Selection of Young Broiler Breeders for Semen Quality Improves

2002 Poultry Science Association, Inc.

Selection of Young Broiler Breedersfor Semen Quality Improves

Hatchability in anIndustry Field Trial1

H. M. Parker and C. D. McDaniel2

Poultry Science Department, Mississippi State University,Mississippi State, Mississippi 39762

Primary Audience: Broiler Breeder Supervisors, Primary Breeding Companies,Researchers

SUMMARYPrevious laboratory research has shown that the sperm quality index (SQI) is predictive of

broiler breeder fertility. The SQI is a tool to estimate overall semen quality by monitoring thenumber of times that sperm movement causes deflections within a light path. An industry fieldtrial was undertaken to determine if life of flock hatchability could be improved by selecting youngmales for house placement based on the SQI. The SQI was used to select males at 26 wk of age.Males with an SQI in approximately the top 80% of the population were moved into two henhouses, whereas the lower 20% of the SQI population was culled. Two control houses receivedmales selected solely on physical appearance. Life of flock hatchability was improved by 1.1% in theSQI-selected houses over that of males selected for house placement based on physical characteristicsalone. The males selected for the SQI numerically outperformed the control males in 64% of thehatches with the greatest difference in hatch occurring during postpeak production. This increasein hatch resulted in 21,000 more chicks being produced in the two houses containing SQI-selectedmales. In conclusion, the SQI is a useful tool for accurately identifying the reproductive ability ofbroiler breeder roosters throughout a complete laying cycle.

Key words: broiler breeder, fertility, hatchability, semen, sperm quality index2002 J. Appl. Poult. Res. 11:250–259

DESCRIPTION OF PROBLEM

In the poultry industry, there are no breed-ing soundness evaluations per se. At hen-houseplacement, roosters are selected based on phys-ical characteristics associated with a reproduc-tively mature male. Such characteristics arecomb and wattle size and color as well as over-

1 This is Journal Article No. J9946 from the Mississippi Agriculture and Forestry Experiment Station supported by MIS-322100. Use of trade names in this publication does not imply endorsement by the Mississippi Agricultural and ForestryExperiment Station of the products or of similar ones not mentioned.

2 To whom correspondence should be addressed: [email protected].

all body size and shank length [1]. Males thatare underweight or that have bad legs are culledand not used. However, Wilson and colleagues[1] showed that physical characteristics are notstrongly predictive of male fertility (r < 0.5).

Prior to or during hen-house placement,semen characteristics of broiler breeders can beevaluated. According to Donoghue [2], semen

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PARKER AND MCDANIEL: SEMEN SELECTION IMPROVES HATCH 251

evaluation tests can be a valuable tool in themanagement of roosters or toms. The mainobjective of evaluating semen quality shouldbe to predict the fertility of an individual male[3]. However, Donoghue [2] stated that semenquality tests currently available to the poultryindustry are time-consuming, labor intensive,and unreliable predictors of fertility and semenquality. If a quick and accurate semen qualitytest was available to predict fertility, malescould be chosen for hen-house placementbased on semen quality and not physical char-acteristics alone. By testing roosters for semenquality, fertility and, ultimately, hatchabilitycould be improved.

One method of semen analysis that is quickand has been correlated to sperm concentra-tion, viability, and motility in rooster [4] andmammalian semen [5, 6, 7, 8] is the spermquality index (SQI). The SQI is generated bythe OptiBreed sperm quality analyzer (SQA)in 20 s. The analyzer has a photocell that moni-tors the number of times sperm movement dis-rupts a path of light.

In a laboratory trial using artificial insemi-nation, Parker and colleagues [9] selectedmales based on the SQI. They demonstratedthat by removing males whose semen qualityranked in the lowest 22% of the SQI popula-tion, fertility was increased by as much as 4%over an unselected population. In a differentartificial insemination study, Parker and col-leagues [10] found that semen from males inthe lowest 25% of the SQI population fertilizedapproximately 20% fewer eggs when com-pared to semen from males in the upper 75%of the SQI population.

As a result of previous mammalian andavian research using the SQI, it was reasonedthat this method of semen evaluation couldbe used to select roosters within the poultryindustry for improved reproductive perfor-mance. Therefore, this research was under-taken to determine if selection of young malesfor the SQI would improve life of flock hatch-ability in an industry field trial.

