Effect On Growth And Meat Quality By Adding Biogas Residues To Diet For Growing-Finishing Pigs

18 duroc-landrace-yorkshire with initial weight 15 kg were divided into one control group and two test groups(test groupⅠand test groupⅡ) with 6 pigs in each group to investigate the effects of adding different levels biogas residues to diet on the growth and meat quality of duroc-landrace-yorkshire using randomized block of single factor by feeding experiment and slaughter experiment. Feeding experiment was separated 3 growth stage of 20~35kg,35~60kg and 60~90kg. Addition of biogas residues in test groupⅠwere 2%,4% and 6% in different growth stages and in test groupsⅡ3%,7% and 10%.Slaughter after feeding experiment, determine the indexes of carcass traits,meat quality and nutritional components of pork. The results were showed as follows:1 Effect on growth and economic benefitThe finishing period reaching the same weight of control group,test groupⅠand test groupⅡwere 99,107 and 112 days respectively. In the whole period, daily gain of control group 710.10g/d and test groupⅠare extremely significantly higher than test groupsⅡ625.89g/d(P<0.01). Feed conversion ratio of control group 3.50 and test groupⅠ3.48 are significantly higher than test groupⅡ3.46(P<0.05). In comparison with control group, feed cost per pig of test groupⅠsaved 17.78 Yuan and test groupⅡ25.25 Yuan.2 Effect on carcass qualityDressing percentage and carcass length of control group and test group had no significant difference(P>0.05),but lean meat percentage,ham percentage and eye muscle area of control group were significantly higher than test group and back fat thickness was significantly lower than test group(P<0.05), and there were not significant differences between test groupⅠand test groupⅡ(P>0.05). And there was a trend that the carcass quality decreased with the increasing of percentages of biogas residues added in diet.3 Effect on meat qualityCooking percentage of control group is significant higher than test groupⅠ(P<0.05) ,extremely significant higher than test groupⅡ(P<0.01) and cooking percentage of test groupⅠis significant higher than test groupⅡ(P<0.05). Drip loss of control group is significant lower than test groupⅠ(P<0.05) ,extremely significant lower than test groupⅡ(P<0.01),and drip loss of test groupⅠis significant lower than test groupⅡ(P<0.05).There were significant differences among each groups at the aspects of muscle color,marbling and tenderness, the score of muscle color of control group was the highest while test groupⅡwas the lowest, the score of marbling control group was the lowest and the tenderness of control group was the lowest while test groupⅡwas the highest. There were no significant differences among each groups at the aspect of water loss rate and pH. And there was a trend that the meat quality decreased with the increasing of percentages of biogas residues added in diet.4 Effect on nutritional componentsCrude protein content of control group was extremely significant higher than test group(P<0.01) , water content of control group was significant higher than test group(P<0.05)and crude fat content of control group was significant lower than test group(P<0.05). There were no significant differences between test groupⅠand test groupⅡat the aspects of crude protein and water content(P>0.05).There were no significant differences among each group at the aspect of crude ash. Crude protein content of control group is higher than it in test group, and there was a trend that the nutritional components decreased with the increasing of percentages of biogas residues added in diet.5 Analysis of nutritive value of biogas residues and heavy metal contentsin feedstuff with biogas residues and the pork feed on itThe contents of dry matter, crude protein, crude fat, crude ash, crude fiber in the biogas residues are 857.7 mg·g-1, 99.0 mg·g-1, 34.9 mg·g-1, 10.7 mg·g-1, 252.7μg·kg-1 respectively. And the contents of cadmium, lead, copper are 18.48μg·kg-1,42.50μg·kg-1,20.80μg·kg-1,mercury is not found. The animal feeds of the control (without biogas residues) and biogas residuesⅠand biogas residuesⅡcontain lower cadmium, lead, and copper contents than the national health standard.Cadmium,lead and copper contents in pork feed on foodstuff of control, biogas residuesⅠand biogas residuesⅡare 0.033 mg·kg-1,0.044 mg·kg-1,0.058 mg·kg-1; 0.268 mg·kg-1,0.364 mg·kg-1,0.393 mg·kg-1;5.555 mg·kg-1,7.180 mg·kg-1,8.404 mg·kg-1 respectively. Mercury is not found in the pork. Biogas residues is a potential additive of pig feed, and 2%~10% addition proportion will not cause heavy metal content exceeding the health standard of the pork.