Transhumance of dairy cows to highland summer pastures interacts with breed to influence body condition, milk yield and quality

This paper aimed at testing the differences of adaptability of bovine dairy, dual purpose and local breeds during the summer transhumance to highland pastures (summer farms), evaluating temporal variations of body condition and of milk yield and quality. Data were from 799 dairy cows of specialised (Holstein Friesian and Brown Swiss), dual purpose (Simmental) and local (mostly Rendena and Alpine Grey) breeds, and were collected before and after the transhumance in 109 permanent dairy farms, and during transhumance in 15 summer farms of the Autonomous Province of Trento, north-eastern Italy. Body Condition Score (BCS), milk production and quality (fat, protein, casein, lactose, urea, SCS) were analysed for the fixed effects of breed, parity, days in milk, month, supplementary concentrate level, and for the random effects of summer farm and individual cow. Body condition score was influenced by transhumance to summer farms, with low values in July and a recovery at the end of the period. This pattern was particularly marked in the specialised breeds. Similarly, also milk production declined, especially for Holstein Friesian and Brown Swiss, so that towards the end of transhumance all breeds had similar milk productions. Returning to permanent farms did not compensate the specialised breeds for the production loss experienced at the beginning of the grazing season. In conclusion, local and dual purpose breeds adapt better than specialised breeds to the summer pastures, and this results into an important reduction of their productive gaps (with lower variations of milk quality) and in maintaining body fat reserves.