Comparison Of Chemical Compositions, Energetic Values,Growth Performance And Carcass Quality Of Some Alternative Feed Sources Fed To Beef Cattle

In order to explore the possibilities for different alternative feed sources (AFS) to improving beef production, a study was conducted to predict the amount of alternative feed sources, to compare the nutritive values of different alternative feed sources, growth performance,carcass traits and meat quality of beef cattle using in vitro gas production experiment, feeding-slaughtering trial.Experiment1:This study was designed to estimate the national amount of alternative feed sources in2012and to analyze the chemical composition and energetic values of maize stover, soybean straw, dry distiller’s grain and packed maize stover silage. According to the ratio of grains to straw, we calculated the annual amount of AFS in China2012, indicating249.6million tons for maize stover,2048million tons for soybean straw,2882.9million tons for dry distiller’s grain, respectively. Chemical analysis showed that dry distiller’s grain had the highest organic content, followed by maize stover, soybean straw and packed maize stover silage. Dry distiller’s grain had highest (P<0.05) contents of EE, CP, NDIN and ADIN than other AFS, while packed maize stover silage had higher (P<0.05) Ash, NDF and ADF than other AFS. According to the INRA model, the GE content of maize stover, soybean straw, dry distillers grains and packed maize stover silage were18.45,18.33,20.88and17.91MJ/kgDM, respectively; the content of NEm was5.52,5.19,1.38and4.18MJ/kgDM, respectively; the content of NEg was2.80,2.55,0.21and1.80MJ/kgDM, respectively. In conclusion, a huge amount of the alternative feed sources annually available in China such as maize stover, soybean straw and dry distiller’s grain, would be used as ruminant feed resources.Experiment2:This experiment was conducted to evaluate the effect of AFSs and their mixed ration on in vitro gas production GP, ruminal fermentation, methane production and ruminal digestibility. The results showed that soybean straw had significantly higher (P<0.05)72h GP and rate of GP (c) than other AFS. The yield of methane production was significantly higher (P<0.05) for packed maize stover silage than dry distiller’s grains. There were no significant differences (P>0.05) in pH values and total volatile fatty acids between groups. Dry distiller’s grains had significantly higher(P<0.05) concentrations of NH3-N, propionate, isovalerate and valerate, but lower acetate than other AFS. As to in vitro DM digestibility, soybean straw was the highest, followed by maize stover, dry distiller’s grains and packed maize stover silage. The ration mixed with AFS showed that there were no significant differences (P>0.05) in potential GP (B), rate of GP (c), fermentation lag time (lag) among rations. Also there were no significant difference (P>0.05) in CH4and CO2production between rations for24h in vitro fermentation. The concentration of NH3-N were significantly higher (P<0.05) for soybean straw ration and packed maize stover silage ration than maize stover ration. Also there was no significant difference (P>0.05) in in vitro digestibility among rations. In conclusion, compared with maize stover, soybean straw has a positively impact on the rumen fermentation pattern and may be potentially used as a good roughage source for ruminant feeding. Experiment3:This experiment was conducted to investigate the effect of feeding different AFS to growing and finishing cattle on growth performance. Sixty crossbred Simmental x local breed bulls aged12months old (average bodyweight335±15kg) were selected and allotted to4treatment diets with15bulls in each of treatments. All bulls were tethered using neck straps in tie stalls and were individually fed. The trial period was22weeks including1-wk for adaptation and21-wk for data collection. The treatment diets were:(1) maize stover diet with40%maize stover (MSD);(2) soybean straw diet with30%maize stover replaced by soybean straw (SBD);(3) dry distiller’s grains diet with30%maize stover replaced by dry distiller’s grain (DDD);(4) packed maize stover diet with40%packed maize stover silage (PMSD). The results showed that dry matter intakes were significantly higher (P<0.05) for PMSD than MSD and SBD during0-7week and8-14week, for PMSD than SBD during15-21week, and for DDD and PMSD than MSD and SBD during0-21weeks. The ADG values were1.56,1.68,1.58and1.72kg for MSD, SBD, DDD and PMSD respectively, although their differences were not significant (P>0.05). In conclusion, dry distiller’s grains and packed maize stover silage used as replacement of maize stover had a promotion effect on feed intake. The packed maize stover silage showed a potential function in improvement of average daily gain, feed intake and feed conversion of beef cattle.Experiment4:This study was conducted to investigate the effect of replacement of different AFS for corn stover in beef cattle diets on blood biochemical indicators. At the end of the feeding trial, the blood samples were taken through the neck before the morning feeding for serum biochemical parameters. The results showed that blood glucose concentration was significantly higher (P<0.05) for MSD than DDD. Urea nitrogen content were significantly higher (P<0.05) for MSD and DDD than that of SBD. The results combined with Experiment3showed that lower blood urea nitrogen was in line with the relatively low average daily gain for MSD and DDD. There were no significant differences (P>0.05) in serum total cholesterol, triglycerides and total protein content, respectively. In summary, DDD was better in glucose metabolism than MSD; SBD was better in promotion of nitrogen deposition than MSD and DDD. Based on blood biochemical indicators, feeding beef cattle with soybean straw and packed maize stover silage would be beneficial to nitrogen deposition.Experiment5:This study was designed to investigate the effect of different AFS on slaughtering performance and carcass quality. Ten bulls with similar body weight were selected at the end of feeding trial and slaughtered for measurement of slaughtering performance, carcass quality and meat chemical composition. The results showed that MSD and DDD groups had significantly higher (P<0.05) shear force values than SBD group. The pH values were significantly (P<0.05) lower for MSD and SBD groups than DDD and PMSD groups. The cooking loss were significantly higher (P<0.05) for MSD than SBD and DDD. The fat color brightness (L*) was significantly greater (P<0.05) for DDD group than SBD and PMSD groups. The cholesterol content was significantly higher (P<0.05) for DDD and PMSD groups than MSD and SBD groups. In summary, there were no significant differences in dressing percentage, meat percentage, high-priced meat cuts, ribeye area, marbling score, meat colour and meat chemical compositions among dietary treatment. There were significant differences in shear force, pH values, cooking loss and cholesterol compositions. In general, the use of soybean straw to replace some maize stovers in the beef cattle diet showed a potential to some extent for improvement of beef quality in relation to its flavor.