MATERIALS AND METHODS

The males and females utilized in this fieldtrial were hatch mates and reared on the samepullet farm. All males (Avian) used in this

study were reared in one cockerel house. Thepullets (Avian) were reared in two pullethouses. At 22 wk of age, 36,000 pullets weredivided into four hen houses equally, on a sin-gle hen farm. Each hen house contained ap-proximately 9,000 pullets. Also, at 22 wk ofage, 1,800 males were divided and placed intotwo of the four hen houses (controls). Each ofthese two control houses received 900 malesthat were chosen for house placement basedsolely on general physical appearance. The in-tegrator was unwilling to move the males thatwere to be selected for the SQI in with thehens at the same time as the control males. Theintegrator did not want to risk disrupting eggproduction in the SQI-selected houses by pen-ning roosters in the hen house for semen collec-tion and SQI testing. As a result, the malesutilized for SQI testing remained in the cock-erel house until they were 26 wk of age, andonly the control birds were moved in with thehens at 22 wk of age. Also, by keeping themales in the cockerel house, mating activitywith hens was eliminated, therefore semen vol-ume was increased.

To establish a preliminary assessment ofsemen quality for the males remaining in thecockerel house, approximately 9% of the maleswere individually tested for the SQI at 25 wkof age. This initial testing was performed toobtain a preliminary distribution of the SQIpopulation and to establish an approximate SQIvalue that would be utilized for culling maleswith SQI values in approximately the lowest20% of the population. The SQI of each malewas determined by diluting the semen 10-foldwith 0.85% saline [9, 10, 11].

Beginning at 26 wk of age, all males re-maining in the cockerel house were individu-ally tested for the SQI. An assembly line wascreated so that two semen diluters and twoSQA operators could be utilized at the sametime. One person collected semen for this as-sembly line. The minimum semen volume de-sired for each test was 50 µL. Each male wasnumbered 1 through 6 on the wattle, using ablack marker, and placed into a cage with acorresponding number. Individual males wereheld in these cages until an SQI reading wasobtained and it was determined what SQI hold-ing pen the male should be placed. Pens held


JAPR: Research Report252

FIGURE 1. Weekly percentage of males relative to females. Each point represents the mean percentage of maleseach week for the sperm quality index-selected males (open symbols) and control males (closed symbols) (P > 0.84).

males with SQI values of < 350, 350 to 400,or > 400. The SQI values for these holdingpens were established utilizing approximateSQI culling values from the preliminary distri-bution obtained at Week 25. For each male, ittook approximately 1 minute to complete se-men collection, SQI determination, and penplacement. Three days were required to testand select males based on the SQI.

FIGURE 2. Weekly egg production. Each point represents the mean egg production for houses containing thesperm quality index-selected males (open symbols) and control males (closed symbols) (P > 0.16).

The males with an SQI in approximatelythe bottom 20% of the SQI population wereculled. The culled males were not used in thisstudy. After SQI selection, the males weremoved into the two treated hen houses to yieldthe same male to female ratio as was present inthe two control hen houses at that time (9:100).

In all houses, both treated and control, hensand roosters were feed restricted according to



FIGURE 3. Weekly body weights of males. Each point represents the mean body weight each week for the spermquality index-selected males (open symbols) and control males (closed symbols) (P > 0.98).

primary breeder recommendations. Approxi-mately 5% of the males in each house wereweighed by the integrator weekly from henhouse placement to 40 wk of age and monthlythereafter. The birds received 14 h of light atplacement, 15 h at 5% egg production, and 16h at 25% egg production. The males remainingin the cockerel house received the same light-ing protocol as the control houses. From thetime the birds were 29 to 51 wk of age, hatch-ability data for each house were obtainedweekly from the local company hatchery. Thebirds in all houses utilized in this trial con-tracted Mycoplasma synoviae and were de-stroyed at 51 wk of age. Therefore the datacollected for 22 wk of hatches were analyzedusing ANOVA [12] with a split plot in time.Each hen house was an experimental unit.

RESULTS AND DISCUSSION

Because it was thought that SQI testingmay interrupt egg production, company man-agement required that this procedure be per-formed prior to hen house placement of males.Therefore, SQI-tested cockerels were moved 4wk after controls. Cumulative male mortalityfrom 22 to 26 wk of age was higher for themales maintained in the cockerel house versusthe males that were placed in the hen house(10% and 5% respectively, SEM = 0.35, P <

0.05). According to Craig [13], when birds areprovided excessive floor space, agonistic be-havioral levels increase. Therefore, increasedaggression may have resulted in increased mor-tality in the cockerel house. During this period,control males were allowed to mate with hens,while the males maintained in the cockerelhouse were not. After selecting males for theSQI and moving them to the hen house, thepercentage of males relative to females re-mained the same for the two treatment groups,due to similar mortality, throughout the trial(Figure 1). In addition, there were no signifi-cant differences in egg production of the hens(Figure 2) or body weight of the males (Figure3) between the control and treated housesthroughout this trial.

