Net Energy of high-protein sunflower meal fed to growing pigs and effect of dietary phosphorus on measured values of NE

Jong Woong Kim, Jinyoung Lee, Charles Martin Nyachoti

An experiment was carried out to determine energy values of high-protein sunflower meal (HP-SFM) and to compare the energy values of HP-SFM determined using either a phosphorus (P)-deficient basal diet or a P-adequate basal diet. Twenty-four growing barrows were randomly assigned to 1 of 4 dietary treatments with 6 replicates per treatment. Four experimental diets including 2 basal diets containing 2 levels of standardized total tract digestible P (i.e., P-deficient and P-adequate) and the other 2 diets containing 30% HP-SFM with each basal diet (i.e., HP-SFM 1 diet and HP-SFM 2 diet) were formulated to determine the energy values of HP-SFM and to compare energy values of HP-SFM determined by the difference method using 2 basal diets. Pigs were fed diets for 15 d including 10 d for adaptation and 5 d for total collections. Pigs were then moved to indirect calorimetry chambers to determine total heat production (THP) and fasting heat production (FHP). A reduced (P < 0.01) amount of nitrogen was retained in pigs fed the P-deficient basal diet compared with those fed the other diets. The THP of pigs fed the HP-SFM 1 and 2 diets was greater (P < 0.01) than those fed the P-deficient basal diet with the intermediate value for pigs fed the P-adequate basal diet. The retained energy (RE) as protein of pigs fed the P-deficient basal diet was less (P < 0.01) but RE as lipid was greater (P < 0.01) than those fed the P-adequate basal, or HP-SFM 1 and 2 diets. However, there was no difference in FHP of pigs among the dietary treatments. The NE of HP-SFM determined using the P-deficient basal diet was 2,062 kcal/kg, as-fed basis, whereas the value determined using the P-adequate basal diet was 2,151 kcal/kg. Although no differences were observed in energy values, the amount of P in basal diet might affect energy balance by modifying N utilization, thus, a diet containing adequate amount of P is a more suitable basal diet when the difference method is used for calculation of NE in a feed ingredient.