Effects of metabolizable energy intake and body weight restriction on layer pullets: 2 - Body composition and onset of lay.

This study aimed to determine the effects of dietary ME and BW restriction on layer pullet sexual maturation, carcass composition and reproductive organs. Two trials were conducted: a precision feeding (PF) (Experiment 1) and a conventional (CON) experiment (Experiment 2). Experiment 1 was a 2 × 4 factorial arrangement with two feed allocation (FA) levels: meal every visit (MEV) or restricted to the lower limit of Lohmann Brown-Lite recommended BW; and three dietary ME levels: Low, Standard (Std), and High (2,600, 2,800, and 3,000 kcal/kg, respectively); the fourth treatment enabled birds to choose from the three diets (Choice).

Linear and nonlinear models for assessing carcass composition using dual X-ray absorptiometry in egg- and meat-type chickens.

The objective of this study was to develop appropriate correction equations for dual energy X-ray absorptiometry (DXA) for total carcass composition of live meat- and egg-type chickens. Linear (bivariate linear and multivariate linear) and nonlinear (polynomial, multivariate polynomial, broken-line and Gompertz) equations were used to estimate carcass composition of DXA-scanned birds based on chemical proximate analysis. A total of 288 laying females (10-30 wk of age) and 305 broiler breeder females (4-32 wk of age) were used.