The effect of in ovo injection with organic zinc on the hatchability of broiler breeder hen eggs and evaluation of productivity in offspring broiler chickens
Description
The present study investigates the effect of in ovo injection with organic zinc on the hatchability of egg breeder hens and evaluation of performance, carcass characteristics, blood parameters, liver enzymes, immune response, cecal microflora and breast fatty acid profile in production broiler chickens. In total, 320 fertile eggs from Ross308 breeder hens at the age of 55 weeks with the same average weight (65±1g) were selected for injection. Experimental treatments for in ovo injection include, treatment 1: negative control group (no injection), treatment 2: positive control (injection of 0.272 ml of normal saline solution), treatment 3: injection of 0.272 ml of saline solution containing 150 μg of organic zinc (40.8 μg for each egg) and treatment 4: injection of 0.272 ml of solution containing 300 μg of organic zinc (81.6 μg for each egg). 160 chickens were used in a completely randomized design including 4 treatments and 4 repetitions and ten birds during three raising periods, respectively, the starter (1-14 days old), growth (15-28 days old) and finisher (29-42 days old). The chickens were raised with diets based on corn-soybean meal. The results showed that the hatchability decreased in positive control and injected treatments (P <0.05). In the starter period, the feed conversion ratio (FCR) improved in the first and fourth treatments (P ≤0.05). In addition, after in ovo injection, no negative effect on production performance (feed consumption, body weight and FCR) was observed in the whole period (P >0.05). The fourth treatment (high zinc) showed the highest levels of cholesterol, triglyceride, VLDL, AST and ALT, as well as alkaline phosphatase and creatine kinase in the groups injected with zinc than the group without was zinc (P <0.05). The leukocytes and antibody titer at 28 days were significantly increased in treatments containing zinc (P <0.05). In addition, the reduction of gram-negative coliform and Escherichia coli bacteria and the parallel increase of gram-positive Bifidobacterium and lactobacillus bacteria in the groups injected with zinc were quite noticeable and significant (P <0.05). In conclusion, the results showed that the in ovo injection with organic zinc can maintain and even improve the hatchability and the performance of the bird, without any negative effect on the carcass characteristics of broiler chickens and with the potential to have a significant effect on health-giving traits including blood parameters, liver enzymes, immune system and intestinal microflora. So, Zn had a positive effect on some outcomes of interest, with no negative outcomes.