Comparative Study On Nutritional Quality And Flavor Of Xiangxi Yellow Beef With Different Carbon Source Diets

The effects of feeding different carbon source diets on conventional nutrients,meat quality,flavor substances,fatty acids and volatile flavor substances of beef were studied.Twenty-one castrated Xiangxi yellow cattle with similar health,body condition and month age were selected and divided into three treatment groups,namely control group,corn group and barley group,with 7 Xiangxi yellow cattle in each treatment.The piglets in the control group were fed a conventional diet(coarse forage type: whole silage corn as the main source),the piglets in the corn group were fed a diet with corn as the main carbon source,and the piglets in the barley group were fed a diet with barley as the main carbon source.The experiment was divided into three stages according to the body weight of Xiangxi yellow cattle,and each stage was fed for about 100 days.According to "Beef Cattle Feeding Standards"(NY-T 815-2004),the diet was formulated according to the isonitrogenous principle to meet the nutritional needs of Xiangxi yellow cattle.The whole experiment lasted for 300 days and ended.The test results show that:1.Conventional nutrition of beef and beef quality.(1)Conventional nutritional composition of beef: the moisture content of beef in corn and barley groups was significantly lower than that in control group(P<0.05),while the crude fat content of beef in corn and barley groups was extremely significantly higher than that in control group(P<0.01).(2)Meat quality: meat color a* of beef in corn and barley groups was significantly higher than that in control group(P<0.05);The cooking loss of beef in corn and barley groups was lower than that in control group(P=0.08),but there was no significant difference in cooking loss among all diet groups.The shear force and water loss rate of beef in maize and barley groups were significantly lower than those in control group(P<0.01).2.Beef flavor substances.(1)5 ’-nucleotide: There were no significant differences in 5’-nucleotide content,equivalent concentration of monosodium glutamate and taste activity value of beef among all diet groups(P>0.05).5 ’-IMP(umami)content was the highest in 5’-nucleotide and TAV>1.(2)Free amino acids: the umami amino acids of beef in maize and barley groups were significantly higher than those in control group(P<0.01);The sweet amino acids and total free amino acids in maize group were significantly higher than those in barley group and control group(P<0.01).3.Fatty acids and volatile flavor substances in beef.(1)Fatty acid: the contents of MUFA,PUFA and n-3 PUFA in beef in maize and barley groups were significantly higher than those in control group(P<0.01);The n-6 PUFA content of beef in maize and barley groups was significantly higher than that in control group(P<0.05);(2)Volatile flavor substances: alcohols,hydrocarbons and aldehydes in corn group were significantly higher than those in barley group and control group(P<0.01);There was no significant difference in beef ester among all dietary groups,but the ester of beef in corn group tended to be higher than that in barley group and control group(P=0.05).In conclusion,feeding the diet with corn and barley as the main carbon sources has no significant effect on the nutrition and meat quality of Xiangxi yellow beef,but compared with the control diet,it can improve the nutritional quality and taste of Xiangxi yellow beef.The contents of free amino acids,fatty acids and volatile flavor substances could be increased by feeding corn as the main carbon source,so that beef with higher flavor quality could be obtained.