Genetic Parameters for Semen Production Traits in Austrian Dual-Purpose Simmental Bulls

Genetic parameters were estimated for semen production traits collected in an Austrian AI centre in the years 2000-2004. In total, 12,746 ejaculates from 301 Austrian dual-purpose Simmental (Fleckvieh) AI bulls were examined considering different effects on ejaculate volume, sperm concentration, percentage of viable spermatozoa in the ejaculate, total spermatozoa per ejaculate and motility. The model for genetic parameter estimation included the fixed effects age of bull, collection interval, number of collections on collection day, bull handler, semen collector, year and month of collection, a random additive genetic component and a permanent environmental effect. Correlations between estimated breeding values for semen traits and male fertility from the routine evaluation were calculated. The fertility trait considered in the routine evaluation is non-return rate 90 for the first insemination. All semen production traits were moderately heritable. Heritabilities for volume, concentration, percentage of viable spermatozoa, total number of spermatozoa and motility were 0.18, 0.14, 0.10, 0.22 and 0.04, respectively. Correlations between breeding values for semen quality traits and routinely estimated breeding values for male fertility were low and ranged from 0.08 to 0.17 indicating that semen production traits are rather poor predictors of male fertility.     

猪精液性状的遗传参数估计

本研究采用单性状重复力模型和双性状动物模型分别对公猪精液体积、精子活力、精子密度、精子畸形率4个性状进行遗传参数估计,并对不同性状间的遗传相关进行估计。结果显示:精液体积为中等遗传力(遗传力为0.29),精子密度、精子活力和精子畸形率性状具有较低遗传力,遗传力分别为0.10、0.16、0.15;这4个性状均有中等偏高的重复力,分别为0.47、0.42、0.36、0.50。精液体积与精子密度具有较强的遗传负相关(-0.389),精液体积与精子畸形率具有较弱的遗传负相关(-0.171),精子活力与精子畸形率具有强的遗传负相关(-0.826),其余性状均无明显遗传相关。以上结果表明可以通过对精液性状进行选择来提高公猪精液品质。     

Genetic Parameters of Foot and Leg Traits in Future AI Bulls: I. Influence of Age at Recording and Classifier

Information on foot and leg traits was collected on 8494 young potential future AI bulls of the three populations Danish Red, Danish Friesian and Danish Jersey by two classifiers between 1985 and 1996. Each animal was assessed at 5 and 10 months of age. The data set was used to examine the influence of age and classifier on genetic parameters of foot and leg traits by treating traits recorded at two different times or by two different people as a different characteristic in a bivariate analysis. The general incidence of foot and leg diseases was very low in young animals: only interdigital dermatitis, heel necrosis and solar bruising showed a frequency higher than 2% in 10-month-old bulls. The same traits measured on different claws yielded very high genetic correlations (r_g 0.77-0.98), suggesting that the number of measurements could be reduced. Hooves increased in size with age, and the genetic correlation between the two age classes was high (r_g 0.60-0.77). The agreement between classifiers was very high for objectively measured traits, especially for the younger age class, and interdigital dermatitis and heel necrosis, but inconclusive for the subjectively scored characteristics.     

广州地区娟姗公牛与荷斯坦公牛精液品质的比较研究

本试验选择亚热带气候条件下广州地区的娟姗公牛和荷斯坦公牛各5头,比较两个品种公牛的精液品质(采精量、原精密度、原精活力、细管精液产量、冻后活力、低渗膨胀率及穿透率)。研究表明,荷斯坦公牛每次采精的采精量(16.14±0.06 mL)和细管精液产量(189.17±3.11支)都极显著地高于娟姗公牛(4.74±0.05 mL,158.46±2.64支)(P<0.01);娟姗公牛的原精密度(8.95±0.08亿/mL)极显著地高于荷斯坦公牛(8.32±0.07亿/mL;P<0.01);娟姗公牛原精活力(0.731±0.004)高于荷斯坦公牛(0.729±0.003),但两者差异不显著(P<0.05);娟姗公牛精液的冻后活力(0.355±0.003)极显著高于荷斯坦公牛(0.339±0.003;P<0.01);娟姗公牛冷冻精液的低渗膨胀率(34.50%±0.49%)显著高于荷斯坦公牛(31.21%±0.59%;P<0.01);娟姗公牛冷冻精液对去透明带仓鼠卵的穿透率(84.51%±13.83%)显著高于荷斯坦公牛(81.52%±6.13%;P<0.05)。     

