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Title: Including dietary fiber and resistant starch to increase satiety and reduce aggression in gestating sows

item SAPKOTA, AVI - Purdue University
item Marchant, Jeremy
item RICHERT, BRIAN - Purdue University
item Lay Jr, Donald

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2016
Publication Date: 3/18/2016
Citation: Sapkota, A., Marchant Forde, J.N., Richert, B.T., Lay Jr., D.C. 2016. Including dietary fiber and resistant starch to increase satiety and reduce aggression in gestating sows. Journal of Animal Science. 94:1-11. doi:10.2527/jas2015-0013.

Interpretive Summary: Pregnant sows are conventionally housed in individual gestation stalls. More countries and states are moving to change from individual housing to group housing for pregnant sows. The main disadvantage with group housing is aggressive behavior displayed by sows. Inherently, sows maintain social hierarchy when housed in groups. For this reason, when sows are introduced for the first time, they fight with each other and express their social behavior to establish a hierarchy. Different approaches have been taken to reduce aggression in group housing which include altering group size, dietary modification and supplementation, and facility (pen) design and modifications; with variable success. The aim of this research was to examine the effect of different dietary fibers on aggressive behavior of sows when mixed in small groups. In addition, heart rate variability, stereotypic behaviors, blood metabolites, and production of sows were also evaluated. The diets included a control (corn-soybean meal based with no additional fiber sources), resistant starch (10.8% resistant starch), beet pulp (27.2 % sugar beet pulp), soyhulls (19.1% soybean hulls) or soyhulls with an additional feed amount (14.05% soybean hulls). All diets included the same amount of energy. Resistant starch could reduce aggression in first hour of mixing but might not be different from control diet or other sources of fiber in terms of affecting overall behavior in their stall, peripheral blood metabolites, aggression at mixing, skin lesions after mixing, heart rate variability and production. The sows on beet pulp diet stood more compared to control, resistant starch, soy hulls and increased intake. Soy hulls could be added to the diet to reduce heart rate. In conclusion, including resistant starch and soy hulls in a proper proportion in the diet fed three weeks prior to mixing might be effective in overall reduction of aggression restlessness and heart rate and improve sow welfare during mixing. Producers aiming to group house sows should consider diet alterations which can help decrease aggression and thus increase sow welfare.

Technical Abstract: The swine industry is under a great deal of pressure to return sows to group housing. However, aggression during mixing of pregnant sows impacts sow welfare and productivity. The aim of this study was to increase satiety and reduce aggression by including dietary fiber and fermentable carbohydrate. Satiety could be obtained through prolonged gut fill and increased nutrient provisions in the blood for a longer duration after the meal. Sows were housed in individual stalls 7 to 14 d post-breeding and were fed (at 0700 h) with either a CONTROL (regular feed with no extra fiber), RSTARCH (10.8% resistant starch), BEETPULP (27.2 % sugar beet pulp), SOYHULLS (19.1% soybean hulls) or INCSOY (14.05% soybean hulls) for 21 d (5 sows/diet × 5 diets × 8 replications = 200 sows). The CONTROL diet was targeted to contain 185 g/d/sow NDF and other diets were targeted to contain 350 g/d/sow NDF. The INCSOY diet was fed at 2.2 kg/d/sow and other diets were fed at 2 kg/d/sow. On d 22, sows were mixed in groups of five (at 1200 h). Behaviors in stalls (on d 1, 7, 14 and 21) and after mixing (d 22 and 23), heart rate (on d 1, 7, 14 and 21), blood metabolites (on d 2, 8, 15, 22 and 25), and the effects of diets on production were collected and analyzed. Sows stood more (P < 0.01) and rested less (P < 0.001) over time irrespective of the diet. Sows on BEETPULP stood more (P < 0.01) and sows on SOYHULLS rested more (P < 0.01). Sham chewing increased over days irrespective of the diet. Chewing behavior (bar and feeder) increased with days on diet (P < 0.001) and was lowest in sows on SOYHULLS diet (P = 0.045). When mixed, biting frequency in the first hour was highest for sows on the CONTROL diet (236.5 ± 62.6) and lowest for sows on the RSTARCH diet (90.5 ± 30.5). Skin lesions increased (P < 0.001) 24 h after mixing sows irrespective of diet. Blood urea nitrogen (BUN) concentration was lowest in BEETPULP and SOYHULLS (P < 0.001). Serum glucose concentration was highest in RSTARCH and BEETPULP (P = 0.04), but there was no day effect (P = 0.62) or diet by day interaction (P = 0.60). The NEFA was greatest in RSTARCH, BEETPULP and SOYHULLS (P < 0.001). Lactate (P < 0.001) and BUN concentrations were greatest on d 2 but dropped and remained constant after d 8. Average heart rate was lowest for sows on SOYHULLS and INCSOY compared to other diets (P = 0.03). Number of piglets born and average weaning weight were not affected by diets (P > 0.05). Average birth weight was lowest in INCSOY diet (P = 0.02). This study demonstrates that RSTARCH and SOYHULLS can improve the welfare of sows by reducing aggression and increasing satiety in limit fed pregnant sows when fed 21 d before mixing into groups of five without affecting production. Resistant starch and soy hulls when used in the correct proportion could have a synergistic effect to increase satiety and reduce aggression.