Study On Energy Metabolism And Requirement Of Dezhou Donkey In Growth Period

In this study,Dezhou donkey in growth period was taken as the experimental object.By exploring the method provided by the experiment of the best endogenous indicator,and combining feeding experiment with digestion and metabolism experiment,the effects of diets with different energy levels on growth performance,apparent digestibility of nutrients,energy metabolism law and other factors of Dezhou donkey in growth period were explored,and the factorial model of energy demand of Dezhou donkey in growth period was established to provide data reference for formulating its feeding standard,It also provides a scientific basis for the rational utilization of feed resources.Explore the best endogenous indicator.Twelve Dezhou male donkeys with good growth and weight of（128.5±5.0）kg were randomly divided into three treatments with four repetitions in each treatment.Single forage alfalfa pellet and two granular total mixed diets（TMR）were used in the digestion test.Three endogenous indicators including acid insoluble lignin（ADL）,lignin containing concentrated sulfuric acid insoluble ash（ADL+SAIA）and hydrochloric acid insoluble ash（AIA）and the total fecal collection method were used respectively.The results showed that ADL,as an ideal endogenous indicator,could quickly determine the digestibility of various nutrients in Dezhou donkey diet during growth period.Effects of diets with different energy levels on the performance of Dezhou donkey in growth period.The experimental study began with a 6-month-old donkey foal with a body weight of（113.65±5.0）and ended with a body weight of（158.72±6.0）kg.The experiment was divided into two phases:phase I,with a body weight of（113.65±5.0）-（137.84±5.0）kg,lasted 75 days,including 15 days of adaptation and 60 days of formal experiment;The weight of（129.58±5.0）-（158.72±6.0）kg was the second stage of the experiment,with a total of 50 days,including 20 days of adaptation and 30 days of formal experiment.The experiment selected 30 Dezhou donkeys in the growth period,half male and half female.After weighing the foals,they were grouped and numbered according to the principle of similar weight.They were randomly divided into three treatments,with 10 repetitions for each treatment and one for each repetition.The feeding experiment was carried out,and the diets of low energy,medium energy and high energy groups were fed respectively.The single factor experiment design was adopted in the experiment.The protein level was similar to that of other nutrients,but the digestible energy level was different.The digestible energy of three diets of low energy,medium energy and high energy were 9.51,10.05 and 12.36 MJ/kg respectively;The digestible energies of three diets of low energy,medium energy and high energy were 10.61,10.95 and 11.82 MJ/kg respectively.In the first month of the formal period of phase I of the experiment,it was fed with a fixed amount（2.0 kg TMR particles per day）and freely in the second month（3.50 kg TMR particles per day）;Experiment II was free feeding.Weigh and collect blood samples on an empty stomach before morning feeding on the last day of each month during the feeding trial.The results showed that:1)there were significant differences in the effects of diets with different energy levels on the daily gain,feed weight ratio and economic benefits of Dezhou donkey during the growth period,and the indexes of high-energy group were significantly better than those of medium energy group and low-energy group（P<0.05）.2)In the growing period of Dezhou donkey fed with three energy levels,the content of urea nitrogen decreased gradually with the increase of energy level,and the contents of glucose,total cholesterol and low density lipoprotein increased gradually with the increase of energy level（P<0.05）.Effects of diets with different energy levels and feed intake on nutrient utilization,protein and energy metabolism of Dezhou donkey during growth period.In this study,ADL endogenous indicator method was used to replace the total fecal collection method,and the digestion test was carried out at the later stage of each feeding stage to determine the apparent digestibility of dietary nutrients.After the end of phase I of the experiment,six donkeys were randomly selected for single cage feeding in each treatment,and the urine was collected by full urine collection method for 6 days of metabolic test.The results showed that:1)the digestibility of digestible energy（DE）,dry matter（DM）,organic matter（OM）,nitrogen free extract（NFE）,carbohydrate（CHO）and neutral soluble carbohydrate（NDSC）in high energy group was significantly higher than that in medium energy group and low energy group（P<0.05）.2)The effects of diets with different energy levels on protein biological value（BV）and net protein utilization（NPU）of Dezhou donkey were significantly different（P<0.05）;There was significant difference in total energy digestibility（DE/GE）and total energy metabolic rate（ME/GE）（P<0.01）;There was no significant difference in the ratio of metabolic energy/digestive energy（ME/DE）of Dezhou donkey in growth period（P>0.05）.3)Under the experimental conditions,Dezhou donkey fed 2.0 kg and 3.50 kg TMR diets had no significant effect on the apparent digestibility of DE,DM,OM,crude protein（CP）,NFE,CHO,acid detergent fiber（ADF）and hemicellulose（CEL）（P>0.05）.Study on energy requirement of Dezhou donkey during growth period.Taking the 0.75th power of the average weight of Dezhou donkey at a certain stage in the growth period（the average value of the initial weight and the end weight of the stage）as the metabolic weight,the linear regression model of energy demand of Dezhou donkey in the growth period is obtained by using the principle of factorial method:DER（k J）=541.07 W^0.75+23.78ADG（r=0.9965,n=90,P<0.01）;MER（k J）=511.23 W^0.75+22.21ADG（r=0.9904,n=90,P<0.01）。According to the above regression models,under the conditions of this experiment,DEm and MEm of Dezhou donkey in growth period are 541.07 and 511.23 k J/kg W^0.75.The requirements of digestive energy and metabolic energy perg of weight gain were 23.78and22.21 k J respectively.