Genetic Parameters of Foot and Leg Traits in Future AI Bulls: II. Correlation to Body Conformation Traits in Daughters

The aim of this investigation was to establish genetic correlations between foot and leg traits in future potential AI bulls and body conformation traits in their daughters. Data consisted of records of 2394, 5002 and 1098 bulls of the breeds Danish Red, Danish Friesian and Jersey, respectively, which were correlated according to breed with 11846, 62875 and 10954 daughters sand their contemporaries, respectively. The bull traits included hoof measurements, horn characteristics and claw disease frequencies recorded at hoof trimming, while the data for the dairy cows contained the scores for rear leg side view, rear leg rear view, bone structure, quality of hocks and foot angle. The correlations between the claw diseases or horn characteristics on one side and the daughters' conformation on the other side were either negligible or inconclusive, while those between the bull's hoof measurements and the two conformation traits bone structure and hock quality were of statistical significance for all three breeds. Moreover, the stance of the rear leg showed a significant relationship to claw measurements in Danish Red and Jersey cattle. Small feet in bulls were correlated with a favourable expression of feet and legs in daughters. An improvement in foot and leg conformation traits in dairy cattle is possible by including claw measurements in the selection of future AI bulls.     

Case Study: Relationships of Scrotal Circumference and Scrotal Volume to Growth and Semen Traits in Beef Bulls

Breeding soundness examinations (BSE) were performed on 327 bulls at three locations in Wyoming and Montana. Scrotal circumference (SC), scrotal volume (SV), and body condition score (BCS) data were also collected. The animals were classified as yearlings, 2-yr-olds, or mature bulls. Age class and BCS had significant (P<0.01) effects on SC. Age class also accounted for significant (P<0.01) variation in SV. The correlation between SC and SV was 0.88. Scrotal circumference, SV, and pelvic area (PA) were measured and adjusted for age on the 139 yearling bulls at Location 1 (MT) to allow comparison with other age-adjusted traits. The linear regression of SC on age was 0.023 cm/d (P<0.05). Scrotal circumference and age were significant (P<0.01) sources of variation for the percentage of motile sperm (MOT). Composite yearling bulls had larger (P<0.05) adjusted SV, adjusted SC, pelvic height (PH), and percentage of MOT than Red Angus yearling bulls. The simple correlation between adjusted SC and adjusted yearling BW was 0.33 (P<0.05). Actual SC and SV were positively correlated with actual BW, actual hip height (HH), and percentage of MOT. Scrotal volume and percentage of MOT were positively correlated (0.22) (P<0.05). Our results indicate that SV could be used interchangeably with SC as a measure of sperm- producing capacity in beef bulls. Results of this study indicate that selecting bulls with larger SC or SV should result in increased yearling BW, greater PA, and bulls with improved fertility.     

