Strategies to Improve Transition Dairy Cows Health and Milk Quality

Despite numerous studies since decades, transition period of dairy cows remains a big issue for both researcher and farmers. The endocrine changes that characterize this period expose the animals to metabolic imbalance, immune depression and oxidative stress. This situation results in the emergence of metabolic and infectious disease in addition to reduced and impaired milk production, that finally lead to the 15% of culling occurring in the first weeks of lactation. Therefore, several strategies have been put in place in order to improve health and welfare of transition cows, taking into account environment, nutrition and management aspects. The main purpose of this work is to investigate through 3 studies the effects of some of these strategies. In the first study, the effects of overcrowding during dry period were evaluated on stress related blood markers, behavior and welfare of animals. Overcrowded cows showed higher blood level of dehydroepiandrosterone (DHEA) and cortisol than controls and a restlessness behavior. The second study aimed to investigate the impact of an immunomodulant feed supplement (Omnigen-AF) fed to 190 cows from dry off to 150 DIM, on their health and milk composition and quality. Supplemented cows, compared to controls, had lower incidence of postpartum disease and lower culling rate within 60 DIM. Milk production and quality was not influenced by the treatment except for a reduction of SCC among Holstein cows. The last study evaluated the consequences on quality of milk and Parmigiano Reggiano cheese of an antiketotic treatment (Kexxtone). Despite the great concern on this aspect among cheese producers, the treatment didn’t impaired nor milk nor cheese production, confirming the usefulness and safety of this treatment for the prevention of ketosis. Overall, this thesis confirms the need and the effectiveness of different strategies that aimed to improve transition dairy cows health and their milk production.