Grazing affects animal health: an examination of survey data collected by accredited veterinarians during visits to dairy farms
Résumé
We developed a grazing index that objectively defines livestock operations based on the proportion of grass in the annual diet of the dairy cow herds. Data were collected from 102 cattle farms, and the results show that, in general, levels of grazing were higher in less intensive farming systems. Simultaneously, higher levels of grazing were associated with a decrease in the number of veterinary visits (notably to treat digestive and metabolic issues), the overall consumption of medications (notably those involved in curative treatments), and the frequency of severe hoof-related lameness. Animal lifespan and perinatal mortality were, respectively, positively and negatively correlated with higher levels of grazing. Some of the limits to interpreting these data are discussed.