Energy requirements in function of two lighting programmes in a broiler breeders flock

Energy is the first limiting "nutrient" for breeders, therefore, it is essential to fed the breeders with correct amount of E to meet maintenance requirements, support growth and egg production. This study aimed to model the effective E requirement (EEr) for broiler breeder flock in response to two lighting programmes (LP) during the rearing period. A population with 200 breeders, from 24 to 40 weeks of age, was simulated using means and SD for body weight (BW, 2.34?0,05 kg), age at first egg (AFE) according to the LP (A: 8h an increase to 16h light/d at 100 d of age = 184?29 d; B: 8h an increase to 16h light/d at 140 d of age = 176?11 d), internal cycle length (ICL=25.4+8.99x0.75^AFE+0.072xAFE, hour) to determine the rate of ovulation. The weights of yolk (YW=18.03x1-e^{-0.015x(AFE-103.}4)xe^-0.001xAFE), albumen (AW=14.38xYW^0.375) and shell (SW=0.358x(YW+AW)^0.687) were calculated. The data of BW, AFE, ICL, YW, AW and SW were used in an Excel spreadsheet to determine the EEr in function of LP by the equation: EEr=(1.63.Pm^0.73.u)+(60.3.BWG)+(0.025.YW+0.0036.AW+0.0012.SW), where 1.63 and 60.3 MJ are the EE needed per unit of maintenance and body weight gain (BWG, 5g/week) per day, respectively; the EE requirement for production of YW, AW and SW are 0.025, 0.0036 and 0.0012 MJ/g, respectively; Pm is body protein weight at maturity (kg); u is the degree of maturity, in this case = 1. It is important to point out the great range of AFE by applying an inappropriate LP and then the EEr exhibit more variation for the LP A compared to B, and this occurs until all the broiler breeders begin laying egg. The EEr were 0.929?0.199 and 0.892?0.174 at 24 weeks of age. For 28 weeks of age, the EEr were 1.018?0.241 and 1.191?0.197 and for 32 weeks of age were 1.170?0.257 and 1.244?0.224 MJ/d, for LP A and B, respectively. Knowing the requirements helps to establish the best nutritional program, and optimize feeding without excesses and deficiencies. These results support the view that a modelling approach has the potential to help nutritionists to make decisions about feeding broiler breeder flocks more efficiently.