Turkson P K, Sualisu M
Animal Science Department, School of Agriculture, University of Cape Coast, Cape Coast, Ghana.
Trop Anim Health Prod. 2005 Jan;37(1):49-64. doi: 10.1023/b:trop.0000047935.78168.46.
A retrospective cohort study was designed to examine the effect of sex, season of birth, type and year of birth, and birth weight on lamb mortality. The method used involved analysis of breeding records for Sahelian sheep kept on a breeding station at Pong-Tamale in northern Ghana from 1994 to 2000. The pre-weaning and post-weaning mortalities were 10% (n = 505) and 19% (n = 453), respectively, while the overall mortality from birth up to 12 months of age was 28% (n = 505). Compared to the pre-weaning period, the post-weaning period recorded significantly higher proportions of deaths in male, single-born, lambs born in the rainy or dry seasons, and in lambs with low (<3 kg) or high (> or =3 kg) birth weight. The odds and risks of death for male lambs were about one and a half times those for females at post-weaning. Lambs born in the dry season had significantly higher mortality than those born in the rainy season. Lambs that died by the time of weaning were not significantly different in weight at birth from those that survived. The mean birth and weaning weights of single-born lambs were significantly higher than those for twins. The mean pre-weaning ADG was significantly higher in lambs born as singles compared to that for twins. The season of birth had influence on mean birth weight, with those born in the rainy season having significantly higher weights than those born in the dry season. The year of birth significantly affected birth weight, weaning weight, weight at 12 months and ADG at all stages of the lambs' life. The study concluded that the most significant risk factors for lamb mortality included sex of the lamb, season of birth and birth weight. The last two could be manipulated, to some extent, to reduce lamb mortality.
一项回顾性队列研究旨在考察性别、出生季节、出生类型和年份以及出生体重对羔羊死亡率的影响。所采用的方法涉及对1994年至2000年期间在加纳北部邦塔马莱一个育种站饲养的萨赫勒羊的繁殖记录进行分析。断奶前和断奶后的死亡率分别为10%（n = 505）和19%（n = 453），而从出生到12月龄的总死亡率为28%（n = 505）。与断奶前期相比，断奶后期记录到雄性、单胎出生、在雨季或旱季出生的羔羊以及出生体重低（<3千克）或高（≥3千克）的羔羊死亡比例显著更高。断奶后雄性羔羊死亡的几率和风险约为雌性羔羊的1.5倍。旱季出生的羔羊死亡率显著高于雨季出生的羔羊。断奶时死亡的羔羊出生体重与存活羔羊相比无显著差异。单胎出生羔羊的平均出生体重和断奶体重显著高于双胎羔羊。与双胎羔羊相比，单胎出生羔羊的平均断奶前平均日增重显著更高。出生季节对平均出生体重有影响，雨季出生的羔羊体重显著高于旱季出生的羔羊。出生年份对羔羊生命各阶段的出生体重、断奶体重、12月龄体重和平均日增重均有显著影响。该研究得出结论，羔羊死亡率的最重要风险因素包括羔羊性别、出生季节和出生体重。后两个因素在一定程度上可以加以控制，以降低羔羊死亡率。
