Effects Of Dietary Guanidine Acetate On Growth, Slaughter Performance And Blood Parameters Of Holstein Bull

Excessive visceral fat and subcutaneous fat deposition are the main problems hindering the development of the beef cattle industry.Reducing visceral fat deposition and subcutaneous fat deposition is of great significance for improving the performance and meat quality of fattening cattle.This experiment was conducted to investigate the effects of guanidine acetic acid(GAA)supplementation on body weight gain and carcass fat deposition of Holstein bulls,and to verify the application effect in the fattening process of Holstein bulls.This experiment was conducted in Hengtai Family Farm,Gannan County,Heilongjiang Province,a cooperative demonstration site of Animal Husbandry Institute of Heilongjiang Academy of Agricultural Sciences.Forty 2-month-old Holstein bulls were selected as experimental subjects and randomly divided into two groups: control group: feeding a basal diet;Experimental group:supplemented with 0.5% GAA additive in the basal diet.The rats were weighed on the 1st day,90 th day,275 th day,335 th day and 485 day of the trial period,respectively,and the average daily gain was calculated.total protein(TP),albumin/Globulin(A/G),alkaline p Hosp Hatase(ALP),blood urea nitrogen(BUN),triglyceride(TG),total cholestero(TC),insulin(INS)and growth hormone(GH)were determined on the 275 th,460th and 485 th days of the trial period.After the feeding experiment,6 bulls in each group were randomly selected for slaughter performance measurement and meat quality analysis.The test results are as follows:(1)Body weight: The weight of the test group was higher than that of the control group for the full period measured in this trial.The body weight of the test group was 14.33%,0.44%,2.37%,and 2.93% higher than the control group on days 90,275,335,and 485 of the test period,but none of the differences were significant(P>0.05).The average daily weight gain of the test group was higher than that of the control group for the whole period measured in this experiment.During the trial period of 1～90 days,276～335 days and 336～485 days,the daily gain of the test group was17.45%,7.89% and 3.75% higher than that of the control group,but the difference was not significant(P>0.05).(2)Blood biochemical indexs: The addition of 0.5% GAA to the ration increased the TP content in the blood of Holstein bulls.On days 460 and 485 of the test period,the TP content of the test group was 11.88% higher than that of the control group,with significant(P<0.05)and 15.01%,respectively,and the difference was highly significant(P<0.01);on days 275,460 and 485 of the test period,the TG content of the test group was 19.05% lower than that of the control group,with significant(P<0.05)and 33.33%,respectively,and the difference was highly significant(P<0.01).51.85%,with highly significant differences(P<0.01);there was no significant effect on other blood indicators.(3)Blood hormone level: The addition of 0.5% GAA to the ration increased the levels of INS and GH in the blood of Holstein bulls.On days 460 and 485 of the test period,the INS levels in the test group were 13.01% and 20.23% higher than those in the control group,respectively,with highly significant differences(P<0.01);on days 275,460 and 485 of the test period,the GH levels in the test group were 12.47%,12.17% and 12.19% higher than those in the control group,respectively,with significant differences(P<0.05).(4)Slaughter performance: Dietary supplementation of 0.5% of GAA can increase pre-slaughter live weight,carcass weight,slaughter rate and eye muscle area of Holstein bulls.The pre-slaughter live weight,carcass weight,slaughter rate and eye muscle area in experimental groups were 4.63% and 7.00% and 2.23% and 2.80% higher than those in control group,but the differences were not significant(P>0.05);Backfat thickness and kidney fat were 76.45% and 63.22% lower than those in the control group,respectively(P<0.01).(5)Beef quality: The p H of experimental group was 1.65% higher than that of control group,and the fat content was 44.12% lower than that of control group,respectively,with extremely significant differences(P<0.01);It has no significant effect on other indexes.To sum up,under this experimental condition,fodder to add 0.5% of the GAA,significantly improve the level of TP content in blood and INS,significantly reduce the Holstein bulls fattening leather fat and body fat deposition,Holstein bulls fattening of weight index and slaughter index showed a trend of growth and preliminary prove fodder to add 0.5% of the GAA can reduce the skin of Holstein bulls fattening.However,the optimal supplemental level of GAA for fattening,weight gain and slaughter indices remains to be further studied.