Efeito da granulometria do milho e do valor de energia metabolizável em rações peletizadas para frangos de corte

Abstract

Aiming to evaluate the effect of particle size and amount of dietary energy on performance, nutrient digestibility, apparent metabolizable energy and apparent corrected for nitrogen balance and use of LIPE ® as an indicator to estimate the production of excreta determining the digestibility of nutrients in comparison to the total collection method were conducted four experiments, two for the initial phase (one to 21 days old) and two for the growth phase (23 to 42 days old) broiler court. To evaluate performance we used 1620 male broiler chicks of Ross. The birds were housed in a shelter made of concrete and distributed in a completely randomized design with six treatments and five replicates of 30 birds and 24 for the initial phase and growth, respectively. The experimental design was completely randomized in factorial arrangement (2x3), with treatments defined by the values of energy (2,900 and 3,000 kcal/kg ME for the initial phase, and 3,100 and 3,200 kcal/kg ME for the phase growth) and the particle size of corn (fine, medium and coarse). For the initial phase, there was a superiority (P0.05) of birds fed the diet with coarse and 3,000 kcal/kg of the digestibility of dry matter (DM), crude protein (CP), ether extract ( EE), apparent metabolizable energy (AME) and apparent metabolizable energy corrected for nitrogen balance (AMEn). Regarding the performance of birds from one to 21 days of age, birds fed the diet with coarse was higher (P0.05) to the other when evaluating the weight gain (BWG), feed conversion (FC) and energy conversion (EC). For the variables feed intake (FI), viability and energy consumption (ECP) no statistical differences (P>0.05) for this phase. For the growth phase of 23 to 42 days of age, birds fed with diets containing coarse and 3,200 kcal/kg of ME were greater (P0.05) to birds fed the other diets on the digestibility DM, CP, EE, AME and AMEn. Regarding the performance of broilers from 23 to 42 days of age, birds fed the diet with coarse and 3,200 kcal/kg of ME was higher (P0.05) on the BWG, viability and ECP. There was no statistical difference (P>0.05) on the performance variables: FI, FC and CE. The energy value of the diet influenced (P0.05) the factor of production, with the largest production factor to the value 3,200 kcal/kg of ME. Regarding costs of feed, even with higher feed costs with coarse and value of 3,200 Kcal/kg of the improved performance stemmed from the higher digestibility of nutrients, promotes reduction of this cost is measured when a kilogram of chicken produced . Use of LIPE® to measure the production of excreta of chickens kept for subsequent calculation of the coefficient of digestibility of nutrients, and the AME and is feasible for the growth phase, and for the initial phase, the exception being the value of AMEn for this phase which differs from the method of total excreta collection. It can be concluded that the digestibility of rations in the initial phase and growth was stimulated by the higher energy level and affected by fine particle size. For the performance of broilers in both phases, the main effect of improvement is related to the increase in energy. The LIPE® as an external, also in both phases can be recommended for the measurement of excreta production and subsequent determination of digestibility and energy values.