Egg Production and Quality in Zinc Propionate-molted Hens with Reference to Certain Blood and Tissue Chemical Parameters

The study aimed to evaluate the effects of 1 % zinc propionate as a molting agent on egg production and quality, certain biochemical blood parameters, hepatic and renal residues of zinc in laying hens. Sixty laying hens of 64 weeks old were divided into two equal groups; control non molted group, that fed a layer ration without additives and molted group, that fed a layer ration with 1% zinc propionate for 9 days to induce molting. Egg production was monitored for hens of both groups 8 weeks premolt and postmolt. Blood samples were collected at 3,5,7 and 9 days of molting period. Tissue samples of liver and kidneys were taken at the end of molting period for determination of zinc residues. Results revealed that egg production or egg quality during postmolt period did not affected significantly. Activities of serum Alkaline phosphatase (ALP), Lactic dehydrogenase (LDH) and glutamic oxalacetic transferase (SGOT) were significantly increased, while that of serum glutamic pyruvic transferase (SGPT) was significantly decreased at days 3 and 5 of molting process. Blood levels of glucose and cholesterol were significantly elevated, while that of albumin was significantly decreased at the same time intervals. Serum total protein level was maintained unchanged allover the molting time. Zinc residues in liver and kidney tissues were significantly elevated in molted hens. In conclusion, molting induction by using a high level of zinc propionate (1%) was associated with a higher liver and kidney residues of zinc.There were a higher levels of certain blood metabolites that could be act as a metabolic pools avoiding body weight loss and ovarian regression usually accompanying different molting procedures.Maitainance of egg production level and quality during postmolt period considered also a practical benefits.