The preliminary SQI population distribu-tion at 25 wk of age (approximately 9% ofthe population) is represented in Figure 4. Themajority of the males tested had an SQI thatranged from 441 to 520 U. The mean for thepreliminary population was 451 U. The prelim-inary population distribution revealed that the20% cull point for this sample population wasan SQI ≤ 400 U (Figure 5). Therefore, the top80% of the population had an SQI ≥ 401 U andhigher as predicted by this sample population.

When the males were tested at 26 wk ofage, the overall population distribution (Figure



FIGURE 4. Distribution of the sperm quality index (SQI) in a 25-wk-old male population used to establish thepreliminary SQI selection value for culling the lowest 20% of the population. Each bar represents the number ofmales grouped by every 40 U of SQI (n = 183).

6) differed slightly from the preliminary distri-bution that had been established the prior week.Most of the males (n = 622) had SQI valuesbetween 450 to 499, and the mean for the totalpopulation tested was 404 U. The overall SQIpopulation, therefore, was skewed to the right(w = 0.86). This skewed SQI population issimilar to that reported by Parker and col-leagues [9]. However, they reported a loweroverall population mean than in the presenttrial. This difference in means could be due tothe utilization of a different strain of bird. Itis possible that semen characteristics and ageof sexual maturity varies among broiler breederstrains [14].

The cumulative percentage distribution ofSQI in the 26 wk old population with the finalcull point is represented in Figure 7. All birdswith an SQI lower than 350 were culled, so that

approximately 77% of the original populationwas kept. By culling the bottom 23% of theSQI population, the mean SQI for the popula-tion was raised from 404 to 446 U. The mean(404 U) and cull point (350 U) utilized for thistrial was approximately 50 U lower than themean and cull points (451 and 400 U, respec-tively) established the previous week for thepreliminary distribution. To obtain the prelimi-nary distribution, approximately 9% of thepopulation was tested. This discrepancy inpopulation means and cull points could be dueto inadequate numbers of males tested whenestablishing the preliminary SQI distributionthe previous week. Another possibility is thatsemen quality of the males may not have stabi-lized by 25 wk of age, because males were stillmaturing sexually after that time [14]. Morerecently it was found that for one strain of



FIGURE 5. Cumulative percentage distribution of the sperm quality index (SQI) in a 25-wk-old male population.Each bar represents the number of males grouped by every 40 U of SQI (n = 183).

broiler breeder males semen quality did notstabilize until 29 wk of age [10, 11]. However,once males reach sexual maturity, their SQIrank in the population does not appear tochange substantially with age [9, 11]. Similarresults were reported by Holsberger and col-leagues for sperm mobility of turkey toms [15].They revealed that toms grouped by sperm mo-bility phenotype maintained their rank in thepopulation over 5 months of semen production.

There was a significant interaction betweentreatment and age (P < 0.0003) for hatchabilityof eggs set as represented in Figure 8. Hatch-ability of the males selected for the SQI wassignificantly greater than that of the controlmales at Weeks 32, 36, 37, 41, 47, 49, and 50.Table 1 further breaks down hatchability bytreatment and production period. When com-paring prepeak hatchability (Weeks 29 to 35)for each treatment, the birds in the SQI-se-lected houses and control houses had similarhatchabilities (88.6 and 88.0, respectively).This occurred despite the fact that the SQI-selected males were placed with the hens 4 wkafter the control roosters. In fact, hatchability

for the first full hatch obtained from these birdsat 29 wk of age was similar for both the controland SQI-selected males. Apparently, the SQI-selected males either did not require a lengthyperiod to adjust to socialization in the henhouse, or semen quality was better for thesemales so that fewer matings were required.

The SQI-selected males significantly out-performed the control males during the post-peak period (Weeks 36 to 51). In addition, lifeof flock hatchability for the SQI-selected maleswas 1.1% higher than that of the control males(Table 1). It is possible that if the SQI-selectedroosters had been placed with the hens at thesame time as the control males, there couldhave been even a greater increase in life offlock and postpeak hatchability due to SQI se-lection of roosters. Research has shown thatbody weight is negatively correlated with fer-tility [1]. However, body weight was similarfor the control and SQI-selected malesthroughout the trial. It also has been suggestedthat libido declines as the rooster ages [16].Even though libido might be decreasing withage, semen quality could be superior for the



FIGURE 6. Distribution of the sperm quality index (SQI) in the total 26-wk-old male population. Each bar representsthe number of males grouped by every 40 U of SQI (n = 1,945). The population of males was skewed to the right(w = 0.86, skewness −1.47, kurtosis 2.6).

