[Non-genetic factors influencing on milk and butterfat production of European Holstein-Friesian cows in a seasonal calving system at the 10 region. 2: Effects of age, calving number service and dry periods]

age allaitement bovin laitier breeds condiciones ambientales condition de milieu cows dairy cattle edad environmental conditions ganado de leche grasa de la leche lactancia lait leche milk milk fat parto parturition pastizales pastures primavera printemps race razas spring suckling vaca vache