Effect of an exogenous fibrolytic enzyme on the performance of dairy cows consuming a

diet with a high proportion of bermudagrass silage

A.A. Pech-Cervantes, K.G. Arriola, J.E. Zuniga, I.M. Ogunade, Y. Jiang, T.F. Bernardes,

C.R. Staples and A.T. Adesogan

Department of Animal Sciences, University of Florida, Gainesville, FL

Year awarded: 2012

We previously reported that milk production by dairy cows was increased by adding

specific xylanase-rich (XYL) and xylanase-cellulase enzymes to corn silage-based diets

containing 0 or 10% bermudagrass silage. This study examined effects of adding XYL on the

intake and performance of lactating dairy cows consuming a totally mixed ration (TMR)

formulated with a greater proportion of bermudagrass silage. Endoglucanase and xylanase

activities of XYL were 3,283 and 46,281 µmol/min/mL, respectively. Forty lactating Holstein

cows (16 multiparous and 24 primiparous; 21 ± 3 days in milk; body weight 589 ± 73 kg) were

stratified by milk production and parity and assigned randomly to Control and XYL diets. The

TMR (crude protein of 16.2% of dry matter [DM], neutral detergent fiber of 36.4% of DM, and

net energy for lactation of 1.65 Mcal/kg of DM) contained 20% bermudagrass silage, 25% corn

silage, and 55% concentrate (DM basis). Immediately before the a.m. (0700 h) and p.m. (1300 h)

feedings, the enzyme was sprayed on the XYL diet at the rate of 1 mL/kg of TMR DM in a

Calan data ranger and mixed. A second data ranger was used to feed control cows. Cows were

fed experimental diets for 70 d after they were fed a common diet for a 9-d covariate period. The

experiment had a randomized complete block design. The statistical model included effects of

enzyme, parity, week, and their interactions as well as covariate milk production or DM intake.

The random effect was cow nested within treatment. Application of XYL did not (P > 0.10)

affect milk yield (35.1 vs. 36.2 kg/d), DM intake (24.0 vs 23.7 kg/d for XYL and Control), 3.5%

fat-corrected milk (FCM) (36.1 vs. 36.9 kg/d), yields of milk fat (1.29 vs. 1.31 kg/d) and protein

(1.07 vs. 1.08 kg/d), milk fat concentration (3.65 vs. 3.61%), and body weight change (0.26 vs.

0.33 kg/d) compared with control cows. However, cows fed the diet treated with XYL had

greater milk protein concentration (P = 0.01; 3.02 vs. 2.95%) and tended to have less feed

efficiency (P = 0.06; 1.52 vs. 1.57 kg of FCM/kg of DMI) compared with cows fed the control

diet. Adding XYL to a diet containing 20% bermudagrass silage and 25% corn silage did not

improve DM intake or milk production.

139

Improving the performance of dairy cattle with a xylanase-rich exogenous enzyme

preparation

J.J. Romero1, E.G. Macias

2, Z.X. Ma

1, R.M. Martins

3, B.Y. Coy

1, F. Martinez

4, D.H.

Garbuio4, C.R. Staples

1 and A.T. Adesogan

1

1Department of Animal Sciences, University of Florida, Gainesville, Florida

2 Departamento de Zootecnia, Universidad Nacional Agraria La Molina, Lima, Peru

3Departamento de Zootecnia, Universidade Federal de Viçosa, Viçosa, Brazil

4Departamento de Zootecnia, Universidade Estadual Paulista, Jaboticabal, Brazil

Year awarded: 2012

The objective was to compare effects of two Trichoderma reesei exogenous fibrolytic

enzyme preparations (EFE) on the performance of lactating dairy cattle fed a bermudagrass- and

corn silage-based totally mixed ration (TMR). The first EFE (MIX) had increased the efficiency

of feed utilization by lactating dairy cows in a previous study and the second xylanase-rich EFE

(XYL) was the best of 18 EFE candidates at improving in vitro neutral detergent fiber (NDF)

digestibility (NDFD) and rumen-like fermentation of bermudagrass haylage. Endoglucanase and

xylanase activities of MIX and XYL were 2,087 and 2,714 and 10,549 and 26,926 µmol/min per

mL, respectivley. Sixty-six lactating Holstein dairy cows in early lactation (588 ± 75 kg; 21 ± 5

days in milk) were grouped by previous milk production and parity and randomly assigned to

Control, XYL, or MIX treatments. The XYL and MIX EFE were added to the diet just before

feeding at rates of 1 and 3.4 mL/kg of TMR dry matter (DM), respectively. Cows were fed

experimental diets for 70 d after they were fed a common diet for an 11-d covariate period. The

statistical model included effects of enzyme, parity, week and their interactions as well as

covariate milk production or DM intake. The random effect was cow nested within treatment and

parity. Body weight and condition score were not affected by treatment. Compared to Control,

application of XYL increased (P < 0.05) intake (kg/d) of DM (28.6 vs. 27.4), organic matter

(26.7 vs. 25.5) and crude protein (4.7 vs. 4.5) but MIX did not. Cows fed XYL had greater milk

yield (kg/d) during wk 3 (41.2 vs. 39.8; P < 0.10), 6 (41.9 vs. 40.1; P < 0.05), and 7 (42.1 vs.

40.4; P < 0.05) as did those fed MIX during wk 6 (41.5 vs. 40.1; P < 0.10), 8 (41.8 vs. 40.0; P <

0.05), and 9 (40.9 vs. 39.5; P < 0.10). Cows fed XYL tended (P < 0.10) to produce more (kg/d)

3.5% fat-corrected milk (41.8 vs. 40.7) and fat (1.48 vs. 1.44) than those fed control.

