Comparison of methods for predicting yearling scrotal circumference and correlations of scrotal circumference to growth traits in beef bulls

From 1981 through 1986, BW, hip height, and scrotal circumference (SC) measurements were obtained on 329 bulls at the start of a 140-d gain test (SOT) and every 28 d to the end of test (EOT). Age, overall ADG, weight per day of age, ADG by period, and SC growth (cm/d) were calculated. Data were analyzed in two data sets because age of dam (AOD) and birth weights were unavailable between 1981 and 1983. Correlations of SC to other traits measured and probabilities for bulls attaining 30 or 32 cm SC by 365 d of age were calculated. Two adjusted 365-d SC (365-d SC) were calculated for each individual from regression analysis and from the following formula: 365-d SC = [(SCEOT-SCSOT)/140 d] x [365-ageSOT] + SCSOT. Except for ADG in Data Set 2, breed group differences (P less than .05) were observed for correlations of SC to all growth traits, age, and AOD. To attain 30 cm SC by 365 d of age with nearly 100% probability, Angus, Simmental and Zebu-derived bulls needed a 23-cm SCSOT, whereas continental (other than Simmental) and Polled Hereford bulls required a 26-cm SCSOT. Overall, 365-d SC means calculated by regression analysis or formula method did not differ (P greater than .10) for either data set.     

Effects of scrotal circumference of sire on age of calving in Ontario beef heifers

Calving records for daughters of 667 Record of Performance tested sires were examined to study factors related to age at first calving. For the 3025 heifers analyzed, mean age (± SD) at first calving was 791.5 ± 161.6 days (26.4 ± 5.4 months). There were significant effects of the breed of sire on age of heifer at first calving. Daughters of Angus sires calved earlier than daughters of Charolais, Hereford, Limousin, and Simmental sires. Mean ages at first calving for daughters of Hereford, Limousin, and Simmental bulls were significantly (p < 0.05) correlated with the sire's end-of-test age-adjusted scrotal circumference, but these correlations were not significant when farm effects were controlled. It appears that unknown herd level factors are more important in determining age at first calving in Ontario herds than using early maturing sires as determined by scrotal circumference measurements.     

Genetic analyses of scrotal circumference size and growth in Rambouillet lambs.

The objectives of this study were to identify nongenetic factors influencing scrotal circumference size and growth and to estimate heritabilities of scrotal circumference size at different ages and scrotal circumference growth between ages. Data on scrotal circumference, live weight, and age were recorded over 6 yr (1982 to 1987) on 541 spring-born Rambouillet ram lambs (109 sires, 307 dams) at the Dixon Springs Agricultural Center. Scrotal circumference and live weight were predicted at four ages (90, 120, 150, and 180 d) for each lamb. The two models used to evaluate factors affecting scrotal circumference size at fixed ages were the same except for the addition of live weight and live weight squared to one of the models. Likewise, the two models used for scrotal circumference growth between ages were the same except for the addition of live weight change and live weight change squared to one of the models. Year and type of birth were significant sources of variation for both traits under both models. Regression coefficients for live weight and live weight squared on scrotal circumference size and for live weight change and live weight change squared on scrotal circumference growth and for day of birth within year for both traits were generally different from zero (P less than .05). Heritability estimates for scrotal circumference size at fixed ages ranged from .19 to .41. Adjustments for live weight led to an average 41.5% increase in heritability estimates. For scrotal circumference growth, heritabilities ranged from .17 to .60 and adjustments for live weight change resulted in an average 13% decrease in estimates.(ABSTRACT TRUNCATED AT 250 WORDS)     

The relationship of scrotal circumference to testicular weight in rams

Scrotal circumference (SC), testicular diameter (TD) and testicular weight (TW) were measured at necropsy of 148 Merino rams of varying age (yearling: 110, 2- to 3-year-old: 5, 4-year-old: 28, greater than 7-year-old: 5). These rams, although culled from flocks in north western Queensland for poor conformation or advancing age, had no clinically palpable or gross necropsy lesions of the genitalia. Despite the fact that SC measurement was performed at necropsy on scrota with greatly varying wool cover and its diverse content of plant material (burrs and grass seeds), the correlation of SC with TW was positive, high and significant (r = 0.92, P less than 0.01). This correlation was greater than that between TD and TW (r = 0.91, P less than 0.01) even though both were measured after dissection of the scrotal contents. The clinically convenient SC measurement deserves wider application as an estimate of testicular weight and therefore fertility in rams.     