酵母硒对种公牛精液品质影响的研究

试验选用12头荷斯坦成年种公牛为试验牛,并随机分为四组。试验前期饲喂基础日粮,试验期添加不同剂量的酵母硒;90d时,采集种公牛的精液,并对精液量及精液品质进行检测。试验结果表明:日粮中适量添加硒能显著提高种公牛的精子冻前活率和冻后活率,并降低精子畸形率(P0.05),而对精液量、精子密度和精子顶体完整率无显著影响。     

热应激对种公牛精液品质的影响

任何生物都依赖于其所处的环境 ,它对气候变化的适应及利用有效资源的能力是其存活的关键 ,因此 ,各种环境因子均可造成动物的生理应激 ,从而给动物的生产带来不利影响 ,牛也不例外。从经济角度看 ,在各种应激反应中 ,对牛影响最大的是热应激 ,而热应激对牛生殖机能会产生非常重要的影响。在热应激的作用下 ,种公牛的精液品质和受精率均显著下降 ,体内的一些血液生化指标也会发生明显变化。本文参考近年来国内外研究热应激的文献 ,论述了其对公牛繁殖性能的影响 ,以便于生产中制定缓解种公牛热应激的技术措施。1　热应激对种公牛繁殖机能的…     

Genetic Correlations Between Beef Traits Measured on Young Performance Test Bulls and Daughter Milk Yield

In a breeding programme where young potential breeding bulls are reared on performance test stations, selection based on own results can be carried out before test inseminations. Both beef and milk production traits are included in the total merit index used for selection, and estimates of genetic and phenotypic parameters of these traits are therefore of interest for an optimal construction of such indices. Data on first lactation milk records from the field and beef records of potential dairy breeding bulls from the Danish performance test stations were analysed in bivariate animal-sire models using the AI-REML algorithm. Genetic correlations of 0.16, 0.25 and 0.43 between feed intake capacity and protein yield were obtained for Red Danish (RD), Danish Black and White (DBW) and Danish Jersey (DJ), respectively. These correlations were significantly different from zero for the two populations (DBW and DJ). Genetic correlations around zero between feed efficiency and protein yield were obtained for all three populations. Genetic correlations of 0.44, 0.19 and 0.47 between average daily gain and protein yield were obtained for RD, DBW and DJ, respectively. The genetic correlations between protein yield and muscle area was close to zero for DBW, while it was -0.31 for RD. Selection index calculations indicate that indices composed of different beef performance traits can be used as early predictors for milk yield. Selection on such an index could increase the breeding value of the young bulls for milk production traits by 0.8-2.0% of the population mean.     

夏南牛与夏洛来公牛精液品质的对比分析研究

[目的]通过比较夏南牛和法系夏洛来的精液品质,探索中原地区肉牛改良的适合品种。[方法]选择中原地区的夏南牛和法系夏洛来种公牛各5头,比较两个品种种公牛的精液品质（采精量、原精密度、原精活力、细管产量、冻后活力、精子畸形率）。[结果]表明：夏南牛公牛精液品质极显著的高于夏洛来牛。[结论]夏南牛公牛更适应中原地区的气候条件...     

Genetic Parameters for Semen Traits in AI Boars Estimated from Data on Individual Ejaculates

Semen volume, sperm concentration, percentage progressive motility, percentage of abnormal spermatozoa and total number of sperms from 215 830 ejaculates were analysed. The ejaculates were collected between 2000 and 2005 and originated from 3675 boars of different breeds and crossbred combinations from 23 AI centres of the Czech Republic. Genetic parameters were estimated using multiple- and single-trait animal models. Factors included in the models were: breed or crossbred combination, year–month, age class of the boar, interval between subsequent semen collections, joint effect of AI centre and year, permanent environment and additive genetic effect of the boar. The estimated heritabilities for semen volume and sperm concentration were approximately 0.20, whereas the estimates were somewhat lower for motility, percentage of abnormal sperm and total number of sperms. High negative genetic correlations were estimated between semen volume and sperm concentration (−0.68 for dam breeds, −0.69 for sire breeds) and between motility and percentage of abnormal sperm (−0.93 for dam breeds and −0.59 for sire breeds). The correlations between both semen volume or sperm concentration and motility or percentage of abnormal sperm were mostly small and negligible. Repeatabilities of 0.43–0.46, 0.37–0.38, 0.29–0.35, 0.42–0.50 and 0.29–0.30 were estimated for semen volume, sperm concentration, motility, percentage of abnormal sperm and the total number of sperms, respectively. On the basis of the estimated genetic parameters presented here, effective selection on sperm characteristics, especially for volume and concentration, should be possible using an animal model.     

