Effects Of Rumen Degradable Starch Levels On Slaughter Performance,Nutrient Digestibility,Energy And Nitrogen Metabolism In Young Dairy Goats

With the rapid development of the animal husbandry industry,the production performance of dairy animals has been continuously improved.In actual production,the energy demand of high-yielding dairy animals is often increased by increasing the level of dietary starch.Starch is the main energy source for ruminants.The ruminant’s utilization efficiency of starch is the result of the combined effect of starch digestion and degradation sites.The utilization efficiency of starch in the small intestine is higher than that in the rumen.The digestion and utilization of starch in the small intestine helps to improve the production performance and starch utilization efficiency of dairy animals.Therefore,regulating the rumen degradation rate of dietary starch is of great significance for improving the energy supply efficiency of starch and body health.In this experiment,crushed corn and whole-grain corn were used to build two diets with high and low RDS levels to regulate the rumen degradation rate of starch.The effects of different RDS levels on the slaughter performance,nutrient content of intestinal chyme and energy metabolism in young milk goats at the age of 6 and 10 months,providing a theoretical basis for production.Experiment 1 Effects of dietary RDS on slaughter performance and nutrient digestibility of dairy goatsThis experiment uses a completely randomized trial design,selecting 32 healthy weaned lambs with similar body condition(body weight 13.6 ± 0.23 kg,3 months old),randomly divided into 2 groups,namely the low rumen degradable starch(LRDS,whole corn)group and the high rumen degradable starch(HRDS,crushed corn)group,each group of 16 sheep,diet composition and basic nutritional components are the same.The trial feeding period is 1 week and the trial period is 28 weeks(3-10 months old).Each group slaughtered 8 sheep at 6 months and 10 months,and a total of 32 sheep were slaughtered.Slime was taken from the small intestine and large intestine,and the nutrient content was determined.The results showed that: LRDS increased the net meat rate and meat-to-bone ratio of 6-month-old dairy goats(P < 0.05),while increasing the net carcass rate of 6-and 10-month-old dairy goats(P < 0.05).It can be seen that LRDS increased the head weight of 6-month-old dairy goats and the proportion of gastrointestinal tract of 10-month-old dairy goats(P < 0.05).Diet RDS had no significant effect on starch total intestinal apparent digestibility of 10-month-old dairy goats(P > 0.05).LRDS increased the content of NDF and ADF in the big intestine chyme of 6-month-old dairy goats(P < 0.05).Experiment 2 Effect of diet RDS on energy and nitrogen metabolism in dairy goatsOn the basis of the first experiment,the 10-month-old sheep to be slaughtered were transferred to a metabolic cage for digestion and metabolism tests.The adaptation period is 3 days and the sampling period is 3 days.Collecting the feces and urine during the sampling period with the method of total fecal collection and urine collection,and recorded the mass and volume after mixing and fixed with 10% H2SO4.Immediately after slaughter,each sheep’s intestinal segments,tissues,muscle fat,etc.were weighed and sampled to determine the content of crude protein.The results of the experiment found that dietary RDS levels had no effect on the energy metabolism and nitrogen metabolism of 10-month-old dairy goats(P > 0.05),and LRDS diet increased the muscle sediment protein content of 10-month-old dairy goats(P < 0.05).There was no difference in organ protein deposition(P > 0.05).This experiment found that dietary RDS has no significant effect on energy and nitrogen metabolism,but LRDS can increase the protein content of muscle deposits in 10-month-old dairy goats.In summary,under the premise of consistent dietary nutrition levels,appropriate reduction of RDS levels can increase the carcass net meat rate of 6-and 10-month-old dairy goats,and increase muscle protein deposition in 10-month-old dairy goats,improve amino acid balance,and improve production performance of dairy goats.