White B R, McLaren D G, Dziuk P J, Wheeler M B
Laboratory of Molecular Embryology Department of Animal Sciences University of Illinois Urbana, IL 61801, USA.
Theriogenology. 1993 Jul;40(1):85-97. doi: 10.1016/0093-691x(93)90343-4.
Studies on the ovulation rate, prenatal survival and litter size of Chinese Meishan pigs have given widely divergent results depending on the extent of inbreeding of the animals, their original genetic diversity, the age and parity, and the conditions of management. To obtain meaningful results, it is necessary to characterize the population under study. The following report characterizes populations of Meishan and Yorkshire of a widely diverse background. First farrowing data were collected on 21 Meishan and 20 Yorkshire gilts. Meishan gilts had 12.4 fully formed piglets and Yorkshire gilts had 7.4 fully formed piglets (P < 0.01). Meishan gilts averaged 1.86 mummified fetuses per litter vs 0.05 per Yorkshire litter (P < 0.01). Yorkshire piglets averaged 1.3 kg body weight at birth vs 0.9 kg for Meishan piglets (P < 0.01). At 47 days of second gestation, 19 Meishan and 12 Yorkshire sows averaged 22.7 and 16.3 corpora lutea (CL), respectively (P < 0.01). Uterine length and number of fetuses were not different (P > 0.40) in the two breeds. Daily estrous detection of 50 Meishan and 34 Yorkshire gilts began at 60 and 120 days of age, respectively. Meishan gilts reached sexual maturity at 95 days of age, which was 105 days earlier than Yorkshire gilts (P < 0.01). Meishan gilts were in estrus nearly 1 day longer than Yorkshire gilts at first, second and third estrus (P < 0.05). No differences in cycle length between breeds were detected for the first or second estrous cycle (P > 0.60). Nineteen Meishan gilts were slaughtered at 51 days of gestation and their reproductive tracts were recovered. The mean number of dissected CL (17.0), number of fetuses (13.1), total uterine length (396 cm), spacing per fetus (29.9 cm), allantoic (124.9 ml) and amniotic (32.2 ml) volumes, crown-rump length (82.8 mm), weight (35.4 g), sex, and direction of each fetus were determined. Chinese Meishan gilts reached puberty much earlier and were in estrus longer than Yorkshire gilts and Meishan sows had more CL than Yorkshire sows.
对中国梅山猪的排卵率、产前存活率和产仔数的研究结果差异很大，这取决于动物的近亲繁殖程度、它们原有的遗传多样性、年龄和胎次以及管理条件。为了获得有意义的结果，有必要对所研究的群体进行特征描述。以下报告描述了背景差异很大的梅山猪和约克夏猪群体的特征。收集了21头梅山母猪和20头约克夏母猪的初产数据。梅山母猪每窝有12.4头发育完全的仔猪，约克夏母猪每窝有7.4头发育完全的仔猪（P<0.01）。梅山母猪每窝平均有1.86头木乃伊化胎儿，而约克夏母猪每窝为0.05头（P<0.01）。约克夏仔猪出生时平均体重为1.3千克，梅山仔猪为0.9千克（P<0.01）。在第二次妊娠47天时，19头梅山母猪和12头约克夏母猪平均分别有22.7个和16.3个黄体（CL）（P<0.01）。两个品种的子宫长度和胎儿数量没有差异（P>0.40）。分别在60日龄和120日龄开始对50头梅山母猪和34头约克夏母猪进行每日发情检测。梅山母猪在95日龄达到性成熟，比约克夏母猪早105天（P<0.01）。在第一次、第二次和第三次发情时，梅山母猪的发情时间比约克夏母猪长近1天（P<0.05）。在第一次或第二次发情周期中，未检测到品种间的周期长度差异（P>0.60）。19头梅山母猪在妊娠51天时被屠宰，并回收了它们的生殖道。测定了解剖的黄体平均数量（17.0）、胎儿数量（13.1）、子宫总长度（396厘米）、每个胎儿的间距（29.9厘米）、尿囊（124.9毫升）和羊膜（32.2毫升）体积、顶臀长度（82.8毫米）、体重（35.4克）、性别以及每个胎儿的方向。中国梅山母猪比约克夏母猪更早达到青春期，发情时间更长，并且梅山母猪比约克夏母猪有更多的黄体。
