Effects of diet and housing density on growth and stomach morphology in pigs.

Two experiments were conducted to evaluate the impact of housing density on the stomach morphology of growing pigs and determine whether there was an interaction between housing density and diet. All diets were corn-soybean meal based. In Exp. 1, 42 barrows (41.0+/-.95 kg BW) were allotted either individually or three pigs per pen to evaluate the effects of crowding on stomach lesions. Pen space per pig was 1.54 and .51 m2, respectively. All pigs were fed a finely ground and pelleted diet (610 microm) for 6 wk. The ADG decreased (P<.05) for the pigs housed three per pen during wk 4 to 6 only. There was no effect of housing density on feed intake or gain/feed ratio. Neither visual nor histological ulcer score differed between the two treatment groups. No stomachs were graded as normal. In Exp. 2, 80 barrows (39.8+/-.9 kg BW) were allotted either two or four pigs per pen. Pen space per pig was .77 and .39 m2, respectively. Half of the pigs in each housing situation were fed a coarse meal diet (1,050 microm), and half of the pigs were fed a finely ground and pelleted diet (577 microm) throughout the 49-d experimental period. Throughout the trial, pigs housed two per pen gained at a greater rate (P<.05) than pigs housed four per pen. From d 14 to the end of the trial, pigs consuming the finely ground and pelleted diet gained at a greater rate (P<.05) than pigs fed the coarse meal diet. The differences in ADG were reflected in final body weight. Stomach weight as a percentage of body weight was higher for animals on the coarse meal diet. Visual and histological ulcer scores were similar, and both were higher (P<.001) on the finely ground and pelleted diet, indicating greater damage. There was no effect of space restriction on stomach morphology. These data show the major effect of diet type on stomach lesions with no interaction with space restriction.