Abe H, Masuda Y, Suzuki M
Department of Life Science and Agriculture, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, 080-8555, Japan.
J Dairy Sci. 2009 Aug;92(8):4055-62. doi: 10.3168/jds.2008-1896.
The objective of this study was to investigate relationships between reproductive traits in heifers and cows and yield traits for Holsteins in Japan. Insemination and lactation records for cows calved between 1990 and 2003 in Hokkaido region were obtained. Age at first service, age at conception, and conception rate for first service were calculated for heifers. Days from calving to first service, days open, and conception rate for first service were calculated for first- and second-parity cows. The yield traits used were 305-d milk, fat, and protein yields. A threshold animal model was applied for the conception rate for first service, and a linear animal model was applied for the other traits. Single-trait and 2-trait genetic analyses were performed by the Bayesian method using Gibbs sampling. Heritability estimates ranged from 0.027 to 0.051 for conception rate for first service, and from 0.074 to 0.128 for the other reproductive traits. If the relationships of other traits were not considered, days from calving to first service was favorable to genetic selection for reproductive traits because of relatively high heritability and because it can be available earlier than the days open. Genetic correlations among reproductive traits were high, especially in cows. The genetic correlations between reproductive traits for heifers and those for cows were lower than the genetic correlations between reproductive traits for first parity and those of second parity, suggesting that reproductive traits for heifers should be evaluated separately from reproductive traits for cows. Genetic correlations between yield and reproductive traits in cows were antagonistic. In contrast, genetic correlations between reproductive traits for heifers and yield traits were slightly desirable. Depending on the reporting rate of insemination records for heifers and the results of investigations for relationships with productive maturity, selection by reproductive traits for heifers will enable the improvement of reproductive performance without a loss in genetic progress for yield traits.
本研究的目的是调查日本荷斯坦奶牛小母牛和母牛的繁殖性状与生产性能性状之间的关系。获取了北海道地区1990年至2003年间产犊母牛的授精和泌乳记录。计算了小母牛的初配年龄、受孕年龄和首次配种的受孕率。计算了头胎和二胎母牛从产犊到首次配种的天数、空怀天数以及首次配种的受孕率。所使用的生产性能性状为305天产奶量、乳脂产量和乳蛋白产量。对首次配种的受孕率应用阈值动物模型，对其他性状应用线性动物模型。采用贝叶斯方法和吉布斯抽样进行单性状和双性状遗传分析。首次配种受孕率的遗传力估计值在0.027至0.051之间，其他繁殖性状的遗传力估计值在0.074至0.128之间。如果不考虑其他性状的关系，从产犊到首次配种的天数有利于繁殖性状的遗传选择，因为其遗传力相对较高，且比空怀天数更早可得。繁殖性状之间的遗传相关性较高，尤其是在母牛中。小母牛繁殖性状与母牛繁殖性状之间的遗传相关性低于头胎与二胎繁殖性状之间的遗传相关性，这表明小母牛的繁殖性状应与母牛的繁殖性状分开评估。母牛的生产性能性状与繁殖性状之间的遗传相关性呈拮抗关系。相比之下，小母牛的繁殖性状与生产性能性状之间的遗传相关性略显有利。根据小母牛授精记录的上报率以及与生产成熟度关系的调查结果，通过小母牛的繁殖性状进行选择将能够在不损失生产性能性状遗传进展的情况下提高繁殖性能。
