بررسی امکان جایگزینی مخلوط پروتئینی به‌جای کنجاله‌ سویا و مکمل‌ مخلوط آنزیمی بر عملکرد جوجه‌های گوشتی

آزمایشی به منظور بررسی اثر سطوح مختلف جایگزینی مخلوط پروتئینی (کنجاله کانولا و پودر ضایعات کشتارگاهی طیور) با کنجاله سویا در جیره و مکمل مخلوط آنزیمی بر عملکرد جوجه‌های گوشتی انجام شد. آزمایش با تعداد 384 قطعه جوجه سویه تجاری راس 308 با 8 تیمار به صورت فاکتوریل4×2 (4 سطح جایگزینی مخلوط پروتئینی: صفر، 25، 50 و 75 درصد×2 سطح مخلوط آنزیمی: صفر و 250 میلی گرم درکیلوگرم خوراک) با 4 تکرار 12 قطعه ای جوجه از هر دو جنس و در قالب طرح کاملاًتصادفی انجام گرفت. در دوره 241 روزگی در جیره های بدون آنزیم، سطح جایگزینی 75 درصد به طور معنی دار باعث بیشترین کاهش وزن و افزایش ضریب تبدیل خوراک شد اما در جیره های دارای آنزیم، سطوح 50 و 75 درصد جایگزینی وزن بدن و ضریب تبدیل مشابهی داشتند. در دوره 1 تا 42 روزگی مصرف آنزیم تاثیر معنی داری صفات تولیدی، اقتصادی و خصوصیات لاشه ایجاد نکرد اما باعث افزایش معنی دار چربی محوطه شکمی شد. جایگزینی 25 درصدی مخلوط پروتئینی با کنجاله سویا  تاثیر معنی داری بر وزن بدن، هزینه خوراک به اضافه وزن، بازده ناخالص اقتصادی و خصوصیات لاشه ایجاد نکرد اما باعث افزایش معنی دار ضریب تبدیل خوراک و کاهش شاخص تولید گردید. سطوح بالاتر جایگزینی باعث کاهش بیشتر وزن بدن، شاخص تولید و بازده ناخالص اقتصادی شد. به طور کلی نتایج نشان داد که استفاده از مخلوط آنزیمی تاثیر چندانی بر عملکرد جوجه های گوشتی نداشت اما بسته به شرایط بازار جایگزینی مخلوط پروتئینی با کنجاله سویا در حد 25 درصد می تواند از نظر اقتصادی برای پرورش دهنده توجیه پذیر باشد.

Investigation on substitution possibility of proteinous mixture with soybean meal and multi-enzyme supplementation on broiler performance

Introduction  It is advantageous to include as many ingredients as possible when formulating a diet for broiler chickens, because the supplementary nature of nutrients in different feedstuffs promotes the reduction of nutrient variation. The results of some experiments have shown that diet uniformity, through variance reduction for nutrients, improves broiler performance. In addition, lower variability of nutrients reduces the possibility of nutrient wastage. Also, in practical feed formulation when using of cheaper feed ingredients such as canola meal (CM) or poultry byproduct meal (PBM) instead of more expensive ingredients such as soybean meal (SBM) in such a way that inclusion of them didn’t result in a lower production and quality indices thus they may result in a lower feed costs and higher economic benefit for producer. Both CM and PBM are good sources of protein for broilers and less expensive than SBM. Canola meal is a worthful feed ingredient and according to climatic condition and type of processing contains 3639% crude protein. It may consider as a good source of calcium, phosphorus, magnesium, manganese, zinc, and iron as well as relatively good source of methionine and lysine. Poultry by product meal can be used in poultry ration up to 6% of total feed if sanitary operations is observed. High levels of fat, moisture and feather contents are main drawbacks of PBM in the poultry rations. However, if PBM mixed with CM that has low levels of fat and moisture, a proteinous mixture will result with similar CP level to SBM and longer storage potential. Both CM and PBM have lower nutrient digestibility as crude protein, fats and trace minerals because of phytate and NSP and dietary exogenous enzymes may improve digestibility of nutrients. The results of some researches showed that Kemin multienzyme supplementation improved broiler performance or carcass characters. This research is carried out for study effect of different substitution of a proteinous mixture composed of CM and PBM (65%:35%) with SBM with Kemin WP multienzyme supplementation on production and economic performances of broiler chickens.      Materials and Methods This experiment was conducted in a factorial arrangement 4×2 (4 levels of proteinous mixture replaced with SBM: 0, 25, 50 and 75%×2 levels of Kemin WP multienzyme supplementation: 0 and 250mg/kg diet) with 8 treatments, 4 replicates of 12 pieces of Ross308 strain broiler chicks of either sex reared on 1×1.25m floor pens in a completely randomized design. Proteinous mixture was made by proper mixing of CM and PBM (65%:35). During experimental period chickens were received mash diet according to Ross308 feed specification booklet (2014) for as hatched broilers. Feed and water were prepared for broilers adlibitum. Body weight, feed intake, feed conversion ratio (FCR), production index, feed cost to gain (Rials/kg), and monetary returns (Rials/bird) were measured or calculated at different phases of growth period. At the end of growth period (42 days of age) one bird similar in body weight to average weight of each replicate was selected and sacrificed for carcass character measurements. Collected data were subjected to analysis of variance by ANOVA procedure of SAS2003Software. Treatment means were separated using Duncan multiple range test at 0.05 significant level.Results and Discussion At shorter growth period of 124 days, there was a significant interaction between dietary multienzyme supplementation and different substitution levels of protein mixture and SBM on body weight and FCR. As, in diets without multienzyme supplement,75% substitution of protein mixture with SBM significantly resulted in the most decrease in body weight and increase in FCR however, in diets with enzyme supplement 50 and 75% substitution levels of protein mixture with SBM resulted in a nonsignificant difference in body weight and FCR of chickens. It is reported that commercial multienzymes in broiler diets resulted in an increase in body weight and decrease in FCR. Also, there are some evidences that the mean retention time of digesta in different parts as well as whole digestive tracts of broilers in diets with CM was significantly less than SBM diets and this may be the cause of decrease in digestion and absorption of nutrients in diets with CM. It is reported that the use of more than 6% poultry offal meal in broiler diet resulted in a lower production performance and higher FCR and the causes of these phenomena should be searched in lower quality and palatability of poultry offal meal with higher level usage in the diet. Protein mixture substituted with SBM resulted in the lower feed cost to gain. However, diets with 50 and 75% substitution levels resulted in a significant decrease in MR compared with 0 and 25% substitution levels. Different substitution levels of protein mixture with SBM had no significant effect on carcass characters, however, dietary multienzyme supplementation resulted in a significant higher abdominal fat percentage. Similar to these results, it is reported that multienzyme supplementation resulted in higher abdominal fat percentages in broiler chickens. The lipase content in multienzyme may cause increase in digestion, absorption and deposition of fat in the body.   Conclusion This study results showed that 25% dietary protein mixture substitution with SBM in the broiler diet did not show significant negative impact on economic performance of broiler chickens and could potentially be used as a substitute for more expensive soybean meal protein. Also, the use of multienzyme supplementation in the diet restricted to the age of chickens and the quality of protein source. As considering lower growth period of 24 days and 75% substitution levels of protein mixture with SBM multi enzyme supplement may result in a better FCR. However, for production of broilers with 42 days of age multienzyme supplementation in the diet had no significant positive effect on broiler performance and its economic traits.