Molting Single Comb White Leghorns with the Use of the Lupron Depot® Formulation of Leuprolide Acetate

Abstract

Reproductive tract regression and cessation of egg production was induced in 80-wk-old Hy-Line W36® strain hens by an i.m. injection of Lupron Depot® at a dose calculated to release 60 μg of leuprolide acetate (LA)/kg of BW for 30 d, by restriction of feed intake (FR) for 28 d, or by total feed deprivation (FD) for 7 d followed by feed restriction for 21 d. Egg production in LA and FD groups dropped to 24 and 19% in the first 7 d after initiation of the treatments and to 3.5 and 0% in the 2nd wk. Production of the FR group dropped to 38% during the 1st wk and to 1.7% in the 2nd wk. Production of both nutritionally deprived groups remained near zero through the 5th wk, whereas it increased to 8.2% in the LA group at that time. Hens injected with LA reached 50% production at about 37 vs 45 d for both nutritionally deprived groups. Egg production of control groups remained unchanged during this time.Shell characteristics did not differ significantly among the molted groups throughout most of the 16 wk of the experiment. However shell weight and shell weight per unit surface area of eggs from LA-treated hens were significantly (P ≤ .05) lower than those of FR, but not FD, hens at several times. Mean values for shell characteristics of eggs from unmolted hens were significantly lower than those of molted hens. There were no differences in albumen quality between any of the groups at any time. Hens molted by FR and FD lost 23 and 26% of their initial BW, respectively, 4 wk after the initiation of the experiment. There was no loss of weight in LA-treated or control hens.