SQI-selected males. Another possibility forthis difference in postpeak hatchability is thatsemen quality in the control males was declin-ing at a faster rate than the SQI-selected males.Overall, the SQI-selected males had numeri-cally higher hatchabilities than the controlmales in 64% of the hatches (14 of 22 hatches).Data are needed after 51 wk of age to see ifthis improvement in hatchability for the SQI-selected males would continue.

In order for an egg to hatch, it must firstbe fertilized, and flocks with high fertility havethe best potential for excellent hatchability[17]. The hatchability results of this trial aresimilar to the fertility results that Parker andcolleagues [9] found when utilizing artificialinsemination. They found that, by culling thelowest 22% of the SQI population, they wereable to improve fertility. Unfortunately, thehatchery utilized in the current trial was not

able to furnish fertility data. However, it isquite possible that fertility of the flocks con-taining SQI-selected males was improved inthis trial because life of flock hatchability im-proved 1.1 percentage points by culling thelowest 23% of the SQI population. This in-crease in hatchability resulted in approxi-mately 21,000 more chicks being produced inthe SQI treated houses. According to Pollock[18], if an integrator producing 15 million eggsper week could improve hatchability by just1%, weekly profits would be increased by$30,000.

This increase in hatch due to the use ofthe SQI could be achieved by all integrators,whether they are broiler or turkey producersor even primary breeders. For example, turkeyproducers utilize artificial insemination andcollect semen from each tom individually.Neuman and colleagues [19, 20] have already



FIGURE 7. Cumulative percent distribution of the sperm quality index (SQI) in the 26-wk-old male population.Each bar represents the number of males grouped by every 40 U of SQI (n = 1,945). The black arrow representsthe cull point utilized in this field trial.

shown that the SQI is indicative of turkey se-men quality. Prior to movement into the tomhouses, each male could be semen tested toobtain a more accurate assessment of fertilizingpotential. By doing so, subfertile toms couldbe culled, allowing the integrator to utilizetoms with superior semen quality. The semen

FIGURE 8. Weekly hatchability of eggs set data. Each point represents the mean hatchability for the sperm qualityindex (SQI)-selected males (open symbols) and control males (closed symbols). *Significant difference betweencontrol and SQI-selected males for a given week of age (treatment by age interaction; P < 0.0003).

from superior toms could be extended morethan that of inferior toms, which would in-crease the number of poults produced [2] pertom housed. It has been revealed that artificialinsemination doses could be reduced in halfwithout negatively affecting fertility, if roost-ers are used based on their SQI [11]. According



TABLE 1. Comparison of prepeak, postpeak, and life of flock hatchability of eggs set

Prepeak, Postpeak, Life of flock,Weeks 29–35 Weeks 36–51 Weeks 29–51

SQI selected 88.6 85.2 86.3Control 88.0 83.9 85.2∆ (difference) 0.6 1.3 1.1P < 0.28 0.05 0.08

to Amman [21], 0.1 mL of rooster semen at thegreat-grandparent level is worth approximately$125. The SQI would allow a primary breederto extend the semen of an elite male over morefemales, maximizing his genetic potential.

Many factors affect fertility in poultry, andbecause of the small number of males in ahouse relative to hens, the rooster is responsi-ble for a greater percentage of flock fertilitythan the hen [1]. Because the male is so respon-sible for flock fertility, monitoring semen qual-

CONCLUSIONS AND APPLICATIONS

1. Selection of young broiler breeder males by the SQI prior to hen house placement, improvedhatchability over selection of males based on traditional physical characteristics alone.

2. Use of the SQI could also benefit primary chicken breeders by allowing them to select maleswith superior semen quality.

REFERENCES AND NOTES

1. Wilson, H. R., N. P. Piesco, E. R. Miller, and W. G. Nes-beth. 1979. Prediction of the fertility potential of broiler breedermales. World’s Poult. Sci. J. 35:95–118.

2. Donoghue, A. M. 1999. Prospective approaches to avoidflock fertility: Predictive assessment of sperm function traits inpoultry. Poult. Sci. 78:437–443.

3. Hammerstedt, R. H. 1996. Evaluation of sperm quality:Identification of the subfertile male and courses of action. Anim.Reprod. Sci. 42:77–87.

