Effect Of Different Proportions Of Dietary Carbohydrate On Gastrointestinal And Blood Nutritional Or Biochemical Indices In Hu Sheep

The Cornell Net Carbohydrate and Protein System (CNCPS) divides the ruminal microbial ecosystem into two microbial groups, microbes that ferment structural carbohydrate (SC) and those that ferment nonstructural carbohydrate (NSC). The former utilize only ammonia as N source, the latter can utilize either ammonia or FAA and peptide. So different proportions of dietary SC and NSC (SC/NSC) can affect the fermentative patterns of ruminal microorganisms and protein degradation in the rumen, give rise to change of quantity and quality of intestinal AA. While blood indices are associated to nutrition status and have correlation with gastrointestinal indices. In this paper, three Hu sheep fitted with ruminal cannulae, duodenal cannulae and jugular fistulae were used as experimental animals , a 4×3 Latin Square experiment was carried out to study the effect of SC/NSC diets on gastrointestinal and blood nutrition or biochemical indices. Four different SC/NSC were 1.62 (A), 1.05 (B), 0.69 (C) and 0.44 (D) , respectively.Chapter1 Effect of different SC/NSC diets on ruminal internal environment parameters and peptides release in rumen of Hu sheepIn this study, effect of different SC/NSC diets on rumen pH, ammonia-N and VFA concentration were investigated, and the type, concentration and ratio of FAA and peptide in rumen were also determined. The results showed that:1.Rumen pH decreased with the decrease of SC/NSC. Rumen ammonia-N (NH3-N) concentration increased with the decrease of SC/NSC, but decrease in D group. The highest acetate concentration was observed in B group, with the decrease of SC/NSC, the rumen propionate, butyrate increased, and the ratio of acetate: propionate decreased.2.Rumen FAA and peptides concentration increased with the decrease of SC/NSC. When SC/NSC decreased from 1.62 in A group to 1.05 in B group, the yield of bacteria increased significantly (P<0.01) and bacteria amino acid increased (P<0.05), too. But when SC/NSC continue decreased ot 0.69 or 0.44, the bacteria yield and AA reduced. It indicated that in hyper-NSC treatment, abundant peptides released in rumen exceeded optimal requirement of bacteria that ferment NSC which limited growth of bacteria and reduced synthesize of MCP.3.Peptides concentration in rumen of A, B group attained peak value at 2h after meal, but this was not observed in group C and D. The composition of AA in peptides weresimilar among four treatments. Rumen peptides contain lower Tyr, Leu and Phe which suggests these AA may be necessary for bacteria growth. The higher concentration of Asp, Glu, Gly and Ala are perhaps resistant to rumen degradation. Chapter 2 Effect of different SC/NSC diets on intestinal internal environment and absorbable AA in Hu sheepThis experiment studied the contribution of bypass-protein-N, bacteria and protozoa to intestinal absorbable AA in different SC/NSC diets.1.Various SC/NSC diets showed significant influences on apparent intestinal AA digestibility. The digestibility increased when SC/NSC decreased from 1.62 in A group to 1.05 in B group, but decreased with further decreasing of SC/NSC. Total flux and composition of AA entering the duodenum were also affected by different diets. Total AA flux was highest in B group, and for AA profile, there were different for 10 out of 17 amino acids measured.2.This experiment proved that DAPA and PC can be used as microbial markers for determining flow of bacteria and protozoa in certain SC/NSC ratio diets, but when in hyper-NSC diet, bacterial DAPA increased.3 Bacteria DM and AA flow entering the duodenum were highest in A group. The absorption of total AA, bacteria and undegraded dietary AA from intestine were also highest in A group. The contribution of protozoa AA was less than bacteria, but it was more easier to absorbed by intestine.4.Comparison of microbial AA profile indicated that 5 amino acids in liquid-associated-bacteria (LAB) and 3 in particulate-associated-bacteria (PAB) were affected by various diets, while 4 amino acids in protozoa were also influenced. Chapter 3 Effect of di...