Environmental Control Of Intensive Goat Buildings And The Effects Of Heat Stress On Rumen Fermentation Of Goats

Goat breeding is the important part of animal husbandry in China. Goat breeding was based on the family as a unit for a long time. But this breeding way has also exposed a lot of problems, such as invested large amount of labor, difficult to control the disease, low efficiency of goat production and easy to damage the ecological environment. Therefore, to develop intensive production of goats is a more effective way to improve efficiency of goat production and to protect the environment. To design and reconstruct the existing goat buildings so as to improve the efficiency of goat production and provide scientific reference to goat production. Under the condition of hot and high humidity environment in summer, there is great possibility for the occurrence of heat stress, the investigation of heat stress on rumen fermentation and the health of goats as well as seeking for the effective solutions are of great value for the intensive development of intensive goat production. This study consists of three parts: the first part mainly introduces the design and reconstruction of goat buildings including the comparable investigation of the microenvironment of the goat buildings; the second part focus on the influence of heat stress on the rumen fermentation and the health of the goats; the last part is the study of the improvement of direct-fed microbes on the rumen fermentation when fed to the heat-stressed goats.The first part: the design and reconstruction of goat buildings and the investigation of microenvironment of goat buildings. We changed the original mud ground goat buildings which manure removed by labor(Control Group) into the high bed with slatted floor and automatic manure scraper(Testing group), then applying the wet curtain-fan system in summer and heating system(stove) in winter. The results of the temperature, relative humidity and the concentrations ammonia(NH3), methane(CH4) and carbon dioxide(CO2) in goat buildings are as follows:1. In summer, the temperature in Testing group had no significantly difference compared with Control group(P>0.05), while the relative humidity in Testing group significantly lower than that in Control group(P<0.05). In winter, both the temperature and the relative humidity in Testing group were higher compared with Control group(P <0.05).2. With the employment of wet curtain and fan cooling system in summer, the temperature was decreased from 33.0±1.5°C to 30.7±0.6°C in Testing group. The employment of stove in winter, the temperature increased from 7.2±1.4°C to18.4±2.3°C。3. The concentrations of NH3, CH4 and CO2 in goat houses were highest(P<0.05) in winter and lowest(P<0.05) in summer and the concentrations of those gases were apparently different(P<0.05) among the four seasons. Besides, the concentration of those three gases in Testing group were significantly lower compared with that in Control group(P<0.05).The aim of the second part was to evaluated the effects of heat stress on rumen fermentation and the health of goats. The results are as follows:1. The result of the investigation of rumen microorganism indicates that the genus of Leucobacter and Blautia in the rumen wasn’t detected in rumen content of Control group(non heat stress group), while genus Bifidobacterium, genus Comamonas, genus Coprococcus, genus Rhodocytophaga and Wautersiella appeared in the Testing group II(hear stress group). The relative abundance of genus Selenomonas and genus Succinivibrio in Testing group II was increased, which was decreased in genus Shuttleworthia and genus Methanobrevibacter compared to that in Control group; The abundance of genus Butyrivibrio, genus Prevotella, genus Ruminococcus, genus Succiniclasticum, genus Bulleidia and Paludibacter in Testing group II changed in varying degrees compared to that in Control group, but the species evenness of those microbes is relatively lower in the microbes group.2. In Testing group II, the ruminal p H declined significantly(P<0.05), the concentration of ammonia-N(NH3-N), TVFA and the activity of the microcrystalline cellulose, CMC hydrolytic enzyme, cellobiase and xylanase decreased significantly(P<0.05). the proportion of acetate and propionate and the ratio of acetate and propionate(A/P) decreased while the proportion of butyrate increased in Testing group II compared to Control group. The oxidation-reduction potential(ORP) increased significantly(P<0.05) compared to Control group. The concentrations of vitamin B1(VB1), B2(VB2), B6(VB6) and niacin in rumen of Testing Group II decreased significantly compared to Control group(P <0.05).3. In Testing group II, the Skin temperature, pulse rate and respiration rate increased significantly compared with Control group(P<0.05). The activity of serum alkaline phosphatase(ALP), creatine kinase(CK) and the concentration of malonaldehyde(MDA) were increased significantly(P<0.05). Compared with Control group, the activity of glutathione peroxidase(GSH-Px) and