Development of edible environmental enrichment objects for weaned pigs

Studies on environmental enrichment for weaned pigs have predominantly focused on stimulating exploration through "nonedible toys." The research on edible enrichment objects is very limited. For this reason, the aim of this study was to develop and characterize edible environmental enrichment objects (EOs) for weaned pigs and to determine behavioral and weight gain responses of pigs. Two types of EOs were evaluated, a cookie form (EO-C) and a donut-shape (EO-D). The EOs were formulated with dried whey (40% w/v) and sodium alginate (2% w/v) in distilled water. Blends were homogenized, molded, refrigerated, gelled, and dried. The EOs were characterized by dimensions, color, mechanical properties, and proximal chemical analysis. To study the interaction of pigs with EOs, 30 hybrid pigs, weaned at 21 days of age, were distributed into 3 groups (5 pairs of pigs per group): (1) control: pigs without EOs, (2) EO-D group, and (3) EO-C group. The interaction time was video-recorded for 3 days for 3 hours per day and then analyzed with the Observer XT 2011 program. The live weight of pigs and the total consumption of the EOs were also determined. The EOs were yellow in color and had different dimensions, with larger sizes for EO-D (height: 2.5 mm, width: 7.6 cm, and weight: 42 g). The EOs were composed mainly of carbohydrates (67-73%) and proteins (10-11%). The pigs consumed the EOs in high percentages, between 75 and 100% for EO-D and 38 and 60% for EO-C. There were no differences in consumption between EOs. The consumption of the EOs did not have an effect on live weight of the pigs; the final weights in the groups were as follows: 7.4 +/- 0.2 kg (control group), 7.6 +/- 0.2 kg (EO-C group), and 7.3 +/- 0.4 kg (EO-D group). The results of the interaction showed that the pigs interacted with both EOs, that on day 2 they spent more time interacting with EO-D, and that the interaction time through the days was reduced for EO-D and remained constant for EO-C. The interactions of the pigs with the EOs included sniffing, manipulation with nose or extremities, licking, and nibbling or consumption of EOs. (C) 2019 Elsevier Inc. All rights reserved.