Effects Of Warm And Hot Environment On Digestion And Metabolism Of Nutrients In Goats

The growth and health of the goat are affected by the environmental factors,especially the warm environment factors.At the same time,these environmental factors also affect the use efficiency of the goat to feed nutrients.The effects of different temperature and humidity on the utilization efficiency of feed nutrients were studied by using the loop control metabolic compartment.A completely random design with two factors and four levels was adopted,the temperature was 26?,30?,34?,38?,and the humidity was 35%,50%,65%,80%,respectively.Eight 1.5-year-old Boer goats with similar body weight and Guanzhong were selected.The hybrid ewes of dairy goats were randomly divided into two groups.Four sheep in each treatment group were fed in a single cage and put into two environmental control cabins to carry out the experiment.Under the suitable environmental conditions of 23 ? and 50% relative humidity(control group),the feces were fed for 5 days,and then different experimental treatments were carried out alternately according to the order of temperature from low to high.The feces were collected for 5 days in each treatment and 3 days after the treatment.Urine digestion and metabolism test was carried out.The results show that: 1.Effect of temperature and relative humidity on the digestion and metabolism of goat nutrients.Temperature and relative humidity had significant interaction on the apparent digestibility of dry matter,calcium,phosphorus,medium washing fiber,pickling fiber and fat in goats(P<0.05).The apparent digestibility of dry matter,calcium,phosphorus and pickling fiber in goats at 38? was significantly lower than that at 26?,30? and 34?(P<0.05),and when relative humidity was 80%,it was significantly lower than 35%,50% and 65%(P<0.05).The apparent digestibility of fat did not change significantly with the increase of temperature(P>0.05),but the apparent digestibility of washed fiber was significant when the relative humidity was 80%.The apparent digestibility of washing fiber in goat group was significantly lower than that in other humidity treatment group(P<0.05),and the apparent digestibility of washing fiber in goat group was significantly lower than that in other humidity treatment group when the relative humidity was 80% and 65% respectively(P<0.05).2.Effects of temperature and relative humidity on Energy digestion and Metabolism in GoatsTemperature and relative humidity had significant interaction on digestive energy,metabolic energy and total energy metabolic rate of goats(P<0.05).The digestive energy and metabolic energy of goats began to decrease significantly at 34?(P<0.05),and the lowest at 38?.The total energy digestibility and metabolic rate of goats at 38? were significantly lower than those at 26?,30? and 34?(P<0.05).The digestive energy and metabolic energy of goats began to decrease significantly at the relative humidity of 65%(P<0.05),and the lowest at the relative humidity of 80%.The total energy digestibility and metabolic rate of goats were 80% at relative humidity.It was significantly lower than that of other humidity treatments(P<0.05).3.Effects of temperature and relative humidity on nitrogen digestion and Metabolism in GoatsTemperature and relative humidity had significant interaction on digestibility,digestibility and deposition rate of nitrogen,deposited nitrogen and nitrogen in goats(P<0.05).The digestible nitrogen and metabolic nitrogen of goats began to decrease at 34? and were significantly lower than 26?,30?(P<0.05),and the lowest at 38?.The digestibility and deposition rate of goat nitrogen at 38?were significantly lower than those at 26?,30?and 34?(P<0.05).The digestible nitrogen of goats began to decrease significantly when the relative humidity was 65%(P<0.05),and the relative humidity was the lowest when the relative humidity was 65%.The deposited nitrogen of goat is 65 at relative humidity.It was significantly lower than 35% at%(P<0.05),and lower than 35% when relative humidity was 80%,50% and 65%(P<0.05).The apparent digestibility of nitrogen at relative humidity of 80% was significantly lower than that of 35%,50% and 65%(P<0.05).To sum up,the feed intake of goats decreased under warm and hot environment,which changed the apparent digestibility of nutrients and the digestion and metabolism of energy and nitrogen,and then affected the performance of goats.With the increase of temperature and humidity,the degree of heat stress of goats deepened.When the relative humidity at 38 ? was 80%,the effect on the performance and nutrient utilization rate of goats was the greatest.