Studies On The Mechanism Of Cysteamine And Hainan-Mycin On The Growth And Meat Quality Of The Goats

1.Effects of Hainan-mycin(HM) on the rumen digestion and metabolism of goats(1) in vitro experimentIn this study,the effects of different doses(0,25,100,250 and 500 mg/L) of HM and different culture time(3,6 and 9 hours) with HM on the rumen digestion and metabolism was studied using the artificial rumen technique.The results showed that HM obviously improved rumen digestion and metabolism.The content of TVFA was not altered,however,the ratio of propionic acid increased,indicating the types of fermentation changed.Meanwhile,the amount of NH₃-N in rumen decreased,and the level of MCP increased.Under the condition of artificial rumen,3～6 hours of culture was the optimal,and HM showed the bioactive function at the dose of 25mg/L, increasing in dose-dependent manner.However,500 mg/mL HM showed the inhibited effect on rumen digestion and metabolism.(2) in vivo experimentThree goats each with one permanent rumen fistula were raised in experimental animal house,given free access to green hay and water.Experiment went through four stages:control,experimentâ… (Expâ… ),Expâ…¡and Expâ…¢,respectively.In order to investigate the effect of HM on the rumen digestion and metabolism,HM was given to the goats through rumen fistula before feeding each morning on doses of 0.0000, 0.0025,0.0100 and 0.0500mg per kg body weight daily during the whole period, respectively.The results showed that the doses of 0.01,0.05mg per kg increased the ratio of propionic acid obviously,and the ratio of A/P was significantly decreased by 5.6%(P＜0.05) and 13.30%(P＜0.01),respectively.The content of NH₃-N was decreased obviously.However,the level of MCP had the tendency to increase by HM treatment.The results from in vitro study were in agreement with the results from in vivo, suggesting that HM could improve the rumen digestion and metabolism.2.Effects of cysteamine(CS) on the rumen digestion and metabolism of goatsCysteamine(CS) is a bioactive substance existing widely in animal body and plants.In order to explore the effects and the mechanism of cysteamine on growth and meat quality in goats,in this study,the influence of cysteamine on rumen digestion and metabolism was first studied.Experiment included two parts,in vitro and in vivo.(1) in vitro experimentArtificial rumen was employed to investigate the effect of CS on the rumen digestion and metabolism in vitro.Experiment included 6 groups,â… (control group),â…¡(3g/L pure CS),â…¢(3 g/L Lactonin^TM),â…£(6 g/L Lactonin^TM),â…¤(9 g/L Lactonin^TM),â…¥(30 g/L Lactonin^TM).Lactonin^TM is a microcapsulated CS feed additive which contains 30%pure CS,therefore,the levels in groupâ…¢,â…£,â…¤andâ…¥were equivalent to 0.9,1.8,2.1 and 9 g/L pure CS,respectively.The samples were harvested after 3,6 and 9 hours culture,respectively.The results showed that there was no time-effect of CS added into the culture medium on rumen digestion and metabolism,and 3 hours incubation had revealed the bioactive function of CS on rumen metabolism. Compared with the control group,the pH value in artificial rumen decreased by CS treatment,however,the content of MCP and NH₃-N increased,then to promote the production of TVFA in CS group.The type of fermentation types had been changed by CS treatment,the amount of C2 decreased,C3 and C4 increased,while the ratio of (C2+C4)/C3 decreased.Additionally,there was a-dose dependent effectiveness of CS on rumen metabolism.(2) in vivo experimentFive goats with rumen fistula were employed in this study,and the experiment was designed as self-control,control period and experimental period.Each period consisted for 3 weeks.During the control period,the goats were fed basal diet,and fed basal diet plus 0.75g Lactonin^TM(containing 30%pure cysteamine) during the experimental period.After 14 days of treatment,samples were collected for analysis. The results showed that compared with the goats in control group,rumen pH in treated goats decreased,while the content of TVFA,NH₃-N and MCP increased significantly by 28.52%(P＜0.01),22.47%(P＜0.01) and 124.64%(P＜0.01), respectively.Additionally,the ratio of C2 increased remarkably by 31.79%(P＜0.01), while the