Effect of Nigella Sativa meal with multi enzyme on growth performance and blood biochemical parameters of broiler chickens

This study was performed to evaluate the effects of nigella sativa meal and multi enzyme on growth performance, relative weight of carcass components, blood parameters and intestinal morphology of broiler chicken.

The experiment was carried out in a completely randomized design with five treatments in four replicates and 14 chickens in each replicate (80 chickens). Broiler chickens was fed with diets including: without nigella sativa meal and enzymes (control), 7.5% nigella sativa meal (without enzymes), 7.5% nigella sativa meal with 0.2% multi enzyme, 15% nigella sativa meal (without enzymes) and 15% nigella sativa meal with 0.2% multi enzyme for 42 days. Then, the performance of chickens, blood biochemical indicators, intestinal morphology and economic index were measured and recorded. Finally, the analysis of data was performed using GLM method by SAS software. The means were compared using Duncan's multiple range tests.

The results showed that, treatments did not have a significant effect on feed intake, daily weight gain and feed conversion ratio during the growth period. Whereas, the effect of experimental treatments was significant on feed intake, daily weight gain and feed conversion ratio in the finishing period. The lowest feed conversion ratio was observed in chickens fed control group and 7.5% nigella sativa meal without enzyme (P<0.05). In total experimental period, the lowest feed intake and weight gain were observed in the groups receiving 15% nigella sativa meal (both with and without enzymes; P<0.05). The lowest feed conversion ratio was observed in the control group and the group receiving 7.5% enzyme-free nigella sativa meal (P<0.05). Finally, in the total experimental period, the final body weight was significantly the highest in the control group (P<0.05). The high levels of nigella sativa meal and enzymes used in this study may have significantly reduced feed intake and feed conversion ratio due to the increase in fiber intake compared to lower levels. On the other hand, the use of different levels of nigella sativa meal and enzymes did not have significant effect on carcass percentages and carcass components, only using 15% nigella sativa meal without enzymes increased the ratio of intestinal length to live weight compared to other treatments. Due to the different results presented in different studies, the levels of use of nigella sativa meal in this study are probably less than the level affecting the relative weight of body organs. According to blood indices, the different treatments did not have any significant effect on serum lipids include cholesterol, triglyceride, HDL and LDL. The lack of significant effect of using different levels of nigella sativa meal in the present study is probably due to the use of low levels. Indeed, the use of enzymes with high levels of nigella sativa meal resulted in significantly increase in height of villus jejunum and ileum compared to the control group (P<0.05). The thickness of villus jejunum and ileum of broiler chicken fed 7.5% nigella sativa meal without enzyme increased significantly than the other treatments (P<0.05). The use of 15% nigella sativa meal significantly decreased villus height to crypt depth ratio of jejunum and ileum than the same level without enzymes, but 7.5% nigella sativa meal with enzyme resulted in higher villus height to crypt depth ratio than the without enzymes group (P<0.05). The improvement in villi height to crypt depth ratio may be related to the antimicrobial properties of black seed. For this reason, when the microbial activity in the contents of the intestine decreases at the surface of brush border, the need for enterocytes and new cells to multiply in the intestine decreases, resulting in higher villi height and less crypt depth. Since the main source of protein in poultry diets comes from soybean meal, replacing new and inexpensive sources is a great economic help to reduce feed costs. The replacement of soybean meal by nigella sativa meal decrease feed costs and increase profitability without adversely affecting the broilers.

According to the results, the use of nigella sativa meal reduced the performance of chickens and the use of enzyme supplements could not eliminate these negative effects. On the other hand, 7.5% nigella sativa meal (without enzyme supplements) had a positive effect on morphometric indices.