Effects Of Ratio Of Structural And Nonstructural Carbohydrates In Diets On Digestion And Metobolism As Well As Rumen Metabolic Parameters For Sheep

The two experiment were carried out to study effect of ratio of structural and nonstructural carbohydrates (SC: NSC) in diets on digestion and metabolism of nutrients as well as rumen metabolic parameters for sheep. Experiment (1): Three mongolia wethers fitted with permanent rumen fistula were chosen to measure DM and OM degradabilities in stiu of four diets with different ratio of structural and nonstructural carbohydrates (SC and NSC) (1.26,1.71,2.28 and 2.80 ). The results show: DM and OM degradabilities of diet of SC:NSC=2.80 were much lower than other 3 diets; DM and OM degradabilities of diet of SC:NSC=1.26 were much higher than other 3 diets ; Although combinations of diets with SC:NSC=1.71and SC:NSC=2.28 were significantly different (included ratio of concentraten and roughage), DM and OM degradabilities in stiu of them were similar in all time of culture except for 42h. Experiment(2): Six one years old gansu high mountain fine wethers(avg wt 25~30 kg) fitted with permanent ruminal and proximal duodenal cannulae were assigned to double 3×3 Latin square design, to measure the apparent digestibilities of nutrients in rumen, postrumen and total tract and the apparent nitrogen retention as well as the dynamic changes of the rumen metabolic parameters in wethers fed with diets which SC:NSC ratio were respectively 1.57(dietⅠ), 1.95( dietⅡ) and 2.29( diet Ⅲ). There were three periods of 19 days (a 10-d adjustment period followed by a 9-d collections) of each period , there were three periods. The results show that: (1) DMI and OMI of wethers offered dietⅠwere higher significantly than those offered dietⅡand diet Ⅲ(P<0.01); DMD and OMD of dietⅠwere higher sifnificantly than diet Ⅲ( P<0.01), there were no difference significantly on DMD and OMD between dietⅡand　dietⅠ, Ⅲ(P>0.05); No significtant difference on DMD of nutrients in rumen and postrumen among there diets were observed (P>0.05); (2) No significant difference on NDFI, ADFI, NDF digestibilities in rumen, postrumen and total tract as well as the apparent digestibilities of ADF among three diets occurred (P>0.05). But the tendency of diet Ⅰhigher　by　contrast　to　diet Ⅱand diet Ⅲon　the apparent digestibilities of NDF in postrumen and total tract as well as the apparent digestant quantity of NDF　was　seen ( P=0.095, P=0.096, P=0.420), the tendency of diet Ⅲ　higher　by　contrast　to dietⅠand dietⅡon the apparent digestibilities of NDF in rumen was found (P=0.483); (3) NI of wethers offered the diet Ⅰwere higher sifnificantly than those offered diet Ⅱand diet Ⅲ( P<0.01), and NI of wethers offered the diet Ⅱwere higher sifnificantly than those offered treatment Ⅲ( P<0.01) , There were no difference significantly on the apparent digestibilities of N in rumen, postrumen and total tract as well as retention of N among three diets (P>0.05), whereas there was a tendency on the apparent digestibility of N in total tract that dietⅡwas superior to diet Ⅰ,Ⅲ( P=0.244); There were tendency on N retention and retained that dietⅠ,Ⅱwere superior to diet Ⅲ( P=0.278, P=0.244, P=0.091 , P=0.452); there was a tendency on the apparent digestibilities of nitrogen in rumen that diet Ⅱwas superior to other diets (P=0.278), there were no difference significant on the digestibilities of nitrogen in postrumen between diet Ⅱand other diets (P=0.429). The no significant difference on flux of pure protein in duodenal digesta among three diets occurred (P>0.05), the flux of nitrogen in duodenal digesta of diet Ⅰwere higher significantly than diet Ⅲ(P<0.01), and higher than diet Ⅱ(P<0.05), there were difference significantly on the flux of NPN between diet Ⅰand the others (P<0.05), there were no significant differents on the flux of N and NPN between dietⅡand diet Ⅲ(P>0.05); (4) The pH average value of rumen fluid of wethers offered diet Ⅰwas lower (6.32) than those wethers offered dietⅡ(6.45) and Ⅲ(6.55) (P<0.05); the pH value of rumen fluid from wethers offered diet Ⅲwas the higher all time (except before feeding). The concentration of ammonia nitrogen in rumen fluid from wethers on dietⅠwas higher (114.23mg/100mL) than diet Ⅲ(96.97mg/100mL) (P<0.05), there were no significantly difference on the concentration of ammonia nitrogen in rumen fluid between diet Ⅱ(110.24 mg/100 mL) and dietⅠ,Ⅲ(P>0.05). The concentration of protein nitrogen of rumen fluid for dietⅠwas higher significantly than diet Ⅱ,Ⅲ(P<0.01), the concentration of protein nitrogen of rumen fluid for dietⅡwas higher significantly than diet Ⅲ(P<0.01) , but there were no sifnificant differences on the concentration of urea nitrogen in rumen fluid among three diets ( P>0.05). (5) It was seen from all items measured that the effect on dietⅠ(SC:NSC=1.57) was better than that on dietⅡ(SC:NSC=1.95) and that on diet Ⅲ(SC:NSC=2.29) was the worsest.