Study on Milk Production Dynamics and Major Chemical Milk Components in Brown Sire Dams of Brown Swiss-Type from the Research and Development Station for Bovine Raising - Arad

The present work was carried out to determine the influence of lactation rank on the milk yield, fat and protein evolution. Observations were carried out on 117 lactations, as follows: 15 first lactations, 22 second lactations, 26 third lactations, 28 fourth and 26 fifth lactations. It was found out that the average milk yield was 7511.66 kg with the maximum in the fifth lactation (7898.19 kg) and the minimum of 7117.06 kg in first lactation. The differences were highly significant until the third lactation. After the fourth lactation the differences between lactations become statistically no significant, as productive maturity is reached. Milk fat percentage reaches the maximum value in the fifth lactation (4%) with a minimum value recorded in the fourth lactation (3.83%). The average milk fat percentage was 3.94%. Significant and very significant differences occurred for the milk fat percentage between the first three lactations and the fourth and fifth lactations. Milk protein percentage has averaged 3.2%. This parameter is less influenced by lactation rank.