Supplementing EFE incorporated into the TMR increased milk production by dairy cows.

140

Feeding value of regrowth forage sorghum for lactating dairy cow

John K. Bernard

Department of Dairy and Animal Science, University of Georgia, Tifton, GA

Year awarded: 2012-2013

The objective of this trial was to compare the production response of lactating Holstein

cows to corn or forage sorghum silage produced from two crops. Corn was planted in April and

harvested in July (CSS). A second corn crop was planted in July and harvested in November

(CSF). A brachytic dwarf forage sorghum was planted in April, harvested in July (FSS),

fertilized, and harvested a second time in November (FSF). All forage was ensiled in plastic

bags and stored until the production trial began. Silages contained (dry matter basis) 8.0, 8.5, 9.0,

and 9.5% crude protein (CP); 39.0, 38.3, 54.2, and 55.1% neutral detergent fiber (NDF); 3.55,

2.83. 7.72, and 7.77% acid detergent lignin; and 48.1, 47.7, 31.5, and 29.1 nonfibrous

carbohydrates (NFC), for CSS, CSF, FSS, and FSF, respectively.

Forty-eight mid-lactation Holstein cows (153.5 ± 37.2 DIM, 35.7 ± 6.2 kg/d milk, and 3.2

± 0.6% fat) were assigned randomly to one of four diets differing in forage source. Cows were

individually fed once daily behind Calan doors for 5 weeks. Diets were balanced to provide

equal concentrations of protein, fiber, and energy. No differences were observed in dry matter

intake (DMI), milk yield, or milk composition among treatments: 22.4, 21.4, 22.0, and 20.6 kg/d

DMI; 33.3, 34.0, 34.1, and 34.3 kg/d milk; 3.26, 3.07, 3.39, and 3.48% fat; and 2.75, 2.66, 2.61,

and 2.66% protein for CSS, CSF, FSS, and FSF, respectively. Concentrations of milk urea

nitrogen were lower (P = 0.001) for CSS compared with CSF, FSS, and FSF (11.2, 14.3, 16.0

and 15.8 mg/dL, respectively). No differences were observed in body weight or body condition

score change during the trial. Results of this trial suggest that silage produced from brachytic

forage sorghum, either as the first crop or regrowth, can support similar intake, milk yield and

composition as diets based on corn silage.

141

Evaluation of cool-season forages to improve nutrient management, forage productivity

and quality for southeastern dairies

Ann Blount1, Cheryl Mackowiak

1, Jose Dubeux

1, Nicolas DiLorenzo

1, Ali Babar

2, Mary

Sowerby3, Elena Toro

3, Courtney Davis

4, Bill Smith

5, Lynn Sollenberger

2, Jerry Wasdin

6,

and Ted Henderson7

1North Florida Research and Education Center, University of Florida, Quincy and Marianna, FL

2Agronomy Department, University of Florida

3Suwannee County Extension, University of Florida, Live Oak, FL

4Okeechobee County Extension, University of Florida, Okeechobee, FL

5 Syngenta, Union, KY

6Department of Animal Sciences, University of Florida, Gainesville, FL

7Shenandoah Dairy, Live Oak, FL

Year awarded: 2014 (and related projects since 2008-2015)

Our goal has been to breed for and evaluate seasonal production, forage quality and

environmental attributes of cool-season forages in the southeastern U.S. Specifically, evaluating

advanced breeding lines of cool-season grass forages targeting both confinement and grazing

dairies. This has been successful because it has allowed us to develop and screen forages directly

on-farm, across a wide-range of soil and environmental conditions under a variety of producer-

run-management systems. Replicated trials of advanced oat, triticale, rye and ryegrass breeding

lines have been tested annually on dairy farms in South Georgia, north, central and south Florida.

Disease, insect, growth habit, forage production and quality have been evaluated at each of these

locations. Annual demonstrations have been planted of side-by-side comparisons (typically 20-

30 varieties) of oat, triticale, rye and ryegrass varieties to offer producers a chance to see how

well commercial varieties perform at these locations and under “real-world” management. Field

days and site visits are common at each location. On-farm testing of advanced forage breeding

lines has led to the release and co-release of four new forage oat varieties, “Horizon 201”, “RAM

LA 99016”, crown rust resistant “Legend 567”, and a newly released, crown rust resistant oat-

“FL0720”. The tetraploid ryegrass, “Earlyploid” was also recently released by UF-IFAS and

was developed specifically for dairies in GA and FL. Three triticale varieties, “Trical 342”,

“Monarch”, and “FL01143” awnless triticale were also developed for cool-season silage crop

production. All of these new varieties have production periods that peak in time for harvest prior

to corn planting. All have excellent disease resistances since they have been developed and

tested at dairies, under spray effluent fertigation. The efforts from this research and extension

outreach aids us with proof-of-concept for dairy BMPs and in making cool-season forage

recommendations for Southeastern dairy operations.

