REPRODUCTIVE AND TESTICULAR CHARACTERISTICS OF PUREBRED AND CROSSBRED BOARS

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1 University f Nebraska - Lincln DigitalCmmns@University f Nebraska - Lincln Faculty Papers and Publicatins in Animal Science Animal Science Department Nvember 1977 REPRODUCTIVE AND TESTICULAR CHARACTERISTICS OF PUREBRED AND CROSSBRED BOARS E. R. Wilsn Oklahma Agricultural Experiment Statin, Stillwater R. K. Jhnsn University f Nebraska-Lincln, rjhnsn5@unl.edu R. P. Wettemann Oklahma Agricultural Experiment Statin, Stillwater Fllw this and additinal wrks at: Part f the Animal Sciences Cmmns Wilsn, E. R.; Jhnsn, R. K.; and Wettemann, R. P., "REPRODUCTIVE AND TESTICULAR CHARACTERISTICS OF PUREBRED AND CROSSBRED BOARS" (1977). Faculty Papers and Publicatins in Animal Science This Article is brught t yu fr free and pen access by the Animal Science Department at DigitalCmmns@University f Nebraska - Lincln. It has been accepted fr inclusin in Faculty Papers and Publicatins in Animal Science by an authrized administratr f DigitalCmmns@University f Nebraska - Lincln.

2 REPRODUCTIVE AND TESTICULAR CHARACTERISTICS OF PUREBRED AND CROSSBRED BOARS 1,2 E. R. Wilsn, R. K. Jhnsn and R. P. Wettemann 3 Oklahma Agricultural Experimen t Statin, Stillwater SUMMARY One-hundred-ninety-five Durc (D), Hampshire (H), Durc X Hampshire (DXH) and Hampshire X Durc (HX D) bars were evaluated fr reprductive perfrmance. One-hundred-sixteen bars were castrated at apprximately 225 days f age t evaluate testicular and epididymidal weights and sperm numbers. Testes frm crssbred bars were g heavier (P.01) and cntained 14.4I billin mre sperm (P.01) than thse frm purebred bars. Testes frm Hampshire bars were g heavier with billin mre sperm than thse frm Durcs. There were n significant differences between breeds fr caput-crpus epididymidal measurements. Durcs had billin mre sperm (P.05) in the cauda epididymis than Hampshire bars. Testes weight and testes sperm numbers were significantly crrelated with caput-crpus epididymidal and cauda epididymidal sperm numbers. Crrelatins f testicular and epididymidal characteristics with grwth rate and backfat t 100 kg were small and nnsignificant. Twenty 7.5-mnth t 9-mnth-ld D, Dx H and HXD bars and 19 H bars were each mated t tw Yrkshire gilts t evaluate reprductive efficiency. Cnceptin rates were: D, 63.2%; DXH, 67.5%; HXD, 60.0%; and H, 48.6%. Number f embrys 30-days pstbreeding was and (P>.10) fr gilts mated t purebred and crssbred sires, respectively. Twenty-eight f 36 crssbred bars mated each time they were expsed t an estrus gilt but nly 11 f 36 f the purebred bars mated each time. Nne f the crssbred bars failed t mate mre than nce, while 15 f 36 purebred bars failed t mate tw r mre times. In general, differences amng breed grups fr time required t munt after expsure t estrus gilt and length f ejaculatin time were small and nnsignificant. (Key Wrds: Male Reprductin, Crssbred Bars. INTRODUCTION Few research reprts are available characterizing breeds f swine fr male reprductive efficiency r evaluating the reprductive perfrmance f the crssbred bar. Hauser et al. (1952) fund that crssbred bars surpassed the parent lines in testis weight, epididymis weight, and stage f spermatgenesis. Swierstra (1968b) reprted that there was n significant difference between l 1-mnth-ld Yrkshire and Lacmbe bars fr testis weight r fr daily sperm prductin/gram net testis weight. Evidence is incnclusive fr evaluating the influence breed f service sire has n number f pigs brn r cnceptin rate. O'Ferrall et al. (1968) reprted breed f sire effects were nt significant fr litter size r weight at birth, 21 r 56 days. Rahnefeld and Swierstra (1970) fund that sire effects were significant in Yrkshire and Lacmbe bars fr number brn alive and the number f pigs weaned per litter. Jhnsn and Omtvedt (1973) and Yung et al. (1976b) fund that sire and breed f sire effects were nt significant fr litter size :Jurnal Article 3193 f the Agricultural Experi- 30-days pstbreeding r at birth but were ment Statin, Oklahma State University, Stillwater. significant fr litter size at 21 and 42 days f Research cnducted by the Department f Animal age. Science and Industry (Prject 1444). This study was designed t evaluate Durc, 2The authrs express appreciatin t Mr. James Hampshire and reciprcal crss bars fr testic- Hlzer fr technical assistance prvided in cllectin f these data. ular and epididymidal develpment, fertility, 3Department f Animal Sciences and Industry, litter size 30-days pstbreeding, mating behav- Oklahma State University, Stillwater ir and the relatinship f grwth and backfat 939 JOURNAL OF ANIMAL SCIENCE, Vl. 44, N. 6 (1977)

