Production Performance,Rumen Fermentation And Heat Production Change Rules Of Jinjiang Beef Cattle Under Different Concentrate Feeding Conditions

Jinjiang beef cattle is one of China’s native varieties of zebu cattle,which adapt to the climate and farming conditions in the west of Hunan province to the north of Jiangxi province for a long term.And Jinjiang beef cattle has the characteristics of resistance to forage,high temperature and humidity and working for a long time.The work sought to evaluate the change rules of production performance,rumen fermentation,blood index and heat production of Jinjiang beef cattle under different concentrate supplemental level conditions,and provise a theoretical basis for scientific management and production practice of Jinjiang beef cattle.This paper is divided into the following three parts.The first part primarily studies the effects of different concentrate supplemental levels on production performance of Jinjiang beef cattle.Twelve healthy Jinjiang beef cattle weighted about 350 kg were randomly divided into four groups with three head per group.Cattle in experimental groups 1.0,2.0,3.0 and 4.0 were fed with 1.0 kg,2.0 kg,3.0 kg and 4.0 kg supplementary concentrate,respectively,and roughage is ad libitum.The animals were allowed 10 days to adapt to the diets and experimental measurements were taken in 60 days.At the end of the experiment,the average daily gain,roughage dry matter intake,total dry matter intake,feed:gain,body size index and backfat thickness were statistically analyzed.The results show that:the average daily gain in experimental group 4.0 kg was significantly higher than group 1.0 and 2.0 kg(P<0.05),and totle dry matter intake in experimental group 4.0 kg was significantly higher than that in experimental group 1.0 kg(P<0.05),and roughage dry matter intake and feed:gain in experimental group 4.0 kg was the lowest,and significantly lower than that in experimental group 1.0 kg(P<0.05);The body height and backfat thickness increments were highest in experimental group 4.0 kg,and were significantly higher than group 1.0 and 2.0 kg(P<0.05).Improving concentrate supplemental levels could significantly increase the total dry matter intake,average daily gain and decrease feed:gain.The second part primarily studies the effects of different concentrate supplemental levels on rumen fermentation and blood index of Jinjiang beef cattle.The experimental design is the same as the first part.At the end of the experiment,the rumen fermentation index and blood index were statistically analyzed.The results show that:pH value,acetic acid concentrate and acetate:propionate of rumen fluid in experimental group 3.0 and 4.0 kg were significantly lower than that in experimental group 1.0 and 2.0 kg(P<0.05),the ammonia nitrogen concentration in 4.0 kg group was lower than 1.0 and 2.0 kg group(P<0.05).And the concentrate of total volatile fatty acid,propionate acid and butyric acid in experimental group 3.0 and 4.0 kg were significantly higher than that in experimental group 1.0 and 2.0 kg(P<0.05);the blood glucose level in experimental group 4.0 kg were significantly higher than that in experimental group 1.0 kg(P<0.05),and the urea nitrogen concentration in experimental group 4.0 kg was significantly lower than that in experimental group 1.0 kg(P<0.05).Improving concentrate supplemental levels could have some significant effects on rumen fermentation and blood index of Jinjiang beef cattle.The third part primarily studies the effects of different concentrate supplemental levels on the relationship between heat production and daily gain of Jinjiang beef cattle.Twelve healthy Jinjiang beef cattle weighted about 350 kg were randomly divided into four groups with three head per group.Cattle in experimental groups were fed with 1.0 kg,2.0 kg,3.0 kg and 4.0 kg supplementary concentrate,respectively,and roughage is ad libitum.The animals were allowed 10 days to adapt to the diets and experimental measurements were taken in 20 days.The metabolic body weight,gross energy intake,average daily gain and metabolic heat production of Jinjiang beef cattle were tested and statistically analyzed,by the combination of production practice and a respiratory calorimetry system.The results show that:The average daily gain of Jinjiang beef cattle was significantly different among the 4 experimental groups(P<0.05),the heat production in experimental group 4.0 kg was highest and were significantly higher than that in experimental group 1.0,2.0 and 3.0 kg(P<0.05).Linear regression of the gross energy intake per kilogram metabolic body weight and ADG is GE(kJ/kg0.75·d)= 423.91 △W+980.79(r=0.79,P<0.01),and the gross energy for maintenance requirements and for per kilogram of weight gain requirements is 980.79kJ/kg0.75·d and 423.91kJ/kg0.75·d,respectively;Linear regression of HP and ADG is HP(kJ/kg0.75·d)=90.758△W+417.53(r=0.77,P<0.01),the Net Energy for maintenance requirements is 417.53 kJ/kg0.75·d,and the Net Energy for per kilogram of weight gain requirements is 180.46 kJ/kg0.75·d.