Comparative analysis of milk production performance,milk quality,and milk amino acid content in Holstein cows with different parity
In order to study the effects of different parities on milk performance,milk quality and milk amino acid content of Holstein dairy cows,the experiment was divided according to parities(1st,2nd,3rd and 4th parities),and 20 healthy and well-immunized dairy cows were selected for each group,with 5 replicates as 1 group and 4 cows per replicate.Cows in each parity group were fed the same diet.The results showed that compared with 1st parity cows,the DMI of 3rd and 4th parity cows significantly increased by 16.70% and 16.13%,respectively(P＜0.05);Compared with parity 1,the milk production of cows with parity 2-4 significantly increased by 5.69%,15.63%,and 15.41%,respectively(P＜0.05);Compared with the second parity,the milk fat percentage of cows in the first,third,and fourth parity decreased significantly by 5.33%,5.84%,and 5.58%,respectively(P＜0.05);The milk protein rate significantly decreased by 11.24%,9.80%,and 10.09%,respectively(P＜0.05);Compared with 1 parity,the 4% FCM of 2-4 parity cows significantly increased by 7.97%,16.88%,and 16.31%,respectively(P＜0.05).Compared with the 1st and 2nd parity,the content of histidine and leucine in milk of the 3rd and 4th parity was significantly reduced(P＜0.05),while the content of methionine was significantly increased(P＜0.05);Compared with other parity,the arginine content in milk of the third parity was significantly increased(P＜0.05);Compared with the first parity,the isoleucine content in milk from 2-4 parity was significantly reduced(P＜0.05).Compared with the 1st and 4th parity,the content of unsaturated fatty acids in milk from the 2nd and 3rd parity was significantly increased(P＜0.05);Compared with the 1st,3rd,and 4th parity,the content of polyunsaturated fatty acids in the milk of the 2nd parity was significantly increased(P＜0.05);Compared to the 1st,3rd,and 4th parity,the long-chain fatty acids in the milk of the 2nd parity are ω-3 fatty acids ω-The content of 6 fatty acids and total fatty acids significantly increased(P＜0.05).Conclusion:With the increase of parity,the milk production performance of cows significantly improves,but the milk quality decreases.The results of this experiment indicate that the milk quality of the second parity is the best.
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