Genetic and environmental analysis of female calf survival in the Israel Holstein cattle population

The objectives were to estimate the effects of various environmental factors on female calf survival of Israeli Holsteins, to estimate the economic value of calf survival under Israeli conditions, to estimate the genetic and environmental variance components for calf and cow survival using the individual animal model, to perform GWAS analyses of survival to first calving and herd life after first calving, to estimate the genetic and environmental trends for calf survival since 1985, to estimate genetic correlations of calf survival with the traits included in the current Israeli breeding index, and to estimate the consequences of inclusion of calf survival in the national selection index. Mean calf survival rate of Israeli Holsteins from 2001 through 2008 was 0.85, and the mean economic value of survival to first calving was $526. Birth month, gestation length, dystocia, and twin birth significantly affected calf survival rate. Dystocia and twin birth each reduced survival rate by 0.034. Survival rate was highest for calves born in October and lowest for calves born in February. The difference between these months was 3.4%. Maximum survival was at a gestation length of 276 d, the mean gestation length for this population. Survival rate was reduced to 0.76 for calves born after a gestation length of 260 d. The individual animal model was applied for all the genetic analyses. Heritability for calf survival to first calving, as estimated by REML, was 0.009, whereas heritability of herd life from first calving was 0.15. The complete data set for genetic analysis of survival to first calving included 1,235,815 calves born between 1985 and 2017. Annual genetic and phenotypic trends for calf survival were 0.019 and 0.015%, respectively. Correlations of transmitting abilities of 226 sires born since 2010 for calf survival with the traits included in the Israeli breeding index were significant only for the maternal effects of dystocia and stillbirth. The GWAS analysis was based on the transmitting abilities of 1,493 bulls with genotypes and reliabilities >0.5 for calf survival and cow herd life. There were 7 single nucleotide polymorphisms with coefficients of determination >0.03 for calf survival and 12 single nucleotide polymorphisms with coefficients of determination >0.05 for cow survival. There was no overlap between the genome-wide significant markers for the GWAS analyses of calf survival and cow herd life. This corresponds to the conclusion from the REML results and the low correlations between the sire evaluations that the genetic control of the 2 traits are not similar. Inclusion of calf survival in the Israeli breeding would result in a 0.5% increase in calf survival over 10 yr but reduce progress for the other traits by 8%.     

Estimated genetic parameters for all genetically evaluated traits in Canadian Holsteins

Genetic improvement is a crucial tool to deal with the increasing demand for high quality, sustainably produced dairy. Breeding programs are based on genetic parameters, such as heritability and genetic correlations, for economically important traits in a population. In this study, we estimated population genetic parameters and genetic trends for 67 traits evaluated on heifers and first-lactation Canadian Holstein cows. The data consisted of approximately 500,000 records with pedigree information collected from 1980 to 2019. Genetic parameters were estimated using bivariate linear animal models under a Bayesian approach. Analyses for the 67 traits resulted in 2,211 bivariate combinations, from which the estimated genetic parameters are reported here. The most highly heritable traits were fat percent (0.66) and protein percent (0.69), followed by stature (0.47). Lowest heritabilities (0.01) were observed for disease-related traits, such as lameness and toe ulcer, and calf survival. The genetic correlations between gestation length, calf size, and calving ease measured on both heifer and cows were close to unity. On the other hand, traits such as body condition score and pin width, cystic ovaries and sole ulcer, rear teat placement, and toe ulcer were genetically unrelated. This study reports genetic parameters that have not been previously published for Canadian Holstein cows, and provides updates of those previously estimated. These estimates are useful for building new indexes, updating existing selection indexes, and for predicting correlated responses due to inclusion of novel traits in the breeding programs.     

一种自适应的遗传算法

针对基本遗传算法的稳定性较差、存在未成熟收敛和易陷入局部最优解的问题,提出一种基于交叉概率和变异概率的自适应遗传算法.该算法通过将交叉概率和变异概率随适应度自动改变,实现有目标地对不同个体进行交叉和变异操作,以达到快速扩大搜索空间、稳定群体中个体多样性的目的.仿真结果表明,该算法的收敛性能优于基本遗传算法,有效地避免了基本遗传算法中因选择压力过大造成未成熟收敛现象,显著提高了遗传算法对全局最优解的搜索能力和收敛速度.     

