Efectele suplimentării raţiei în cupru şi zinc asupra performanţelor de producţie şi reproducţie la taurinele de lapte în primele 5 luni de lactaţie

In the North-East of Romania, the soil has a low concentration of copper and zinc. 40 Holstein-Friesian lactating cows were selected and divided into 4 groups of 10 (Copper, Zinc, Copper-Zinc and Control). For 20 weeks the cows from Copper group received 1.5 g CuSO4 5H2O/cow/week, CopperZinc group 1.5 g CuSO4 5H2O and 5g ZnSO4 7H2O/cow/week and the Zinc group 5 g ZnSO4 7H2O/cow/week. The protein, fat and the total number of somatic cells in the milk as well as copper and zinc concentrations in the blood plasma of the individual cows were analyzed once a month. It has also been monitored monthly the milk production. Registered breeding indicators during the study were: calving - fecundant artificial insemination interval (days), first artificial insemination - fecundant artificial insemination interval (days) and insemination index. Significantly higher milk production was found in cows from Zinc group compared to Copper group. Pearson test showed a positive correlation between plasma Zn and milk production in cows. Higher amounts of fat and milk protein were observed in the cows receiving both mineral supplements. Total number of somatic cells in examined cows was higher than the maximum number of cells in milk from healthy mammary gland. Number of artificial insemination was lower in cows receiving both mineral supplements than in the other groups. Rate of success after first artificial insemination in the 4 groups was 21%. The shortest calving-first insemination interval, in cows diagnosed pregnant was in Copper-Zinc group. At baseline all cows were deficiencies in Cu and Zn. During the 140-day study, supplementation of the ration in Cu and / or Zn as sulphate, allowed a substantial change in plasma, but after passing the peak of lactation, when cows reached the normal parameters for Cu and Zn plasma.