High-protein maize in diets for growing pigs

The objective of the study was to evaluate three commercial hybrids of high-protein maize against conventional maize using growing pigs in a 42 day performance study. The following experimental diets were compared: (1) basal diet containing conventional maize (control); (2) diet containing hybrid IPM1; (3) diet containing hybrid IPM2; and (4) diet containing hybrid IPM3. The diets were offered to female and castrated male commercial piglets (MBI LW, Fomeva; 36 pigs/treatment) in 2 phases: starter (D0-21) and finisher (D22-42). The 36 piglets for each dietary treatment were divided into 9 pens (replicates), with each pen containing 4 piglets of the same sex (5 and 4 pens with castrated males and females, respectively). The animals were housed in 5 rooms. The diets were assigned to the pens in a randomised complete block design and all the diets were iso-nitrogenous and iso-energetic. The protein contents of the high-protein maize hybrids were from 14.7 to 38.2% higher than the conventional maize and, with the exception of lysine, contained higher levels of both essential and non essential amino acids. The high-protein maize hybrids also contained more oil (range 19.4-53.1%) and less starch (range 14.5-17.9%) than the conventional maize. The pigs fed the diet based on IPM2 ate more feed in the second period (D22-42) (782, 744, 970 and 730 g/d, respectively, in conventional, IPM1, IPM2, and IPM3 maize; with P<0.05) than those on the other treatments and tended to grow faster (350, 361, 431 and 334 g/d, respectively, in conventional, IPM1, IPM2, and IPM3 maize; with P=0.06) and to be heavier at D42 (20.59, 21.23, 22.61 and 20.03 kg, respectively, in conventional, IPM1, IPM2, and IPM3 maize; with P=0.07) than pigs on the other three treatments. Pigs fed diets formulated with conventional and high-protein maize exhibited a similar feed conversion ratio. The results suggest substitution of conventional maize with high-protein maize may enable soybean meal to be reduced in pig diets without adverse effect on animal performance.