3 940 WILSON, JOHNSON AND WETTEMANN with testicular measurements. MATERIALS AND METHODS The bars studied were brn during fall 1973, spring and fall 1974 and spring 1975 at the Stillwater Swine Farm. Purebred Durc and Hampshire herds have been maintained since 1969 with at least tw new herd sires intrduced each year. Crssbred bars were prduced frm reciprcal matings between randmly selected individuals frm the purebred herds. All bars were raised n a cncrete flr frm 8 weeks f age until reaching 100 kilgrams. Bars were weighed ff test weekly at which time they were prbed fr backfat and placed in dirt lts with 10 t 12 bars per lt. Six bars frm each breed grup (Durc, Hampshire, Durc Hampshire and Hampshire Durc) were randmly selected t be kept fr the breeding phase f the study and the remaining bars were castrated as they reached 7.5 mnths f age. The distributin f bars by breed grup is listed in table 1. The mean age at castratin was 229 days (SD = 3). Bars were bilaterally castrated and the right testis was retained fr evaluatin. Testicular parenchymae, caput-crpra epididymides and caudae epididymides were weighed and hmgenized in saline-tritn-merthilate fluid (Amann and Lambiase, 1969), and sperm numbers were determined in the tissues (Kirtn et al., 1967). All values were multiplied by tw t place n a bar basis. Each f fur breeding seasns fr the repr- Breed a TABLE 1. NUMBER OF BOARS BY BREED GROUP THAT WERE CASTRATED OR MATED N. bars castrated N. f bars that were mated DX D DX H H X D H H Ttal ad = Durc, H = Hampshire, breed f sire listed first. ductive efficiency prtin f the study began when the yungest bars had reached 7.5 mnths f age. The bars ranged in age frm 7.5 t 9 mnths at the start f the breeding seasn which began apprximately Nvember 10 in the fall and May 1 in the spring. Six bars, which were littermates t ne r mre f the castrated bars, were used per breed grup. All six bars were individually expsed t Yrkshire gilts until five had successfully mated with a gilt. Bars were randmly chsen acrss breed grups t mate with 7.5- t 9-mnth ld gilts. Gilts were checked daily fr estrus with a teaser bar. If a bar failed t mate, he was remved frm the pen and a different bar was allwed t mate. When a bar mated with his first gilt, he was given a repeat breeding with the same gilt the fllwing day. The same prcedure was fllwed fr the secnd gilt t which the bar was mated but n bar was allwed t mate with the secnd gilt until five bars per breed grup had successfully mated with ne gilt. All matings were made in a 5 X 5 m pen with a cncrete flr. Time was recrded fr tw perids during each mating. Perid 1 was the interval frm when the bar entered the pen until he made a munt. Perid 2 was the interval frm intrmissin until the cmpletin f ejaculatin. The bars were given assistance nly when it appeared that the mating wuld nt be cmpleted withut assistance. Apprximately 30-days pstbreeding the gilts which had nt returned t estrus were slaughtered. The reprductive tracts were dissected t determine the number f embrys and the varies were examined fr crpra lutea. Least-squares prcedures were used fr analysis f testicular and epididymidal characteristics and mating behavir times. The mdel was: Yijkl = /2 + A i + Sj + D k + (AS)i j + (AD)ik + (SD)jk + (ASD)ij k + eijkl where Yijkl = the bserved trait f the lth bar frm the i th seasn, jth breed f sire and k th breed f dam; /a = ppulatin mean; A i = fixed effect f the ith seasn; Sj = fixed effect f the jth breed f sire; D k = fixed effect f the k th breed f dam; (AS)ij, (AD)ik, (SD)jk and (ASD)ij k represent the respective interactins, and eijkl is the randm effect assciated with the ijklth bservatin. Fr the analysis f number f embrys, the linear and quadratic regressins n number f crpra lutea were added t the mdel. Crrelatins amng traits were btained frm

