Carriquiry M, Dahlen C R, Weber W J, Lamb G C, Crooker B A
Department of Animal Science, University of Minnesota, St Paul 55108-6118, USA.
J Dairy Sci. 2009 Oct;92(10):4876-88. doi: 10.3168/jds.2008-1675.
Multiparous cows (n = 59) were blocked by expected calving date and previous 305-d mature-equivalent milk yield and assigned randomly to a 2 x 2 factorial design to determine the effects of bovine somatotropin (bST; Posilac, Monsanto Animal Agricultural Group, St. Louis, MO) and dietary fat on ovarian activity during the first 90 d in milk (DIM). Diets that included whole, high-oil sunflower seeds [SS; 10% of dietary dry matter; rich in linoleic acid (18:2)] or a mixture of Alifet-High Energy and Alifet-Repro [AF; Alifet USA, Cincinnati, OH; 3.5 and 1.5% of dietary dry matter, respectively; protected source of linolenic (18:3), eicosapentaenoic, and docosahexaenoic fatty acids] were provided from calving. Diets were isocaloric at equal intakes, but AF provided more net energy for lactation at actual intakes (1.54 vs. 1.66 Mcal/kg of dry matter). Cows received 0 or 500 mg of bST (N, Y) every 10 d from 12 to 70 DIM and at 14-d intervals from 70 to 280 DIM. Breeding was initiated after 90 DIM. Follicular dynamics, luteal growth and development (15 to 90 DIM), and plasma progesterone concentrations (1 to 90 DIM) were evaluated (3 times per week). Days to first ovulation (33.6 +/- 1.4) and incidence of anovulation at 45 or 70 DIM did not differ among treatments. Interovulatory intervals were similar among treatments (22.1 +/- 0.9 d). Incidence of estrous cycles with 2 follicular waves was greater for SSY (71.0%) and AFN (80.0%) than for other groups, but more 3-wave cycles occurred with AFY (83.3%). Growth rate of the ovulatory follicle was greater for AF than SS (1.9 vs. 2.2 +/- 0.11 mm/d) and diameter of ovulatory follicles was larger for AFN than the other treatments (17.9 vs. 15.7 +/- 0.7 mm). Area under the progesterone curve was reduced for SSY (63.2, 48.1, 55.5, and 61.4 +/- 5.1 ng.d/mL for SSN, SSY, AFN, and AFY, respectively). The number of class 1 (3 to 5 mm) follicles was decreased and the number of class 2 (6 to 9 mm) follicles was increased by bST. The number of class 2 follicles was reduced by AF. Initiation of bST administration at 12 DIM and dietary n-3 fatty acids altered ovarian activity during the first 90 DIM and could benefit reproductive performance. Dietary n-3 fatty acids interacted with bST administration in early lactation to increase the incidence of estrous cycles with 3 follicular waves. Although these changes could benefit reproductive performance, evaluation with a larger number of cows is needed to determine if these alterations improve fertility.
经产母牛（n = 59）按预期产犊日期和之前305天成熟当量产奶量进行分组，并随机分配到2×2析因设计中，以确定牛生长激素（bST；重组牛生长激素，孟山都动物农业集团，密苏里州圣路易斯）和日粮脂肪对产奶期前90天（DIM）卵巢活动的影响。从产犊开始提供包含整粒高油向日葵籽[SS；占日粮干物质的10%；富含亚油酸（18:2）]或Alifet-高能和Alifet-繁殖混合物[AF；美国Alifet公司，俄亥俄州辛辛那提；分别占日粮干物质的3.5%和1.5%；亚麻酸（18:3）、二十碳五烯酸和二十二碳六烯酸的保护来源]的日粮。日粮在等量摄入时等热量，但AF在实际摄入量下为泌乳提供了更多净能量（1.54对1.66兆卡/千克干物质）。从产犊后12至70天，母牛每10天接受0或500毫克bST（N，Y），从70至280天每14天接受一次。90天泌乳期后开始配种。评估卵泡动态、黄体生长和发育（15至90天泌乳期）以及血浆孕酮浓度（1至90天泌乳期）（每周3次）。各处理间首次排卵天数（33.6±1.4）以及45或70天泌乳期无排卵发生率无差异。各处理间排卵间隔相似（22.1±0.9天）。SSY组（71.0%）和AFN组（80.0%）具有两个卵泡波的发情周期发生率高于其他组，但AFY组出现更多三个卵泡波的周期（83.3%）。AF组排卵卵泡的生长速度高于SS组（1.9对2.2±0.11毫米/天），AFN组排卵卵泡直径大于其他处理组（17.9对15.7±0.7毫米）。SSY组孕酮曲线下面积减小（SSN、SSY、AFN和AFY组分别为63.2、48.1、55.5和61.4±5.1纳克·天/毫升）。bST使1级（3至5毫米）卵泡数量减少，2级（6至9毫米）卵泡数量增加。AF使2级卵泡数量减少。产犊后12天开始使用bST和日粮n-3脂肪酸改变了前90天泌乳期的卵巢活动，并可能有利于繁殖性能。日粮n-3脂肪酸与泌乳早期使用bST相互作用，增加了具有三个卵泡波的发情周期发生率。尽管这些变化可能有利于繁殖性能，但需要用更多母牛进行评估，以确定这些改变是否能提高繁殖力。
