Various dietary energy and protein levels on growth performance, blood profiles and carcass characteristics in growing-finishing pigs

Abstract

In livestock industry, providing adequate nutrients has been noted as the most important factor to efficient and profitable animal production. Inadequate nutrient utilization reduces efficiency of animal production and causes detrimental effects on environment. Supplementation of excess nutrients is not efficient way for animal growth and it leads to economical loss by increasing fecal and urinary excretion of nutrients, while deficiency of nutrients limits the growth and production. Growing-finishing period in swine is very important that growth rate and pork quality are dependent on this period. However, some feeding standard overlooked the importance of growing-finishing period compared to that of young pig. In order to maximize the growth of pig, it is needed to divide the growing-finishing period into more phases for providing adequate nutrient. The present study was performed to evaluate the subdivision of growing-finishing phase divided by different dietary protein and energy levels on growth performance and carcass characteristics. A total of 128 growing pigs ([Yorkshire × Landrace] × Duroc) averaging 26.62 ± 3.07 kg body weight were assigned in a 2 × 4 factorial arrangement with 4 pigs per pen. The first factor was two dietary energy level (3,265 or 3,365 kcal of ME/kg), and the second factor was four different levels of dietary protein by phase feeding (1growing(G)-2finishing(F) phases, 2G-2F phases, 2G-3F phases and 2G-3F phases with low dietary CP treatment). In feeding trial, there was no significant difference in growth performance among treatments. The BUN concentration was decreased as dietary protein level decreased in 6 week and blood creatinine showed a significant difference in 13 week when pigs were fed diets with different dietary energy level. The digestibility of crude fat was improved as dietary energy levels increased and excretion of urinary nitrogen was reduced when pigs were fed low protein diets. Meat color, pork pH and proximate analysis of longissimus muscle were not affected by dietary treatments. In backfat thickness at P2 tended to increase when pigs were fed high energy diet or low subdivision of phase feeding was applied. When pigs fed the low energy diet (3,265 kcal of ME/kg), contents of proline, methionine and cysteine were increased in pork. In addition, cooking loss and water holding capacity were decreased as dietary protein level decreased. Low energy diet (3,265 kcal of ME/kg) had positive effect on reducing feed cost. When pigs were fed high energy diet with low subdivision of phase feeding, days to 120kg market weight was reached earlier compared to other treatments. Consequently, subdivision of phase had no significant effect on growth performance and carcass characteristics. However, feeding the diet low energy level (3,265 kcal of ME/kg) and low protein level had no negative effects in growth performance and carcass characteristics but economical profit was improved because of high carcass price as well as low feed cost.