142

The use of rumen temperature boluses to monitor dairy cow health and production in a

compost-bedded pack barn

Jessica Carter, Warren Gill and Tim Redd

School of Agribusiness and Agriscience

Middle Tennessee State University, Murfreesboro, TN

Year awarded: 2012

The use of a bolus to constantly monitor body temperature of cows is not a widespread

practice in today’s dairy industry. The objective of this project was to evaluate the use of rumen

temperature boluses and pedometers as an aide for early detection and treatment of disease. A

project was conducted at the MTSU Experiential Learning and Research Center during late

fall/early winter to compare milk production, activity levels, and body temperatures across three

breeds of milk cows. The breeds monitored in this study were Holstein, Jersey, and Jersey x

Holstein crosses. The study was conducted using 82 lactating dairy cows (35 Holstein, 32 Jersey,

and 15 Crossbreds) for a period of 60 days. All cows were housed together in a compost bedded

pack barn. Cows were milked twice daily in a double-8 parallel milk parlor and measurements

were recorded during milking (daily milk production amounts, conductivity of the milk). Each

cow was equipped with a pedometer to measure activity (steps walked each day) and

conductivity levels in the milk (an indication of somatic cell count). The pedometer also

included the individual cow identification so that individual records are recorded during each

milking. Cows also had a rumen bolus (Bella Ag©

) that monitored their core body temperature

daily. The cows were housed together in a compost-bedded pack barn with cedar shavings. The

daily milk yield, activity levels and conductivity levels are measured when the cows enter the

parlor for milking. Body temperature was recorded at random times throughout a 24 hour period

and readings were sent to the computer to be downloaded. An average body temperature per day

per cow was calculated and compared with production records and activity levels. Data were

analyzed using mixed model analysis of variance with repeated measures. Least significant

means were separated using a Tukey’s test and measures with a P < 0.05 were considered

significant. There were no significant differences in milk conductivity, cow activity, or body

temperatures. When comparing cow daily milk yields, the Holstein and X-bred cows produced

significantly more milk than the Jersey cows. The temperature boluses were helpful to monitor

individual cow health, and an alert was sent to the office computer anytime a cow’s temperature

reached above 102°F. This was beneficial for early detection and treatment of disease. Cow

temperature also increased during estrus so this was helpful by improving artificial insemination

success.

143

Economic evaluation of dairy cow stocking density

Albert De Vries1, Haile Dechassa

2, Henk Hogeveen

2

1Department of Animal Sciences, University of Florida, Gainesville, FL 2Business Economics Group, Wageningen University, the Netherlands

Year awarded: 2014

Stocking density is a quantitative measure of the area occupied by cows. One measure is

the number of cows per stall in a pen. Adding another cow to the pen may reduce each cow’s

performance, such as lowering lying time or milk yield, but also adds the net revenue of the

additional cow. The economic optimal stocking density is reached when the marginal return of

the pen equals the marginal cost of the pen. At this stocking density, the profit per stall is

maximized. It is not clear how variations in stocking density affect profit per stall. Therefore, the

objectives were to 1) Quantify the effects of stocking density on cow performance using

literature review, 2) Perform an economic evaluation of stocking density, and 3) Make a

spreadsheet available for custom evaluations. The study focused on lactating cows and not

transition cows. Many studies exist that document the effects of (short term) stocking density on

cow behavior but quantitative measures of stocking density on factors that directly affect cow

cash flow (such as milk yield, fertility, lameness) are scarce. Lying time is reduced when

stocking density >100% and starts to really be affected when stocking density >120%. Studies

from Spain and New York both showed decreases of approximately 0.55 kg/day per 0.1 greater

cows/stall in the range from 100% to 150% stocking density. Wisconsin data showed a loss of

0.01 conception rate per 0.1 greater cows/stall. Economic analyses of stocking density are

therefore hampered by a lack of good performance data. The effect of stocking density on

conception rate implies that the herd demographics change when stocking density is varied.

Therefore a comprehensive herd budget spreadsheet was used to capture the combined effects of

milk production loss and changes in demographics. The effects of milk losses of 0.50, 0.70 and

0.90 kg/cow per day on gain in profitability for each 0.1 greater #cows/stall were calculated. The

level of milk loss had a large effect on the optimal stocking density and the gain in profitability.

At a loss of 0.50 kg/cow per day, the maximum profit per stall was at a stocking density greater

than 150%. The profit per stall per year at 150% stocking density was $145 greater than at a

100% stocking density. At a loss of 0.70 kg/cow per day, the optimum stocking density was at

122% and the profit per stall per year was $43 greater than at 100% stocking density. At a loss

of 0.90 kg/cow per stall, the optimum stocking density was at 107% and the profit per stall per

year was only $6 greater than at a 100% stocking density. Changes in prices had large effects on

the optimum stocking density. The optimum stocking density was very sensitive to changes in

cow performance and prices. Some overstocking typically was economically warranted.

De Vries, A., H. Dechassa, and H. Hogeveen. 2015. Crowding your cows too much costs you

cash. WCDS Advances in Dairy Technology, Vol.27:275-285.

144

Inducing ovulation early postpartum influences uterine health and fertility in dairy cows

J.H.J. Bittar†, P.J. Pinedo

†, C.A. Risco

†, J.E.P. Santos

‡, W.W. Thatcher

‡, K.E. Hencken

†, S.

Croyle†, M. Gobikrushanth

†, C.C. Barbosa

§, A. Vieira-Neto*, and K.N. Galvão

†

†Department of Large Animal Clinical Sciences, University of Florida, Gainesville, FL

‡Department of Animal Sciences, University of Florida, Gainesville, FL

*Universidade do Estado de Santa Catarina (UDESC), Lages, SC, Brazil. § Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Botucatu, SP, Brazil.

