248. Utilization of Enrichment Blocks in Group-Housed Sows Under Commercial Conditions: Effects on Aggressive Interactions and Sow And Litter Performance.

Abstract Group-housing sows during gestation is becoming more prevalent in the swine industry. However, this housing strategy may increase aggressive interactions thereby increasing injuries and reducing farrowing performance. Therefore, the study objective was to determine whether provision of environmental enrichment during late gestation would reduce aggressive interactions resulting in reduced physiological stress and improved sow and piglet performance under commercial production conditions. We hypothesized that environmental enrichment would reduce aggressive interactions thereby reducing physiological stress and improving overall sows and piglet performance. Gestating sows (N = 960; parity = 3.36 ± 0.61) were randomly assigned to control (CON) pens with no enrichment (n = 9 pens; 53.2 ± 2.2 sows/pen) or pens containing three molasses and beet pulp-based enrichment blocks (BLK; n = 9 pens; 53.4 ± 1.1 sows/pen). Body weights were collected for all sows on gestation d 103.0 ± 1.1 and as sows entered farrowing on gestation d 110.7 ± 1.1 and feed intake was assessed daily. Sows were video recorded in 2-h intervals across a 12-h period on d 3 and 5 following treatment administration to assess feeder based, non-feeder based, and total number of aggressive interactions per h within each pen. Saliva samples were collected on d 3 and 5 post-treatment administration on one focal sow within the pen to assess salivary cortisol. One d prior to weaning, two piglets representing the mean litter weight of focal sow litters (n = 1 barrow and 1 gilt) were subjected to a stress test followed by blood collection to assess plasma cortisol concentrations and hair samples were collected to determine hair cortisol concentrations. Litter characteristics including total born, live born, mummies, stillborn, and number weaned were recorded on all litters. Pen was considered the experimental unit for all measures. Aggressive interactions were reduced (P = 0.03) in BLK (12.54 ± 2.42 interactions/h) versus CON (14.99 ± 2.55 interactions/h) pens. Regardless of treatment, feeder-based, non-feeder-based, and total aggressive interactions were greater (P < 0.01; 13.7, 6.2, and 17.1%, respectively) on d 3 versus 5 and declined (P < 0.01; 85.7%) from 0100-0300 h to 2100-2300 h. No differences (P > 0.10) in sow average daily gain (0.96 ± 0.07 kg/d), feed intake (2.24 ± 0.05 kg/d), sow salivary cortisol concentrations (7.45 ± 1.34 ng/mL), piglet hair cortisol concentrations (7.21 ± 0.98 pg/mg), piglet plasma cortisol concentrations (43.42 ± 5.19 ng/mL), total born (17.5 ± 0.19 piglets), live born (15.19 ± 0.18 piglets), stillborn (1.81 ± 0.14 piglets), mummies (0.44 ± 0.04 piglets), or number weaned (12.29 ± 0.17 piglets) were observed. Overall, the provision of environmental enrichment during late gestation reduced aggressive interactions but did not affect sow and litter physiological stress biomarkers or performance under commercial conditions.