| This study explored the effects of dietary crude protein level on performance,nutrient apparent digestibility,blood indexes,slaughter performance,meat quality,muscle nutrient composition and intestinal microorganisms of Texas donkeys during fattening period,and explored the appropriate crude protein level for Texas donkeys during fattening period,providing theoretical reference for scientific feeding of Texas donkeys during fattening period.A single factor randomized trial design was used in this study.Twenty-four 11-month-old healthy male donkeys with a body weight of 165(±1 kg)were selected and divided into three treatment groups,namely TMR1(low protein),TMR2(medium protein)and TMR3(high protein)groups with 8 replicates per treatment and 1 donkey per replicate.The feeding experiment was conducted for 99 days(formal period).The feeding experiment was divided into two stages: early fattening(165-190 kg)and late fattening(190-225 kg).TMR1,TMR2 and TMR3 groups were fed diets with the same energy level(10.90 MJ/kg)and crude protein level of 11.51%,13.02% and 14.57%,respectively,in the early fending period.The prefeeding period lasted for 10 days and the formal period for 39 days.TMR1,TMR2 and TMR3 groups were fed diets with the same energy level(11.80 MJ/kg)and crude protein level(11.03%,12.52%and 14.06%),respectively,in the late fending period.The prefeeding period lasted for 3 days and the formal period for 60 days.All the experimental donkeys were raised in a single pen,fed three times a day and fed freely.During the test,the average daily gain,feed to gain ratio,gain benefit and other production performance indexes were measured;Nutrient apparent digestibility was determined.Serum biochemical index and blood routine index were determined.After the feeding experiment,4donkeys in each group were slaughtered randomly,and the left longissimus dorsi muscle of the donkeys was taken for the determination of meat quality,conventional nutrients in meat,amino acids and fatty acids in meat.After the feeding experiment,rectal fecal samples were collected randomly from 6 donkeys in each group to determine the composition of intestinal microflora.The test results are as follows:(1)Dietary crude protein level had no significant effects on average daily feed intake and final weight of donkeys at early and late fattening stages(P > 0.05).At the early fattening stage,the average daily gain,feed to gain ratio and gain benefit of TMR2 group were the best,and the average daily gain and gain benefit of TMR2 group were significantly superior to that of TMR3 group(P < 0.05),but there were no significant differences between the average daily gain,feed to gain ratio and gain benefit of TMR2 group and TMR1 group(P > 0.05).There were no significant differences in average daily gain,feed to gain ratio and weight gain benefit among all groups at late fattening stage(P > 0.05),but the weight gain benefit of TMR1 and TMR2 groups was basically the same and better than that of TMR3 groups.(2)In the early fattening stage,dietary protein level significantly affected the apparent digestibility of CP,CHO and NDSC(P < 0.05),and extremely significantly affected the apparent digestibility of EE,NFE and HCEL(P < 0.01);At the later fattening stage,dietary protein level significantly affected the apparent digestibility of CP and CF(P < 0.05),and extremely significantly affected the apparent digestibility of HCEL(P < 0.01).(3)In the early fattening stage,the content of serum urea nitrogen increased with the increase of dietary crude protein level(P < 0.01).In the late fattening period,with the increase of dietary crude protein level,the serum total protein,albumin and urea nitrogen indexes had an increasing trend(P < 0.01);Serum total cholesterol and phosphorus had an increasing trend with the increase of dietary crude protein(P < 0.05).The high density lipoprotein and calcium in serum increased with the dietary crude protein increasing(P < 0.05).At the early fattening stage,the standard deviation of erythrocyte distribution width in TMR1 group was significantly higher than that in TMR3 group(P < 0.05).At the late fattening stage,the volume distribution width of platelet in blood of donkeys in TMR2 group was significantly higher than that in TMR1 group(P < 0.01).There were no significant differences in other blood routine indexes among all groups(P > 0.05).(4)The dressing rate of donkeys in TMR2 group was significantly higher than that in TMR1 and TMR3 groups(P < 0.05);The carcass weight and slaughter benefit of TMR2 group were significantly higher than those of TMR1 and TMR3 groups(P < 0.01).(5)Dietary crude protein level had no significant effects on meat quality indexes such as shear force,cooking loss,drip loss and meat color in muscle of Dezhou donkeys during fattening period(P > 0.05).(6)The EE content in donkey muscle in TMR2 group was significantly higher than that in TMR3 group(P < 0.05),but had no significant difference with that in TMR1 group(P > 0.05);The contents of DM and OM in muscle of TMR2 group were higher than those of TMR3 group(P = 0.092,0.062).(7)Dietary crude protein level had no significant effects on various amino acid contents in muscle of Dezhou donkey during fattening period(P > 0.05).Dietary crude protein level had significant effects on the contents of some fatty acids in muscle of Dezhou donkey during fattening period.The content of saturated fatty acids in muscle of donkey in TMR3 group was significantly higher than that in TMR1 and TMR2 groups(P < 0.01).The contents of total unsaturated fatty acid and monounsaturated fatty acid in donkey muscle of TMR1 and TMR2 groups were significantly higher than those of TMR3 group(P < 0.01),and the content of polyunsaturated fatty acid in donkey muscle of TMR3 group was significantly higher than that of TMR1 and TMR2 groups(P < 0.05).The total fatty acid content in donkey muscle in TMR1 and TMR2 groups was significantly higher than that in TMR3 groups(P < 0.05).(8)According to Alpha index,intestinal flora richness of donkeys increased with the increase of dietary crude protein level,but did not reach a significant difference change(P >0.05);Compared with TMR1 and TMR3 groups,intestinal flora diversity of Dezhou donkeys in TMR2 group was the lowest,but no significant difference was achieved(P > 0.05).According to PCo A and LEf Se analysis,the diversity of intestinal microbes in TMR3 group was the highest,followed by TMR1 group and TMR2 group.The beneficial bacteria such as Bacteroidota and Prevotellaceae＿UCG-001＿group in TMR2 group showed an increasing trend.unidentified Bacteria,Oscillospiraceae,Lachnospiraceae,Ruminococcus＿NK4A214＿group,unidentified Bacteria,Oscillospiraceae,Lachnospiraceae,The bacterial community of Ruminococci UCG-002 genus(Ruminococcus＿UCG-002＿group)which was negatively correlated with production and slaughter performance decreased.In conclusion,the crude protein requirements of Texas donkeys can be met by feeding diets with a crude protein level of 13.02% and 11.03% in the early and late fattening stages,respectively,under the premise of feeding a fully mixed diet(granule)and considering production performance.Considering slaughter performance(slaughter rate,carcass weight and slaughter economic benefit),diets with crude protein level of 13.02% and 12.52% in early and late fattening stages had higher slaughter rate and slaughter economic benefit.In addition,EE,DM and OM contents were higher in the muscle of Texas donkey at fattening stage.The contents of monounsaturated fatty acids,total unsaturated fatty acids and total fatty acids were higher in the muscle of Texas donkey during fattening period,and the content of saturated fatty acids was lower.Intestinal flora diversity decreased,intestinal beneficial bacteria increased,and bacteria negatively correlated with production and slaughter performance decreased. |
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