Effects of low protein diet on milk production efficiency,milk quality,and carbon and nitrogen emission of dairy cows
The study was to investigate the effects of low protein diet based on amino acid balance on the milk production efficiency,milk quality,and carbon and nitrogen emission of dairy cows.A total of 60 healthy dairy cows with 2～3 parturients,80 days of lactation,and a milk yield of 42～43 kg were randomly divided into two groups:A control group(high protein group,17.5％CP)and a test group(low protein group,16％CP+rumen lysine,rumen digestion rate 85％,intestinal absorption rate 95％),with five replicates in each group and six cows in each replicate.The preliminary trial period was seven days,and the formal trial period was 90 days.The results showed that compared with the control group,the dry matter intake of the test group had an increasing trend,but there were no significant differences in milk yield and milk production efficiency(P＞0.05).Lactose in milk composition of the test group was higher than that of control group at the 30th days and the 60th days(P＜0.05),the MUN content of the test group was lower than that of the control group(P＜0.05),but there were no significant differences in milk fat percentage,milk protein percentage,and other milk composition between the control group and the test group(P＞0.05).During the experiment,the concentrations of CO2 and NH3 in the test group were both lower than those in the control group.The study indicates that the addition of rumen lysine in diets with low protein level can reduce carbon and nitrogen emissions without affecting production level and product quality.
low protein dietmilk compositionmilk production efficiencycarbon and nitrogen emission
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