Neonatal survival in swine: effects of low birth weight and clinical disease.
Data were collected for 3,636 full-term pigs born in a commercial swine herd to determine the effects of birth weight and clinical disease on survival during the first 3 weeks of life. Logistic regression models were constructed for 7-day survival for all live-born pigs, and for 21-day survival for pigs surviving the first week of life. Estimates of birth weight and disease effects were adjusted simultaneously for other risk factors including litter size, parity, and within-litter variation in birth weight. The 7-day survival model indicated that survival odds improved significantly with increasing birth weight. Maximal survival, relative to pigs weighing less than 601 g at birth, was evident in pigs weighing greater than 2 kg at birth (odds ratio [OR] = 349). Diarrhea (OR = 2.7) and splayed limbs (splay leg; OR = 37.3) significantly (P less than 0.05) reduced 7-day survival. Models of 21-day survival indicated a smaller, but still significant, effect of birth weight on survival. Adjusted survival odds for pigs in the heaviest weight group (greater than 2 kg) were 20.1 times higher than pigs weighing less than 801 g. Diarrhea (OR = 2.7) and lameness (OR = 2.6, 2 limbs) significantly (P less than 0.05) decreased 21-day survival.
Gardner
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Department of Epidemiology and Preventive Medicine, School of Veterinary Medicine, University of California, Davis 95616.
Hird
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Franti
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D000821:Animal Feed; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001724:Birth Weight; D005260:Female; D008297:Male; D009026:Mortality; D012307:Risk Factors; D013552:Swine / Q000502:physiology*; D013553:Swine Diseases / Q000401:mortality*; D013997:Time Factors