lameness (score ≥ 3); 11-80, 81-90, 91-100, 101-

110, 111-120, 121-251 for each conformation trait); LWk = fixed effect of the kth lactation

week (k = 2 to 50); pl =

random permanent environmental effect of the lth cow (l = 1 to 1,802

for claw and leg diseases; l = 1 to 293 for lameness; l = 1,528 for body weight); am = random

additive genetic effect of the mth animal (m = 1 to 5,113 for claw and leg diseases, lameness

(score ≥ 3), each conformation trait, and body weight); eijkmn = random residual effect of

conformation trait model; eijklmn = random residual effect of body weight model.

Heritabilities were estimated univariately and genetic correlations among all traits were

obtained from bivariate analyses. Pedigree information contained sires and dams three

generations back, so in total, 5,113 animals were in the pedigree file.

35

Results

The mean daily body weight and the prevalence of claw and leg diseases and lameness (score

≥ 3) during 10 to 350 DIM are shown in Figure 2. Mean body weight is around 590 kg at

lactation week 2, decreases to a minimum of 570 kg by week 5 and rise to the initial weight of

590 kg at week 13. At the end of the lactation (week 50) the body weight has increased to 680

kg. The trajectory of the claw and leg diseases shows three outstanding peaks. The strongest

peak is found around lactation week 16. The prevalence of lameness is high at the beginning

(week 2) and at the end of the lactation (week 47). Until lactation week 29 the prevalence is

on a clearly higher level than in the following weeks up to the end of the lactation.

Figure 2. Means of body weight and prevalence of claw and leg diseases and lameness

(score ≥ 3) during 10 to 350 DIM

Estimated heritabilities using threshold models are 0.18 for claw and leg diseases and 0.28 for

lameness (score ≥ 3) (Table 5). The standard error for the heritability estimate of lameness is

much higher than that of the other analysed traits. Heritability estimates for the foot and leg

conformation traits range from 0.01 (locomotion) to 0.21 (rear leg side view). Stature has the

highest heritability among all linear conformation traits (h2 = 0.40). A moderate heritability is

estimated for body weight (h2 = 0.39).

560

600

640

680

720

0

4

8

12

16

2 6 10 14 18 22 26 30 34 38 42 46 50

Mea

ns

of

body w

eight

(kg)

Pre

vale

nce

of

claw

and l

eg d

isea

ses

and l

am

enes

s (s

core

≥ 3

) (%

)

Lactation week

claw and leg diseases lameness (score ≥ 3) body weight

36

Table 5. Additive genetic variance (σ2

a), permanent environmental variance (σ2

pe), residual

variance (σ2

e), heritability estimates (h2) for claw and leg diseases, lameness (score ≥ 3),

stature, foot and leg conformation traits, and body weight from univariate models (standard

errors in parentheses)

Trait in univariate model1 σ

2a σ

2pe σ

2e h

2

Threshold

CLD 0.34 1.13 0.41 0.18 (0.003)

LAME 0.60 1.12 0.43 0.28 (0.132)

Linear

STA 2.59

3.88 0.40 (0.086)

RLr 0.16

0.59 0.21 (0.074)

RLs 0.12

1.25 0.09 (0.056)

HQ 0.25

1.02 0.20 (0.071)

FH 0.18

0.87 0.17 (0.067)

FA 0.21

1.22 0.14 (0.096)

LOC 0.13

1.17 0.01 (0.083)

FUN 1.26

5.65 0.18 (0.066)

BW 980.02 1225.82 288.65 0.39 (0.064) 1CLD = claw and leg diseases; LAME = lameness (score ≥ 3); STA = stature; RLs = rear leg side view; RLr =

rear leg rear view; HQ = hock quality; FH = foot height; FA = foot angle; LOC = locomotion;

FUN = overall index for feet and legs; BW = body weight.

Genetic correlations and standard errors among claw and leg diseases, lameness (score ≥ 3),

stature, foot and leg conformation traits and body weight from bivariate models are given in

Table 6. Standard errors for genetic correlations are large and range from 0.10 to 0.60. Some

estimates are not significantly different from zero. With the exception of hock quality (-0.21 ±

0.15), the genetic relationship between claw and leg diseases and foot and leg conformation

traits is moderate to high and ranges from 0.59 ± 0.13 (rear legs side view) to -0.87 ± 0.11

(locomotion). There is also a moderate genetic correlation among claw and leg diseases and

lameness (score ≥ 3) (0.41 ± 0.49). The trait lameness is highly negatively correlated with rear

leg rear view (-0.82 ± 0.45) and the overall index for feet and legs (-0.85 ± 0.21). The

relationship between the foot and leg conformation traits ranges from -0.07 ± 0.40 (rear leg

side view with locomotion) to -0.97 ± 0.11 (rear leg side view with foot height). As expected,

the relationship among body weight and stature is positive and high (0.72 ± 0.05). The genetic

correlations between body weight and claw and leg diseases (0.11 ± 0.17) as well as among

stature and claw and leg diseases (0.06 ± 0.11) are not significantly different from 0. No

model convergence is obtained for the genetic relationship between lameness (score ≥ 3) and

locomotion as well as among foot angle and foot height.

