RESUMO
The value of dietary exogenous enzymes in promoting growth and efficiency of feed utilization is well recognized in poultry industry. In a case of high-cost yellow corn, several feed producers are choosing to replace yellow corn with other ingredients that have lower nutritional value like triticale, wheat, barley or sorghum. These crops are rich in non-starch polysaccharides (NSPs), and there is an inverse relationship between the content of NSPs in the feed and its nutritional value. Dietary supplementation of enzymes can enhance the nutritional value of crops containing high contents of soluble NSPs. Numerous studies have shown that supplementation of exogenous enzymes in wheat, barley, sorghum or triticale-based rations can improve performance of poultry to a level compared to that obtained by corn-soya-based rations. Naturally, the gastrointestinal tract of poultry produces enzymes to aid the digestion of nutrients. However, the birds do not have enough enzymes to digest fiber completely and need some commercial exogenous enzymes in the diets to improve the digestion. Enzyme is a biological catalyst composed of proteins, amino acids with minerals and vitamins. The advantages of using commercial enzymes in poultry feeds include improved productive performance and feed utilization, minimized environmental pollution due to reduced nutrient of manure. The present review covers the information on enzyme uses and its applications in poultry production. Furthermore, this article demonstrates that the exogenous enzymes are very important factors in the study of metabolic and physiological mechanisms. Such data will improve our understanding regarding the role of commercial enzymes in poultry feeds.
RESUMO
The present study investigated the toxic impacts of lead (LD) on the productive and reproductive performances of Japanese quails and the role of Yucca schidigera extract (YSE) in reducing these impacts. A total of 360 mature Japanese quails (at 2 months of age) were used and the experiment was lasted for 8 wk. The birds were divided into 6 equal groups as follows: control (basal diet), basal diet + 100 mg LD/kg diet, basal diet + YSE (100 mg/kg diet), basal diet + YSE (200 mg/kg diet), basal diet + LD (100 mg/kg diet) + YSE (100 mg/kg diet), and basal diet + LD (100 mg/kg diet) + YSE (200 mg/kg diet). LD resulted in a significant decrease in feed intake (FI), feed conversion ratio (FCR), and egg production of birds compared with the control group. Supplementation of YSE (100 or 200) to LD containing diet could significantly improve the quail performance parameters to be comparable with the control values. Fertility and hatchability % were decreased by LD, whereas YSE at both levels (100 or 200) separately or in combination with LD showed fertility and hatchability percentages comparable to that of control. Triglycerides, cholesterol, and LDL contents in LD plus YSE100 or LD plus YSE200 groups were significantly decreased than LD alone group. LD significantly decreased superoxide dismutase and catalase activities in the serum with no effect on reduced glutathione content. Co-exposure to YSE100 or YSE200 with LD significantly increased the catalase activity and numerically increased the superoxide dismutase activity than LD alone. YSE100 or YSE200 decreased malondialdehyde contents than LD alone group. LD plus YSE100 or YSE200 groups exhibited significant improvements in the level of immunoglobulins. Co-exposure to YSE with LD significantly decreased the LD residues in egg than the LD group. The obtained results showed that YSE exhibited a potential modulatory role against the LD-induced inhibitory effects on the productive and reproductive performances of Japanese quails and YSE at 200 mg/kg diet was more effective than 100 mg/kg diet in reversing the LD-induced alterations.