4 REPRODUCTIVE CHARACTERISTICS OF BOARS 941 within seasn and breed grup crrected sums f squares and crss prducts and pled acrss subclasses. Intervals fr munt and ejaculatin fr the first and secnd gilt mated t each bar were first analyzed separately. Differences between times were small and nnsignificant. Als, the crrelatin fr interval t munt fr the first and secnd gilt mated t each bar was.02 while the crrelatin fr interval fr ejaculatin was.11; therefre, the data were pled. This increased the number f bar recrds since each bar culd be represented ne r tw times. Since crrelatins amng intervals fr gilts mated t each bar were small, this shuld nt bias the errr variance. Ejaculatin time was nt recrded the first seasn s the number f recrds fr munt times is nt equal t the number fr ejaculatin time. Mating behavir data (number f successes and failures f a bar t mate when expsed t an estrus gilt) were cllected in the last three seasns. The median test (Cnver, 1971)was used t analyze these data. Cnceptin rate was analyzed by chi-square (Steel and Trrie, 1960). RESULTS AND DISCUSSION Testicular and Epididymidal Characteristics. Seasn, breed f sire and the interactin f breed f sire by breed f dam were significant surces f variatin fr mst testicular and epididymidal traits. Seasn effects were significant fr all testicular measurements and all epididymidal measurements except caputcrpus epididymis weight. Breed f sire f bar was significant fr testicular weight, caputcrpus epididymidal and cauda epididymidal weight. Breed f sire by breed f dam f bar interactin, an indicatin f hetersis, was significant fr testicular weight, number f testicular sperm and cauda epididymidal weight. The breed grup means fr testicular characteristics are presented in table 2. The crssbred mean testicular weight f g was 16% heavier (P.01) than the purebred mean f grams. Testicular weights were nt significantly different fr Hampshire and Durc bars (614.9 and g, respectively). Swierstra (1968b) reprted mean testis weights f g and fr ll-mnth-ld Yrkshire and Lacmbe bars, respectively, which were nt significantly different. Crssbred bars had 25.1% ( ) mre testicular sperm (P.01) than purebred bars. Testicular sperm numbers fr Durc and Hampshire bars were nt significantly different. Wettemann et al. (1976) bserved ttal testicular sperm in yearling Yrkshire bars. Sperm numbers fr the purebred and crssbred bars in this study were 55 and 69%, respectively, f this value. This wuld suggest that these bars were nt sexually mature. Sperm cncentratins (testicular sperm n./ testes weight) were nt significantly different between breed grups. Therefre, it appears that the increased sperm numbers in crssbred bars are mainly a functin f increased testes weight and nt due t hetersis fr increased sperm prductin per gram f tissue. Crssbred bars had mre caput-crpus epididymidal sperm than purebred bars and Hampshires had mre sperm than Durcs (table 2), althugh differences were nt significant. The cauda epididymides f crssbred bars were g heavier (P.05) and tended t have a higher sperm cunt. Durc bars had x 109 mre sperm (P.05) than Hampshire bars in the cauda epididymis and a higher sperm cncentratin. There are several pssible explanatins fr increased testicular sperm in crssbreds cmpared t purebreds even thugh epididymal sperm numbers were nt significantly different. Since these are yung bars that are still maturing, they may be prducing sperm at different rates (Amann, 1970). If this is the case, the crssbred bars may be increasing sperm prductin faster than purebreds, but these sperm may nt have arrived in the epididymis r traveled thrugh the epididymis since epididymal transit time is apprximately 10 days (Swierstra, 1968a). This may als explain the differences in the Durcs and Hampshires where Hampshires tend t have mre testes sperm numbers, but the Durcs have significantly mre ttal epididymidal sperm. Sampling and measurement errrs may als be invlved. A mre explicit explanatin may be that the epididymis has the capacity t stre a similar number f sperm regardless f breed and that excess sperm are reabsrbed in the epididymis r are excreted thrugh the urine. Amann and Almquist (1962) suggest that in dairy bulls the cauda epididymis is the site f sperm reabsrptin. They estimate that mre than 57% f

