Behavior, reproduction, and immunity of crated pregnant gilts: Effects of high dietary fiber and rearing environment

The objective of this study was to examine effects of increased gut fill an d diverse developing environments on pregnant gilts' behavior and physiolog y. Gilts were cross-fostered at 1 d of age and transferred to either an ind oor or outdoor production unit. Littermate gilts remained in their differen t environments during development and were moved into individual gestation crates in an indoor gestation unit. Of the 42 gilts, 19 were fed a control diet of fortified sorghum-soybean meal and 23 were fed the same diet with 2 5% beet pulp thigh fiber). Control sows ate 2.0 kg/d and high-fiber sows at e 2.67 kg/d in a large pellet (thus resulting in approximately equal energy intake and differing total dietary intakes). Pregnant gilts had behavior a nd immune measures sampled at 30, 60, and 90 d of gestation. The day x diet interaction was significant (P = 0.01) for duration of standing: sows fed high-fiber diets stood less on d 30, but on d 60 and 90 they and the contro l sows stood for a similar duration. Sham chewing duration and frequency sh owed significant (P < 0.05) effects of gestation stage x diet x environment . Gilts reared outdoors and fed high fiber increased sham chewing over gest ation, whereas all other treatment groups decreased this behavior over time . Outdoor-reared gilts had greater (P < 0.05) frequency and duration of dri nking behavior than indoor-reared gilts. White blood cell numbers were high er (P < 0.05) for gilts fed high-fiber diets than for gilts fed the control diet. Immune (humoral and cellular systems) and reproductive measures (far rowing rate and litter size) and plasma cortisol concentrations were genera lly not influenced (P > 0.10)by diets and rearing environments, suggesting that in spite of significant changes in behavior and feed intake gilts' imm une systems were not suppressed or enhanced. Behavioral data alone suggeste d that indoor-reared gilts showed fewer behavioral adaptations to the crate s than outdoor-reared gilts. However, immune measures did not indicate that any treatments resulted in physiological effects indicative of stress.