One possible candidate is using lysozyme (LZM), which can be used as a growth promoter in feed ingredient as a potential replacement for dietary antibiotics ( 15, 16). Several alternatives to antibiotics have been used, such as probiotics, prebiotics, organic acids, enzymes, essential oils, and immunostimulants ( 5, 10– 14). Especially after the COVID-19 pandemic, it becomes crucial to look for “alternative friendly additives” which can replace the routine usage of drugs, antibiotics, and vaccines in the field of rabbits' production ( 9). The continuous application of chemotherapies weakens the natural immunity of rabbits, and its prolonged usage induces accumulated amounts in animals' meat which can transfer to the human body and threatens the natural resistance against invaders ( 2, 8). Thus, antibiotics have been banned in several countries around the globe because of its harmful effects on human health ( 7). It is worth noting that using antibiotics and chemicals over a long time has resulted in the emergence of pathogens that became resistant to such treatment ( 5, 6). In such cases, antibiotics usually are used to relieve the effects of environmental stressors and contagious diseases on rabbits ( 4). Pursuing intensive production systems with simultaneous attendance of one or multifactorial stressors (environmental, nutritional, and managerial), this caused several negative impacts on the health status and the ability of rabbits to resist infectious diseases. Furthermore, it has high levels of zinc, iron, selenium, potassium, magnesium, and vitamin B, as well as low cholesterol and sodium levels ( 3). Rabbit meat offers excellent nutritive and dietetic properties for the consumers' needs as a rich source for animal protein (20–21%) ( 1, 2). Therefore, LZM is required at the rate of the hobx100-200 mg/kg diet as a potential feed additive and a friendly alternative for antibiotics in rabbit feed. It could be concluded that supplementation of the rabbit's diet with chicken egg LZM was able to improve the growth performance and hematological and serum biochemical parameters compared with the control group. On the other hand, ALT, AST, urea, and creatinine were significantly ( P < 0.05) decreased by increasing LZM supplementation.
The total protein and globulin concentrations were significantly ( P < 0.05) increased by feeding with LZM.
The LZM supplementation linearly ( P < 0.05) increased hematological parameters (RBCs, PCV, Hb, and WBCs) together with an increase in lymphocyte count compared to the control group. In contrast, total bacterial count and the total count of Lactobacilli had increased considerably by increasing LZM at different levels relative to the control groups. The total count of Escherichia coli and Clostridium count was linearly ( P < 0.05) decreased by adding LZM at 100 and 200 mg/kg in the diets compared to the control groups. The best result was for rabbits fed a 200 mg per kg diet supplemented with LZM, followed by a 100 mg per kg diet. The obtained results revealed that rabbits fed the basal diet supplemented with different concentrations of LZM linearly ( P < 0.05) displayed improved growth performance and reduced feed intake and FCR. The first group was fed a basal diet without LZM supplementation and served as a control group, whereas the remaining groups of rabbits were fed a basal diet supplemented with LZM at 50, 100, and 200 mg/kg diet, respectively, for 8 weeks. A total number of 48 rabbits averaged 611.25 g (5 weeks of age) of APRI line-rabbits (Egyptian developed line) were allocated into four treatments (three replicates and each contained four rabbits) of 5-week weaning APRI rabbits. The dietary chicken egg lysozyme (LZM) at different concentrations was tested on the growth performance, blood health, and resistance against Escherichia coli of growing rabbits.
0 kommentar(er)