Genetic relationships between scrotal circumference and female reproductive traits

Records for yearling scrotal circumference (SC; n = 7,580), age at puberty in heifers (AP; n = 5,292), age at first calving (AFC; n = 4,835), and pregnancy, calving, or weaning status following the first breeding season (PR1, CR1, or WR1, respectively; n = 7,003) from 12 Bos taurus breeds collected at the Meat Animal Research Center (USDA) between 1978 and 1991 were used to estimate genetic parameters. Age at puberty (AP) was defined as age in days at first detected ovulatory estrus. Pregnancy (calving or weaning) status was scored as one for females conceiving (calving or weaning) given exposure during the breeding season and as zero otherwise. The final model for SC included fixed effects of age of dam at breeding (AD), year of breeding (Y), and breed (B) and age in days at measurement as a covariate. Fixed effects in models for AP and AFC were AD, Y, B, and month of birth. Fixed effects in models for PR1, CR1, and WR1 included AD, Y, and B. For all traits, random effects in the model were direct genetic, maternal genetic, maternal permanent environmental, and residual. Analyses for a three-trait animal model were carried out with SC, AP, and a third trait (the third trait was AFC, PR1, CR1, or WR1). A derivative-free restricted maximum likelihood algorithm was used to estimate the (co)variance components. Direct and maternal heritability estimates were 0.41 and 0.05 for SC; 0.16 and 0.03 for AP; 0.08 and 0.00 for AFC; 0.14 and 0.02 for PR1; 0.14 and 0.03 for CR1; and 0.12 and 0.01 for WR1. Genetic correlations between direct and maternal genetic effects within trait were -0.26, -0.63, -0.91, -0.79, -0.66, and -0.85 for SC, AP, AFC, PR1, CR1, and WR1, respectively. Direct genetic correlations between SC and AP and between those traits and AFC, PR1, CR1, and WR1 ranged from -0.15 (between SC and AP) to 0.23 (between AP and WR1). Estimates of heritability indicate that yearling SC should respond to direct selection better than AP, AFC, PR1, CR1, and WR1. Variation due to maternal genetic effects was small for all traits. No strong genetic correlations were detected between SC and female reproductive traits or between AP and the other female traits. These results suggest that genetic response in female reproductive traits through sire selection on yearling SC is not expected to be effective.     

Excessive dietary selenium to primiparous sows and their offspring. I. Influence on reproduction and growth

The effect of high dietary selenium (Se) on the reproductive performance, growth and health in pigs was examined. Addition of 0 to 16 mg Se per kg feed to sows and their piglets up to nine weeks of age did not cause any manifest toxic effect. None of the sows died due to the Se treatment. The piglets were all fullborn and showed no macroscopic abnormalities. The treatment did not influence neither the number of liveborn and stillborn piglets in the litter, nor the survival of the piglets until 9 weeks of age. The weight of the whole litter at birth was unaffected by the Se supplementation, while there was a significant difference in body weight of the piglets at 9 weeks of age. The weaned pigs receiving 8 or 16 mg Se per kg feed had a reduced feed intake. As the feed utilization was unaffected by treatment, these pigs had a significantly lower weight at 9 weeks of age.     

Assessment of reproduction and growth performance of offspring derived from somatic cell cloned pigs

Since cloned pig was successfully produced, a new opportunity for porcine breeding industry to conserve genetic resources has been opened. However, there has been no report to investigate whether both somatic cell nuclear transfer (SCNT) pigs and their offspring have the characteristics of the donor breed. In this study, we compared the reproductive and growth performance of American Large White boars cloned by SCNT with the donor boar, and analyzed the test parameters, including semen quality, re‐service rate, rate of parturition, and average daily gain. The results showed that these cloned boars and the donor boar had no significant differences in the tests (P > 0.05) and the growth performance of their offspring was similar to the naturally bred American Large White pigs. In summary, the reproductive and growth performance of cloned pigs are similar to the donor pig and within the normal range. This suggests that pigs cloned by SCNT have the potential to be used in reproduction and breeding.     

