Da Silva Carolina L A, Mulder Han A, Broekhuijse Marleen L W J, Kemp Bas, Soede Nicoline M, Knol Egbert F
Adaptation Physiology Group, Wageningen University and Research, Wageningen, Netherlands.
Animal Breeding and Genomics, Wageningen University and Research, Wageningen, Netherlands.
Front Genet. 2018 Apr 5;9:111. doi: 10.3389/fgene.2018.00111. eCollection 2018.
We investigated (1) the relationship between the estimated breeding values (EBVs) for litter traits at birth and ovulation rate (OR), average corpora luteal weight, uterine length and embryonic survival and development traits in gilts at 35 days of pregnancy by linear regression, (2) the genetic variance of OR, average corpora lutea (CL) weight, uterine length and embryonic survival and development traits at 35 days of pregnancy, and (3) the genetic correlations between these traits. Landrace ( = 86) and Yorkshire × Landrace ( = 304) gilts were inseminated and slaughtered at 35 days of pregnancy. OR was assessed by dissection of the CL on both ovaries. Individual CL was weighed and the average CL weight calculated. The number of embryos (total and vital) were counted and the vital embryos were individually weighed for calculation of within litter average and standard deviation (SD) of the embryo weight. Length of the uterine implantation site of the vital embryos was measured and the average per gilt calculated. Results suggests that increasing the EBV for total number of piglets born would proportionally increase OR and number of embryos, while decreasing the average CL weight. On the contrary, increasing the EBV for average piglet birth weight and for within litter birth weight standard deviation would increase the average CL weight. There was no relationship between the EBVs for BW and for BWSD and vital embryonic weight at 35 days of pregnancy. OR, average CL weight, number of embryos, average weight and implantation length of the vital embryos had all moderate to high heritabilities, ranging from 0.36 (±0.18) to 0.70 (±0.17). Thus, results indicate that there is ample genetic variation in OR, average CL weight and embryonic development traits. This knowledge could be used to optimize the balance between selection for litter size, average piglets birth weight and within litter birth weight uniformity.
（1）出生时窝产性状的估计育种值（EBV）与妊娠35天后备母猪的排卵率（OR）、黄体平均重量、子宫长度以及胚胎存活和发育性状之间的关系；（2）妊娠35天时OR、黄体（CL）平均重量、子宫长度以及胚胎存活和发育性状的遗传方差；（3）这些性状之间的遗传相关性。对86头长白母猪和304头约克夏×长白母猪进行授精，并在妊娠35天时屠宰。通过解剖两侧卵巢上的CL来评估OR。对单个CL称重并计算CL平均重量。统计胚胎数量（总数和存活数），并对存活胚胎分别称重，以计算窝内胚胎重量的平均值和标准差（SD）。测量存活胚胎子宫着床部位的长度，并计算每头后备母猪的平均值。结果表明，提高出生仔猪总数的EBV会按比例增加OR和胚胎数量，同时降低CL平均重量。相反，提高平均仔猪出生体重和窝内出生体重标准差的EBV会增加CL平均重量。妊娠35天时，BW和BWSD的EBV与存活胚胎重量之间没有关系。OR、CL平均重量、胚胎数量、存活胚胎的平均重量和着床长度都具有中等至高的遗传力，范围从0.36（±0.18）到0.70（±0.17）。因此，结果表明OR、CL平均重量和胚胎发育性状存在丰富的遗传变异。这些知识可用于优化窝产仔数、平均仔猪出生体重和窝内出生体重均匀度选择之间的平衡。