the concentration of vitamin C(VC), vitamin E(VE) declined significantly(P<0.05). Feed intake and average daily gain(ADG) of goats in Testing group II declined significantly(P <0.05); has a significant rise(P<0.05)Since the negative impact of heat stress on goats, especially the negative influence on rumen ervironment and rumen fermentation. In order to alleviate the influence of heat stress, a experiment was carried out by the supplement of direct-fed microbials in diets of goats. In the third part of our study, the effects of Saccharomyces cerevisiae(SC) and the Clostridium butyricum(CB) on rumen fermentation were evaluated through vitro and vivo expriments. In the vitro experiment, the level of SC as follow: 0.15‰ DM(Group S1), 0.30‰ DM(Group S2), 0.60‰ DM(Group S3) and 1.20‰ DM(Group S4); The level of CB as follow: 0.025‰ DM(Group C1), 0.05‰ DM(Group C2), 0.10‰ DM(Group C3) and 0.20‰ DM(Group C4); The level of the mixture of SC and CB as follow: 0.30‰ DM SC and 0.05‰ DM CB(Group H1), 0.30‰ DM SC and 0.10‰ DM CB(Group H2),0.60‰ DM SC and 0.05‰ DM CB(Group H3), 0.60‰ DM SC and 0.10‰ DM CB(Group H4). To test the p H values, the concentrations of NH3-N, TVFA and apparent digestibility of DM, NDF, ADF in inoculum(P<0.05). The results as follow:1. the inoculum p H of each Testing group were raised significantly compared with Control group.2. Supplements of the SC and CB or the mixture of SC and CB could significantly raised the concentration of the NH3-N and TVFA yield(P<0.05), increased the proportion of acetate and decreased the proportion of propionate leading to the increase in the ratio of acetate and propionate, and exerted no effect on the proportion of butyrate; And separated or mixed supplements significantly increased the concentration of VB2 in rumen of goats during heat stress(P<0.05).3. Supplements of the SC or the mixture of SC and CB could significantly improve the activity of CMC hydrolytic enzyme, cellobiaseand, xylanase(P<0.05). Supplement of the CB could significantly improve the activity of microcrystalline(P<0.05); Supplements of the SC or the CB could significantly increase the apparent digestibility of DM, NDF, ADF in feed(P<0.05).According to the result of in vitro experiment, the suitable added level for goats rumen fermentation are Group S2 and Group S3 of the Saccharomyces cerevisiae and Group C2 and Group C3 of the Clostridium butyricum and Group S2 mixed with Group C2 in the same proportion(Group H1), Group S3 mixed with Group C2 in the same proportion(Group H4).Both the SC and the CB or their mixture could improve the rumen fermentation, since the results in vitro could not reflect the real function of direct-fed microbials, a feed experiment was carried out according to an incomplete latin square(4×3), which last for 6 cycles, results are as follows:1. Compared to Control group, the ruminal p H in S3, C2, H1 and H4 significantly rose(P<0.05), and ORP in S2, S3, C2 decreased significantly(P<0.05);2. The concentration of NH3-N and TVFA of S2, C2 and H1 significantly increased(P<0.05), compared to Control Group. In the group S3, C3 and H4, the proportion of acetate increased significantly(P<0.05), while the proportion of propionate decreased significantly(P<0.05), the ratio of acetate and propionate increased significantly(P<0.05) compare with those in Control Group.4. the activity of microcrystalline cellulose in C2, the activity of CMC hydrolytic enzyme, in S2, S3, C2, H1 and H4, the activity of cellobiase and the activity of xylanase in S2, S3, C2, H1, H4 are significantly higher than that in Control group.5. It has no effect on feed intake when supplemented with different levels of the SC and CB or their mixtures, while the ADG in S2, S3, C2, H4 increased significantly(P<0.05). The addition of probiotics in all the groups increased the apparent digestibility of DM, NDF, ADF in feed in varying degrees.Taking all the results of the rumen fermentation into account, the suitable added dose of the direct-fed microbials is 0.05‰ DM of Clostridium butyricum. In conclusions of this study are as follows:1. The application of the high bed with slatted floor and automatic manure scrapers system in goats buildings can significantly decrease the concentrations of NH3, CH4 and CO2, thus improve the air quality in goat houses. With the employment of wet curtain and fan cooling system in summer, the temperature was decreased from 33.0°C to 30.7°C. The employment of stove in winter, the temperature increased from 7.2°C to18.4°C.2. During heat stress, the population of microorganism were decreased and the composition of microorganism were changed; The rumen fermation was influenced by heat stress.3. Heat stress can affect the physiological and biochemical were affected by heat stress and the blood antioxidant system was damaged during heat stress.4. The supplement of Saccharomyces cerevisiae and Clostridium butyrate in diets were of good effects on alleviating the negative impact on rumen environment and rumen fermentation bringing about by heat stress.