Effects Of Dietary Protein Level On Growth And Fattening Performance,slaughter Performance And Meat Quality Of Donkeys

Dietary protein level is one of the main limiting factors for the growth and fattening performance of meat donkeys,but there is still a lack of supporting feeding standards and systematic research on the protein nutrition requirements of meat donkeys for growth and fattening.This thesis mainly studies the effects of diets with different protein levels on the growth and fattening performance,slaughter performance and meat quality of meat donkey,as well as the effects on nutrient digestion and serum biochemical indicators,in order to seek appropriate dietary protein levels.Formulate the nutritional requirements of meat donkeys for growth and fattening,optimize the feed formula and improve the efficiency of meat production to provide scientific basis.A single factor test method was used to select24 meat donkeys(male)aged 1 year old and similar in weight and randomly divided into 3treatment groups,namely the high protein group(H group)and the medium protein group(M group)And low protein group(L group),each treatment group has 8 replicates.All donkeys are fed and fattened in a house.The pre-test period is 10 days,and the trial period is 18 weeks.It is divided into early fattening period(1-6 weeks),middle period(7-12weeks)and late period(13-18 weeks).Feeding 2 times a day,7:00 in the morning and14:00 in the afternoon,free drinking water.During the test period,the test was weighed every two weeks.During the test period,3 digestion and metabolism tests were performed,and blood was collected.After the test,all the test donkeys were fasted for 12 hours,and water-free for 2 hours,then slaughtered and sampled.The test is mainly divided into three parts:Experiment 1 mainly studied the effects of dietary protein levels on the growth and fattening performance and nutrient digestibility of donkeys.The results showed that during the entire test period,the body weight,daily gain,total gain and feed conversion efficiency of the donkeys in the M and H groups were significantly higher than those in the L group(P<0.05),and there was no significant difference between the M and H groups difference.This shows that the diets of the medium and high protein group can better exert the growth performance of the meat donkey and improve the feed conversion efficiency,and the low protein group slows down the growth and fattening speed of the meat donkey.The digestibility of CP and EE of the donkeys in the M and H groups was significantly higher than that in the L group(P<0.05),and there was no significant difference between the M and H groups(except for the early fattening period).The digestibility of DM,NDF,ADF and GE in group H was higher before and after fattening.In the middle of fattening,compared with the L group,the meat donkeys of the M and H groups improved the digestibility of dietary DM,ADF and GE(P<0.05),and there was no significant difference between the M and H groups.In the early fattening period,the energy and protein metabolism rate of the H group donkey was higher(P<0.05);in the middle and late fattening period,the protein and energy metabolism rate of the M and H groups were significantly higher than that of the L group(P<0.05),and There was no significant difference between the M group and the H group(except for the later energy metabolism rate).Experiment 2 mainly studied the influence of dietary protein level on the slaughter performance of meat donkey and the conventional physical and chemical properties of muscle.The results showed that compared with the L group,the pre-slaughter live weight and eye muscle area of the M and H groups were significantly increased(P<0.05).The GR value,carcass weight,and mesenteric fat weight of the M group were significantly higher than those of the L and H groups(P<0.05).Compared with the H group,the kidney fat and intra-abdominal fat weight of the L and M groups increased significantly,the weight of the large intestine and cecum and their proportion to the pre-slaughter live weight increased significantly(P=0.042,P=0.002),fur,The weight of the liver and its proportion to the live weight before slaughter were significantly reduced(P<0.05).Compared with the L group,the lung index of the M group and H group was significantly lower(P=0.004).The total length of jejunum,small intestine and digestive tract is M>H>L(P<0.05).Compared with the H group,the muscle drip loss,shear force and b* value of the L and M groups were significantly reduced(P<0.05);the cooking loss of the muscles of the L group was significantly lower than that of the M and H groups(P<0.05);It shows that the muscles of the middle and low protein groups have higher muscle water power and tenderness,and the flesh color is better,while the high protein group is just the opposite.Compared with the L group,the crude protein content of the longissimus dorsi muscle and the triceps brachii in the M and H groups were significantly increased(P<0.05),and the crude fat in the longissimus dorsi,triceps brachii and gluteal muscles in the M group The content was significantly higher than that of group L and group H(P<0.05).The influence of dietary protein level on the distribution of mineral elements in donkey meat varies with the part of the muscle and the types of elements.Experiment 3 mainly studied the effect of dietary protein level on blood biochemical indexes of donkeys.The results showed that in the early fattening period,compared with the L group,the serum TP and TG levels of the M and H groups were significantly increased,while the GLU and P levels were significantly decreased(P<0.05).The CRE content of the M group was significantly higher than that of the L,Group H(P<0.05).In the middle fattening period,compared with the L and H groups,the serum GLU,Ca,P and CHOL levels in the M group were significantly increased(P<0.05),and the CRE content decreased(P<0.05);in the late fattening period,the serum TP and ALB levels The content of UREA and UREA was H>M>L(P<0.05).Compared with the L and H groups,the serum GLU,HDL-C and LDL-C levels in the M group were significantly increased,and the CRE was decreased(P<0.05).In summary,feeding the diets of medium and high protein levels promotes the growth and fattening performance and slaughter performance of meat donkeys,promotes the development of the digestive tract,the digestion and absorption of nutrients,and the utilization of energy and protein,especially the medium protein The group is better,and the low-protein group is the worst.The middle and low protein group muscles have higher muscle water power and tenderness,and the meat color is better.The high protein group has higher protein content in the muscle tissue,but the meat quality is lower.