Alimentazione e fertilità nella bovina da latte

Nutrition has an important impact on the reproductive performance of dairy cattle. Energy is the major nutrient required by adult cattle and inadequate energy intake has a detrimental impact on reproductive activity of bovine. Cows under negative energy balance have extended periods of anovulation. Postpartum anestrus, as well as infertility, is magnified by losses of body condition during the early postpartum period. Resumption of ovulatory cycles is associated with energy balance, but seems to be mediated by a rise in plasma IGF-I; which is linked to nutritional status and concentrations of insulin in blood. Feeding diets that promote higher plasma glucose and insulin may improve the metabolic and endocrine status of cows. Feeding behavior of dairy cows during the transition period, particularly a decline in feed intake prior to calving, is associated with risk of postpartum uterine disease, such as metritis. Because metritis has a profound negative effect on risk of pregnancy in dairy cows, providing adequate bunk space and environment to maximize feed intake is expected to minimize the risk of uterine diseases and improve fertility. The aim of this tesis was to investigate the relationships between nutrition and management on reproductive efficiency and metabolism of transition dairy cows. The first study used lactating dairy cows to examine the effects of silymarin from Milk Thistle on metabolism, production, milk composition and fertility of dairy cows. The second experiment investigated the effects of salicin from willow on metabolism, production and milk composition. The reproductive indices were also been collected. In the last study, length of dry period was correlated with body condition score and energy balance of transition cows. Furthermore, the relationship between dry period length and performance of dairy cows was examined (production, milk composition and fertility).