Diurnal Variations in Milk Macro-Mineral Concentrations in Holstein Dairy Cows in Urmia, Iran

Abstract

A total of 1064 milk samples were collected from 40 high yielding and 36 moderate yielding cows during the morning and afternoon milking consecutively for seven days cows, to determine the diurnal variations in macro-mineral concentrations. Milk macro-mineral concentrations in the morning milking and in low producers were greater than in the afternoon and in high producers, respectively. The daily'] mean milk macro-minerals for Ca, IP, Mg, Na and K concentrations were 13.25, 10.76, 3.84, 76.2 and 17.1 mmol/l, respectively. The highest and lowest concentrations were observed in Na and Mg, respectively. Mean comparison of milk values (ANOVA) between low and high producers in the morning, afternoon and daily milking times were all significantly different (P<0.01). Significant and positive correlations were found among all macro-minerals except for Na and K, in which there was a significant negative correlation. The highest and lowest correlations were found between Ca & IP (r=0.37, P<0.01) and Na & IP (r=0.10, P<0.01'\), respectively. It is concluded that the milk macro-mineral concentrations varied according to milk production of cows and milking times. Thus, by balancing the macro-minerals in animals' diets, it may be possible to achieve the highest milk quality and quantity yield.