R. Taherkhani

Effects of ethylenediaminetetraacetic acid on phytate phosphorus utilization and efficiency of microbial phytase in broiler chicks.

Previous studies have suggested that organic acids may improve P utilization in animals. To evaluate the ability of ethylenediaminetetraacetic acid (EDTA) to improve phytate P utilization and the possible synergistic effect between EDTA and microbial phytase (MP) an experiment was conducted using 360 Ross 308 broiler chicks. The experiment was carried out using a completely randomized design with a 3*2 factorial arrangement (0, 0.1 and 0.2% EDTA and 0 and 500 IU MP). Four replicate of 15 chicks per each were fed dietary treatments including (i) P-deficient basal diet [0.2% available phosphorus (aP)] (NC); (ii) NC + 500 IU MP per kilogram of diet; (iii) NC + 0.1% EDTA per kilogram of diet; (iv) NC + 0.1% EDTA and 500 IU MP per kilogram of diet; (v) NC + 0.2% EDTA per kilogram; and (vi) NC + 0.2% EDTA + 500 IU MP per kilogram of diet. Weight gain (WG), feed efficiency and serum Ca, P and alkaline phosphatase (ALP) were assessed. Addition of 0.2% EDTA to low aP diets resulted in significantly lower feed consumption (FC) and WG, but 0.1% EDTA did not depress WG compared to NC. Phytase supplementation of P-deficient diets significantly improved WG and feed efficiency, but it had no effect on FC. Microbial phytase supplementation significantly decreased ALP concentration. Results obtained in our study suggest no synergistic effect between phytase and EDTA in broiler chicks.

Effects of progesterone injection on performance, plasma hormones and ovarian morphology of ad libitum and restricted fed broiler breeder hens

An experiment was conducted to evaluate responses of feed-satiated and feed- restricted breeder hens to daily injection of progesterone (P4). A total of 64 Cobb 500 hens were fed either restricted or ad libitum from 27 to 38 wk of age. Fourteen laying hens from each group were selected to conduct P4 injection assay. Half of birds in each group (n = 7) were injected daily by 2.5 mg P4/kg BW and remaining birds were used as control. The P4 was injected subcutaneously, at the base of the neck daily (at 0900 h) for 21 d. Settable and abnormal eggs were recorded daily. Blood samples were taken just before initiation of injections, 10-d and 20-d after initiation of injection. Plasma samples were analyzed for glucose, cholesterol, triacylglycerol (TAG), P4, estradiol (E2), testosterone, T3 and T4 concentration. Settable egg production declined following P4 injection, whereas total egg production (including soft shell egg) remain at high levels in injected birds during the first week after initiation of P4 injection. Progesterone injection in feed-satiated and feed-restricted birds resulted in ovary regression; the ovary of these birds had no hierarchical follicle. Progesterone injection increased incidence of holding hardshelled eggs in the uterus. Plasma E2 concentrations were affected both by feeding pattern and P4 injection. Progesterone injection depressed plasma E2 concentration in both ad libitum and restricted fed hens. Hens with free access to feed had significantly lower plasma E2 levels compared to restricted fed hens. Our results revealed that whereas injection of P4 induced frequent ovulation early in the injection period in both feed- satiated and feed-restricted breeder hens; however this higher ovulation rate did not result in more settable egg production.