37

Table 6. Genetic correlations (rg) among claw and leg diseases, lameness (score ≥ 3), stature,

foot and leg conformation traits and body weight from bivariate models (standard errors in

parentheses)

Trait1

Trait1 LAME STA RLs RLr HQ FH FA LOC FUN BW

CLD 0.41

(0.49)

0.06

(0.11)

0.59

(0.13)

-0.77

(0.23)

-0.21

(0.15)

-0.78

(0.12)

-0.77

(0.17)

-0.87

(0.11)

-0.86

(0.10)

0.11

(0.17)

LAME

0.47

(0.24)

0.05

(0.27)

-0.82

(0.45)

-0.24

(0.29)

-0.23

(0.32)

-0.36

(0.32) ...2

-0.85

(0.21)

0.27

(0.40)

STA

-0.16

(0.20)

-0.38

(0.30)

-0.25

(0.20)

0.13

(0.22)

0.24

(0.28)

0.01

(0.34)

-0.12

(0.21)

0.72

(0.05)

RLs

-0.58

(0.30)

0.14

(0.25)

-0.97

(0.11)

-0.95

(0.18)

-0.07

(0.40)

-0.66

(0.21)

-0.37

(0.10)

RLr

-0.14

(0.37)

0.70

(0.33)

0.85

(0.41)

0.48

(0.42)

0.58

(0.24)

0.37

(0.15)

HQ

-0.46

(0.27)

0.13

(0.36)

0.52

(0.32)

0.52

(0.20)

-0.75

(0.10)

FH

...2 0.43

(0.36)

0.60

(0.20)

0.44

(0.13)

FA

-0.47

(0.60)

0.56

(0.29)

0.53

(0.15)

LOC

0.44

(0.27)

0.46

(0.16)

FUN

0.27

(0.11) 1CLD = claw and leg diseases; LAME = lameness (score ≥ 3); STA = stature; RLs = rear leg side view; RLr =

rear leg rear view; HQ = hock quality; FH = foot height; FA = foot angle; LOC = locomotion; FUN = overall

index for feet and legs; BW = body weight. 2did not converge.

Discussion

Laursen et al. (2009) have shown that claw and leg diseases (claw and leg health) are different

traits with a low genetic correlation of 0.35. Therefore it might be expedient to consider the

traits separately in the genetic evaluation. Nevertheless, due to the low frequencies of leg

diseases, claw and leg diseases were here combined into one trait. The disease pattern (Table

1) is rather specific in comparison to the frequencies showed in other studies. Sole

haemorrhages or laminitis were counted among the most frequently diseases in several studies

(Sogstad et al., 2005; van der Waaij et al., 2005; van der Linde et al., 2010), whereas these

claw diseases are not recorded in our investigation. The claw trimmer measured single cases

of mild forms of haemorrhages in the horn of the sole but these cases were assigned to the

claw disease sole ulcer. The early phase of laminitis is characterized by minor haemorrhages

38

in the horn of the sole and most commonly appear in regions, which are the rear part of the

claw bone and are recognized as the typical sole ulcer site (Bergsten, 2003).

Totally, 36.4% of the 1,802 primiparous cows had at least one occurrence of claw or leg

diseases. Our findings are lower than the prevalence of 69% reported by van der Linde et al.

(2010). A possible explanation for this distinct difference can be the consideration of different

parities. As shown by Rowlands et al. (1985) and Sogstad et al. (2005), claw diseases are most

frequently in higher parities. In our study, only first lactating cows were considered.

Of the 293 classified cows 36.5% are lame (score ≥ 3) at least once in the examination. A

similar prevalence of nearly 37% was found by Frankena et al. (2009). However, different

scoring methods and parities do not allow a direct comparison of these prevalences.

The trajectory of body weight follows an expected pattern with expeditious decrease in early

lactation until lactation week 5. This is due to the mobilization of body reserves to provide

energy for milk production followed by gradual increase throughout the lactation due to the

building up of new reserves, the beginning enlarge of the fetus as well as the continuing

growth process of the heifers (Berry et al., 2002) (Figure 2).

The peaks of the claw and leg diseases might be a result of the routine hoof trimming at that

time. The trajectory of the lameness prevalence indicates a lower prevalence from lactation

week 29 up to the end of the lactation. This trend might result from the fact that from lactation

week 26 strongly preselected cows (qualified bull dam candidates) represent a large

proportion of the herd. These cows seem to be less susceptible to severe claw and leg diseases

and consequently less frequently develop lameness.

Estimated heritability of claw and leg diseases in this study from univariate analysis was

slightly higher than the estimates found in other studies. For the Dutch population, van der

Linde et al. (2010) reported a heritability of 0.07 for a binary combined claw trait and

estimates of different claw diseases ranged from 0.02 (wall ulcer) to 0.09 (digital dermatitis)

in primiparous cows. Laursen et al. (2009) found in first-lactating Danish Holsteins

heritabilities of 0.06, 0.01, 0.04 for claw health, leg health and, absence of all claw and leg

diseases, respectively. As the diseases were scored by veterinarians and not by claw trimmers

as in most of the other studies, the low estimate might stem from the fact, that probably only

the most severe cases of claw and leg diseases were registered. Our estimate for claw and leg

diseases as well as the results of previous studies show that substantial genetic variation does

exist.

39

Heritability of lameness (score ≥ 3) is in the range of the value found by Boettcher et al.

(1998) (0.22). However, due to the small number of lameness records in the present study, the