The Identification of Risk Factors for Mortality and Respiratory Disease in Lambs: An Evaluation of Risk Factor Based Health Management Strategies

Abstract

The production simulation model evaluated two regression based strategies: decreased prevalence of poor milking ability (MLK) to <1% via culling over three years, and decreased prevalence of low birth weights (BWT) to 10% by improved gestational feeding. The comparison flock (BASE) had 15% poor milking ability and 25% low birth weight lambs. MLK strategy decreased POST and RM compared to BASE (0.4% and 0.8% respectively), but early years retained more replacement ewe lambs, lowered the number of market lambs, and initially decreased annual profits. Over ten years, average profits increased 0.7% under MLK, until the last seven years when poor milk prevalence was <1% and profits were 2.7% higher. The BWT strategy lowered PERI, POST, and RM (1%, 0.6%, 0.5% respectively). BWT increased profits by 12.6% over BASE, primarily due to the 2.9% increase in market lamb revenues, and was affected to a lesser extent by the 1% cost reduction associated with the lower mortality.