广州地区娟姗种公牛精液品质随月份的变化研究

选择在广州地区亚热带气候条件下2岁～6岁的娟姗公牛5头,观察其精液品质(采精量、原精密度、原精活力以及细管精液产量)在全年不同月份的变化情况.结果表明:娟姗公牛的每次采精量和细管精液产量在气温较高的7～9月份会因为采精频率的减少而增加,10月份会因为周采精频率增加而使每次采精量和细管精液产量有明显减少;娟姗公牛的原精密度在气温适宜的2月份和采精频率较低的8月份会出现两个高峰值;娟姗公牛的原精活力在气温较高的月份会出现明显的下降趋势,2月份气温适宜时原精活力最好.     

不同季节和气候条件对种公牛精液品质的影响的研究

[目的]研究不同季节气候条件对种公牛精液品质的影响。[方法]从采精种公牛中随机抽出5头,选取气温最高（7月份）最低（1月份）和适中温度（4,9月份）进行试验,分别对不同时期所采得的精液进行检测。[结果]在最高温度月份7月份（25℃）时5头种公牛的平均精液量为5.88mL,原精活率67.2%,精液密度16.64亿/mL,冻后活率33.8%,生产冻精数143.4剂,精子畸形率23%。1月份环境温度平均在-11.2℃时,5头种公牛的精液量平均为5.7mL,原精活率66.8%,精液密度13.3亿/mL,冻后活率37.4%,生产冻精数为275.8剂,精子畸形率17.8%。在4,9月份环境温度12℃时精液量为6.6mL,原精活率73.2%,精液密度16.92亿/mL,冻后活率41.8%,生产冻精数404.4剂,精子畸形率12.6%。精液量之间差异显著（P〈0.05）,原精活率之间差异显著（P〈0.05）,精子畸形率之间差异显著（P〈0.05）。冻后活率和冻精生产数差异不显著。[结论]环境温度过高或者过低都会影响精液品质,种公牛在适宜的温度下生产的精液品质也会更加优良,种公牛在温度较高的条件下生产精液品质比在低温条件下还要差,种公牛最适宜的生产温度为12℃～16℃。     

种公牛阴囊周径与部分精液指标之间的相关性研究

通过对山东中大种公牛站现有四个品种(西门塔尔、利木赞、盖普威、荷斯坦)种公牛阴囊周径(scrotal circumference,SC)的测量,分析其与采精量、精子活率、精子密度、6周总采精量、6周总有效精子数5个指标间相关关系.结果表明:不同品种的种公牛SC之间差异显著(P＜0.01);同品种不同年龄的种公牛SC之间差异极显著(P＜0.01);不同品种间种公牛SC与精子活力、精子密度、总有效精子数呈正相关.     

季节变化对不同品种种公牛精液品质的影响研究

 选择3~4.5岁的四个品种种公牛25头,观察季节变化对其次均采精量、平均密度、平均活力、精子畸形率、精液利用率及制冻数量的影响并进行比较。结果显示：在四季变化中,除次均采精量要显著低于国外引进品种外,鲁西牛种公牛精液的平均密度、平均活力、精子畸形率、精液利用率及次均制冻数量均表现出一定的优势。因此,鲁西牛作为地方品种受季节变化影响最小,繁殖性能更为稳定。     

