title: Diurnal variations in milk macro-mineral concentrations in Holstein dairy cows in Urmia, Iran.
abstract: Milk samples from high and low milk producer Holstein cows, were obtained during the morning and afternoon milking over a one week period. Overall, 1064 samples were tested within 14 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 < 0.05). The individual comparison of milk parameters between both groups in the different milking times were also different (p < 0.05). 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 < 0.05). The highest and lowest correlations were found between Ca(++) and inorganic phosphorus (IP) (r=0.37, p < 0.05) and Na(+) and IP (r=0.10, p < 0.05), 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.
authors: Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran.
authors: Shahram
authors: S
authors: Nozad
authors: Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran.
authors: Ali-Gholi
authors: AG
authors: Ramin
authors: Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran.
authors: Siamak
authors: S
authors: Asri Rezaie
keywords: Cows; Holstein; Macro-minerals; Milk; Milking time
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