Year awarded: 2011

The objective was to evaluate the effect of GnRH early postpartum on induction of

ovulation, uterine health, and fertility in dairy cows. Holstein cows without a corpus luteum (CL)

at 17 ± 3 DIM were assigned randomly to receive i.m. GnRH (n = 245) at 17 ± 3 and at 20 ± 3

DIM or remain as controls (n = 245). Ovaries were scanned by ultrasonography (US) twice

weekly totaling 4 examinations. Ovulation was characterized by the appearance of a CL ≥ 20

mm at any US or CL < 20 mm in 2 consecutive examinations. Clinical and cytological

endometritis were diagnosed at 35 DIM. Compared with control, GnRH increased ovulation up

to 3.5 d after the last treatment (78.7% vs. 45.0%), and did not affect the prevalence of clinical

endometritis (23.9% vs. 18.6%) or cytological endometritis (30.9% vs. 32.8%). Prevalence of

clinical endometritis increased in cows that had calving problems (32.6% vs. 15.9%) and metritis

(40.6% vs. 15.8%). Metritis increased prevalence of cytological endometritis (50.7% vs. 23.5%).

Treatment with GnRH did not affect pregnancy per artificial insemination (PAI) at 32 (37.6% vs.

38.6%) or 74 d after AI (35.0% vs. 31.5%), but reduced pregnancy loss (6.8% vs. 18.1%). There

was no overall effect of GnRH treatment on hazard of pregnancy; however, an interaction

between GnRH treatment and ovulation showed that GnRH-treated cows that ovulated had

increased hazard of pregnancy by 300 DIM compared with GnRH-treated and control cows that

did not ovulate (HR = 2.0 and HR = 1.3, respectively), but similar to control cows that ovulated

(HR = 1.1). Gonadotropin-releasing hormone early postpartum induced ovulation without

affecting uterine health, but failed to improve PAI or time to pregnancy, although it reduced

pregnancy loss.

145

Development of tools to select cattle genetically resistant to heat stress

Peter J. Hansen1 and Serdal Dikmen

2

1Department of Animal Sciences, University of Florida, Gainesville, FL

2Uludag University, Bursa, Turkey

Year awarded: 2014

Dairy cows with increased rectal temperature during heat stress experience lower milk

yield and fertility. Given that rectal temperature during heat stress is heritable in dairy cattle,

genetic selection for regulation of body temperature should reduce effects of heat stress on

production. One goal of the study was to validate the relationship between genotype and heat

tolerance for mutations (called SNPs) previously related to resistance to heat stress. A second

goal was to identify new candidate gene SNPs related to resistance to heat stress.

Thermotolerance was assessed in 625 lactating Holstein cows during the hottest part of

the day in summer by measuring rectal temperature, respiration rate and sweating rate. Specific

genetic markers and candidate genes responsible for genetic variation in these variables were

identified. Two SNPs previously related to heat tolerance were related to rectal temperature and

three closely-located genetic markers on bovine chromosome 24 and another on chromosome 29

were associated with sweating rate. New candidate gene SNPs were identified for rectal

temperature (n=7), respiration rate (n=9), and sweating rate (n=6). The largest effect on rectal

temperature was for progesterone receptor, which explained 2.1% of the phenotypic variation

after adjustment for dry bulb temperature. These genetic markers could prove useful in genetic

selection for heat tolerance in Holstein cattle.

146

Florida’s dairy youth development program

Chris Holcomb

Department of Animal Sciences, University of Florida, Bartow, FL

Years awarded: 2012-15

Our youth are often exposed to many different draws on their time, many of which can be

very detrimental to their development. The Florida youth dairy program has designed a

curriculum and many activities to stimulate these youth and expose them to the dairy industry.

These events are also designed to help the youth hone their skills in public speaking, critical

decision making, leadership, career development, and develop valuable future industry

connections.

The youth are given the opportunity to compete in many events that will help accomplish

the program objectives. In the past three years there have been over three hundred (300) youth

that have attended multiple events throughout the state and country. These events include state,

regional, and national dairy judging events in over twelve (12) states, and state and national quiz

bowl competitions in over eight (8) states. There have been over sixty (60) different youth that

have traveled to the Southeast Dairy Youth Retreat and National 4-H Dairy Conference which

covers six (6) different states. There are also multiple dairy shows and workshops held

throughout the state that have developed over 300 (three hundred) youth. There have also been

over fifty (50) different adult leaders trained through the youth dairy programs volunteer leader

training.

The youth dairy program continues to grow at a large rate. This is demonstrated by the

number of both cattle and exhibitors at shows, events, and workshops throughout the state and

country. Sarasota county has had an exceptional growth in their program. In 2012 there were

about ten (10) exhibitors and fifteen (15) head with one youth that participated beyond the

county level. In 2015 there were fifty six (56) exhibitors and seventy one (71) head, with over

fifteen (15) participating in events beyond the county. At the national competitions, Florida had

national winners in many competitions as well as being the most recognized state in the country

at the National Guernsey Convention in 2014. There is a marked increase in knowledge of the

dairy industry and improvement in life skills such as public speaking and decision making.

The overall numbers of animals and exhibitors is growing exponentially throughout the

state as demonstrated by participation throughout the many fairs and events. The most impactful

results are seen through the development in both communication skills and personal confidence.

Thus the youth that are graduating from the youth dairy project are much better communicators,

are more decisive, and have a much increased amount of knowledge in the dairy industry. This

makes them more marketable and is developing a new group of leaders and ambassadors for the

dairy industry and agriculture in general.