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8 REPRODUCTIVE CHARACTERISTICS OF BOARS 945 TABLE 5. MATING BEIIAVIOR FOR BOARS OF EACH BREED GROUP WHEN EXPOSED TO AN ESTRUS GILT Breed grup a N. f bars that Mated a Had fur Ttal gilt each Had ne Had tw Had three r mre n. time failure failures failures failures bars expsed t mate t mate t mate t mate D D X H H D H II ad = Durc, H = Hampshire, breed f sire listed first. sperm prduced are reabsrbed in bulls which were ejaculated eight times per week and 97% f sperm prductin is reabsrbed in bulls at sexual rest. Testicular weight is significantly crrelated with all testicular and epididymidal characteristics except testicular sperm cncentratin and caput-crpus epididymidal weight (table 3). The crrelatin cefficients f testicular weight with testicular sperm numbers, caput-crpus epididymidal sperm numbers and cauda epididymidal sperm numbers were.65,.51 and.49, respectively. The crrelatins f testicular sperm numbers with caput-crpus epididymidal and cauda epididymidal sperm numbers were.45 and.51, respectively. Almquist and Amann (1961) reprted a crrelatin f.65 between testicular weight and testicular sperm numbers in mature, sexually-rested dairy bulls. Hauser et al. (1952) suggests that testis grwth is highly assciated with bdy weight. Bar weights at castratin were nt recrded s the nly estimate f bdy size is daily gain and days t 100 kg alng with backfat prbe at 100 kilgrams. The crssbred bars gained kg/day faster (P.001) than purebred bars; similarly, Durc bars gained kg/day faster (P.001) than Hampshires. tlampshires had crn less prbe backfat (P.001) than Durcs. There was virtually n difference between purebreds and crssbreds fr prbe backfat at 100 kilgrams. These breed differences agree well with thse reprted by Yung et al. (1976a) fr barrws and gilts. The crrelatins f testicular and epididymidal characteristics with grwth rate, days t 100 kg and backfat prbe were small and nnsignificant (table 3). Crrelatins between testicular and epididymidal characteristics and age at castra- tin were very small as wuld be expected since little difference existed amng bars in age at castratin. Reprductive Efficiency. There was n significant difference between breed grups fr the percent f gilts pregnant (table 4). The crssbreds had a 7.9% higher cnceptin rate than purebreds; hwever, this was due mainly t the 14.6% lwer cnceptin rate fr Hampshire bars cmpared t Durc bars. Crssbred bars sired mre embrys per gilt expsed than purebreds and Durc bars sired mre embrys per gilt expsed than Hampshire bars. Durc bars were similar in this trait t crssbreds. Much f the lw perfrmance f the ltampshire bars fr number f embrys per gilt expsed can be attributed t eight ut f 19 (42%) f these bars that failed t settle a single gilt. The linear and quadratic partial regressins f number f embrys n number f crpra lutea were significant; therefre, breed grup embry number means were adjusted t the verall mean vulatin rate. Litter characteristics were nt significantly affected by breeding f bar; hwever, crssbred bars sired litters which had mre embrys per pregnant gilt than purebred bars. Embry survival rate (percent embrys f crpra lutea) was fr litters by crssbred bars cmpared t fr litters by purebred bars. Survival rates are belw the 84% reprted fr Hampshire Yrkshire and Durc x Yrkshire matings in an earlier study (Jhnsn and Omtvedt, 1973). The failure f breed f sire t be significant fr embry numbers is cnsistent with Reddy et al. (1958) and O'Ferrall et al. (1968) wh reprted nnsignificant breed f sire effects fr litter size