Inbreeding Depression on Semen Quality in Austrian Dual‐Purpose Simmental Bulls

Using pedigree data, the inbreeding coefficients of 715 Austrian dual‐purpose Simmental (Fleckvieh) bulls stationed in two artificial insemination (AI) centres in Upper and Lower Austria were calculated and incorporated in statistical models for the analysis of semen quality. Five semen quality parameters (volume, concentration, motility, number of spermatozoa per ejaculate and percentage of viable spermatozoa) of approximately 30 000 ejaculates, used in two separate data sets, were investigated. The mixed model included the fixed effects age class of the bull, bull handler, semen collector, month and year of collection, number of collection per bull and day, time interval since last collection, the linear continuous effect of the inbreeding coefficient of the bull, interactions between age class and month, and age class and interval since last collection, respectively, as well as the random effect of the bull and the random residual effect. Non‐linear effects of inbreeding were significant for motility only. Despite the quite low inbreeding coefficients (mean 1.3%), all semen quality traits showed inbreeding depression, in four of the five traits significantly in at least one of the data sets. The magnitude of inbreeding depression was small, which might partly be caused by the low inbreeding levels and a potential pre‐selection of the bulls in the AI centres. However, monitoring of inbreeding depression on fertility traits is recommended to avoid unrecognized deterioration of such traits.     

季节和品种对种公牛鲜精液品质的影响

研究按季节和品种对种公牛采精记录进行方差分析,分别比较了季节对夏洛来、西门塔尔、利木赞、红安格斯、荷斯坦种公牛和弗莱维赫6个品种鲜精液品质的影响以及相同季节下的6个品种精液品质间的差异。分析了在季节和品种的双重条件下,精液品质间的相关性。结果表明:(1)西门塔尔、夏洛来和荷斯坦种公牛的单次射精量随季节变化排序均依次是:夏季秋季春季冬季。(2)西门塔尔、夏洛来、利木赞和红安格斯的鲜精子密度随季节变化排序依次是:春季夏季冬季秋季,且这四个品种鲜精子密度在四季的排序均为:西门塔尔夏洛来利木赞红安格斯。(3)各品种种公牛四季鲜精子活力排序均依次是:冬季春季秋季夏季;各品种种公牛鲜精子活力在四季的排序均为:利木赞夏洛来弗莱维赫、西门塔尔荷斯坦红安格斯;各品种夏季鲜精子活力均极显著低于其它三个季节(P0.01)。(4)荷斯坦种公牛鲜精子活力夏季占春季活力比率最高为(0.54/0.59),利木赞次之(0.5/0.63),弗莱维赫第三(0.47/0.6),安格斯最低(0.34/0.49)。(5)红安格斯的单次射精量、精子密度和精子活力在相同季节下都低于其它5个品种。(6)在不同季节不同品种下,种公牛的射精量与鲜精子密度和鲜精子活力的相关系数分别是0.006和~0.019,鲜精子密度和鲜精子活力的相关系数是0.253。     

The Relationship between Semen Quality and the Nonreturn Rate of Bulls

Contents
The value of routine evaluation of bull semen was analysed for 117 AI bulls placed in two studs. Data from semen analysis of a total of 1635 ejaculates was compared statistically with the nonreturn rates of the bulls. The semen parameters which were significantly correlated to nonreturn rates were the motility of the freshly collected ejaculates (p = 0.0140) and post-thaw motility (p = 0.0075). The total number of motile sperm in the inseminate ranged from 10.9 to 19.3 × 10⁶ and according to previous reports the effects of low motility should be fully 'compensated' when doses above 10 × 10⁶ sperm/dose are used for insemination. In conclusion, the motility of freshly collected semen does not appear to be 'compensation' and a low percentage of motile sperm in an ejaculate may indicate other dysfunctions of the population of motile cells. Furthermore, post-thaw motility appears to correlate significantly with nonreturn rates. The largest proportion of the variation was explained by the breed of the bull and stud (42.2% of the variation), whereas the two motility parameters explained 10% of the total variation in nonreturn rates. Objective and precise evaluation of sperm motility in combination with other semen traits are needed to improve breeding efficiency. Although microscopic evaluation of sperm motility correlates with nonreturn rates of bulls, the methods are subjectively assessed and inaccurate and therefore do not allow a satisfactory prediction of fertility.