Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061-0315, USA.
J Dairy Sci. 2012 Feb;95(2):698-707. doi: 10.3168/jds.2011-4666.
Holsteins (HH), Jerseys (JJ), and their crosses in first (n=157) and second (n=107) lactation were used to determine if reproduction, progesterone (P4), insulin-like growth factor 1 (IGF-1), insulin, nonesterified fatty acids (NEFA), and milk production differed between genetic groups. Thirty-four cows were Holstein-Jersey (HJ) crosses, 46 were Jersey-Holstein (JH) crosses, 48 were purebred Holsteins (HH), and 29 were purebred Jerseys (JJ) in first lactation, whereas the second-lactation animals included 23 HJ, 35 JH, 35 HH, and 14 JJ. Blood samples were collected weekly for the first 10 wk postpartum. Analyses were conducted using the MIXED, chi-square, and GLIMMIX procedures (SAS Institute Inc., Cary, NC). Seasons of calving were cold (November to May) and hot (June to October) and were combined with year to form 8 year-seasons. Days open and number of services were affected by genetic group. The HH were open 169±8 d, which was greater than HJ (143±9 d), JJ (132±10 d), and JH (127±8 d). The HH had 2.4±0.1 services per pregnancy, which was greater than JH (1.9±0.1), but not different from HJ (2.1±0.2) or JJ (2.1±0.2). Concentrations of NEFA were greater in lactation 2 (0.52±0.02 mEq/L) than in lactation 1 (0.45±0.02 mEq/L) and decreased over the 10-wk period. Concentrations of NEFA were greater in the cold season except in yr 3. Insulin in lactation 1 (0.81±0.03 ng/mL) was greater than in lactation 2 (0.72±0.03 ng/mL); insulin decreased to wk 2 then gradually increased. The HJ had the greatest insulin concentrations (0.87±0.04 ng/mL) and the JJ had the lowest (0.66±0.04 ng/mL), and IGF-1 gradually increased over the 10-wk period. Milk production (actual yield in the first 305 d, not adjusted for fat and protein) was affected by genetic group, lactation number, year-season, and wk 1 insulin. The HH produced 10,348±207 kg of milk, which was greater than the HJ (9,129±230 kg), the JH (9,384±190 kg), and the JJ (7,080±240 kg). Milk production in lactation 2 (9,676±163 kg) was greater than that in lactation 1 (8,294±160 kg). The JJ (10.3±4.7%) had the highest frequency of mastitis. The chance of getting mastitis for HH (1.1±0.9%) differed from that for HJ (9.4±4.1%), JH (8.1±3.4%), and JJ (10.3±4.7%). Genetic group affected hormones and metabolites, which may partially explain differences in reproductive measures and milk yield.
荷斯坦奶牛（HH）、泽西奶牛（JJ）及其杂交后代（第一泌乳期 n=157，第二泌乳期 n=107）用于确定繁殖性能、孕酮（P4）、胰岛素样生长因子 1（IGF-1）、胰岛素、非酯化脂肪酸（NEFA）和产奶量是否因遗传群体而不同。第一泌乳期有 34 头荷斯坦-泽西（HJ）杂交奶牛、46 头泽西-荷斯坦（JH）杂交奶牛、48 头纯荷斯坦奶牛（HH）和 29 头纯泽西奶牛（JJ），第二泌乳期动物包括 23 头 HJ、35 头 JH、35 头 HH 和 14 头 JJ。产后前 10 周每周采集一次血液样本。使用 MIXED、卡方和 GLIMMIX 程序（SAS Institute Inc.， Cary，NC）进行分析。产犊季节为冷季（11 月至 5 月）和热季（6 月至 10 月），与年份合并形成 8 个年季。胎次和配种次数受遗传群体的影响。HH 的开放天数为 169±8d，大于 HJ（143±9d）、JJ（132±10d）和 JH（127±8d）。HH 的每胎次配种次数为 2.4±0.1，大于 JH（1.9±0.1），但与 HJ（2.1±0.2）和 JJ（2.1±0.2）无差异。NEFA 浓度在泌乳期 2（0.52±0.02 mEq/L）高于泌乳期 1（0.45±0.02 mEq/L），并在 10 周内逐渐下降。NEFA 浓度在冷季较高，除第 3 年外。泌乳期 1（0.81±0.03ng/mL）的胰岛素高于泌乳期 2（0.72±0.03ng/mL）；胰岛素在第 2 周下降，然后逐渐增加。HJ 的胰岛素浓度最高（0.87±0.04ng/mL），而 JJ 的胰岛素浓度最低（0.66±0.04ng/mL），IGF-1 在 10 周内逐渐增加。产奶量（实际产量，前 305 天，未调整脂肪和蛋白质）受遗传群体、泌乳次数、年份-季节和第 1 周胰岛素的影响。HH 产奶量为 10348±207kg，大于 HJ（9129±230kg）、JH（9384±190kg）和 JJ（7080±240kg）。泌乳期 2 的产奶量（9676±163kg）大于泌乳期 1（8294±160kg）。JJ（10.3±4.7%）的乳腺炎发病率最高。HH（1.1±0.9%）患乳腺炎的几率与 HJ（9.4±4.1%）、JH（8.1±3.4%）和 JJ（10.3±4.7%）不同。遗传群体影响激素和代谢物，这可能部分解释了繁殖性能和产奶量的差异。
