Genetic analysis of true profit for Spanish dairy cattle

In this study, 7738 cows with production, type, and productive life traits from 239 herds with information on milk, meat, food, housing, and labour costs were used. A lifetime net profit value was calculated for each cow. An average cow had the first calf at 28.6 months of age, 6149 kg of milk in the first lactation, a productive life of 1236 days, 3.28 lactations and a net profit of 410 euros per year of productive life. Heritability of true profit was equal to 0.091. Genetic correlations with production and longevity traits were moderately high, ranged between 0.76 to 0.83. Genetic correlations with type traits were low, around zero, ranged between -0.33 and 0.21. A high genetic correlation was achieved with milk per day of productive life (0.92). Net merit index was the best predictor of the breeding value of true profit, with only 32% as coefficient of determination. Protein yield alone explained a 30% of the true profit. The best prediction of the true profit was achieved with the net merit index, plus rear leg side view, udder cleft and body depth, with 40% of total variation.