The Impact of Copper and Zinc Deficiency on Milk Production Performances of Intensively Grazed Dairy Cows on the North-East of Romania

The influence of copper and zinc supplements on milk production performances and health indicators was tested in a 20week feeding trial, with 40 Holstein-Friesian lactating cows, divided in four groups (copper, zinc, copper-zinc and control). Correlations of the Cu and Zn plasma values with some animal performance criteria of health (body condition score and somatic cell counts) and production (milk yield, peak milk yield, fat and crude protein content) were done. During the 140 days of the experiment, the two added minerals caused a statistically significant increase (p < 0.05) of their plasma values after the peak of the cows’ lactations. It was also observed that subjects that have received copper and zinc supplements had the lowest number of somatic cell counts in milk. The Pearson correlation test showed a positive correlation (p = 0.007, r = +0.851) between the plasma Zn and the milk production. The improvement of the nutritional status improved the milk production performances of the cows as well as their health performances. Keywords—Copper, dairy cows, health, milk production, zinc.