Reproductive response of two laying strains subjected to force molting either by feed withdrawal or oral administration of antiestrogenic drug, tamoxifen

ABSTRACT

The anti-estrogenic drug, Tamoxifen, was evaluated as a molt inducer in two strains of Hy-line laying hens. Birds were divided equally into four groups as follows group one in which birds received daily oral administration of Tamoxifen [20 mg/kg body weight] for 5 days, group two in which birds received the same dose as in group one for 10 days, group three in which birds were fasted for 7 days, gorup four in which birds served as a control group. Body weights were recorded at the beginning and the end of treatments. Pre and postmolt egg production were recorded daily. Blood samples were taken at the end of treatment for determination of plasma calcium [Ca], inorganic phosphorus [Pi], total protein [TP], albumin [AL], Urea [U], total lipids [TL], triacylglycerol [TG], Alanine aminotransferase [ALT], Aspartate aminotransferase [AST], progesterone [P[4]], and triiodothyronine [T[3]]. Brids treated with Tamoxifen lost less body weight compared to feed removal birds. Post-molt rates of lay were not significantly different for Tamoxifen and fasted birds. Plasma levels of Ca, TG, TL, and P[4] were reduced in the force molting groups. Plasma levels of T[3] were reduced in feed removal group while elevated in Tamoxifen group comapred to the control. It can be concluded that Tamoxifen maybe a useful agent for molt induction