Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India125001.
Zygote. 2022 Dec;30(6):797-800. doi: 10.1017/S0967199422000272. Epub 2022 Aug 1.
The present study was carried out to estimate lamb survival (in days) from birth to weaning under survival analysis using data records from 2057 Harnali lambs born to 134 sires and 623 dams between the period from 2001 to 2020. The weaning age in resourced population was 90 days from birth. The hazard ratio in terms of risk of death up to weaning was determined using Cox proportional hazards model by subjecting some fixed factors such as year of birth, sex of lamb, birth weight (kg), dam's weight at lambing (kg) and dam's age at lambing (years). The overall survivability up to weaning among lambs was 91.59% and Kaplan-Meier estimates of mean survival time up to weaning was 85.77 days. Cox proportional hazard modelling revealed that the hazards of death up to weaning was higher in male lambs [1.66, 95% confidence interval (CI): 1.22-2.26] compared with female lambs [hazard ratio (HR) = 1.00]. It was also observed that the hazards of death (HR = 0.91, 95% CI: 0.88-0.94) had decreasing trends over years. For birth weight (kg), hazard rate was 0.34 (95% CI: 0.25-0.46), which indicated that the risk of pre-weaning mortality was lower as birth weight increases. The weight and age of dams at lambing did not influence the survival time of studied population. The present findings indicated that survival time increased in studied lambs over the years and it could be increased more by giving more emphasis on better litter weight and general health aspects at farm level.
本研究旨在通过生存分析来估计羔羊从出生到断奶的存活率（以天计），数据来源于 2001 年至 2020 年期间 134 头公羊和 623 头母羊所产的 2057 只哈纳利羔羊。资源种群的断奶年龄为出生后 90 天。通过 Cox 比例风险模型，考虑了一些固定因素，如出生年份、羔羊性别、出生体重（kg）、母羊产羔时体重（kg）和母羊产羔时年龄（岁），确定了直至断奶的死亡风险的风险比。羔羊断奶前的总存活率为 91.59%，断奶前平均存活时间的 Kaplan-Meier 估计值为 85.77 天。Cox 比例风险模型显示，雄性羔羊断奶前的死亡风险高于雌性羔羊[1.66，95%置信区间（CI）：1.22-2.26][风险比（HR）=1.00]。还观察到，死亡风险（HR=0.91，95%CI：0.88-0.94）随着年份的增加呈下降趋势。对于出生体重（kg），风险率为 0.34（95%CI：0.25-0.46），这表明随着出生体重的增加，断奶前死亡率的风险降低。母羊产羔时的体重和年龄并不影响研究人群的生存时间。本研究结果表明，研究羔羊的生存时间随着时间的推移而增加，如果在农场层面更加重视更好的窝重和整体健康状况，生存时间可以进一步增加。
