Evaluation of Digestible lysine levels in diets with high energy density for finishing pigs

Objective. To evaluate the effects of different levels of digestible lysine in diets with high energy density on productive performance and carcass characteristics of finishing pigs. Materials and Methods. Seventy crossbred barrows (initial body weight of 83.36 kg) were used and allotted in a randomized block design with five treatments, seven replications and two pigs per experimental unit. Pigs were fed ad libitum with diets containing 3.5 kcal/kg of ME and five levels of digestible lysine (0.46, 0.52, 0.58, 0.64 and 0.70%) during four weeks. Final live weight (FLW), daily feed intake (DFI), daily weight gain (DWG), feed conversion (FC), daily lysine intake (DLI), and the amount of lysine per body weight gain (DLI/DWG), were evaluated. At the end of the experiment, blood samples were taken from each pig to determine urea nitrogen concentration (UN) in serum and slaughtered to evaluate quantitative and qualitative carcass characteristics. Results. The FLW increased linearly (p<0.05).There were no differences among treatments for DFI, DWG, FC, carcass characteristics and UN. The DLI and DLI/DWG varied significantly (p<0.001) and increased linearly (p<0.001) with each lysine level. Pigs that consumed the limiting diet in lysine (0.46%) showed less DLI and DLI/DWG (p<0.001) than pigs fed the other diets. Conclusions. The amount of DLI/DWG increased with the evaluated levels of digestible lysine in diets with high energy density, without effects on productive performance and carcass characteristics of finishing pigs.Objetivo. Evaluar los efectos de diferentes niveles de lisina digestible en dietas con alta densidad energética sobre el desempeño productivo y características de la canal de cerdos en finalización. Materiales y métodos. Se utilizaron 70 cerdos (peso inicial de 83.36 kg) mestizos castrados, distribuidos en un diseño de bloques al azar con cinco tratamientos, siete repeticiones y dos cerdos por unidad experimental. Los cerdos fueron alimentados ad libitum con dietas que contenían 3.5 Mcal/kg de energía metabolizable y cinco niveles de lisina digestible (0.46, 0.52, 0.58, 0.64 y 0.70%) durante cuatro semanas. Se evaluaron: peso vivo final (PVF), consumo diario de alimento (CDA), ganancia diaria de peso (GDP), conversión de alimento (CA), consumo diario de lisina (CDLis) y la cantidad de lisina por peso ganado (CDLis/GDP). Al final de experimento, se extrajeron muestras de sangre de todos los cerdos para determinar la concentración de nitrógeno ureico (NU) en suero sanguíneo y luego se sacrificaron para evaluar las características cualitativas y cuantitativas de la canal. Resultados. No se observaron diferencias significativas entre tratamientos para CDA, GDP, CA, características de la canal y NU. El PVF incrementó linealmente (p<0.05). El CDLis y la CDLis/GDP variaron significativamente (p<0.001) e incrementaron linealmente (p<0.001) con cada nivel de lisina. Los cerdos que consumieron la dieta limitante en lisina (0.46%) mostraron menor consumo y CDLis/GDP (p