1Instituto de Ciencia y Tecnología Animal,Universitat Politècnica de València,Camino de Vera s/n,46022 Valencia,Spain.
2GenPhySE,Université de Toulouse,INRA,ENVT,31326 Castanet Tolosan,France.
Animal. 2018 Nov;12(11):2347-2355. doi: 10.1017/S1751731118000162. Epub 2018 Feb 20.
Factors influencing early development such as birth weight, nest competition, and the diet received during rearing have been proposed as elements conditioning the future reproductive performance of European rabbit (Oryctolagus cuniculus) females. To evaluate their effects, we followed the life of 1513 females from birth to time of death, culling or censoring (animals alive at a fixed date). Between 0 and 63 days of age 353 females died. From the remaining 1160 females, 864 were chosen based on their birth weight to be transferred from the selection to the production farm. At this farm, 431 females received the control diet (184 g of CP, 381 g of NDF and 11.8 MJ of DE per kg DM), while the other 433 received the fibrous diet (134 g of CP, 436 g of NDF and 10.0 MJ of DE per kg DM). Throughout the rearing period, we checked for the individual live weight and body condition (perirenal fat thickness) at first artificial insemination. Reproductive lifespan was defined as the number of days between the first parturition and the time of death, culling or censoring. Birth weight affected the survival of newborn females during lactation and the presence of a milk spot at birth (related to nest competition) increased the survivability of newborns weighing <45 g (P<0.001). Rearing diet altered the growth curve of females and their body condition at first insemination. The diet also altered the relative risk of death during the rearing period, which was lower among females fed on the fibrous diet (-12.5%; P<0.001). Therefore, a higher number of females fed with this diet reached their reproductive life, directly affecting the productivity measured per housed female. Fatter females at first insemination had smaller litter sizes and a higher risk of being culled than lean ones (P<0.05). In general, the fibrous diet reduced the risk of leaving the herd at early rearing, and both birth weight and perirenal fat thickness affected female's reproductive lifespan. An excess of fat (positive change in one unit of perirenal fat) at their first insemination represented an increased the risk of death or elimination of 13%.
影响早期发育的因素，如出生体重、巢竞争和饲养期间的饮食，被认为是调节欧洲兔（Oryctolagus cuniculus）雌性未来繁殖性能的因素。为了评估这些因素的影响，我们从出生到死亡、淘汰或截止（固定日期存活的动物）的时间，对 1513 只雌性进行了跟踪研究。在 0 到 63 天的年龄内，有 353 只雌性死亡。在剩下的 1160 只雌性中，根据出生体重选择 864 只转移到生产农场。在这个农场，431 只雌性接受了对照饮食（每公斤 DM 含有 184 克 CP、381 克 NDF 和 11.8MJ DE），而另外 433 只雌性接受了纤维饮食（每公斤 DM 含有 134 克 CP、436 克 NDF 和 10.0MJ DE）。在整个饲养期间，我们在第一次人工授精时检查了个体的活体重和身体状况（肾周脂肪厚度）。繁殖寿命定义为第一次分娩和死亡、淘汰或截止之间的天数。出生体重影响哺乳期新生雌性的存活，出生时的奶斑（与巢竞争有关）增加了体重<45 克的新生仔兔的存活率（P<0.001）。饲养饮食改变了雌性的生长曲线和第一次授精时的身体状况。饮食还改变了饲养期间的死亡相对风险，纤维饮食组的死亡率较低（-12.5%；P<0.001）。因此，更多的雌性在这种饮食下达到了繁殖寿命，这直接影响了每只饲养雌性的生产力。第一次授精时较胖的雌性产仔数较小，淘汰风险高于较瘦的雌性（P<0.05）。一般来说，纤维饮食降低了早期饲养时离开群体的风险，出生体重和肾周脂肪厚度都影响雌性的繁殖寿命。第一次授精时肾周脂肪的增加（增加一个单位）代表死亡或淘汰的风险增加了 13%。