147

Reduced risk management and current status of insecticide resistance of horn flies and

stable flies on southeastern dairies

Phillip E. Kaufman

Entomology and Nematology Department, University of Florida, Gainesville, FL

Year awarded: 2012

The objectives were to evaluate horn fly control using a walk-through vacuum fly trap –

the Cow•Vac, and to evaluate horn fly insecticide resistance from selected dairies in the

Southeast. For the first objective, we operated vacuums on three Florida dairies (250-750

lactating cows) from Oct. 2012-Dec. 2013 (Figure 1). Criteria were: installation at entrance to

milk barn, cement pad for device, electricity, willingness to run cows through 1-2 times daily,

producer agreement to operate/help maintain device. Fly densities determined by counting flies

on 10 animals on a weekly basis. Trap contents were returned to the laboratory and flies sorted

and counted. Our goal was to demonstrate that this device reduced fly densities below economic

thresholds without use of insecticides. The effectiveness of the fly trap was determined by

comparing the weekly on-animal fly counts from the 3 fly trap farms to the fly counts from the 3

control farms.

For objective 2, we attempted to survey horn flies from the six farms where the vacuum

trap studies occurred, but were unable to obtain sufficient numbers of viable flies to test. As a

part of a Multi-State Hatch project to which I belong, we surveyed stable fly resistance with

assistance of researchers in DCO and other Southeastern states. Flies were collected from farms

and screened using standard insecticide-treated glass jar protocols. Fly mortality was evaluated

over 4 diagnostic doses found to separate susceptible and resistant fly types. Additionally,

several of these populations were screened through a PCR technique to identify the presence of a

sodium-channel mutation known to confer resistance to permethrin.

Figure 1. Cow vacuum in place at a FL dairy. Air is blown in on the left side and flies collected on the right

side, ultimately deposited in the mesh bag that technician is holding.

148

As expected, horn fly numbers on cows under the vacuum treatment declined within

weeks, however, this is due to both the removal of flies and the seasonal decline in replacement

flies, as a portion of the population hibernates in the Fall (Figure 2). Results from summer 2013

show the complete effect of the device. Similarly, stable flies were active in the Spring and the

vacuum kept these flies at low levels. Overall, data document the effectiveness of the vacuum.

Horn fly captures were most heavy on one farm, with more modest collections at the other two

farms due to lower horn fly numbers resulting from insecticide use and mechanical issues with

vacuums. In total, well in excess of 1.6 million flies were removed from the farms. Additionally,

large numbers of house flies were captured. Although room prohibits graphs, stable flies were

largely susceptible to insecticides in the southern U.S.

The Cow•Vac is currently for sale by Spalding Labs. The costs are approximately

$7,500.00, which includes shipping this large and heavy device. By completing this study we

will be able to provide dairy producers with a better understanding of the benefits and drawbacks

of this trap technology. In examining the insecticide resistance status of the horn and stable fly,

we will be better able to assist producers with proper selection of insecticides (or insecticides +

synergists) or to assist them to move to alternative solutions, such as the vacuum trap.

Continuing to use insecticides that are ineffective is both economically and environmentally an

unsound business practice.

Figure 2. Data showing horn (A) and stable (B) fly captures (red) and on animal counts at vacuumed (black) and

control (yellow) dairies. Spike in yellow and red lines indicates fly increase on controls & capture, and no increase in

on-cow flies (black line).

149

Are nitrogen and water contributions from spray effluent adequate for winter forage

production?

C.L. Mackowiak1, A.R. Blount

1, M. Sowerby

2, E. Toro

2, C. Davis

3, and W. Smith

4

1North Florida Research and Education Center, University of Florida, Quincy and Marianna, FL

2 Suwannee County Extension, University of Florida, Live Oak, FL

3 Okeechobee County Extension, University of Florida, Okeechobee, FL

4 Syngenta, Union, KY

Year awarded: 2013

Over the past several years, our goal has been to examine cool-season forages and

management practices, in order to expand production options for both, confinement and grazing

dairy systems, while minimizing environmental impacts (primarily N and P). Objectives over the

years have included assessing N and P removal from winter forage systems under different

harvest management (from greenchop to single cuttings). More recently (2013 to 2014), effluent

N and water delivery, soil N mineralization, and forage response was tested. These data are

helping with the development of more nutrient and water efficient cool-season forage production

options for dairies. Replicated trials of advanced cool-season forages grown on Florida dairy

farms where tested for productivity and tissue N and P uptake. More recently, transects under 6

different dairy pivots, receiving lagoon effluent were sampled, along with forage and soil for N

content (inorganic and total), as well as potentially mineralizable N). These studies also included

annual demonstrations of several different forage variety options (typically 20-30 varieties) that

provided producers and extension agents a look at forage responses under “real-world”

management. Field days and site visits were common at three or more dairies each year. On-farm

testing demonstrated that forage harvests are the principal driver of N and P export. Multiple

cutings or using later maturing forage cultivars tended to result in lower N and P export. A small

(30 lbs N per acre) dry N fertilizer application often improved cool-season forage yields. This

response is likely due to lower mineralization rates of effluent-derived N during the winter

months, and the exceptionally short cropping cycle (approximately 60 to 80 days) used by many

dairies. Low pivot nutrient and water uniformity across the field resulted in greater yield

variations than often existed among the different forage selections. The sponsored on-farm

research and extension efforts provide an opportunity to assess what nutrient- and water-use

savings may be realized. Variable rate technologies are becoming more refined in many other

cropping systems. Our results will help us identify which of these technologies might benefit

dairy producers and aid us in developing more economically and environmentally sustainable

forage production systems.

