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Using designer diets to reduce aggression in pregnant sows
The US Swine industry is under pressure to switch from individual to group housing for pregnant sows. The study objective was to evaluate effects of increased dietary fibrous ingredients to reduce aggression during mixing by increasing satiety. Five isocaloric (NE basis) treatment diets (CONTROL, Resistant-STARCH, BEET pulp, soy hulls INCREASED INTAKE and SOY Hulls+FAT diets) were fed to five sows (parity 1 to 6) per treatment per replicate. 150 sows (25 sows/rep*6 reps) were used for the study. Sows were bred and moved into individual crates (0.61 m*2.13 m) on d 7-14 post-breeding. Sows remained in crates for 21 d while fed assigned diets. Data on weight, backfat and BCS for each sow were collected on first and last day in crates. On d 22, sows were moved into mixing pens (2.13 m*3.05 m mixing area and five 0.61 m*2.13 m crates). As a measure of aggressiveness, lesions on left and right in front, mid and rear parts of each sow were counted before mixing and on d 1, 2 and 3 of mixing. After 72 h of mixing, sows were switched to regular diets and management. Production data (piglets born, % alive, average birth weight, average wean weight, % weaned, farrowing rate) were collected from 75 sows (3 replications). The effects of diets on skin lesions, backfat, weight, BCS and production data were compared using PROC GLM and lsmeans in SAS 9.3. Chi-square test was performed to compare farrowing rates. Skin lesions in the front left portion of sows were 6.7±0.9ab, 6.8±0.9a, 7.4±1.0ac, 4.0±1.0b and 9.9±1.0c for CONTROL, Resistant-STARCH, BEET, INCREASED INTAKE and SOY Hulls+FAT diets respectively on day 1 (P=0.002). Skin lesions in the front left portion of sows were 11.2±1.6a, 11.5±1.6 a, 10.3±1.6 a, 9.7±1.6 a and 16.5±1.7 bfor CONTROL, Resistant-STARCH, BEET, INCREASED INTAKE and SOY+FAT diets respectively on day 3 (P=0.038). Diets did not affect (P>0.05) other skin lesion scores, number of piglets born, % alive, average birth weight, average wean weight, % weaned and farrowing rate. Change in weight, backfat and BCS did not differ with treatments (P>0.05). There were fewer skin lesions in INCREASED INTAKE treatment on d 1 indicating less aggression, and higher skin lesions in left front parts of the sows fed SOY Hulls+FAT diet indicating more aggression compared to other diets.
Keywords: sow, aggression, group housing