Effects of Dietary Protein Level on Growth Performance,Serum Biochemical,Immune and Antioxidant Indices and Serum Metabolites of Lactating Calves
This experiment was conducted to investigate the effects of dietary protein level on growth perform-ance,serum biochemical,immune,antioxidant indices and serum metabolites of lactating Simmental hybrid calves.Thirty newborn Simmental hybrid calves with average body weight of(42.00±2.5)kg and similar age were randomly divided into 3 groups with 10 calves in each group(half male and half female).Calves were suckled with cows and supplemented with pellet diets starting at 7 days of age.Calves in the three groups were fed the high protein level pellet diet with 22％crude protein(CP)and 5.40 MJ/kg combined net energy(NEmf)(high protein group),medium protein level pellet diet with 20％CP and 5.62 MJ/kg NEmf(medium protein group)and low protein level pellet diet with 18％CP,5.70 MJ/kg NEmf(low protein group),respec-tively,and fed the same alfalfa hay.The pre-trial period lasted for 10 days,and the experimental period lasted for 90 days.The results showed as follows:1)the body weight on day 60 and day 90 and average daily gain of calves in high protein group were significantly higher than those in medium and low protein groups(P＜0.05).2)The contents of total protein(TP),glucose(GLU)and immunoglobulin A(IgA),the activities of superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)and total antioxidant capacity(T-AOC)in serum of calves in high protein group were significantly higher than those in medium and low protein groups(P＜0.05),and the contents of tumor necrosis factor-α(TNF-α)and malondialdehyde(MDA)in ser-um were significantly lower than those in medium and low protein groups(P＜0.05);the serum interleukin-4(IL-4)content in high protein group was significantly higher than that in low protein group(P＜0.05).3)Through serum metabolomics analysis,124 differential metabolites were screened out among the three groups,and mainly enriched in metabolic pathways such as cholesterol metabolism,bile secretion and protein digestion and absorption,etc.,among which 6 metabolites as carnitine,glycochenodeoxycholic acid,cholic acid,de-oxycholic acid,lithocholic acid and ceramide C18 could be used as the main indicators to identify the serum metabolomics characteristics of the growth and development of calves.In conclusion,diets with high protein level can increase the average daily gain,enhance the immune and antioxidant capacity,and promote the cho-lesterol metabolism,bile secretion and protein digestion and absorption of lactating calves.Under the conditions of this experiment,the pullet diet with 22％CP and 5.40 MJ/kg NEmf for lactation calves is suitable.[Chinese Journal of Animal Nutrition,2024,36(9):5776-5792]
万方数据
维普
