Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523, USA.
J Anim Sci. 2012 Nov;90(11):3698-708. doi: 10.2527/jas.2012-5140. Epub 2012 Jun 4.
The objective of this study was to evaluate the effects of overfeeding naturally-mated adolescent ewes (Ovis aries) on maternal, fetal, and postnatal lamb growth, hormone concentrations, and lamb carcass characteristics. Two experiments were conducted in which singleton-bearing adolescent ewes were fed a diet containing 2.72 Mcal/kg ME at a rate which met NRC gestational age requirements (MN; n = 10 in Exp. 1, n = 7 in Exp. 2) or were fed the same diet ad libitum (15% refusal rate) throughout gestation (HN; n = 7 in Exp. 1, n = 6 in Exp. 2). Ewe BW was greater (P < 0.05) for HN than MN ewes beginning on 75 d and 52 d of gestation for Exp. 1 and 2, respectively. Final BCS was greater (P ≤ 0.05) for HN than MN ewes in both experiments; 3.5 vs. 3.0, respectively, for Exp. 1, and 4.8 vs. 2.9, respectively, for Exp. 2. Fasting maternal blood insulin concentrations were greater (P ≤ 0.05) in HN ewes near term (135 d of gestation), whereas fasting maternal glucose concentrations were greater (P ≤ 0.05) during most of the second half of gestation in HN ewes, for both experiments. Gestation length did not differ (P = 0.69) between treatments in Exp. 1, but in Exp. 2, HN ewes had shorter (P = 0.01) gestation lengths (144 vs. 149 d) and had increased (P = 0.002) dystocia scores. Fetal abdominal circumference was greater (P < 0.05) in lambs from MN than HN ewes at 97 d of gestation in Exp. 1 (20.8 vs. 17.4 cm) but did not differ (P = 0.94) between treatments at 95 d of gestation in Exp. 2 (averaging 20.5 cm). There were no differences (P ≥ 0.15) in lamb BW, abdominal circumference, crown-rump length, and biparietal distance at birth; or in postnatal BW and plasma concentrations of glucose, insulin, and lactate in either experiment. There were no differences (P ≥ 0.18) in HCW, dressing percentage, LM area, fat thickness, or KPH between treatments in Exp. 2. Although there was no difference (P ≥ 0.31) between treatments in concentrations of IGF1 or IGF2 mRNA in liver samples collected at harvest, lambs from MN ewes had greater (P ≤ 0.05) concentrations of IGF1R and INSR mRNA, suggesting long-term effects of maternal diet on postnatal hepatic function. In conclusion, excess nutrition during gestation in naturally-mated adolescent ewes did not affect birth weight or postnatal performance of offspring.
本研究旨在评估青春期自然交配母羊过度喂养对母体、胎儿和产后羔羊生长、激素浓度以及羔羊胴体特征的影响。进行了两项实验，其中单胎妊娠的青春期母羊分别饲喂含有 2.72 Mcal/kg ME 的日粮（ME 为代谢能），其饲喂量满足 NRC 妊娠年龄要求（MN；实验 1 中为 10 只，实验 2 中为 7 只）或自由采食（15%的拒食率）整个妊娠期（HN；实验 1 中为 7 只，实验 2 中为 6 只）。从妊娠 75 天和 52 天开始，HN 母羊的 BW 大于 MN 母羊（P < 0.05），这分别是实验 1 和实验 2 的情况。两个实验中，HN 母羊的最终 BCS 均大于 MN 母羊（P ≤ 0.05）；实验 1 分别为 3.5 和 3.0，实验 2 分别为 4.8 和 2.9。临近分娩时（妊娠 135 天），HN 母羊的空腹胰岛素浓度较高（P ≤ 0.05），而在 HN 母羊妊娠后半期的大部分时间内，空腹血糖浓度较高（P ≤ 0.05），这两个实验均是如此。实验 1 中，处理间的妊娠期没有差异（P = 0.69），但在实验 2 中，HN 母羊的妊娠期较短（P = 0.01）（144 天 vs. 149 天），难产评分较高（P = 0.002）。在实验 1 中，妊娠 97 天时，MN 母羊的胎儿腹围大于 HN 母羊（20.8 厘米 vs. 17.4 厘米），但在实验 2 中，95 天妊娠时，两组之间没有差异（P = 0.94）（平均为 20.5 厘米）。两组之间羔羊 BW、腹围、头臀长和双顶骨径无差异（P ≥ 0.15）；出生后 BW 和血浆葡萄糖、胰岛素和乳酸浓度也无差异；实验 2 中，HCW、出肉率、LM 面积、脂肪厚度或 KPH 也无差异。实验 2 中，两组间 IGF1 或 IGF2 mRNA 肝样采集时的浓度无差异（P ≥ 0.18）；但 MN 母羊的羔羊 IGF1R 和 INSR mRNA 浓度较高（P ≤ 0.05），表明母体日粮对产后肝脏功能有长期影响。总之，青春期自然交配母羊在妊娠期过度营养并未影响后代的出生体重或产后性能。
