Effect Of Rumen Protected Methionine And Nicotinic Acid On The Performance And Blood Biochemical Parameters In Lactating Cows

The experiment was conducted to study the effects of rumen protected Methionine (Met) and nicotinic acid (NA) in dairy ration on the apparent digestibility, milk performance and blood biochemical parameters of Chinese-Holstein cows during early lactation.Eight multiparous Chinese-Holstein cows in early lactation were arranged randomly into 4x4 Latin square design. Treatments in a 2x2 arrangement were A: Og/d-head rumen protected Met, Og/d-head nicotinic acid;B: Og/d-head rumen protected Met, 6g/d-head nicotinic acid;C: 25g/d-head rumen protected Met, Og/d-head nicotinic acid;D: 25g/d-head rumen protected Met, 6g/dhead nicotinic acid. The results showed that apparent digestibilities of ADF and NDF were not different among treatments (P> 0.05). Addition of rumen protected Met to the diet significantly increased the CP apparent digestibility, milk fat percentage and milk protein percentage by 10.60% (P<0.01), 6.80% (P<0.01) and 3.02% (P<0.05), respectively. Milk yield was not affected by rumen protected Met (P>0.05). Milk production and milk protein percentage were significantly increased by 5.68% (P<0.05) and 1.09% (P<0.05) with the addition of nicotinic acid, but there was no significant influence on milk fat percentage (P>0.05). In this experiment, there was no obvious difference in SNF among treatments (P>0.05). When the rumen protected Met fed, the concentrations of serum urea nitrogen and non-esterified fatty acid (NEFA) were significantly decreased 12.01% (P<0.01) and 7.67% (P<0.01), Met and Cys in serum were significantly improved 8.75% (P<0.01) and 50% (P<0.01);Ser, Ile and Asp were decreased 9.40% (P<0.01), 12.46% (P<0.01) and 9.22% (P<0.01);branched chain amino acid (BCAA) and essential amino acid (EAA) decreased 9.45% (P<0.05) and 7.66% (P<0.05);non-essential amino acid (NEAA) and total amino acid (TAA) decreased 5.31% (P<0.01) and 6.64% (P<0.01). However, there were no significant influence (P>0.05) on the concentrations of cholesterol and triglyceride by addition of the rumen protected Met to the diet. The concentrations of blood glucose increased 8.82% (P<0.05), non-esterified fatty acid and total cholesterol (TC) decreased 9.94% (P<0.01) and 4.32% (P<0.01), when the supplementation of nicotinic acid. The concentrations of BUN (P>0.05) and AA (P>0.05) were not affected by nicotinic acid. The experiment indicated that rumen protected Met and nicotinic acid had a significant interact on the decrease of NEFA in dairy cow (P<0.05). The economic benefit was daily increased by 2.30 RMB, 1.27 RMB and 2.68RMB per cowin the three treatment groups. Therefore, it is of most important significance to add rumen protected Met and nicotinic acid to early lactating cow diets.