Age adjustment factors, heritabilities and genetic correlations for scrotal circumference and related growth traits in Hereford and Brangus bulls

Field data records on 10,511 Hereford and 2,522 Brangus bulls between 330 and 430 d of age were analyzed to find age of calf and age of dam adjustment factors for yearling scrotal circumference. Age of calf adjustment factors were .024 cm/d for Hereford bulls and .041 cm/d for Brangus bulls. Sons of Hereford dams were adjusted to a 6- to 8-yr dam age basis by adding .7, .3, .2, .2 or .3 cm for dams 2, 3, 4, 5 or 8 or more years old, respectively. Age of dam adjustment factors for Brangus bulls were .8, .4, .3 and .2 for dams 2, 3, 4 or 8 or more years old, respectively. Variance and covariance components for yearling scrotal circumference and several growth traits were estimated within breed using multiple-trait models and pseudo expectations involving the solutions and the right-hand sides of the mixed-model equations. Additive heritability estimates for yearling scrotal circumference of .53 and .16 were found for Hereford and Brangus bulls, respectively. Maternal heritability estimates of .12 and .10 were found for Hereford and Brangus bulls, respectively. Genetic correlations between yearling scrotal circumference and other growth traits were positive for both sets of data indicating that selection for yearling scrotal circumference should not adversely affect other growth traits in either breed. Environmental correlation estimates between yearling scrotal circumference and adjusted birth weight and between yearling scrotal circumference and adjusted 205-d weight and adjusted 365-d height were positive and moderate in magnitude for both breeds.     

Additive genetic relationships between heifer pregnancy and scrotal circumference in Nellore cattle

To estimate heritability (h2) for yearling heifer pregnancy and to estimate the genetic correlation between heifer pregnancy and scrotal circumference, 18,145 records of Nellore heifers exposed to breeding at an age of approximately 14 mo and 25,466 records of contemporary young bulls were analyzed. Heifer pregnancy was considered as a categorical trait, with the value 1 (success) assigned to heifers that were pregnant after rectal palpation approximately 60 d after the end of a 90-d breeding season and the value 0 (failure) otherwise. A single-trait animal model for heifer pregnancy and a two-trait animal model including heifer pregnancy and scrotal circumference were used. Contemporary groups were defined in two ways: including (CG2) or not including (CG1) weaning management of the heifer. Heritability estimates obtained by Method R in single-trait analyses were 0.68 +/- 0.09 and 0.61 +/- 0.10 using CG1 and CG2 definitions, respectively. Heritability estimates for two-trait analyses were 0.69 +/- 0.09 (CG1) and 0.63 +/- 0.08 (CG2) for heifer pregnancy and 0.57 +/- 0.03 (both CG) for scrotal circumference. The genetic correlation estimates between the two traits were 0.20 +/- 0.12 (CG1) and 0.20 +/- 0.13 (CG2). Based on the results of this study, EPD for heifer pregnancy can be used to select bulls for the production of precocious daughters and will be more effective than selecting on scrotal circumference EPD in Nellore cattle. However, scrotal circumference can be incorporated in a two-trait analysis to increase the accuracy of prediction for heifer pregnancy EPD for young bulls. Using contemporary group without heifer weaning management gave higher h2 and, for two-trait analysis, converged more quickly.     

Evaluation of American Wagyu sires for scrotal circumference by age and body weight

Thirty-six percent of American Wagyu bulls do not meet the current minimum standards set by the Society of Theriogenology for the breeding soundness exam. In contrast, only 15% of bulls of domestic breeds do not meet the minimum standards. Scrotal circumference measurements of Wagyu are smaller than those of other breeds. The objective of this research was to describe scrotal circumference of Wagyu bulls as it relates to age and BW. The data set consisted of 190 Wagyu bulls housed at two locations. One hundred forty-one bulls constituted the first set of data (location 1); scrotal circumference was measured one to six times per bull aged between 13 and 70 mo. Ninety-four of the bulls underwent semen evaluation for motility and morphology. Forty-nine bulls constituted the data set for which scrotal circumference and BW was measured one to nine times per bull between 5 and 21 mo of age (location 2). Mean scrotal circumference of bulls within each age group was as follows: 12 to 14 mo, 29.8 0.2 cm (mean +/- SE); 15 to 17 mo, 31.8 +/- 0.2 cm; 18 to 20 mo, 32.9 +/- 0.3 cm; 21 to 24 mo, 31.8 +/- 0.5 cm; and > 24 mo, 35.5 +/- 0.2 cm. Both age and BW were highly correlated to scrotal circumference (r = 0.81 and 0.82, respectively). Within each age group, there were a percentage of bulls that did not meet the minimum standard for scrotal circumference set by the Society of Theriogenology. The percentages were as follows: 12 to 14 mo, 46%; 15 to 17 mo, 25%; 18 to 20 mo, 33%; 21 to 24 mo, 42%; and > 24 mo, 32%. Morphology and motility were > 50% each in 91% of the bulls between ages 12 and 20 mo at location 1. Based on these data, it is recommended that Wagyu bulls be evaluated with the breed-specific minimum standards for scrotal circumference of 26 cm from 12 to 14 mo, 29 cm from 15 to 17 mo, and 30 cm from 18 to 20 mo of age.     