浅析转变赊销制对解决社店关系僵化问题的可行性

多年以来,社店双方一直围绕着产业政策和自身利益进行博弈.目前我国出版业的社店关系并不理想,图书交易结算方式是社店关系僵化中的主要矛盾.这个矛盾得不到有效解决,其他问题也难以根除.是否转变图书赊销制仍然是书业内外争论不止的问题.提倡转变赊销,并不仅仅是为出版社说话,对书店经营也有促进作用.     

卫星太阳能电池板光散射特性的实验测试

探讨一种用双向反射分布函数测定仪测量目标表面光散射的方法,运用该测量系统在特定激光波段(0.808μm)下对卫星上太阳能电池板进行了实验测量.根据样片的BRDF实验数据,将遗传模拟退火算法应用于目标表面BRDF统计模型的参数反演中,获取样片的BRDF模型参数.实验数据曲线表明,拟合后的实验数据与参与优化的实验数据吻合的很好,结果说明用这种方法分析目标的散射特性是可行的和有效的.     

The genetic relationship of body weight and early-lactation health disorders in two experimental herds

The objectives of this study were to estimate genetic parameters for body weight (BW) and BW change (BWC) and genetic correlations of BW and BWC with diseases and genomic predicted transmitting abilities (PTA) of productive and conformation traits of Holsteins during the first 120 DIM. Daily BW data were from the Afiweigh cow body weighing system (SAE Afikim, Kibbutz Afikim, Israel), which records BW as a cow exits the milking parlor. Disease categories included metabolic diseases, ketosis, infectious diseases, mastitis, reproductive diseases, and other diseases. Edited data included 68,914 and 11,615 daily BW observations from 441 Pennsylvania State University and 72 Virginia Tech Holstein cows, respectively. Two-trait random regression models were used to estimate relationships between BW, BWC, and diseases at 25, 38, and 58 mo of age at calving. Fixed effects for BW were age at calving nested within lactation group, week of lactation, and herd date; random effects for BW included animal, permanent environment, and error. Fixed effects for disease were herd-year-season of calving and age at calving nested within lactation group; random effects for disease were animal, permanent environment (for mastitis only), and error. Correlations of PTA for BW and BWC with genomic PTA for productive and type traits were also estimated with data from 117 cows. Heritability estimates for daily BW ranged from 0.34 to 0.63. Greater BW and less BWC were favorably correlated with ketosis, metabolic diseases, infectious diseases, and other diseases. The genetic correlation estimate between BW and ketosis was strongest at 60 DIM (−0.51), and genetic correlation estimates at 60 DIM with metabolic diseases (−0.52), infectious diseases (−0.81), and other diseases (−0.48) followed the same trend as ketosis. The genetic correlation estimate between BWC and ketosis was strongest for the change from 5 to 20 DIM (0.70) and was similar for metabolic diseases (0.37), infectious diseases (0.74), and other diseases (0.49). Correlations of BW and BWC with reproductive diseases tended to be in the reverse direction of those reported for ketosis. A larger PTA for BW was significantly correlated with smaller genomic PTA for milk yield, dairy form, rear udder height, and udder cleft. Predicted transmitting ability for BWC was negatively correlated with genomic PTA for protein percentage, strength, and hip width (ranging from −0.26 to −0.13 across lactation) and was positively correlated with dairy form, rear udder height, and udder cleft (ranging from 0.20 to 0.37 across lactation). Selection for reduced BW loss can be implemented with automated body weighing systems and may be successful in decreasing disease incidence in the early stages of lactation.     

Short communication: characterization of a new genetic variant in the caprine kappa-casein gene

A new polymorphism has been identified in the goat kappa-casein gene by evaluating genomic DNA from the Montefalcone breed in Italy. The polymorphic site consists of a single nucleotide substitution A to G at position 242 of the exon 4 and produces an amino acid substitution Asp/Gly. A polymerase chain reaction-restriction fragment length polymorphism protocol for rapid genotyping of the variant has been developed, using the HaeIII enzyme. Animals from Italian, Spanish, and French breeds have been analyzed to investigate the occurrence of the allele in other populations. The allele appears to be exclusive to the Montefalcone breed.     

