Quality Evaluation Of Corn Silage And Its Effect On The Growth Performance And Beef Quality Of Finishing Cattle

In order to make a guideline for high-quality corn silage production and its efficient utilization in beef cattle,the effects of corn varieties and harvest stages,silage additives on the silage quality were evaluated as well as the effects of different silage-based diets on the fattening performance and beef quality were compared.Exp.l Based on quality determination of lab-level bag silage,the effects of corn variety and harvest stage on the output,fermentation and nutrition value of corn silage were investigated.The results showed that,the chemical compositions of corn plant and the quality of its silage varied with harvest time and corn variety,where corn silage harvested in dough stage contributed to the most dry matter production.The fermentation quality and nutrition value of com silage were determined by corn variety and its harvest time,where ensilage in ripe stage resulted in lower ammonia nitrogen,lactate,acetate and organic acid relative to those in milk stage and dough stage.Exp.2 Based on quality evaluation of lab-level bag silage,the effects of silage inoculants(YZB,WSS,XLW,RCL,RFR and RCF)on the fermentation and nutrition value of corn silage were investigated.The results showed that,the addition of inoculant YZB,WSS,XLW and RFR decreased the contents of lactate and organic acid while it was reversed with the addition of RCF;inoculants inclusion decreased the starch content of silage along with different fiber components.Exp.3 Based on quality determination of lab-level bag silage,the effects of silage additives(organic acid,enzyme,ammonium and LAB inoculant)on the fermentation and nutrition value of corn silage were investigated.The results showed that,the addition of LAB inoculant,cellulase and ammonium chloride would increase the contents of lactate and organic acid along with decreased pH while the addition of organic acid resulted in lower contents of ammonia nitrogen,lactate,acetate and organic acid.Additionally,cellulase inclusion decreased the starch content of corn silage along with increased NDF,ADF and ash.Exp.4 Based on in vitro gas production trial,the inclusion effects of LAB inoculants(RCL,RFR and RCF)in culture fluid on the in vitro rumen fermentation were investigated.The results showed that,the silage inoculated with RCL resulted in lower(P<0.05)GP24 and gas production rate(c)relative to those inoculated with RFR,and the inclusion effects of different LAB inoculant in incubation fluid on in vitro gas production and total volatile fatty acid concentration were different,being either promotion or inhibition.Exp.5 The cattle(Bohai black,n=60)were randomly allocated to five isonitrogenous diets,which were different in forage,i.e.,whole plant corn silage(WPC),inoculated whole plant corn silage(WPC-M),ear-free corn silage(CSS),inoculated ear-free corn silage(CSS-M)and ear-free corn silage supplemented with equivalent corn grain(CSS-CG,the output ratio of stalk to corn is 1.5:1),where the growth performance,blood parameters and production benefit of beef cattle were investigated.The results showed that,compared to CSS and CSS-M,the cattle fed WPC and WPC-M had higher weight gain,feed efficiency and finishing benefit during the early finishing period(62 d);cattle fed WPC would result in better fattening benefit relative to CSS-CG and inoculated silage slightly improved fattening benefit relative to non-inoculated silage though no significant improvement in growth performance was found.Exp.6 By the end of feeding trial,ten cattle were randomly selected from each group,and then slaughtered to measure carcass traits and collect meat samples on sirloin(12-13th rib)for beef quality analysis.The results showed that,the dressing percentage of group WPC-M was higher than those of group CSS-M,CSS and CSS-CG as well as that of group WPC was higher than group CSS-M;there were no differences found in the sensory quality and nutrition value of beef cattle;the muscular concentrations of MDA and protein carbonyle in group CSS-CG were higher(P<0.05)than those in the other groups along with lower glycolytic potential than WPC-M,CSS and CSS-M.In conclusion,the quality of corn silage was affected by corn variety and its harvest time,where ensilage in dough stage could harvest the most energy yield.The application of combined LAB inoculant,cellulase and ammonium chloride would contribute to silage fermentation while it was converse for the addition of organic acid.The addition of homo-fermented LAB in some level would potentially promote in vitro rumen fermentation.Compared to ear-free corn silage,it’s more economical to use corn silage in the early finishing phase.The application of corn silage in beef cattle fattening would result in better benefit relative to that of ear-free corn silage supplemented with equivalent corn grain,and inoculated silage could slightly improve fattening benefit.There were no differences found on the carcass performance(except for dressing percentage)and beef quality(except for antioxidant capacity)of the cattle fed corn silage or ear-free corn silage.