| This topic explores the most suitable level of methionine in diets by reducing the amount of methionine in the diet.And by reducing the content of soybean meal,the main source of protein in the diet,to reduce the dependence of the rabbit industry on imported soybean meal in order to obtain certain economic benefits.At the same time,by reducing the protein content in the feed,nitrogen emissions are reduced and the environment is protected.In this project,the effects of different amounts of amino acids on hair production,digestion and metabolism,hair follicle development,reproductive performance,and economic benefits of Angora long-hair rabbits under the condition of reducing protein content in feed were determined through experiments.This subject is divided into two tests,one is the hair production performance test of producing rabbits,and the other is the reproduction performance test of breeding female rabbits.225 rabbits with sheared adult Angora who were in good health at the age of 10 months were divided into 5 groups with 45 rabbits in each group.There was no significant difference in hair production performance and average body weight among the groups.Group I was a high-protein control group,and the amount of methionine was 0.1%.The other four groups all reduced protein levels by about 2 percentage points and added methionine at 0.1%,0.2%,0.4%,and 0.6%,respectively.During the breeding test period,all the test rabbits were kept in single cages.The rabbits were regularly disinfected according to conventional breeding management,immunization,and natural lighting and ventilation.Each experimental rabbit was fed 200 g of diet daily,and the remaining feed weight was recorded daily.Drink freely.Pre-feeding for 5 days,the formal test period was 65 days,and the metabolic test was 7 days.The reproduction test subjects selected 150 breeding female rabbits with good health at 6months of age,which were divided into 5 groups on average,30 in each group.The animalswere pre-fed for 5 days and the formal test period was 180 days.Test feed and feeding management are the same as above.The test results are as follows:(1)Reducing the protein content in the diet and adding different levels of methionine had no significant effect on the average daily feed intake of the experimental rabbits(P> 0.05),but had a significant effect on the yield and feed-to-gross ratio(P <0.05).Between the four groups with low protein,the hair production increased first and then decreased with the increase of methionine level,and reached the highest when the methionine addition amount was 0.4%.The coarse hair ratio,specific gravity of coarse hair,and average fineness of rabbit hair of each group of test rabbits were significantly different(P <0.05).The low-protein diet supplemented with 0.6% methionine group had three aspects in coarse coarse hair ratio,specific gravity,and average fineness of rabbit hair They were significantly higher than the other four groups;between the four groups with low protein,the coarse hair specific gravity and the average fineness of rabbit hair increased with the increase of methionine level.There were no significant differences in the length of the tufts of rabbits,the average elongation of rabbit hair,and the average breaking strength of rabbit hair(P> 0.05).(2)In the case of reducing the protein content in the diet and adding different levels of methionine,the urine nitrogen content of the experimental rabbits was very significantly different(P <0.01),the high-protein control group was significantly higher than the low-protein four groups.It also significantly affected the fecal nitrogen,apparent nitrogen digestibility and nitrogen utilization rate of the experimental rabbits(P <0.05).The high-protein group had significantly higher fecal nitrogen than the other four groups,with the addition of methionine between the low-protein four groups The increase of the level first decreased and then increased,and reached the lowest when the amount of methionine was0.4%;the apparent digestibility and nitrogen utilization rate of nitrogen in the high protein group were significantly lower than those in the other four groups.Digestibility and nitrogen utilization rate increased with the increase of methionine level.There was no significant difference in the deposited nitrogen and biological biological titers of experimental rabbits in each group(P> 0.05).Reducing the protein content in the diet and adding different levels of methionine had a significant effect on the apparent digestibility of phosphorus in theexperimental rabbits(P <0.05),which was highest when the amount of methionine added was0.4%;the crude fat and crude ash of the experimental rabbits,Crude fiber,neutral detergent fiber,acid detergent fiber and calcium apparent digestibility has no significant effect(P>0.05).(3)In the case of reducing the protein content of the diet and adding different levels of methionine,the concentrations of uric acid and alanine transferase in the serum of the experimental rabbits were significantly different(P <0.05),serum uric acid in the high protein control group The concentration was significantly higher than that of the four groups with low protein.Among the low protein groups,the serum uric acid concentration increased with the increase of methionine level;the concentration of alanine transferase was the highest when the amount of methionine was 0.2%.Test rabbit serum total protein,albumin,urea nitrogen,glucose,triglycerides,total cholesterol,high density lipoprotein,low density lipoprotein and aspartate transferase concentrations and serum immunoglobulins IgA,IgM There was no significant difference in the concentration of IgG and IgG(P> 0.05).(4)When the protein content in the diet was reduced and different levels of methionine were added,there was no significant difference in the total hair follicle density and secondary hair follicle density of the experimental rabbits(P> 0.05).It has a very significant effect on the primary hair follicles and the ratio of hair follicles(P <0.01).The decrease of protein can reduce the density of primary hair follicles and increase with the increase of methionine addition.The protein content can increase the ratio of hair follicles,and it increases first and then decreases with the increase of methionine.The expression levels of EGF,KAP3.1,KAP6.1,and TGF?-2 in rabbit hair follicle development were not significantly different in all groups(P> 0.05).The expression levels of hair follicle development-related genes IGF-I and TGF?-1 The difference was significant(P <0.05).The expression levels of IGF-I and TGF?-1decreased significantly when only the protein was reduced.The expression level of IGF-I increased with the increase of methionine,and the expression of TGF?-1 As the amount of methionine increased,the amount decreased first and then increased,all reached the highest when the amount of methionine added was 0.6%.(5)Reducing the protein content of the diet and adding methionine can reduce the cost of the diet and increase the economic benefits.In the case of reducing the protein content in thediet by about 2 percentage points,the optimal amount of methionine was 0.4%,and the economic benefit of the experimental rabbit reached the highest.(6)When the protein content in the diet is reduced and different levels of methionine are added,the number of live births,litter weight,and weaning survival rate of the experimental rabbits are significantly different(P <0.05).The number of live births is the highest.After reducing the protein content,the live births increase with the increase of methionine content,and reach the highest when the methionine content is 0.4%.There were no significant differences in the conception rate and litter size of the experimental rabbits in each group(P>0.05). |
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