Relationships among age, body weight, scrotal circumference, semen quality and peripheral testosterone and estradiol concentrations in pubertal and postpubertal Holstein bulls

In the present study, the correlations among age, body weight, scrotal circumference (SC), semen quality and peripheral testosterone and estradiol-17beta (E(2)) concentrations were investigated in pubertal (n=5) and postpubertal (n=7) groups of Holstein bulls over a 6 week period. There were significant positive correlations (P<0.01) among age, body weight and SC in both groups, and similar significant correlations between sperm motility and SC in pubertal bulls (P<0.01) and between sperm concentration and SC in postpubertal bulls (P<0.05). The sperm motility after collection (P<0.05) and after freezing and thawing (P<0.01) of the postpubertal bulls correlated positively with the E(2) concentration. Estrogen may be important for the function of postpubertal bull testes, in which it may regulate spermatozoa motility in vivo.     

Effects of zeranol on reproduction in beef bulls: scrotal circumference, serving ability, semen characteristics, and pathologic changes of the reproductive organs

Effects of zeranol on scrotal circumference, serving ability, semen characteristics, and postmortem measurements of the genital organs were determined in beef bulls from 9 to 20 months of age. Group 1 (n = 5) served as a nonimplanted control group. Group 2A (n = 5) was implanted with 36 mg of zeranol at birth and at 3 and 6 months of age. Group 2B (n = 5) was implanted with 36 mg of zeranol every 3 months from birth through 18 months of age. Scrotal circumference was adversely affected by zeranol in groups 2A and 2B, but values approached those of group 1 with increasing age. Serving ability was also affected adversely but tended to recover with increasing age. Semen quality was low in groups 2A and 2B and did not improve with increasing age. There was no difference in testicular weight, vesicular gland weight, and penis length among groups when bulls were slaughtered at 20 months of age. Epididymal weight was greater in group-2B bulls and was most likely a consequence of epididymal lesions. Histologic examination of the genital organs revealed that zeranol induced adenomyosis and sperm granulomas in the caudae epididymidis and markedly altered the structure of the sexual accessory glands of bulls in groups 2A and 2B. Alterations in the vesicular glands were characterized by reduced alveolar development and an increase in connective tissue. Low epithelium associated with focal areas of squamous metaplasia were common in the prostate of groups 2A and 2B bulls. Lesions in the bulbourethral glands were characterized by low glandular epithelium, focal areas of squamous metaplasia, cystic collecting ducts, and an increase in connective tissue. Groups 2A and 2B had more abnormal seminiferous tubules than did group 1. Lesions in groups 2A and 2B may have been direct effects of zeranol or may have resulted from reduced testosterone secretion.     

Comparison of models for genetic evaluation of scrotal circumference in crossbred bulls