content of C4 decreased.There was no obvious change about C3 content in tureen between control and treatment group.The results from in vitro were largely consistent with the results from in vivo, VFA,NH₃-N and MCP significantly increased.Additionally,the change of fermentation types were different between in vivo and in vitro.3.Influence of Hainan-mycin and cysteamine on neuroendocrine of goats(1) Hainan-mycin(HM)Five goats with rumen fistula and blood catheter were employed in this study, and the experiment was designed as self-control,control period and experimental period.Each period consisted for 3 weeks.During the experimental period, Hainan-mycin dissolved in 33%V/V ethanol on dose of 0.05 mg per kg body weight was given through rumen fistula,twice per day at 8:00 and 20:00,respectively.The goats in control group were only given the same amount of ethanol.After 15 days of treatment,the blood was collected every 2 hours for total 10 hours.The results showed that the concentration of plasma insulin was not changed,the level of plasma glucagon decreased significantly by 26.22%(P＜0.05),and plasma I/G tended to increase(P=0.074) by HM treatment,while plasma IGF-I increased significantly by 16.83%(P＜0.05) by HM treatment.(2) Cysteamine(CS)In order to investigate the effect of cysteamine on the growth axis and relative metabolic hormones,6 goats were installed temporary blood catheter.Experiment was designed as self control.Cysteamine was given through i.v on dose of 50 mg per kg body weight.Blood samples were collected for analysis after 2 days treatment.The results showed that the concentrations of plasma IGF-I and glucagon significantly increased by 16.32%(P＜0.05) and 8.29%(P＜0.05),respectively,and plasma I/G tended to decrease.However,plasma insulin was not altered by two days of cysteamine treatment.4.Effects of Hainan-mycin and cysteamine on the growth and meat quality of goats and the mechanism involved in the pathwayNinety goats on average of 15 kg body weight were allocated to 3 groups at random,control group,Hainan-mycin group and cysteamine group.Each goat in control group was fed basal diet plus 500 gram concentrate daily.Goats in cysteamine group were fed basal diet plus 500 gram concentrate containing 30%cysteamine every day,and the goats in Hainan-mycin group were fed basal diet plus 500 gram concentrate containing 2.5 mg Hainan-mycin every day.After 10 days of preliminary trial,the experiment was started.The body weight was recorded after 2 month of treatment,and 10 goats from each group were selected randomly and were slaughtered for samples after 12 hours of fasting.Compared with their counterparts,after 60 days of treatment,the body weight of goats in Hainan-cymin group increased by 48.59%(P＜0.05),and the body weight of goats in cysteamine group increased by 41.18%(P＜0.05).After 60 days of treatment, Hainanmycin and cysteamine increased the content of intramuscular fat by 27.1%and 9.7%in longissimus dorsi(LD),respectively,and by 13.4%and 15.0%in semitendinosus,respectively,without statistical difference.Hainan-mycin and cysteamine increased the content of CLA in LD,but the difference did not reach the statistical significance(P＞0.05).However,cysteamine significantly increased the content of CLA in semitendinosus by 26.5%(P＜0.05),without alteration with Hainanmycin treatment.Additionally,dietary cysteamine supplementation significantly improved the tenderness of semitendinosus(6.66±1.10 kg in cysteamine group VS 5.46±0.35 kg in control group,P＜0.05).In this study,the results showed that supplementation with cysteamine had the obviously positive effect on promoting growth,while the gene expression of GH receptor(GHR) and IGF-I in semitendinosus and longissimus dorsi were not altered (P＞0.05).The significant down-regulation of IGF-I receptor gene expression in semitendinosus might be related with the effect of cysteamine on promoting growth in goats.Additionally,cysteamine significantly increasedμ-calpain(p94) gene expression in semitendinosus(P＜0.05).In conclusion,both Hainan-mycin and cysteamine improved the rumen digestion and metabolism,not only promoted the growth of goats through regulating neuroendocrine,but also improved the meat quality remarkably.