Performance and economic analyses of barrows on effect of different standardized ileal digestible lysine/metabolizable energy ratios, during growing and fattening period.

Due to the importance of swine production in the national agribusiness economy, it is necessary to develop efficient techniques to improve performance of this activity. Pig industry in developing countries like Brazil, is demanding improved information on pig nutrition in order to create better economical feeding programs. Therefore, this exeriment was aim to compare the performance of 03 different treatments, in barrows of female line, providing diets with different lysine and energy ratios in growing and fattening periods. It were conducted at Fazenda Santa Rita, located in Dois Vizinhos - PR - Brazil, during the months of January to April 2014. The animals were evaluated from growing and fattening phase until slaughter, in relation to average daily gain (ADG), feed conversion ratio (FCR), backfat thickness (BT) and carcass yield (CY). Composed by 03 blocks, of 120 barrows each, totalizing 360 pigs, separated by weight and allotted in a completely randomized block design, per experimental unit, represented by the pen. It were used 01 entire shed with 12, in full capacity of 40 animals/pen. The entrance of the animals were at once with 65 days of life (±3) and ending with 165 days of life (±3), raised on different feeding regime, with 03 diet changes. Animals of the growing phase (65 to 96 days of life) had a diet with different treatments of 0.69g (T1), 0.73g (T2) and 0.77g (T3) of standardized digestible lysine, containing 3,300 kcal of ME/kg and 19.5% of crude protein. Animals from growing 2 phase (96 to 127 days of life) had a diet with different treatments of 0.64g (T1), 0.67g (T2) and 0.71g (T3) of standardized digestible lysine, containing 3,250 kcal of ME/kg and 17% of crude protein. At the fattening phase (127 to 158 days of life), the animals had a diet with different treatments with 0.58g (T1), 0.62g (T2) and 0.66g (T3) of standardized digestible lysine containing 3,200 kcal of ME/kg and 16% of crude protein. For all the treatments, it were used the same basal diet formulated based on maize and soybean meal. Animals were weighted at the entrance, during the transfer from growing to growing 2, from growing 2 to fattening, from fattening to slaughter, where backfat thickness were measure at the point P2. Performance data and carcass variables were analyzed using linear and quadratic regression (GLM procedure of SAS 2012). Analysis of variance (ANOVA), and the average were compared by Tukey test at 5% significance. Regarding all the variables, It was found no significant difference (P<0.05) only for variable W1. Variables W2, W3, W4, BT, W5 and BT2 presented a significant (P