Diurnal variations in milk macro-mineral concentrations in Holstein dairy cows in Urmia, Iran

Milk samples from high and low milk producer Holstein cows, were obtained during the morning and afternoon milking over a one week period. Overall, ۱۰۶۴ samples were tested within ۱۴ times sampling in Urmia, Iran. Milk macro-mineral concentrations in the morning milking and in low producers were greater than in the afternoon and in high producers. The highest and lowest concentrations were observed in Na+ and Mg++, respectively. Mean milk values between low and high producers in the morning, afternoon and daily milking times were different (p < ۰.۰۵). The individual comparison of milk parameters between both groups in the different milking times were also different (p < ۰.۰۵). The results of correlation among macro-minerals in the morning, afternoon and overall milking showed significant and positive correlations among all macro-minerals except for Na+ and K+, in which there was a significant negative correlation (p < ۰.۰۵). The highest and lowest correlations were found between Ca++ and inorganic phosphorus (IP) (r=۰.۳۷, p < ۰.۰۵) and Na+ and IP (r=۰.۱۰, p < ۰.۰۵), respectively. It is concluded that the concentration of macro-minerals in different producers varied between milking times. The sodium concentration was the highest while Mg++ was the lowest among macro-minerals. The correlation between Ca++/ IP was the highest, while Na+/K+ revealed a negative correlation. Therefore, by organizing the appropriate macro-minerals in the ration, it would be possible to achieve an optimal purpose from animal husbandry.

کلیدواژه ها:

Milk ، Cows ، Milking time ، Holstein ، Macro-minerals