عنوان مقاله [English]
Introduction Corn and wheat are the grains most routinely used in commercial poultry diets. For consumption of these cereals, there are a competition between humans and mono-gastric animals. Due to corn crop limitation in Iran, approximately 50% of the corn required for poultry nutrition is supplied through imports. Since triticale is more resistant to various diseases, dry weather and in similar culture and weather conditions can produce higher yield than wheat, triticale considered as a crop suitable for cultivation in inefficient lands and its culture in the world has being increased. The use of triticale in broiler feed has been limited because of the presence of soluble non-starch polysaccharides components. The purpose of this study was to evaluate the effects of different replacement levels of corn by triticale in grower diets with and without exogenous enzyme supplementation on growth performance, relative weight of digestive organs, jejunal morphology, and intestinal viscosity of broiler chickens.
Materials and Methods Five hundred 11 d old male broiler chicks (Ross 308), were assigned to a factorial arrangement (5×2) with a completely randomized design with 5 replicates of 10 chicks each. The factors included 5 levels of triticale replacement levels for corn (0, 10, 20, 30 and 40%) and 2 levels (zero and 0.5 g /kg of diet) of enzyme cocktail “Xylanase & β-Glucanase” in the broiler grower diets. The experimental diets were isocalric and isonitrogenous and fed ad-libitum from 11 to 24 d of age. The growth performance as mean body weight at 24 d of age, daily weight gain, daily feed intake, and feed conversion ratio were calculated. At 24d of age, one bird from each pen, close to the average pen weight was selected, weighed, and euthanized by cervical dislocation. The gastrointestinal (GI) tract organs were emptied and weighed. Approximately 1.5 g of wet weight of the fresh digesta was immediately placed in a micro centrifuge tube and centrifuged at 12.700 × g for 5 min. The supernatant viscosity was determined using a Brookfield digital viscometer (Model DV-п). About 0.5 cm in length of the jejunum midpoint was taken, fixed in 10% neutral buffered formalin solution. The tissue samples were treated in tissue processor apparatus, embedded in paraffin wax, transverse sections were cut (5μm thickness) by using a rotary microtome and stained with Hematoxylin and Eosin (H&E) to prepare intestinal slide. Morphological measurements of intestinal slide were performed by light Microscope on 9 vertically oriented villus. The investigated morphological traits contained villus height, villus width, crypt depth, muscular thickness, and the villus surface area.
Results and Discussion The weight in 24 d and daily weight gain and feed intake significantly decreased and feed conversion rate significantly increased with increasing dietary level of triticale to 40%. The dietary enzyme supplementation (xylanase and β-glucanase), significantly improved broiler growth performance, and reduced adverse effects of high levels (40%) of triticale in grower diet. The poor growth performance of birds fed grower diet with high (40%) level of triticale may be related to lower nutrient digestibility, or higher anti- nutrient factors in triticale as compared to corn. The relative weights of whole gastrointestinal tract, gizzard, small intestine, large intestine, and pancreas numerically increased with increased triticale level, the highest relative weight of digestive organs was observed in the birds fed diet with 40% triticale level and the lowest one was observed in the birds fed corn-soy based diet. The ileum chyme viscosity significantly increased with increase in the dietary triticale level to 30 and 40%. Enzyme supplementation to grower diet caused a reduction in the pancreas relative weights and ileum chyme viscosity. The significant increase in relative weight of digestive organs of the birds with high level of triticale in their diet may be due to the enhanced function of these parts, because of an increase in water soluble NSP and subsequent increase in chyme viscosity, which implying a feedback mechanism in gut motility and thus size of this organ. The higher NSPs in triticale compared to corn can increase digestive chyme viscosity and reduce endogenous enzyme-nutrient actions and their subsequent substrates, leading to significant modifications of the structure and function of intestine. Therefore; to adapt to these changes, the activities of the intestinal secretary mechanisms may be enhanced. Thus, this may lead to an increase in the size of the gastro intestinal tract and pancreas weight. The villus height (VH) and crypt depth (CD) significantly decreased and muscular thickens significantly increased with increased levels of triticale to 40% in diet. The birds fed 40% triticale showed shorter of the villi compared with the longer villi from birds fed the corn-soy diet. Villus hight and VH/CD significantly increased and CD significantly decreased in birds fed diet with enzyme supplementation compared to those fed diet without enzyme supplementation. Histological observations on the small intestine epithelium of birds fed corn-triticale-soy diet showed morphological changes in the jejunum (shortening, thickening, and atrophy of the villi). The birds examined in our study showed short, thick, and damaged villi, especially with the higher level (40%) of triticale in diet compared to those fed a corn-soy diet. The addition of enzymes supplementation to diet improved these histological alterations.
Conclusion This study revealed that 1) triticale can be used as an alternative source of grain in grower broiler chickens’ diets. 2) Using up to 30% triticale in grower diet did not have any adverse effect on broiler chicken performance. 3) The exogenous enzyme supplementation (xylanase and β-glucanase), significantly affectsbroiler growth performance, and reduces anti-nutrient effects of high levels (40%) of triticale in broiler chickens’ grower diet.