150

Developing improved alfalfa cultivars for Florida

Patricio R. Munoz1, José Dubeux

1,2, and João Vendramini

1,3

1Agronomy Department, University of Florida, Gainesville, FL

2North Florida Research and Education Center, University of Florida, Marianna, FL

3Range Cattle Research and Education Center, University of Florida, Ona, FL

Year awarded: 2014

Alfalfa is widely grown throughout the world and is primarily used to feed high-

producing dairy cows, as it has high protein content and high digestible fiber. It is typically

grown in rotation systems as a complement to low protein corn silage. It is very versatile; can be

used as hay, silage, haylage, grazed or chopped. It can be grown without N fertilization. Despite

all these benefits no alfalfa breeding program exists in Florida. The objectives of this proposal

are to 1) evaluate a wide range of national and international alfalfa cultivars under Florida

conditions for variety recommendations, 2) evaluate economics of the “alfalfa project” under

Florida conditions, and 3) select the best performing cultivars to be used as a base for developing

new, improved alfalfa for Florida. Two field experiments including 28 different national and

international alfalfa varieties were established Fall 2014 in Citra and Marianna, FL. Alfalfa

cultivars, developed in the southern United States, as well as international cultivars, developed

under similar conditions from Uruguay, Argentina, Chile, and Brazil were included. These two

experiments complement two experiments established in the same locations in 2013 with 4

alfalfa varieties. Yield, disease, and quality were evaluated. The experiment established in Oct

2013 was harvested during the year 2014 accumulating yields from 7,000 lb/A without irrigation

in North Florida to 15,000 lb/A in North-Central Florida with irrigation. There was a range of

more than 1,000 lb/A between the best and the worst cultivars used in this experiment. First

harvest was performed March 20, 2014 and continued every 28-35 days until Dec, 2014 in

Central-North Florida and until October in North Florida. Mean protein level of alfalfa 23.6

while mean TDN was 64.4 across the year. Yield and diseases on farms in similar locations to

the experiments was also monitored; the farm in North Florida using minimal irrigation reached

a yield of 14,000 lb/A with the best variety, while more than 16,000 lb/A were obtained in

North-Central Florida when using irrigation. The 2013 experiment will continued to be

monitored for yield and disease during 2015. The 2014 experiment with 28 varieties will be

monitored as well during this year. Data from 2014 is being used to provide an economic

evaluation of hay, grazing, and dairy conditions. Alfalfa can be effectively grown under Florida

conditions with exceptional yields, comparable only to those of California. Differences of more

than 1,000 lb/A in 2014 yield among varieties indicate the importance of continued evaluation

and breeding of varieties for Florida conditions. We expect to have the first solid variety

recommendation for Florida conditions by the end of 2015. Alfalfa yields forage in the transition

points from winter to spring and from fall to winter, which are the most complicated periods for

producers in Florida. The quality, yield, and distribution of forage across the year, paired with

the high prices of fuel, feed and fertilizer, make alfalfa one of the best forages for Florida. We

are also finding positive results in the evaluation of the establishment of alfalfa over

Bermudagrass. The two species have complimentary growing seasons, with alfalfa producing

more in early spring and late fall and Bermudagrass producing more during the summer.

151

Use of vitamin D to enhance antimicrobial mechanisms of the udder

Kathryn E. Merriman, Jessica L. Powell, Mercedes F. Kweh, Emily Wilkes, O. Monika

Trejos Kweyete, and Corwin D. Nelson

Department of Animal Sciences, University of Florida, Gainesville, FL

Year awarded: 2014

The innate immune defenses of the mammary gland are critical for elimination of

bacterial pathogens that cause mastitis. Laboratory experiments have demonstrated that the

active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25D), enhances the expression of

multiple host defense genes, such as, β-defensin antimicrobial peptides, inducible nitric oxide

synthase (iNOS), and the chemokine RANTES. Previous work using an experimental model of

mastitis also has shown that CYP27B1, the enzyme that catalyzes 1,25D production from 25-

hydroxyvitamin D3 (25D), is activated in the mammary gland during mastitis, and that

intramammary 25D treatment inhibited experimental Streptococcus uberis infection. The

objective of this study was to determine the effects intramammary 25D and 1,25D treatments on

mammary host-defense gene expression. In the first experiment, contralateral quarters of seven

healthy Holstein cows (SCC ≤ 200,000 cells/mL) were treated intramammary with 10 μg of

1,25D or placebo (10 mL of phosphate buffered saline with 10% fetal bovine serum). Milk

samples were collected at 0, 2, 4, 8, and 12 h relative to treatment, and somatic cells were

collected for analysis of host-defense gene expression. At 2, 4, 8, and 12 h post 1,25D infusion

CYP24A1, a positive control gene for 1,25D activity, was increased in the infused quarters

relative to the control quarters (P < 0.0001). The 1,25D treatment increased iNOS expression >2-

fold in milk somatic cells at 8 h and 12 h post infusion relative to the control quarters (P < 0.05),

and β-defensin 3 (DEFB3) and DEFB7 expression >2-fold at 4 h post infusion relative to the

control quarters (P < 0.05). In addition, macrophages isolated from milk somatic cells using

fluorescence-activated cell sorting had 2-fold greater DEFB4 and DEFB7 expression in response

to 1,25D treatment (P < 0.05). In the second experiment, all four quarters of five cows were

treated with either 5 μg of lipopolysaccharide (LPS, from E. coli), 100 μg of 25D, a combination

of 100 μg 25D and 5 μg LPS (LPS+25D), or placebo. At 8 h post infusion, somatic cells from

LPS and LPS+25D treated quarters had increased CYP27B1, iNOS, DEFB3, DEFB4, DEFB7,

DEFB10, and lingual antimicrobial peptide gene expression relative to control quarters and pre-

challenge (P < 0.05). Treatment with 25D either alone or in combination did not affect host-

defense gene expression. The neutrophils from the LPS and LPS+25D treated quarters had

increased CYP27B1, iNOS, RANTES, DEFB3, DEFB7, and DEFB10 expression relative to the

control quarters at 8 hours post treatment (P < 0.05). In contrast, only iNOS and CYP27 were

increased in macrophages from LPS and LPS+25D treated quarters compared to macrophages

from the control quarters (P < 0.05). In conclusion, 1,25D enhances expression of critical host-

defense genes in mammary macrophages. However, 25D, the precursor to 1,25D did not affect

host-defense gene expression, despite expression of CYP27B1 in macrophages and neutrophils.