4. McDaniel, C. D., J. L. Hannah, H. M. Parker, T. W. Smith,C. D. Schultz, and C. D. Zumwalt. 1998. Use of a sperm analyzerfor evaluating broiler breeder males. 1. Effects of altering spermquality and quantity on the sperm motility index. Poult. Sci.77:888–893.

5. Bartoov, B., J. Ben-Barak, A. Mayevsky, M. Sneider, L.Yogev, and A. Lightman. 1991. Sperm motility index: a new pa-rameter for human sperm evaluation. Fertil. Steril. 56:108–112.

6. Johnston, R. C., G. N. Clarke, D. Y. Liu, and H. W. G.Baker. 1995. Assessment of the sperm quality analyzer. Fertil.Steril. 63:1071–1076.

7. Matilsky, M., M. Ben-Ami, V. Eyali, Y. Geslevieh, Y.Ben-Barak, and E. Shalev. 1993. Correlation between sperm motil-ity index as measured by the sperm quality analyzer and the out-come of intrauterine inseminations. Human Reprod. 8 (Suppl.1):98. (Abstr.)

ity throughout the reproductive life of a flockwith the SQI could be beneficial to hatchabilityand integrator profits. For example, if a flockis experiencing low hatchability due to envi-ronmental or management problems, the SQIcould be obtained for a sample of males inthe flock. Thus, poultry managers would thenknow if a hatchability problem was due to poorsemen quality. As a result, an informed deci-sion could be made as how to best alter theenvironment surrounding the male so as to im-prove his reproductive potential.

8. Zavos, P. M., J. R. Correa, and P. N. Zarmakoupis-Zavos.1996. Measurement of the sperm motility index via the spermquality analyzer and its relationship to other qualitative spermparameters. Theriogenology 46:421–427.

9. Parker, H. M., J. B. Yeatman, C. D. Schultz, C. D. Zumwalt,and C. D. McDaniel. Use of a sperm analyzer for evaluating broilerbreeder males. 2. Selection of young broiler breeder roosters forthe sperm quality index increases fertile egg production. Poult.Sci. 79:771–777.

10. Parker, H. M., A. G. Karaca, J. B. Yeatman, and C. D.McDaniel. 2001. Fertility following selection for the OptiBreed�Sperm Quality Index when hens are inseminated with a constantnumber of sperm. Poult. Sci. 80(Suppl. 1):45. (Abstr.)

11. Parker, H. M., A. G. Karaca, J. B. Yeatman, L. R. Frank,and C. D. McDaniel. 2002. Fertility of broiler breeders followingcategorization by the OptiBreed Sperm Quality Index when hensare inseminated with a constant number of sperm. Poult. Sci.81:239–245.

12. SAS Institute. 1996. The SAS System for Windows, Re-lease 6.12. SAS Inst. Inc., Cary, NC.

13. Craig, J. V. 1992. Measuring social behavior in poultry.Poult. Sci. 71:650–657.

14. Lake, P. E. 1983. Factors affecting the fertility level inpoultry, with special reference to artificial insemination. World’sPoult. Sci. 39:106–117.



15. Holsberger, D. R., A. M. Donoghue, D. P. Froman, andM. A. Ottinger. 1998. Assessment of ejaculate quality and spermcharacteristics in turkeys: sperm mobility phenotype is independentof time. Poult. Sci. 77:1711–1717.

16. Mauldin, J. M. 1992. Applications of behavior to poultrymanagement. Poult. Sci. 71:634–642.

17. Eslick, M. L., and G. R. McDaniel. 1992. Interrelationshipsbetween fertility and hatchability of eggs from broiler breederhens. J. Appl. Poult. Res.1:156–159.

18. Pollock, D. L. 1999. Geneticist’s perspective from withina broiler primary breeder company. Poult. Sci. 78:414–418.

19. Neuman, S. L., C. M. Braun, and P. Y. Hester. 2000.Utilization of a sperm quality analyzer to assess traits in maleturkey breeders. Poult. Sci. 79(Suppl. 1):49. (Abstr.)

20. Neuman, S. L., C. D. McDaniel, J. Radu, L. Frank, and P.Y. Hester. 2001. Use of the OptiBreed� sperm quality analyzer forevaluating semen quality of turkey breeders. Poult. Sci. 80(Suppl.1):172. (Abstr.)

21. Amann, R. P. 1999. Lessons for the poultry industrygleaned from experiences with other commodity species. Poult.Sci. 78:419–427.


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Selection of Young Broiler Breeders for Semen Quality Improves