Researches On Slaughter Traits And Meat Quality Of Zaozhuang Heigai Pigs

On April 29,2019,Zaozhuang Heigai pigs have passed the national genetic identification of local livestock and poultry breeds.There are few studies and reports on the characteristics of Zaozhuang Heigai pigs'genetic resources.In order to fully understand the germplasm characteristics of Zaozhuang Heigai pigs,this experiment was conducted to investigate the effects of different slaughter weights on slaughter performance,meat quality traits,blood biochemical indexes,muscle chemical composition,muscle antioxidant performance and amino acid content of Zaozhuang Heigai pigs,to determine the suitable market slaughter weight of zaozhuang heigai pig,and to analyze the correlation degree of slaughter performance,meat quality and blood biochemical indexes.90 castrated boars of same batch,well-developed,healthy and weighing about 30kg were selected as experimental pigs.The fattening experiment was carried out at the same nutrition level and conditions.When the average body weight reached 95,105 and 115kg,the experimental pigs that met the weight requirements were randomly selected with 10 heads in each body weight group.The main results of the measurement show that:1.Comparison of blood biochemical indexes of different slaughter weight:There was no significant difference in UREA content between the 105kg group and the 115kg group?P>0.05?,significantly different from the 95kg group?P<0.05?.Meanwhile,there was no significant difference in UREA content between the 115kg group and the 95kg group?P>0.05?.The content of AST in the 115kg group was 16.64%and 36.95%higher than that in the 105kg group and the 95kg group.There was no significant difference in blood biochemical indexes?P>0.05?.2.Comparison of slaughtering performance of different slaughter weight:with the increase of slaughter weight in 95¹15kg segment,the carcass weight was significantly increased?P<0.05?.The skin thickness of the 95kg group was significantly different from that of the115kg group?P<0.05?,with an increasing trend.The 3-point average backfat thickness of the105kg group was significantly higher than that of the 95kg group?P<0.05?,and lower than that of the 115kg group,but the difference was not significant?P>0.05?,with an obvious increasing trend.The ocular muscle area of the 115kg group was higher than that of the 105kg group and the 95kg group by 16.09%?P<0.05?and 19.00%?P<0.05?.The lean meat rate of the 95kg group was higher than that of the 105kg group and the 115kg group by 9.94%?P<0.05?and 12.14%?P<0.05?.There was no significant difference in slaughter rate and carcass length?P>0.05?.3.Comparison of meat traits of different slaughter weights:pH₁ of the 115kg group,was significantly higher than 95kg group?P<0.05?,higher than 105kg group?P>0.05?.And there were no significant differences in other meat quality traits?P>0.05?.The water loss and napole yield tend to increase.Drip loss,cooking loss and tenderness have a decreasing trend.4.Comparison of the conventional chemical composition of different slaughtered weight meats:the three groups were not significantly different in the dry matter content,crude protein content,crude ash content and intramuscular fat content?P>0.05?;The intramuscular fat content of the 115kg group was higher than that of the 105kg group and the 95kg group by4.20%and 16.31%,with the increase of slaughter weight,intramuscular fat tended to increase.5.Comparison of antioxidant properties of muscle at different slaughter weight:T-SOD of95kg group was significantly higher than that of the 115kg group?P<0.05?,with the increase of slaughter weight,T-SOD tended to decrease.There was no significant difference in MDA and T-AOC among the three groups?P>0.05?.6.Comparison of muscle collagen,inosine monophosphate and cholesterol of different groups:the inosine monophosphate content of 95kg group was significantly lower than that of the other two groups?P<0.05?,the 105kg group was higher than the 115kg group?P>0.05?.There was no significant difference in the content of total muscle collagen and cholesterol?P>0.05?.7.Comparison of amino acid content of different groips:The content of Glu,Gly,Val,Lle,Pro,Yhr and Phe in 95kg group were significantly higher than 115kg group?P<0.05?and higher than 105kg group?P>0.05?.The difference of His content between the 115kg group and the105kg group was not significant?P>0.05?,but it was significantly lower than that of the 95kg group?P<0.05?.The content of DAA in the 95kg group was higher than 105kg group?13.78%??P<0.05?and higher than 115kg group?18.67%??P<0.05?.The content of EAA and TAA in the 95kg group was significantly higher than that of the 115kg group?P<0.05?.In general,the amino acid content decreased with the increase of slaughter weight.8.Correlation analysis of blood biochemical indexes with slaughter performance and meat quality traits showed that:There is a very significant or significant correlation between some of the traits.Such as ALT was significantly positively correlated with meat color,marble pattern and Napole yield?P<0.05?,and was negatively correlated with cooking loss?P<0.05?.Lean meat rate was positively correlated with serum phosphorus?IP?,drip loss and tenderness?P<0.05?,and negatively correlated with premortem weight?P<0.05?.Lean meat rate was significantly positively correlated with serum phosphorus?IP?,drip loss,tenderness?P<0.05?,and negatively correlated with pre-slaughter weight?P<0.05?.The skin thickness is significantly positively correlated with the three-point average backfat thickness,ocular muscle area and IMF?P<0.05?,and significantly negatively correlated with cooking loss?P<0.05?,etc.This correlation can be used as a prediction between slaughter performance and meat quality characteristics index,and provides reference for early selection and performance determination.