The aim of this study was to evaluate the effect of including concomitant body weight and(or) a random dam effect in genetic evaluation models on variance component estimates and standard error of prediction for scrotal circumference (SC) at 6, 8, 10, and 12 mo. Variance components and average standard errors of prediction were compared under models differing in either the number of related traits (M11 [SC], M12 [SC and BW]) or an uncorrelated random dam effect (M21 [SC], M22 [SC and BW]) using records on 1,547 bull calves. In a single-trait model (M11), estimates of direct heritabilities (h2a) for SC were .45, .49, .57, and .66 at 6, 8, 10, and 12 mo, respectively. In a two-trait model (M12), h2a were similar to those in M11 model. In M21, h2a for SC were .37, .42, .54, and .65, whereas the proportions of phenotypic variance due to dams (d2) were .12, .11, .04, and .02 at 6, 8, 10, and 12 mo, respectively. Similarly, in M22, h2a for SC were .36, .44, .56, and .65 and d2 were .13, .10, .02, and .02. Standard errors of prediction for SC EBV from M22 were reduced by 2.86, 1.21, 3.02, and 1.99% relative to M21 and by 6.45, 2.70, 2.72, and 1.21% relative to M11 at 6, 8, 10, and 12 mo, respectively. Standard errors of prediction for SC EBV from M12 were reduced by .06, .73, 1.56, and .87% relative to M11 at 6, 8, 10, and 12 mo, respectively. The importance of the dam effect decreased with age for both SC and BW. These results demonstrate that a two-trait (SC and BW) animal model would result in more accurate evaluations of yearling SC EBV in beef cattle than a single-trait model.     

Additive genetic relationships between heifer pregnancy and scrotal circumference in Hereford cattle.

The objective of this study was to determine an appropriate method for using yearling scrotal circumference observations and heifer pregnancy observations to produce EPD for heifer pregnancy. We determined the additive genetic effects of and relationship between scrotal circumference and heifer pregnancy for a herd of Hereford cattle in Solano, New Mexico. The binary trait of heifer pregnancy was defined as the probability of a heifer conceiving and remaining pregnant to 120 d, given that she was exposed at breeding. Estimates of heritability for heifer pregnancy and scrotal circumference were .138+/-.08 and .714+/-.132, respectively. Estimates of fixed effects for age of dam and age were significant for heifer pregnancy and bull scrotal circumference. The estimate of the additive genetic correlation between yearling heifer pregnancy and yearling bull scrotal circumference was .002+/-.45. Additional analyses included models with additive genetic groups for scrotal circumference EPD for heifer pregnancy or heifer pregnancy EPD for scrotal circumference to account for a potential nonlinear relationship between scrotal circumference and heifer pregnancy. Results support the development of a heifer pregnancy EPD because of a higher estimated heritability than previously reported. The development of a heifer pregnancy EPD would be an additional method for improving genetic merit for heifer fertility.     

Genetic relationship among stayability,scrotal circumference and post-weaning weight in Nelore cattle

Improvement of female fertility has become of fundamental importance for profit maximization in the beef cattle herds. Consequently, animal breeding programs in Brazil have applied selection effort to traits related to reproduction as for scrotal circumference (SC), which is already incorporated to the selection routine of the breeders. However, studies have reported no favorable genetic correlation (r_g) of SC with some fertility traits. Recently, stayability (STAY) has been used as means to better indicate and improve female fertility. Values for r_g of STAY with reproductive and productive traits are not available in literature. Therefore, the objectives of the present study are to analyze the r_g between SC and STAY and STAY with weight at 550 days (W550) in Nelore cattle. Data set of 55,682, 28,507 and 59,750 animals for STAY, SC and W550, respectively, were analyzed using two-trait animal model based on Gibbs sampling algorithm. The estimate of posterior r_g between STAY and SC was 0.07 ± 0.03, which can be considered as low and suggesting that STAY does not have sensible relation with SC. The r_g of STAY and W550 was 0.15 ± 0.01, considered low, although positive. It means that selection for W550 should not negatively affect STAY.     

Genetic parameter estimates for scrotal circumference and semen characteristics of Line 1 Hereford bulls

