Effects Of Different Protein Source Diets On Production Performance,Blood Indices And Rumen Environment Of Fattening Cattle

With the development of animal husbandry,soybean meal,as a conventional protein feed source,is facing the problems of insufficient supply and low conversion efficiency.Canola meal,with its high yield and high nutritional value,has been used as a substitute for soybean meal,which has been valued in the field of animal husbandry.There are many anti-nutritional factors in soybean meal and canola meal,which result in poor feeding effect,so microbial fermentation gradually become a new focus to improve feed quality.At present,soybean meal,fermented soybean meal,canola meal,fermented canola meal and other different protein source diets have been studied in poultry and monogastric animals,with remarkable effects,but the research in ruminant livestock is still to be explored.This experiment was conducted to study the effects of different protein source diets on growth performance,apparent digestibility,blood biochemistry,slaughter performance and rumen environment of Simmental crossbred cattle during fattening period.The overall study consists of the following four parts.Experiment 1: Effects of different protein source diets on growth performance,nutrient apparent digestibility,and nitrogen metabolism of fattening cattle.This experiment was conducted to study the effects of soybean meal,canola meal,fermented soybean meal and fermented canola meal as dietary protein sources on growth performance,nutrient apparent digestibility,and nitrogen metabolism of cattle during fattening period.Forty Simmental crossbred cattle with an average body weight of455.5±5.0 kg and similar body condition were used as experimental animals.A single factor experiment design was used to randomly divide them into 4 treatment groups with10 replicates in each group and 1 head in each replicate.Cows were fed soybean meal,fermented soybean meal,canola meal and fermented canola meal,respectively.During the experiment,the experimental cattle were fed in single stall,fed freely,and drank water for 15 days in pre-feeding period and 150 days in normal feeding period.The normal feeding period was divided into three periods with 50 days in each period and slaughtered on the 151 st day.The results showed as follows: 1.Fermented soybean meal and fermented canola meal significantly increased the DMI of cattle in the early and middle stages of the experiment(P < 0.05),and the dry matter intake(DMI)in the late stage of the experiment gradually tended to the same.2.Because of the significant increase of DMI,crude protein(CP)digestibility and crude fiber(CF)digestibility of cattle were significantly increased by fermented soybean meal and fermented canola meal(P < 0.05).The results showed that canola meal had no significant effects on growth performance,nutrient apparent digestibility,and nitrogen metabolism of cattle,and could be used as a protein diet instead of soybean meal(P > 0.05).Fermented soybean meal and fermented canola meal can improve the growth performance,CP digestibility and CF digestibility of early fattening,which are suitable for short-term fattening.Experiment 2: Effects of different protein source diets on blood biochemical indices of fattening cattle.This experiment was conducted to study the effects of soybean meal,canola meal,fermented soybean meal and fermented canola meal as dietary protein sources on blood biochemical indices of fattening cattle.The experiment design was the same as experiment 1.At the end of each experiment,blood was collected from tail vein of cattle and serum was separated to determine serum biochemical indexes.The results showed as follows: 1.Fermented soybean meal and fermented canola meal significantly increased the concentrations of total protein(TP),albumin(ALB)and globulin(GLB)in blood(P< 0.05)and promoted protein metabolism.Fermented soybean meal and fermented canola meal increased total antioxidant capacity(T-AOC)of fattening cattle(P < 0.05),fermented canola meal could increase Glutathione peroxidase(GSH-Px)and Superoxide dismutase(SOD)concentration(P < 0.05),and canola meal and fermented canola meal significantly decreased Malondialdehyde(MDA)concentration(P < 0.05).2.Feeding fermented canola meal significantly increased the concentrations of Immunoglobulin A(Ig A),Immunoglobulin G(Ig G),and Immunoglobulin M(Ig M)in blood of cattle(P <0.05);There was no significant difference in serum lipid index among experimental groups(P > 0.05).Fermented soybean meal and fermented canola meal could increase the concentrations of Growth Hormone(GH)and Insulin(INS)in serum of cattle(P <0.05)but had no significant effect on glucagon(GC)(P > 0.05).3.Fermented soybean meal significantly increased the contents of Val,Met,Leu,Tyr,and Lys in serum of fattening cattle.In conclusion,diets with different protein sources have certain effects on blood biochemical indexes of cattle(P < 0.05).Feeding fermented canola meal can improve amino acid metabolism and protein metabolism of fattening cattle,and improve the immune capacity and antioxidant capacity,which can improve the physiological status and health level of cattle to a certain extent.Experiment 3: Effects of different protein source diets on slaughter performance and meat quality of fattening cattle.This experiment was conducted to study the effects of soybean meal,canola meal,fermented soybean meal and fermented canola meal as dietary protein sources on slaughter performance and meat quality of fattening cattle.The experiment design was the same as experiment 1.At the end of the experiment,the carcass weight was calculated,the viscera index of heart,liver,spleen,kidney,and lung were measured,and the longissimus dorsi muscle was measured.The results showed as follows: 1.Fermented canola meal significantly increased the slaughter rate of cattle(P < 0.05);Canola meal and fermented canola meal significantly increased backfat thickness(P < 0.05).The experimental groups had no effect on the organ coefficient of cattle(P > 0.05).2.There were no difference in cooking loss,shear force and meat color among experimental groups(P > 0.05),but fermented canola meal could reduce drip loss(P < 0.05)and p H at24 h after slaughter(P < 0.05).3.Feeding fermented soybean meal and fermented canola meal could significantly increase muscle CP content(P < 0.05).The results showed that feeding fermented canola meal could improve slaughter performance and meat quality of cattle to a certain extent.Experiment 4: Effects of different protein source diets on rumen environment of fattening cattle.This experiment was conducted to study the effects of soybean meal,canola meal,fermented soybean meal and fermented canola meal as dietary protein sources on rumen environment of fattening cattle.The experiment design was the same as experiment 1.The results showed as follows: 1.Fermented soybean meal and fermented canola meal significantly increased the contents of propionic acid,total volatile fatty acid and microbial protein in rumen of beef cattle(P < 0.05)and decreased the ratio of AA to PA.(P < 0.05).2.Fermented soybean meal and fermented canola meal tended to increase the relative abundance of Firmicutes(P < 0.1),and fermented canola meal significantly decreased proteobacteria(P < 0.05).Fermented soybean meal significantly increased the relative abundance of Succinate bacteria(P < 0.05).In conclusion,diets with different protein sources have certain effects on rumen environment.Compared with soybean meal and canola meal,fermented soybean meal and fermented canola meal can improve rumen fermentation parameters and optimize rumen microbial community structure.