This study indicates that 1,25D, the active form of vitamin D, may be a useful therapeutic or

adjuvant to minimize the cost of mastitis in dairy cattle. Further work is needed to determine

effects of 1,25D treatments on clinical and subclinical mastitis, and to understand how dietary

vitamin D influences mammary immunity.

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Lymphatic fluid for the detection of Mycobacterium avium subsp. paratuberculosis in cows

by PCR, compared to fecal sampling and detection of antibodies in blood and milk

Johannes L. Khol1,*, Pablo J. Pinedo

2, Claus D. Buergelt

3, Laura M. Neumann

4, D. Owen

Rae4

1Department for Farm Animals and Veterinary Public Health, University of Veterinary

Medicine, Vienna, Austria 2Texas A&M AgriLife Research, Texas A&M University System, Amarillo, TX

3Department of Infectious Diseases and Pathology, University of Florida, Gainesville, FL

4Department of Large Animal Clinical Sciences, University of Florida, Gainesville, FL

Year awarded: 2013

Johne’s disease (JD), caused by Mycobacterium avium subsp. paratuberculosis (MAP),

can cause considerable economic losses in affected herds. Early diagnosis of JD is hampered by

the chronic nature of the disease with a slow subclincal progression. The aim of the present study

was to challenge the hypothesis that lymphatic fluid is of diagnostic value in the early stages of

the disease. Lymphatic fluid from 122 animals was collected and tested for MAP by nested PCR

for IS900 and compared to the results of testing for MAP in feces (culture), blood and milk

(ELISA) in 110 of these samples. MAP was detected by PCR in 27.1% of the lymph samples.

Agreement between the tests was poor: 6.9% of the lymph positive cows were also positive in all

other tests applied, and 69.0% had negative results in fecal culture, blood and milk ELISA.

Resampling of 25 cows after 8 to 12 and 16 to 20 months revealed 20.0% lymph positive animals

at the first, 5.5% at the second and 27.8% at the third sampling, respectively. Only one cow

showed positive lymph-PCR results at more than one sampling date. Lymph-positive cows had a

7.2 times greater likelihood of being culled within 8 to 12 months after sampling, compared to

negative cows, mainly due to other health issues than JD. It can be concluded, that lymphatic

fluid might be promising for the detection of early MAP-infection in cows, but further studies to

elucidate the potential of this diagnostic approach are needed.

Veterinary Microbiology (2014) 172: 301–308

153

Jiggs bermudagrass and Mulato II brachiariagrass: Are they viable options for use on

north Florida/south Georgia dairies?

Lynn Sollenberger1, Joe Vendramini

2, Jose Dubeux

3, and Ann Blount

3

1Agronomy Department, University of Florida, Gainesville, FL

2Range Cattle Research and Education Center, University of Florida, Ona, FL

3North Florida Research and Education Center, University of Florida, Marianna, FL

Year awarded: 2014

Productive and high quality forages are critical to the success of dairy operations, but this

combination of high yield and quality has been difficult to find among warm-season perennial

grasses adapted to the Gulf Coast region. Mulato II brachiariagrass and Jiggs bermudagrass are

attractive to dairy farms, but additional plot and on- farm evaluation is needed. The objective

was to assess the potential of Jiggs and Mulato II grasses for use as forages on dairies by

measuring yield, persistence, and nutritive value in two research station experiments and on-farm

demonstrations at three farms. On station, Experiment 1 treatments were two grasses (Jiggs and

Tifton 85), two cutting heights (3 and 6 inches), and three K fertilization rates (0, 20, and 40 lb

potash/acre per harvest). The plots were planted in 2013 at the University of Florida Beef

Research Unit and were harvested five times at a 28-day intervals in 2014. Plots were fertilized

in spring and after each harvest but the last with 40 lb N/acre (total of 200 lb N/acre/year).

Experiment 2 treatments were two grasses (Jiggs and Mulato II) and two N rates (120 and 240 lb

N/acre/year). Plots were planted in 2013 at the University of Florida Beef Research Unit and

were harvested every 28 days beginning in May 2014. Plots were fertilized with P and K

according to soil test. In the on-farm evaluation, the grasses were planted in side-by-side, 0.5-

acre strips on three dairies in the north Florida/south Georgia region between July 24 and August

6, 2014. Establishment success was followed throughout the remainder of the growing season.