The objectives of this study were to estimate heritability for scrotal circumference (SC) and semen traits and their genetic correlations (rg) with birth weight (BRW). Semen traits were recorded for Line 1 Hereford bulls (n = 841), born in 1963 or from 1967 to 2000, that were selected for use at Fort Keogh (Miles City, MT) or for sale. Semen was collected by electroejaculation when bulls were a mean age of 446 d. Phenotypes were BRW, SC, ejaculate volume, subjective scores for ejaculate color, swirl, sperm concentration and motility, and percentages of sperm classified as normal and live or having abnormal heads, abnormal midpieces, proximal cytoplasmic droplets (primary abnormalities), bent tails, coiled tails, or distal cytoplasmic droplets (secondary abnormalities). Percentages of primary and secondary also were calculated. Data were analyzed using multiple-trait derivative-free REML. Models included fixed effects for contemporary group, age of dam, age of bull, inbreeding of the bull and his dam, and random animal and residual effects. Random maternal and permanent maternal environmental effects were also included in the model for BRW. Estimates of heritability for BRW, SC, semen color, volume, concentration, swirl, motility, and percentages of normal, live, abnormal heads, abnormal midpieces, proximal cytoplasmic droplets, bent tails, coiled tails, distal cytoplasmic droplets, and primary and secondary abnormalities were 0.34, 0.57, 0.15, 0.09, 0.16, 0.21, 0.22, 0.35, 0.22, 0.00 0.16, 0.37, 0.00 0.34 0.00, 0.30, and 0.33, respectively. Estimates of rg for SC with color, volume, concentration, swirl, motility, and percentages of live, normal, and primary and secondary abnormalities were 0.73, 0.20, 0.77, 0.40, 0.34, 0.63, 0.33, -0.36, and -0.45, respectively. Estimates of rg for BRW with SC, color, volume, concentration, swirl, motility, and percentages live, normal, and primary and secondary abnormalities were 0.28, 0.60, 0.08, 0.58, 0.44, 0.21, 0.34, 0.20, -0.02, and -0.16, respectively. If selection pressure was applied to increase SC, all of the phenotypes evaluated would be expected to improve. Predicted correlated responses in semen characteristics per genetic SD of selection applied to SC were 0.87 genetic SD or less. If selection pressure was applied to reduce BRW, the correlated responses would generally be smaller but antagonistic to improving all of the phenotypes evaluated. Predicted correlated responses in SC and semen characteristics per genetic SD of selection applied to BRW were less than 0.35 genetic SD.     

Effect of banding or burdizzo castration on plasma testosterone, acute-phase proteins, scrotal circumference, growth, and health of bulls

The objective was to assess the effect of banding or burdizzo castration performed on farms on plasma testosterone, acute-phase proteins, scrotal circumferences, growth, and well-being of bulls. 243 Continental bulls (12 months; 399.2 ± 5.72 kg) from three different farms were allocated at random, after stratification on weight within breed type, to one of three treatment groups: banding castration (BAND; n = 80), burdizzo castration (BURD; n = 83), or controls (CON; n = 80). The castration methods were conducted under local anaesthesia, and tetanus toxoid vaccine and antibiotic were also injected at castration. BAND and BURD castrates had lower (P < 0.001) plasma testosterone concentration than control bulls, with no difference between BAND and BURD castrates on 28 d post-castration. From days 0 to 14 post-castration, BAND (P = 0.0002) and BURD (P < 0.0001) castrates had lower average daily gain (ADG) than CON bulls, no difference (P = 0.46) was found between BAND and BURD castrates. From days 15 to 28, BAND castrates had lower ADG compared with BURD castrates (P = 0.03) and CON bulls (P = 0.01), while no difference (P = 0.76) was found between BURD and CON. From days 29 to 56, BAND (P = 0.01) and BURD (P = 0.002) castrates had lower ADG than CON bulls, no difference (P = 0.55) was found between BAND and BURD. From days 57 to 84, the ADG of BAND castrates was not different compared with BURD castrates (P = 0.12) and CON bulls (P = 0.38), while BURD had lower (P = 0.02) ADG compared with CON. The integrated ADG from day 0 to 112 of BAND (P = 0.0001) and BURD (P = 0.02) groups were lower compared with CON, while there was no difference (P = 0.09) between BAND and BURD castrates. On d 14 post-castration, BAND castrates had lower scrotal temperature than BURD (P < 0.0001) and CON (P < 0.0001), and BURD castrates had greater (P < 0.006) scrotal temperature than CON; BAND castrates had lower scrotal latitudinal and longitudinal circumferences than BURD castrates (P < 0.001) and CON bulls (P < 0.001), and BURD castrates had greater (P < 0.001) scrotal latitudinal and longitudinal circumferences than CON bulls. BAND (P < 0.0001) and BURD (P = 0.01) castrates had greater glucose concentration than CON bulls, and BAND castrates had greater (P = 0.04) glucose concentration than BURD. In conclusion, BAND or BURD castration significantly reduced plasma testosterone concentration; reduced average daily weight gain mainly during the first 2 weeks, which was not compensated during the subsequent 16 weeks; increased withdrawal of stored energy and increased plasma protein concentration. BURD showed an advantage over BAND in growth during days 15 to 28 following castration.     

