The Effect Of Dietary Starch Sources On Growth Performance, Starch Digestion Of Small Intestine And Protein Synthesis Of Splanchnic Tissues In Weaned Pigs

Three experiments were conducted to investigate the influence of different dietary starch sources on the performance of growing pigs and the relative mechanisms. Base on the comparison of different feeding effect of dietary starch source, starch in vivo digestion and absorption as well as it's effect on energy and protein utilization, and fractional protein synthesis rate of splanchnic tissues in weaned pigs were further studied. The reasons for the different feeding effect of dietary starch source were elucidate from both digestive tract and splanchnic tissues.Trail 1. A feeding trail covered 21ds and a 4×4 Latin square design metabolism experiment using 52 (ABW8.8± 1.0kg) 28d Duroc × Landrace ×Yordshire crossbreed weaning pigs were conducted to study the effect of dietary starch source on the performance,nitrogen metabolism, and blood biochemical parameters. 4 iso-nitrogen, iso-energy and iso-starch diets were formulated use Corn, Brown rice, Stick and Resistant starch(Hi-maizw-1043) as starch sources.Trail 2. 20(ABW8.0 ± 0.6kg) crossbreed (Duroc × Landrace × Yordshire) 28d weaning pigs were conducted to evaluate digestibility of different dietary starch on different sites of small intestine, and its effects on in vitro dietary starch degradation. Degesta of anterior jejunum, posterior jejunum, anterior ileum and terminal ileum were collected using the slaughter technique to determine the digestibility of different starch source. In vitro starch degradation were assayed when starch incubated by amylase after 0.25, 0.5, 0.75, 1, 2, 3, 4, 5, 6h.Trail 3. 16(ABW8.0± 0.4kg) crossbreed (Duroc × Landrace × Yordshire) 28d weaning pigs were used to determine the effects of different starch source to FSR of splanchnic tissues by an intraperitioneal injection of a flooding dose of L-[²H₅]Phenylalanine (1.5mmol/kgBW). Venous Blood and splanchnic tissues samples were collected to determine isotopic enrichment of free pool and bound pool.The results showed as follow:l.The growing performance of weaning pigs was affected by fed diets containing different starch source. Corn diet increased ADG significantly (P<0.05), reduced F/G significantly(P<().05-0.01), and enhanced whole body protein deposition. Its ADG was 10.77%(P<0.05), 24.53%(P<0.01) and 36%(P<0.01)higher than Brown rice, Stick rice and RS diets respectively. And the F/G of Corn diet was 7.88%. 12.73%(P<0.05) and 18.18%HM).O1) lower than Brown rice, Stick rice and RS diet respectively. Stick rice starch was better to increase the digestion rate of energy and dry mass, while reduced weight gain, increased UN excretion, and had lower total nitrogen utilization rate than Corn starch(P<0.05). The lower weight gain of Stick starch was mainly effected by the lower feed utilization rate. RS significantly reduced growing performance, increased FN excretion, reduced UN excretion, and decreased ADR of nitrogen. RS diet reduced weight gain, the effect degree of reduce of FI and FCR were 61.98% and 38.02% respectively.The results of blood biochemical parameters analysis indicated that, the digestion and absorption of Stick rice diet starch were rapid , the Stick rice group increased concentration of blood glucose, lactic acid, insulin and insulin/glucose significantly (P<0.05) in postprandial lh, the concentration of blood glucose and lactic acid were 5.23% and 4.64%. 15.58% and 35.15%> 20.51% and 31.52% higher than Brown rice, Corn and RS diet group respectively. The Corn diet group decreased change range of concentration of blood glucose, lactic acid, insulin in postprandial. The Corn diet group increased concentration of GH,T3 and T4. The concentration of blood glucose, lactic acid, insulin,GH/T? and T4 were lowest in RS diet group.2. The extent of starch digestion in different sites of small intestine and in vitro degradation was affected significantly" by dietary starch sources. The affects were related to amount of amylose and amylopectin. The amount of amylopectin intake were positive correlation with starch digestibility and starch digestion rate.The starch digestibility of Stick rice starch diet in anterior jejunum, posterior jejunum, anterior ileum and terminal ileum were increased significantly(P<0.05). The Stick rice starch digestibility of anterior jejunum and terminal ileum were 81.90% and 99.81% respectively, which was 68.35% and 3.82%, 73.63% and 7.03%, 139.89% and 21.31%highcr than brown rice, corn and RS groups respectively. The digestion of starch in anterior jejunum(Yi), posterior jejunum(Y2), anterior ileum(Y.-i) and terminal ileum(Y4) were related to Amylose(Xi) and amylopectin(X2), the regression formulaas follow:Y, =0.35 1Xi+0.799X2 n=20 R2=0.947 p<0.001 Y2=0.665X,+1.053X2 n=20 R2=0.990 p<0.001 Y3=0.899Xi+1.138X2 n=20 R2=0.988 p<0.001 Y4=t.013Xi + 1.199X2 n=20 R2=0.991 p<0.001As to tho in vitro starch degradation rate and starch degradation coefficients in different incubate hours, Stick rice diet starch was significantly higher than other groups(P<0.05-0.01).3. The different source starch effected FSR of splanchnic tissues of weaning pig significantly. The starch of corn diet starch enhanced FSR of splanchnic tissues of weaning pig. The FSR of splanchnic tissues corn groups was higher than other groups. The FSR of duodenum, jejunum, ileum, colon, pancreas and liver of corn group were 85.87% (P<0. 05) > 47.47% (P<0. 05) , 37.29% (P<0. 05) > 56.29% (P<0. 05) , 43.55% (l'<0. 05) ^ 17.63% higher than stick rice group respectively. The influence of RS to FSR of splanchnic tissues of weaning pig was between stick rice and brown rice groups.