Influence Of The Chromium On Performance, Physiological And Biochemical Indicators Of Beef Cattle In Summer

This experiment was designed to study the effects of adding different sources of the chromium on the growth and feeder performance,physiological index and blood biochemical index of beef cattle in heat stress, and to compare with each other for the effects of different sources chromium in two levels. Also, supplied some information for the production of the beef cattle.We chose 30 head cross-breed bulls of 200kg, that were same age and similar three-dimensional structure. This experiment was applied single factor design. 30 head bulls were divided into 6 groups, among these included 5 handle groups and 1 control group. Each group contained 5 repetitions and one repetition included 1 head bull. The control group was fed basis diet, and handle groups was fed the diet of adding chromium on the basis diet. The five handle groups were added CrCL₃,CrPic,CrNic,CrY and CrGly to basis diet respectively. The experiment stage was 70 days which from 1 July to 8 September in 2007. The preparation period was 10 days and formal experiment period was 60 days. The experiment stage was divided into earlier stage and later stage according to the difference of the adding levels and every stage was 30 days. Adding 0.4mgCr/kg in earlier stage and 0.8mgCr/kg in later stage.The study results as follows:(1) The average environment temperature THI was 82.46±4.03 in whole stage. So all the beef cattle were in the situation of midrange heat stress.(2) To the beef cattle's body rulers: The two levels of chromium to beef cattle's effects of body index such as body height, body slope length, body straight length and chest circumference had obviousily boost, and the effects of the organ-chromium had better than inorganic-chromium. In tube surround, the difference were not significance, but CrY had better effects obviously than CrNic,CrCL₃ and the control group's.(3) To the cram performance: The daily gain of CrY, CrPic and the control group were 0.78±0.03kg,0.72±0.14kg and 0.41±0.12kg in whole stage. CrY and CrPic have extreme significance raise than the CrCL₃ and the control group in the dry matter intake and daily gain(p<0.01). The feeds/gain of CrY, CrNic and the control group were 7.77±0.65,8.46±1.17 and 14.58±4.67 in whole stage. CrY, CrNic and CrGly have extreme significance raise than the control group in feeds/gain(p<0.01).(4) To the physiological index: CrY have extreme significance lower than the conrol group in breathing rate and rectal temperature(p<0.01). CrNic have extreme significance lower than the control group in breathing rate too(p<0.01). The effect of the groups of adding chromium to depress the skin temperature was not obviously to the control group.(5) To the blood-serum biochemical indicators: CrY, CrPic have extreme significance raise than CrCL3 and the control group in the content of TP, GLU(p<0.01).CrY, CrNic and CrPic have extreme significance lower than CrCL₃ and the control group in the comtent of the UN, TG and CHOL(p<0.01).CrGly have better significance lower than the control group in the content of the UN, TG and CHOL(p<0.05).(6) To the blood-serum HSP70 content: CrY had better significance raise than the control group in the two adding levels(p<0.05). CrNic had better significance raise than CrCL₃ at the level of0.4mgCr/kg(p<0.05).The study results showed that the beef cattle was in midrange heat stress state in the region of SanXia in summer. And adding different chromium had some promotion to beef battle's growth, feeder performance under heat stress circumstance. Furthermore, the effectiveness of the organ-chromium had better than inorgan-chromium. So adding chromium on the basis diet that it can depressed the respiration rate, rectal temperature and mean skin temperature of beef cattle under heat environment. Also chromium can elevated the content of the GLU and TP and depressed the content of the TC, TG and UN, and promoted the expression of the HSP70. Above all, the organ-chromium had better effects than inorgan-chromium, and CrY had the best effect. as follows that were CrPic, CrNic and CrGly.