| Summary: | 碩士 === 國立中興大學 === 畜產學系 === 89 === The purpose of this study was conducted to determine the effects of different levels and sources non-starch polysaccharides (NSP) on intestinal physiology in broilers. A group of 20 male and 20 female broilers (Arbor Acers) was allotted to 5 treatments at 19- and 40 days old. Using corn, casein and fish meal to prepare the semipurified diet as the control, NSP extracted from barley or wheat bran were incorporated at 50 and 100g kg-1 in the control diet. After 7 days feeding experiment, to examine the effect of NSP on performance, nutrient availability, intestinal physiology, microflora population and the lipid metabolism of broilers.
The result showed that, the total dietary fiber content increased with the incorporated levels of NSP in the diet, and barley NSP treatment groups were rich in soluble dietary fiber, but the wheat bran NSP treatment groups was rich in insoluble dietary fiber. The feed conversion of 19-25 days old broilers was significantly increasing in barley and wheat bran NSP treatments (P<0.05), especially in 10% wheat bran NSP treatment. The digesta viscosity of barley NSP 10% treatment was also significantly higher than wheat bran NSP or control treatments, in result reduce the availability of dry matter, protein and lipid; the nutrient availability of 5% barley NSP treatment and wheat bran NSP treatments also has slight reduce, but not reach the significantly level. However, there was no effect in the growth performance and nutrient availability in broiler during 40-46 days old.
NSP incorporated to the diet was significantly increasing the relative weight of colonic-rectum (P<0.05), and also has slight effect in caecum. The barley NSP treatments were significantly effect in the length of jejunum and ileum than the wheat bran treatments (P<0.1). In the aspect of intestinal mucosa, the ileal crypt depth and caecal mucosa height of 3 weeks old broiler was significantly affect or has the slight increasing effect with NSP. And the intestinal muscle layer also has the same trend, indicate the proliferation activity of intestinal mucosa was increasing with NSP supplement.
With increasing the level of NSP in diet, the dietary nutrient digestion and absorption in proximal small intestinal was reduced, therefore more of nutrient would reach the distal intestinal, and it can provide as fermentable substrate for microorganism. Thus, the anaerobic microflora in the ileum and caecum of 3 weeks old broilers was increased with the higher NSP level, and the effect by barley NSP was significantly than wheat bran NSP (P<0.05). The aerobic flora was also increasing with the NSP inclusion, in particular the higher amount of NSP in diet (P<0.05). With increasing levels of NSP in the diet, the volatile fatty acid concentration in the content of the distal small intestine and caecum not increased, but the percentage of butyric acid in caecum was significantly increased in 3 weeks old broilers (P<0.05). No matter the days old of broiler, the serum cholesterol concentration was significantly lower in 10% NSP treatment group than the 5% NSP treatment group (P<0.1). And with the increasing NSP level, the amount of bile salts excretion also significantly increased (P<0.05). To Summarize, the broilers growth performance would decreased with the content of barley- or wheat bran NSP, and the different influence mechanism was reflect in intestinal mucosa histology and microorganism fermentation. Barley NSP treatments could significantly increasing the digesta viscosity and microflora population in distal intestinal; the bulk ability of wheat bran NSP could increasing the digesta passing rate, thus reduce the fermentation. And the intestinal mucosa proliferation ability was both increased in barley- and wheat bran NSP treatments. If the dietary NSP contents were under the level that broiler could tolerate, the NSP negative effect was slight. And with the age increase, the development of intestinal was complete, broilers could endure the anti-nutritive factors in diets.
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