[Effect of the copper status on the reproduction performance and the milk yield of cows in 2 copper-deficient locations. 2. Effect of copper deficiency on the reproduction performance and the milk yield of cows].

The influence of copper deficiency on the reproduction performance of cows has not often been investigated. In two habitats feeding cows with mineral mixtures rich in copper resulted in a significant reduction of the aperiodically extended sexual cycles. The beginning of the first visible symptoms of heat, the period between gravidities, the duration of gravidity, the birth weight of the calves and the Cu-content of the colostrum remained uninfluenced by Cu-supply. The liver weight increase of the calves from cows without Cu-supplement during gravidity was by 5% lower during the first 90 days of life than that of the offspring of cows with additional intrauterine Cu-supply (p greater than 0.05). The mineral mixture increased the milk yield by 0.4 resp. 0.5 kg and the milk fat content by 0.10 resp. 0.13%. This resulted in an excess production of 32 resp. 62 g milk fat per cow and day of the experiment (p greater than 0,05).