基于遗传算法的浆池循环泵V带可靠性优化设计

通过运用可靠性设计理论及优化设计理论，建立了浆池循环泵V带可靠性优化设计的数学模型。以V带传动依概率不发生疲劳断裂和打滑为主要可靠性约束条件，带传动的体积最小为优化目标，利用遗传算法进行优化求解。设计结果显示它不仅使V带有较高的可靠性而且体积有较大减小。     

Analysis of fertility and dystocia in Holsteins using recursive models to handle censored and categorical data

A method based on the analysis of recursive multiple-trait models was used to 1) estimate genetic and phenotypic relationships of calving ease (CE) with fertility traits and 2) analyze whether dystocia negatively affects reproductive performance in the next reproductive cycle. Data were collected from 1995 through 2002, and contained 33,532 records of CE and reproductive data of 17,558 Holstein cows distributed across 560 herds in official milk recording from the Basque Country Autonomous Community (Spain). The following fertility traits were considered: days open (DO), days to first service, number of services per pregnancy (NINS), and outcome of first insemination (OFI). Four bivariate sire and sire-maternal grandsire models were used for the analyses. Censoring existed in DO (26.49% of the data) and NINS (12.22% of the data) because of cows having been sold or culled before reaching the next parturition. To avoid bias, a data augmentation technique was applied to censored data. Threshold models were used for CE and OFI. To consider that CE affects fertility and the genetic determination of CE and fertility traits, recursive models were applied, which simultaneously considered CE as a fixed effect on fertility performance and the existence of a genetic correlation between CE and fertility traits. The effects of CE score 3 (difficult birth) with respect to score 1 (no problem) for days to first service, DO, NINS, and OFI were 8 d, 31 d, 0.5 services, and - 12% success at first insemination, respectively. These results showed poorer fertility after dystocia. Genetic correlations between genetic effects of fertility traits and CE were close to zero, except for the genetic correlations between direct effects of DO and CE, which were positive, moderate, and statistically different from 0 (0.47 ± 0.24), showing that genes associated with difficult births also reduce reproductive success.     

Effects of management and genetics on udder health and milk composition in dairy cows

Milk production per cow has increased significantly as a result of breeding, feeding, and other management factors. This study aims to address concerns about udder health risks for low- and high-producing dairy cows. In a 2 × 2 × 2 factorial design, Holstein-Friesian heifers (n = 100) of low or high genetic merit for milk production, milked 2 or 3 times a day, and fed a mixed ration with low or high energy content, were compared during the first 14 wk of lactation. Milk composition and cell counts were determined weekly; quarter milk samples for bacteriology were taken in wk 2, 8, and 14; and teat condition was scored in wk 2, 6, 10, and 14 during the experiment. The experimental factors resulted in substantial differences in milk production between treatment groups (24.1 for low vs. 25.6 kg/d for high genetic merit; 23.3 for 2 times vs. 26.5 kg/d for 3 times daily milking; and 20.9 for low-energy ration vs. 29.0 kg/d for high-energy ration). Ration composition was the most important determining factor for milk production, but did not affect cell counts or intramammary bacterial infections, although cows that received low-energy rations had rougher teat ends than cows receiving high-energy rations. This indicates that high production itself is not a major risk factor for udder health in the first lactation. A higher milking frequency impaired teat condition and improved cell counts in general, but did not clearly influence bacteriological status. High genetic merit was related to higher cell count, more Staphylococcus, and less Bacillus and other environmental pathogens in cultures and did not affect teat condition. The effects of milking frequency and feeding on udder health were similar for cows with high and low genetic merit. Genetic selection on milk production, without taking udder health into account, reduces udder health. As a result, maintaining udder health will require increasing the skills and time of dairy farmers who have to divide their attention to more cows when farm sizes increase, or selection should put more emphasis on udder health traits.