Effects of Different Levels of Zero-Tannin Faba Bean on Performance and some Physiological Responses of Broiler Chickens

The quality and quantity of dietary protein are primary factor influencing growth and feed costs. Seeds of faba bean (Vicia faba L), similarly as soybean meal, belong to high-protein feeds. The use of faba beans in poultry feed is limited despite having a suitable chemical composition, the main reason of which is the presence of anti-nutritional factors in this seed. Golestan Agricultural and Natural Resources Research and Education Center has produced a zero-tannin faba bean seeds variety (Mahta cultivar) that does not have the nutritional limiting factors of normal beans. The aim of this study was to investigate the effect of different levels of zero-tannin faba bean seeds (Mahta cultivar) on growth performance, some immune and biochemical parameters of blood, morphology and microbial population of small intestine and meat quality of broiler chickens.

320 of one-day-old Ross 308 broilers with 4 treatments were used in a completely randomized design with 4 replications and 20 equal mixed birds of each sex in each replication for 42 days. Experimental treatments included 1- control diet (without faba beans and based on corn-soybean meal) 2- diets containing 10% zero-tannin faba bean 3- diets containing 20% zero-tannin faba bean and 4- diets containing 30% zero-tannin faba bean. Then, the growth performance of chickens, blood biochemical (triglyceride, cholesterol, LDL, VLDL and HDL concentrations) and immune (heterophil and lymphocyte percentage) indicators, intestinal jejunum morphological (villi length, villi width, crypt depth and thichness of muscle layer) and ileum contents microbial population (lactobacillus and escherichia coli) parameters and meat quality (pH, malondialdehyde, peroxide number and free fatty acids) of broiler chickens were measured and recorded. Finally, the analysis of data was performed using GLM method by SAS software. The means were compared using Tukey's multiple range tests.

The results showed growth performance (feed intake, weight gain and feed conversion ratio) of the whole period (1 to 42 days) of birds fed with different levels of diets containing zero-tannin faba bean (0, 10, 20 and 30%) was not significant. There was also no difference between the growth performance of birds fed diets containing zero-tannin faba bean compared to birds receiving the control diet (without beans). A decreasing linear change in the weight gain of the whole period was observed with the increase in the percentage of zero-tannin faba bean (P<0.05). So, the birds that were fed with the control diet (without beans) and 10% zero-tannin faba bean had a better weight gain compared to other treatments, equal to 1738 and 1748 grams respectively, followed by the birds receiving the diet containing 20% zero-tannin faba bean had weight equal to 1623 grams and finally, the birds fed with a diet containing 30% zero-tannin faba bean had weight equal to 1574 grams (P<0.05). Some blood biochemical and immune parameters of broilers were not affected by different levels of zero-tannin faba bean in the diet. However, the amount of changes in HDL, the ratio of HDL to cholesterol, serum LDL and the percentage of heterophil, lymphocyte and the ratio of heterophil to lymphocyte in the blood of broiler chickens fed with a diet containing 20% of zero-tannin faba bean is worthy of consideration and requires further investigation and study (P>0.10). Also, morphological parameters of intestinal jejunum were not affected by different levels of zero-tannin faba bean in the diet. However, citizenship analysis showed linear changes in villi length, villi width and crypt depth of broiler intestines. The tendency to increase villi length was observed in birds fed diets containing 10% zero-tannin faba bean compared to other diets (P= 0.08). Villi width (P<0.05) and crypt depth (P=0.05) were lower in birds fed diets containing zero-tannin faba bean compared to the control treatment (without faba beans). Microbial population of escherichia coli and lactobacillus ileum contents were not affected by different levels of zero-tannin faba bean in the diet. The use of different levels of zero-tannin faba bean improved meat quality by decreasing pH, malondialdehyde concentration, peroxide and free fatty acids in broiler thighs (P<0.05).

Finally, according to the present results, it seems that among the different levels of zero-tannin faba bean (10, 20 and 30%) in the diet of broiler chickens, the level of 10% zero-tannin faba bean in terms of broiler performance should be more appropriate and competitive with the control diet (without faba beans and based on corn-soybean meal).