Strategies for Controlling Neonatal Diarrhea in Cow-Calf Herds - The Sandhills Calving System

摘要

Undifferentiated neonatal diarrhea is an economically important cause of morbidity and mortality in beef calves. Understanding the multifactorial nature of neonatal calf diarrhea in cattle populations is the basis for developing strategies for prevention. The common pathogens of neonatal calf diarrhea are endemic, and it is unlikely that cattle populations could be made biosecure from these agents. Managers of extensive beef cattle systems have limited practical opportunities to improve rates of passive transfer, and vaccines have not always been protective. Lactogenic immunity wanes, making calves age-susceptible and age-infective. For these reasons a biocontainment approach to control neonatal calf diarrhea seems prudent. The Sandhills Calving System is a biocontainment strategy to protect calves from effective contact with the agents of neonatal diarrhea by: 1) segregating calves by age to prevent direct and indirect transmission of pathogens from older to younger calves; and 2) scheduled movement of pregnant cows to clean calving pastures to minimize pathogen dose-load in the environment and contact time between calves and the larger portion of the cow herd. The effect of the system is to re-create the more ideal conditions that exist at the start of the calving season during each subsequent week of the season. The Sandhills Calving System has been tested over six and five calving seasons, respectively, in two privately-owned ranch herds. We have observed important and statistically significant reductions in morbidity and mortality due to neonatal calf diarrhea, and greatly reduced use of medications on these operations. Although the system has been tested and adopted in ranches typical of the Nebraska Sandhills, it should be useful elsewhere because the principles on which it is based are widely ap-plicable.