On farm, dry weather at time of planting was a challenge to the grasses at two locations and

annual grass weeds were a challenge at one location. In all locations, Jiggs establishment was

superior to either Tifton 85 or Mulato. In Experiment 1, the total production of Jiggs and Tifton

85 was the same, but they responded differently to cutting height. Jiggs performed better when

cut to 3 inches (5 tons/acre) versus 6 inches (4.2 tons/acre), whereas Tifton 85 performed best

when cut to 6 inches (5.1 tons/acre) versus 3 inches (4.3 tons/acre). There was no effect of rate of

potash on yield in the first year. In Experiment 2 conducted on station, Mulato II was superior to

Jiggs in yield (4.8 vs 4.0 tons dry matter/acre), but their seasonal pattern of production was

different. Jiggs started growth earlier in the spring than Mulato II, but Mulato II was more

productive during the summer and fall. Persistence is a response of major interest for Mulato and

Jiggs, and that response will not be effectively quantified until the end of 2015. Through the end

of the first year it is clear that Jiggs is the best suited of these grasses for establishment,

particularly under drought stress and weed pressure. It is also apparent that Mulato is slower to

initiate forage growth during spring than Jiggs and Tifton 85 which can be a limitation because

the first hay crop of the year is important because of more favorable weather conditions for

drying hay and also because forage quality is greater. It is also clear that Jiggs performs better

when using a shorter cutting height than does Tifton 85, most likely a function of their growth

habit. Currently the role of K fertilizer on production and persistence is not yet clear, and these

results are expected to become more apparent throughout the 2015 growing season.

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Precision trapping of house flies on dairies using fly density indices

Mary Sowerby1 and Jerry Hogsette

2

1Suwannee County Extension Office, University of Florida, Live Oak, FL

2USDA/ARS Center for Medical, Ag and Veterinary Entomology, Gainesville, FL

Year awarded: 2012

House flies are a health hazard and general nuisance for livestock and humans. Traps

with house fly specific baits (Captivator traps) were found more effective for farm fly trapping

than QuikStrike scatter bait and the QuikStrike bait stations in a previous study. But where

should they be placed to optimize capture? The objective of this study was to determine if an

instantaneous fly density index made with an 18-inch square Scudder grid sampling device

correlates with the number of flies actually trapped at that location. One to four Captivator Traps

were placed in each of three attractive locations (calf rearing area, feed barn and commodity

storage area) on two northeast Florida dairies. Before trap placement, a fly density estimate was

obtained by placing a Scudder grid on each potential trap site and counting the house flies resting

there after 1 minute. A Captivator Trap was placed at that location and captured flies were

counted after 24 hours. After counting, bait was replaced and traps were set at the same sites

after first obtaining a fly density index. Original trap locations were not changed and trapping

continued for 4 weeks. Regression analysis indicated no correlation exists between a fly density

index and numbers of flies trapped at the same site. Number of flies trapped in groups of traps

varied from one trap to another over time. Results show how quickly localized groups of house

flies can change locations. If a density index is high, it might be expected that many flies will be

trapped at that site. However, that was not always true. If several traps are placed around one

site, e.g. calf pens, the traps do not necessarily capture similar numbers of flies. Also numbers of

flies captured by each trap can vary daily from low to high. Data indicate the best method for

trapping flies in localized areas is to use groups of traps instead of just one.

155

Inoculant effects on mycotoxins, fermentation characteristics, and nutritive value of

bermudagrass silage

Joe Vendramini1, Lynn Sollenberger

2, and Jose C. Dubeux Jr.

3

1 Range Cattle Research and Education Center, Ona, FL

2 Department of Agronomy, Gainesville, FL

3 North Florida Research and Education Center, Marianna, FL

Year awarded: 2014

The objective of this research project was to evaluate the effects of commercial silage

inoculants on mycotoxins, fermentation characteristics, and nutritive value of bermudagrass

silage. The experimental area was located at the Range Cattle Research and Education Center,

Ona, FL. A Jiggs bermudagrass hayfiled was subdivided in 36 plots of 10 x 10 ft each plot. The

plots were staged on June 15 2014 at 3 inches stubble height and fertilized with 80 lbs N/ac. The

harvest occurred from July 15 to July 17 2014 with target regrowth interval of 4 weeks.

Treatments were 7 commercial inoculants and control (untreated treatment) in a randomized

complete block design with 6 replicates. The inoculants tested were B500, Biotal Plus II, Early

Sile Advance, Promote HQ, Promote VS-3, F20, and F600. The mini-silos (PVC pipes with

rubber caps with capacity of 2 lb of green forage) were filled immediately after harvest with the

target 20-30% forage dry mater concentration. The inoculants were applied with a hand sprayer

before ensiling. The silos were opened on October 22 2014. There were no effects (P > 0.05) of

the inoculants on silage nutritive value. The mean values of nutritive value measurements among

treatments were: dry matter (DM) = 25%, DM recovery = 89%, crude protein (CP) = 10.5%,

neutral detergent fiber (NDF) = 73.0%, acid detergent fiber (ADF) = 40.0%, in vitro digestibility

(IVTD) = 51%, and NDF digestibility (NDFD) = 30%. The treatments Promote VS-3 and

Control had lower (P < 0.01) pH than B500, Biotal Plus II, and F600 (4.6 vs. 4.9) and similar to

the other treatments. Lactic acid was greater (P = 0.01) in silage treated with Promote VS-3 and

Control than F600 (2.0 vs. 0.6%) but similar among the other treatments. B500 had greater (P =

0.04) acetic acid concentration than Promote VS-3 (3.3 vs. 0.3%) and similar among other

treatments. There were no differences (P > 0.05) in propionic (mean = 0.4%) and butyric (mean

= 3.5%) acids and ammonia (25 % of the CP) concentrations among treatments. Aerobic stability

(240 h) and mold and yeast counts pre- and post-aerobic stability measurements were similar

among treatments. In addition, there was no presence of aflatoxin (< 5 ppb), zearalenone (< 500

ppb) and T2 (< 500 ppb) on the silage in any of the treatments tested. In summary, Promote VS-

3 showed an improvement in fermentation characteristics of the bermudagrass silage in this trial.

The second year of this research project will be important to increase the power of the statistical

analyses and likely detect some numerical differences observed in year 1.

156