Data for birth weight (BW), lamb survival (LS) and neonatal behaviour, including records of between 1494 (latency of birth to first suckling or LBS) and 2705 (BW and LS) lambs were used. Additionally to the lamb data, ewe data comprising of between 1003 ewe-year records for the latency of stay on the birth site (SBS) and 2024 ewe-year records for number of lambs weaned per ewe mated (NLW) were analysed. These records were from selection lines that had been divergently selected from the same base population since 1986, either for NLW (termed the High or H line) or against NLW (termed the Low or L line). Overall, H line lambs had an improved LS compared to their L line contemporaries, while H line ewes were superior to L line ewes for NLW. Latency of parturition of H line progeny was shorter than in L line progeny while ewe lambs had shorter births than ram lambs. Lamb sex and selection line had no effect on the latency from birth to suckling, which decreased as dam age increased. The second of multiples took longest to progress to suckling from birth, with singles being the quickest. H line ewes had shorter parturitions and cooperated better with the first suckling attempts of their offspring. Single-trait direct heritability estimates (h²) in lambs were 0.15 for BW, 0.07 for LS, 0.06 for latency of parturition (LP) and 0.14 for LBS. The inclusion of the maternal genetic variance ratio (m²) resulted in an improvement in the log likelihood ratio for BW, LP and LBS, yielding estimates of respectively 0.37, 0.18 and 0.12. The maternal permanent environment variance ratio for LS amounted to 0.07. The genetic correlation of LS with LP was favourable at -0.69. Estimates of h², as ewe traits, were 0.04 for NLW, 0.17 for LP, 0.07 for ewe cooperation score (ECS) and 0.20 for SBS. Genetic correlations indicated that ewes with a high NLW had shorter parturitions while ECS was genetically correlated to SBS. Genetic trends suggested divergence between the lines for breeding values for LP, suggesting that parturitions became shorter in the H line and longer in the L line. Selection for NLW would yield desirable outcomes for ewe and lamb behavioural traits based on genetic trends and correlations. Such selection would putatively benefit animal welfare by reducing birth stress in ewes and lambs and by promoting maternal cooperation with their offspring’s first suckling attempts in ewes.

使用了出生体重（BW），羔羊存活率（LS）和新生儿行为的数据，包括记录在1494（羔羊出生后首次哺乳或LBS）到2705（BW和LS）羔羊之间。除羔羊数据外，还分析了母羊数据，其中包括在出生地停留潜伏期（SBS）的1003个母羊年记录和每个母羊断奶的羔羊数（NLW）的2024个母羊年记录。这些记录来自自1986年以来从同一基本种群中有别地选择的选择系，无论是NLW（称为高或H线）还是NLW（称为低或L线）。总体而言，与同期L线母羊相比，H线羔羊的LS有所提高，而NLW的H线母羊优于L线母羊。H系后代的分娩潜伏期短于L系后代，而母羊羔的出生时间短于公羊羔。羔羊的性别和选择系对从出生到哺乳的潜伏期没有影响，随潜伏期的增加而降低。自出生起，倍数的第二个过程花费了最长的时间，单身最快。H系母羊的分娩期较短，并且与其后代的初次哺乳尝试更好地配合。羔羊的单性状直接遗传力估计值（h²）分别为BW 0.15，LS 0.07，分娩潜伏期（LP）0.06和LBS 0.14。包括母亲遗传变异率（m²）导致BW，LP和LBS的对数似然比得到改善，估计分别为0.37、0.18和0.12。LS的孕产妇永久环境方差比为0.07。LS与LP的遗传相关性良好，为-0.69。作为母羊性状，h²的估计值是：NLW为0.04，LP为0.17，母羊合作得分（ECS）为0.07，SBS为0.20。遗传相关性表明，NLW较高的母羊的分娩期较短，而ECS与SBS具有遗传相关性。遗传趋势表明，LP的育种值在品系之间存在差异，这表明H品系中的分娩时间变短，L品系中的分娩时间变长。根据遗传趋势和相关性，选择NLW会为母羊和羔羊的行为特征产生理想的结果。