Effects Of Dietary Carbohydrate Structure On Rumen Fermentation And Nitrogen Metabolism In Goats

Four Xuhuai wethers fitted with permanent ruminal cannulas were used in this study. Different ratio (0.46, 0.75, 1.28, 2.26, 7.87) of non-structural and structural carbohydrates (NSC/SC) were used as substrates to determine the effect of different carbohydrate structure on rumen fermentation patterns and internal environmental management in vitro discontinuous cluture. A 4×4 Latin Square animal experiment was carried out to study the effect of equal nitrogen but different NSC/SC (0.63, 1.03, 1.65, 2.74) diet on rumen fermentation patterns and rumen nitrogen metabolism and bacterial population quantity. The results of the study showed:1. Different NSC / SC ratio of substrate affected changes in the rumen microbial cultivate environment. With the NSC/SC ratio increased, the pH value gradually decreased from 0.63 group to 2.18 group and the difference between each of the treatment groups were significant (P<0.05) to the end of the culture. All kinds of VFA and TVFA Concentration gradually increased with NSC/SC ratio increasing, but the proportion of acetic acid and acetic acid and propionic acid ratio decreased, the proportion of propionic acid and butyric acid increased gradually and the different reached a very significant (P<0.01) level from 0.46 to 7.87 group.2. Different NSC/SC ratio of substrate caused by internal environmental management in culture fluid changes. With the NSC level increased in the substrate, protozoa and bacterial protein production increased after decreased, The microbial protein yield reached its maximum when the NSC/SC ratio is 1.28 and Significantly (P<0.05) or highly significant (P<0.01) higher than that of the other groups; The protozoa and bacterial true protein ratio (P/B) increased with the NSC level increasing and each group were significantly different (P<0.05) to the end of training; With the increase of the proportion of NSC, the soluble protein, ammonia concentration, peptide and amino acid nitrogen content in the culture fluid gradually decreased; For average of observed values, the soluble protein, ammonia concentration and peptide content decreased significantly (P<0.05) from 0.46 to 7.87 group, while the amino nitrogen content no obvious decreased (P>0.05).3. There is a significant effect on rumen fermentation with equal nitrogen but different NSC/SC ratio diets feeding goats. With the increase of the dietary NSC level, rumen pH values decreased significantly (P<0.05); With the level of dietary NSC raising, acetic acid, propionic acid and TVFA molar concentration showed an upward trend, but the percentage of acetic acid and the acetic acid-propionic acid ratio decreased and the percentage of propionic acid gradually increased, The molar concentration and percentage concentration of butyric acid decreased after increased and have a maximum value in the NSC/SC is 1.65; With the dietary NSC level increasing, the protozoa, bacteria and total microbial protein production were firstly increased and then decreased and reached the maximum respectively in the NSC/SC is 1.03, 1.65 and 1.65; The protozoa protein and bacterial protein ratio increased after an initial drop with the NSC/SC increasing and reached the minimum value in the NSC/SC is 1.65.4. The nitrogen metabolism of rumen changes was caused by NSC/SC ratio diets. Rumen soluble protein content gradually decreased with the dietary NSC level increasing, but the other groups were not significantly different (P>0.05) except for 0.63 group and 2.74 group (P<0.05). The rumen ammonia concentration and urea-nitrogen content initially increased and then decreased with NSC/SC ratio increasing and reached a peak value in the NSC/SC ratio is 1.65, significantly (P<0.05) higher than 0.63 Group; With the dietary NSC level increasing, rumen peptides and amino nitrogen content gradually increased, and the difference between the other groups have achieved a significant (P<0.05) or highly significant (P<0.01) level except that 1.03 group and 1.65 group was not significantly (P>0.05);The content of rumen metabolic nitrogen and organic nitrogen have higher levels when NSC/SC value is 1.03 and 1.65 and there is no significant difference between these two groups(P<0.05), but these two groups significant higher(P<0.05)than 0.63 group and 2.74 group; With the dietary NSC level increasing, the ratio of rumen organic nitrogen and rumen metabolic nitrogen decreased , but there is no significant difference(P>0.05)between the other groups except for 0.63,1.64 and 2.74 group.5. The number of the rumen bacterial population quantity changes was caused by NSC /SC ratio diets. With the ratio of the NSC/SC increased, the number of Prevotella ruminicola,Ruminobacter amylophilus and Streptococcus bovis gradually increased, the number of Fibrobacter succinogenes and R. albus gradually decreased, and the number of R. flavefaciens and Butyrivibrio fibrisolvens were firstly increased and then decreased and reached the maximum respectively in the NSC / SC is 1.03 and 1.65.