Growing-finishing pigs kept under low sanitary conditions (LSC) eat and grow less than pigs kept under high sanitary conditions (HSC). Researchers at Wageningen Livestock Research investigated whether growth performance can be improved by increased levels of dietary energy and essential amino acids (Lys, Met, Thr, Trp, Val and Ile) in the diet. Both LSC and HSC pigs had a higher daily energy intake and daily gain on the diets with increased levels of energy and amino acids. However, the effect was greater in LSC than in HSC pigs. This suggests opportunities to at least partly compensate for the reduction in growth performance in pigs kept under low sanitary conditions and/or sub-optimal health condition by modification of the energy and amino acid composition of the diet.
At Swine Innovation Centre Sterksel, a study was performed to evaluate the effects of dietary energy source (starch vs fat) and of increased levels of dietary energy and essential amino acids (EAA) on the growth performance of growing-finishing (GF) pigs under low sanitary conditions (LSC), in which the immune system of the pigs was activated, or under high sanitary conditions (HSC) associated with a lower state of activation of the immune system. In a 2 × 2 × 2 factorial design, pigs were allocated to either high sanitary conditions (HSC) or low sanitary conditions (LSC). A contrast in sanitary conditions was generated by imposing to the pigs differences in strategy for vaccination against specific pathogens, cleaning and hygiene protocol, antibiotic treatment and deworming. Pigs were fed one of four experimental diets, a diet with starch as main energy source or a diet with a combination of fat and starch as main energy source, each diet having either basal energy and EAA concentrations (B diet) or increased concentrations in energy and EAA (I diet).
HSC GF pigs showed a 4% higher average daily feed intake (0.08 kg/d) and average daily gain (47 g/d) than LSC GF pigs, whereas feed conversion ratio was similar in HSC and LSC GF pigs. On the B diet, LSC pigs grew 68 g/d (6.4%) less and ate 0.17 EW/d (6.4%) less than HSC pigs, whereas on the I diet, LSC pigs grew 26 g/d (2.4%) less and ate 0.06 EW/d (2.2%) less than HSC pigs.
It can be concluded that an increase in contents of dietary energy and EAA increases growth performance and energy intake more in LSC than in HSC pigs. Compared with studies in which only EAA were supplemented and not energy to increase growth performance of immune challenged pigs, it seems that dietary supplementation of both EAA and energy is more effective in increasing performance of LSC pigs than dietary supplementation of EAA alone. Partly replacing dietary starch with fat does not seem an interesting approach to increase the performance of the LSC GF pigs.