Resumen de Estrés térmico en razas autóctonas de rumiantes lecheros

M.J. Carabaño, M. Ramón, H.M. Abo Shady, María Dolores Pérez-Guzmán Palomares, M. Serrano, C. Diaz, A. Molina, A. Menéndez Buxadera, K. Bahchaga, María Ángeles Pérez-Cabal, Juan Manuel Serradilla Manrique

• Fat and protein production from 191.768 ewes and 11.259 goats, together with climatic variables were used to determine the threshold and response to heat stress (HS) in dairy sheep (Manchega) and goat (Florida) Spanish local populations. Models including the effects of herd-year of test day, number and stage of lactation, age of the animal at recording, prolificacy, milking time, animal and a regression (b) on the climatic variable that operates only after a certain threshold (To) were used. Average (Tave) and maximum temperature (Tmax) plus an index combining both temperature and humidity (THI) were used as climatic variables. The analyses were carried out for the whole population and for the highly producing (AP) animals (1.5 sd above average). To was lower for goats than for sheep around 10ºC vs. 29 ºC for Tmedia and Tmax. respectively. Small b values were observed for the whole sheep population, but a larger impact of HS was found for the AP animals. For these, b ranged between 6 (fat) and 16 (protein)g/ºC. For the goat population, declines were similar for the global and AP data, but larger for fat%, ranging between 0.05 and 0.09% per unit of climatic variable.