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10 REPRODUCTIVE CHARACTERISTICS OF BOARS 947 at birth, 21 days r 56 days. Jhnsn and Omtvedt (1973), hwever, fund a significant breed f sire effect fr number f pigs in a litter at 21 and 42 days. In the same study they bserved n significant difference amng breeds f sire fr number f embrys at 30-days pstbreeding. Mating Bebavir. Mating behavir f crssbred bars was significantly different (P.001) frm that f purebred bars (table 5). Twentyeight f the crssbreds mated every time they were expsed t an estrus gilt and eight failed ne time. Only three f the Durcs and eight f the Hampshires mated every time. Nne f the crssbred bars had mre than ne failure t mate while 15 (42%) purebred bars had tw r mre failures. Dewsbury (1975) reprted that the prprtin f inbred parental male rats that failed t mate in a series f fur cnsecutive mating tests was much greater than the prprtin f the F1 males that failed the test. There was little difference amng breed grups fr interval frm expsure t an estrus gilt t munting r fr ejaculatin time (table 6); hwever, Durc bars ejaculated sec lnger (P.05) n the secnd mating than did Hampshires. Bth purebred and crssbred bars munted faster and ejaculated lnger n the secnd day a gilt was in estrus (repeat mating) than the first day. Since crssbred bars had fewer failures t mate and tended t munt faster n the first munt, it appears that crssbred bars are quicker t munt. Hwever, nce the purebreds have munted a gilt there is little difference between the breed grups in length f time fr ejaculatin r in time required fr additinal munts. There was a large amunt f bar variatin fr intervals measured during mating (SD = 84.9 and 73.8 sec fr munt and ejaculatin times, respectively). This study suggests that unless a mre descriptive methd t quantify mating behavir is develped the inherent and envirnmental causes f bar variatin will make it very difficult t study sexual behavir r t adequately relate male sexual activity t ther measures f reprductive efficiency. LITERATURE CITED Almquist, J. O. and R. P. Amann Reprductive capacity f dairy bulls. 11. Gnadal and extra- gnadal sperm reserves as determined by direct cunts and depletin trials; Dimensins and weight f genitalia. J. Dairy Sci., 44:1668. Amann, R. P Sperm prductin rates. In A. D. Jhnsn, W. R. Gmes and N. L. VanDemark (Ed.) The Testis. Vl. 1. Academic Press, New Yrk. p Amann, R. P. and J. O. Almquist Reprductive capacity f dairy bulls. VI. Effect f unilateral vasectmy and ejaculatin frequency n sperm reserves; aspects f epididymal physilgy. J. Reprd. Fertil. 3:260. Amann, R. P. and J. T. Lambiase, Jr The male rabbit. Ill. Determinatin f daily sperm prductin by means f testicular hmgenates. J. Anim. Sci. 28:369. Cnver, W. J Practical Nnparametric Statistics. Jhn Wiley and Sns, Inc., New Yrk. Dewsbury, D. A A diallel crss analysis f genetic determinants f cpulatry behavir in rats. J. Cmp. and Physil. Psychl. 88:2, 713. Hauser, E. R., G. E. Dickersn and D. T. Mayer Reprductive develpment and perfrmance f inbred and crssbred bars. MO. Agr. Exp. Sta. Res. Bull Jhnsn, R. K. and I. T. Omtvedt Evaluatin f purebreds and tw-bred crsses in swine: reprductive perfrmance. J. Anim. Sci. 37:1279. Kirtn, K. T., C. Dcsjardins and H. D. Hafs Distributin f sperm in male rabbits after varius ejaculatin frequencies. Anat. Rec. 158:287. O'Ferrall, G. J. Mre, H. O. Hetzer and J. A. Gaines Hetersis in preweaning traits in swine. J. Anita. Sci. 27:17. Rahnefeld, G. W. and E. E. Swierstra Influence f the sire n litter size in swine. Can. J. Anim. Sci. 50:671. Reddy, V. B., J. F. Lasley and D. T. Mayer Genetic aspects f reprductin in swine. MO.Agr. Exp. Sta. Res. Bull Steel, R. G. D. and J. A. Trrie Principles and Prcedures f Statistics. McGraw-Hill Bk C., New Yrk. Swierstra, E. ~ E. 196ga. Cytlgy and duratin f the cycle f the seminiferus epithelium f the bar. Duratin f the spermatzan transit thrugh the epididymis. Anat. Rec. 161:171. Swierstra, E. E. 1968b. A cmparisn f spermatza prductin and spermatza utput f Yrkshire and Lacmbe bars. J. Reprd. Fertil. 17:459. Wettemann, R. P., M. E. Wells, I. T. Omtvedt, C. E. Ppe and E. J. Turman Influence f elevated ambient temperature n reprductive perfrmance f bars. J. Anim. Sci. 42:664. Yung, L. D., R. IC Jhnsn, I. T. Omtvedt and l_. E. Waiters. 1976a. Pstweaning perfrmance and carcass' merit Of purebred and tw-breed crss pigs. J. Anita. Sci. 42:1124. Yung, L. D, R. K. Jhnsn and I. T. Omtvedt. 1976b. Reprductive perfrmance f swine bred t prduce purebred and tw-breed crss litters. J. Anita. Sci. 42:1133.