Animal & Grassland Research & Innovation Centre,Teagasc,Mellows Campus,Athenry,Co. Galway H65 R718,Ireland.
Animal. 2018 Apr;12(4):713-721. doi: 10.1017/S1751731117002038. Epub 2017 Aug 24.
Plane of nutrition (PN) offered to ewe replacements during the rearing phase (8 to 17 months) affects BW at joining and may affect reproductive performance when joined at ~19 months. The effects of PN offered to ewe replacements during their first winter (winter_1) and second summer (summer_2) were evaluated over 3 consecutive years, using 287 spring-born ewe lambs, representing four genotypes (Belclare (Bel), Charmoise×Scottish Blackface (C×SBF), Bel×SBF (Bel×SBF), Bel×SBF that were heterozygous either FecGH or FecXG mutations that increase ovulation rate (OR) (BelMG×SBF)). During extended (deferred) grazing in winter_1 (November to March) the lambs were offered herbage DM allowances (HA) of 0.75 (L) or 1.75 (H) kg/day. During summer_2 (March to August) the replacements were set stocked to maintain sward heights of 4 (L) or 6 (H) cm, thus yielding a 2×2 factorial design for the nutrition treatments (71 to 73 animals/treatment). Increasing HA during winter_1, and residual sward height during summer_2, increased (P0.05) on OR. Mean BW at joining was 53.3, 56.8, 56.6 and 61.7 (SEM 0.74) kg for ewes offered the LL, LH, HL and HH treatments, respectively. Mean OR of C×SBF and BelMG×SBF differed (P<0.001) from that of Bel×SBF by -0.58 and +0.47, respectively. Correlations between linear measurements (LMs) of body size and BW at 7, 12 and 17 months were all positive and significant (P<0.001). The precision of the set of LMs as a predictor of BW at joining improved with age (R 2 0.46, 0.54 and 0.74 at 7, 12 and 17 months) but BW at a given age was a better predictor at all age time points. Chest girth was the best predictor, among the LMs, of BW at joining and its explanatory power increased with age. Equations developed using LMs at 7, 12 or 17 months, to predict BW at joining exhibited biases of -2.1, -1.5 and +0.9 kg, respectively. It is concluded that whilst altering PN during the rearing phase changed BW by 16% it had no effect on OR. There was no interaction (P>0.05) between the PN offered during winter_1 and summer_2, or PN and ewe genotype for BW at joining or OR. LMs, either at 7, 12 or 17 months of age, are useful predictors of BW at joining.
在育肥阶段（8 至 17 个月）提供给后备母羊的营养水平（PN）会影响其配种时的体重，并且在约 19 个月时配种可能会影响其繁殖性能。在连续 3 年的时间里，使用 287 只春季出生的母羊羔羊，代表了 4 种基因型（Belclare（Bel）、Charmoise×Scottish Blackface（C×SBF）、Bel×SBF（Bel×SBF）和携带 FecGH 或 FecXG 突变的 Bel×SBF 杂合子，这些突变可提高排卵率（OR）（BelMG×SBF）），评估了在第一个冬季（冬季_1）和第二个夏季（夏季_2）期间提供给后备母羊的 PN 的效果。在冬季_1（11 月至 3 月）的延长（推迟）放牧期间，羔羊每天提供 0.75（L）或 1.75（H）kg 的牧草 DM 允许摄入量（HA）。在夏季_2（3 月至 8 月）期间，将替换物设置为放养，以维持 4（L）或 6（H）cm 的草丛高度，从而产生 2×2 的营养处理因子设计（71 至 73 头/处理）。冬季_1 期间增加 HA 和夏季_2 期间的剩余草丛高度，增加了（P0.05）OR。接受 LL、LH、HL 和 HH 处理的母羊的配种时平均体重分别为 53.3、56.8、56.6 和 61.7（SEM 0.74）kg。C×SBF 和 BelMG×SBF 的平均 OR 分别与 Bel×SBF 的差异（P<0.001）为-0.58 和+0.47。身体尺寸的线性测量（LM）与 7、12 和 17 个月时的 BW 之间的相关性均为正且显著（P<0.001）。一组 LM 作为配种时 BW 的预测指标的精度随着年龄的增长而提高（7、12 和 17 个月时 R 2 分别为 0.46、0.54 和 0.74），但在所有年龄阶段，BW 本身都是更好的预测指标。胸围是配种时 BW 的最佳预测指标，其解释能力随着年龄的增长而增加。使用 7、12 或 17 个月时的 LM 开发的预测配种时 BW 的方程分别表现出-2.1、-1.5 和+0.9 kg 的偏差。综上所述，虽然在育肥阶段改变 PN 会使 BW 变化 16%，但对 OR 没有影响。冬季_1 和夏季_2 期间提供的 PN 之间或 PN 和母羊基因型之间没有相互作用（P>0.05），对配种时的 BW 或 OR 没有影响。无论是在 7、12 还是 17 个月大时，LM 都是配种时 BW 的有用预测指标。
