Abstract
Abstract The objective of this study was to investigate behavioral and stress responses to feeding frequency in pregnant sows under isocaloric conditions. Eighteen sows (Landrace × Yorkshire); BW 226.10 ± 1.29 kg; parity 3.1 ± 0.42); were blocked by parity and randomly assigned to 1 of 3 feeding frequency regimes. Sows were fed corn-soybean meal-based diet 1× [0730 (Control, T1), 2× “[half ration at 0730 and 1530 h (T2)]” and then “[one-third portion at 0730, 1130, and 1530 h (T3)]”. On average, sows received 7190 kcal ME d−1 during gestation from 2.25 kg of diet formulated to contain SID Lys/ME of 1.71 g/Mcal. Saliva samples were collected from 0630 to 1830 h, 2 hrs apart and assayed for cortisol using ELISA technique. Behavior data were collected for 7 d from d 53 of gestation by affixing a Remote Insights ear tag to each sow. Each sow had 120,960 data points categorized into: “Active,” “Feed” or “Dormant”. The data were analyzed using GLIMMIX procedure of SAS 9.4 with treatment as fixed effect and sow as random effect. Results were considered statistically significant when P < 0·05 and were considered as trends when P ≤ 0·10. Sow was the experimental unit. A 24 h area under the curve (AUC) was calculated by trapezoidal method. The P-values were adjusted for multiplicity based on Tukey Kramer’s method. A 24 h total activity and total feeding activity AUC were reduced in sows fed 2× daily compared with sows fed 1× and 3× daily (P < 0.01). A 12 h cortisol AUC was lower for sows fed 2× daily relative to treatment groups fed 1× and 3× daily (P < 0.02). In conclusion, feeding pregnant sows twice daily may improve sow welfare by reducing feeding activity, total activity, and the activation of hypothalamic-pituitary-adrenal (HPA) axis.
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