Evaluation Of Fibrous Feed’ S Digestibility In Vivo/ In Vitro And Its Effect On Intestinal Digestive Function For Growing Pigs

This experiment evaluated several fibrous feeds’ digestibility in vivo and in vitro method usingsimulated digestion system, studied the effects of different fiber sources on the main nutrients’ digestibility and intestinal digestive function in growing pigs. The study was conducted to providecertain scientific basis for fibrous feeds’ application in actual production for swine nutrition. Theexperiment included three parts :The EXP.1 was to study on the effects of sugar beet pulp,wheat bran and oat bran on nutrients’ digestibility. The experiment was designed by a replicated 7 × 3 incomplete Latin square. FourteenDuroc × Landrace × Yorkshire crossbred barrows fitted with simple T-cannula on terminal ileum werefed 7 experiment diets alternately for 3 periods.The 7 experiment diets were: the basal diet, 20% sugarbeet pulp diet, 30% sugar beet pulp diet, 20% wheat bran diet, 60% wheat bran diet, 20% oat bran diet,60% oat bran diet(add corresponding ratio of sugar beet pulp, wheat bran and oat bran to replace thebasal diet, respectively). Main nutrients’ apparent total tract digestibility(ATTD) and apparent ilealdigestibility(AID) were determined, and the fibrous ingredients’ digestibility was calculated byalgorithm. The p H, volatile fatty acid(VFA) and water-binding capacity of ileal digesta and feces werealso determined. The results showed that:1) The digestibility values of fiber raw materials under twoaddition levels were determined by algorithm showed as follows:ATTD of DM, CP and GE in sugarbeet pulp, wheat bran and oat bran had no significant changes in two addition levels(P > 0.05); AID ofCP, DM and GE in sugar beet pulp significantly increased as the addition proportion rose(P < 0.01).2)the digestibility of different fibrous diets were showed as follows: ATTD and AID of DM and GE in 6fiber diets were significantly lower than basal diet’s value for growing pigs(P < 0.05)(the AID of 20%wheat bran diet wasn’t significantly different from basal diet’s value).When wheat bran’s additionamount increased from 20% to 60%, diets’ ATTD and AID of GE and DM decreased(P < 0.05);improving the addition level of sugar beet pulp had no significant effect on ATTD and AID of DM, GEand CP for growing pigs(P > 0.05); when oat bran’s adding level increased from 20% to 60%, AID ofGE decreased(P < 0.05), while AID of CP increased(P < 0.05).The AID of CP and ATTD of GE indiets were negatively correlated with IDF/TDF intake(P < 0.05).20% sugar beet pulp significantlyimproved the amount of acetic acid and total VFA(P < 0.05), reduced the p H value of feces and ilealdigesta(P < 0.05), and increased the water-binding capacity of ileal digesta(P < 0.05) in growing pigs.The Exp.2, Evaluation of fibrous feeds’ dry matter and energy digestibility in vitro method usingsimulative digestion. Seven fiber diets and three fibrous raw materials in Exp.1 were digested bysimulative digestion system(SDS-II),gaining DM and GE digestibility of two-steps(simulating stomachand small intestine digestion)and three-steps(simulating stomach、small intestine and large intestinedigestion)enzyme method using SDS-II. The results showed that: The digestibility values betweentwo-steps and three-steps method of fibrous diets and raw materials were close(difference was 0.07%~6.42 %); 6 fibrous diets’ DM and GE digestibility in vitro method using SDS-II were significantly lowerthan basal diet’s value(P < 0.05), DM and GE digestibility of diets in vitro method using SDS-II weresignificantly decreased as the addition level of sugar beet pulp, wheat bran and oat bran improved(P <0.05). The GE digestibility of bionic two-steps method and the AID value in vivo had a significantpositive correlation(R2 = 0.80).The Exp.3: effects of different fiber sources on the production performance, intestinal digestivefunction in growing pigs. 15 healthy barrows(initial body weigh 46.45±3.20 kg)were randomlyallocated into three treatments: basal diet, wheat bran diet, oat bran diet(add 20% wheat bran or oatbran to replace control diet, respectively), each barrow was one replicate, the feeding period lasted for28 d. All the barrows were slaughtered on day 29, intestinal tissue, mucosa and digesta samples werecollected for detailed analysis, such as intestinal morphology, mucosa disaccharidase activity, gut floraand VFA. The results showed that: oat bran reduced pigs’ average daily feed intake(ADFI)significantly(P < 0.05).Compared with basal diet, both of wheat bran and oat bran significantlyincreased mucosal disaccharidase activity in jejunum(P < 0.01), and the effect of oat bran was betterthan wheat bran(P < 0.01). Oat bran significantly increased butyrate content(P < 0.05), and reducedbifidobacterium population(P < 0.01) in cecum digesta. In conclusion, both of wheat bran and oat brancould increase gut digestive function in growing pigs, but the effect of oat bran was higher than wheatbran.In conclusion, sources or levels of dietary fiber had obvious influence on main nutrients’ digestibility and intestinal digestive physiology function in growing pigs, which is related to theSDF/IDF content of dietary fiber.The addition of fiber raw materials could decrease diets’ GE and DMdigestibility, while 20% wheat bran or oat bran didn’t cause the inhibition of pigs’ growth, and wereable to improve intestinal digestive function to a certain extent.