Relationship of age to body weight,scrotal circumference,testicular ultrasonograms,and semen quality in Sahiwal bulls

The objective of the present study was to determine the relationship of age to body weight (BW), scrotal circumference (SC), number of pixels of testicular ultrasonograms (NP), and semen quality in Sahiwal bulls. The study was based on 128 Sahiwal bulls of different age groups (from 0 to >100 months of age). Bulls were evaluated for SC, BW, and NP. Semen was evaluated once a week for five consecutive weeks from regularly collected donor bulls (n = 86) ranging in age from 25–30 to >100 months. Ejaculate volume, sperm motility, sperm concentration, sperm morphology, percent live sperms, sperm plasma membrane integrity, and normal acrosome were compared among different age groups. Mean SC and BW increased (P < 0.05) in a curvilinear manner from birth to >100 months of age. Mean NP of testicular ultrasonograms increased (P < 0.05) from 0 to 24 months and then plateaued until >100 months of age. Body weight, SC, and NP were positively correlated with age from birth until >100 months (r = 0.91, 0.87, and 0.40, respectively). Ejaculate volume (5.7 ± 0.2 vs. 4.6 ± 0.09 ml) and sperm concentration (1,281.6 ± 17.7 vs. 1,115.8 ± 55.9 × 10⁶/ml) increased (P < 0.05) in mature bulls compared to younger ones. However, motility (68.6 ± 0.3%), plasma membrane integrity (50.8 ± 1.0%), and normal acrosome (74.8 ± 0.5%) remained insignificant due to age. In six of eight age groups studied, morphological abnormalities were well within the range (18.1 ± 0.3%). In conclusion, the BW, SC, and NP of testicular ultrasonograms, ejaculate volume, and concentration increased with age. Moreover, semen quality is fairly independent of age except volume and concentration in Sahiwal bulls.     

Effects of sire line, sire, and sex on plasma urea nitrogen, body weight, and backfat thickness in offspring of Duroc and Landrace boars

In pork production, the efficiency of dietary protein (AA) use is low, resulting in urinary excretion of large quantities of nitrogen as urea. Use of AA and formation of urea are under enzymatic regulation, suggesting genetic regulation. The current study examined the effects of sire line, sire, and sex on growth characteristics and plasma urea nitrogen (PUN) concentrations in the offspring of 11 Duroc sires and 11 Landrace sires bred to Yorkshire-Landrace dams. Plasma samples were obtained at approximately 107 (age class = 107 d), 128 (age class = 128 d), and 149 (age class = 149 d) d of age from 511 boars, gilts, and barrows group-penned and fed standard finishing diets. Body weight and backfat (BF, mean of 3 measurements) were recorded at the time of blood sample collection. Sex, age class, and their interaction influenced (P < 0.01) BW, BF, and PUN. Predicted traits (i.e., ADG, BW at 21 wk, average daily change in BF, BF at 21 wk, and the mean of 3 PUN measures) were generated. Means (+/-SD) were: ADG, 888 +/- 204 g; BW at 21 wk, 94.2 +/- 12.5 kg; average daily change in BF, 0.083 +/- 0.052 mm; BF at 21 wk, 13.8 +/- 3.0 mm; and the mean of 3 PUN measures, 16.2 +/- 4.4 mg/dL. Predicted weight traits were influenced (P < 0.05) by sire line, and sex influenced (P < 0.01) all predicted traits. Heritability estimates for PUN at 107, 128, and 149 d of age were 0.35 +/- 0.15, 0.21 +/- 0.13, and 0.16 +/- 0.12, respectively. Phenotypic correlations of PUN with growth and fat traits were low. Genetic correlations of PUN measured at 107 d with growth and fat traits were low. However, genetic correlations of PUN measured at 128 or 149 d with growth and fat traits ranged from 0.81 to 0.95. Determination of PUN, as herein, may be of sufficient precision to allow its use in a selection protocol. Selection of pigs with superior growth performance and low PUN may result in a greater efficiency of dietary nitrogen use and a reduced negative environmental impact.