74 Feeding style and its influence on growth, circulating insulin, and spatial preference of young pigs

Abstract

Abstract In this study, we investigated the influence of feeding style on growth performance, circulating insulin concentrations, and spatial preference within the home-cages (HC) of young pigs. Pigs (n = 43 boars) were weaned on postnatal day (PND) 2, allotted to treatment based on litter of origin and body weight (BW), and reared artificially over a 15-d period. Pigs were provided a nutritionally adequate milk replacer 20 h per day using one of two feeding styles: 1) ad libitum (i.e., continual access to milk replacer), and 2) prescribed [330 mL/kg of BW from PND 3-7 (wk 1), and 357.5 mL/kg of BW from PND 8-18 (wk 2)]. In addition to water in the reconstituted milk replacer, free choice access to fresh water was provided throughout the study. Milk intake (i.e., disappearance) and BW were recorded daily, with pigs undergoing continuous top-down video surveillance throughout the study. On PND 17, blood was collected from a subset of pigs (n = 24) for quantification of insulin concentrations. Video analysis of pigs (n = 43) was performed to establish time spent in each HC quadrant. All data were analyzed via a 1-way ANOVA using the MIXED procedure of SAS. During wk 1, ad libitum pigs exhibited increased (P < 0.05) average daily BW gain (152 g/d) and average daily milk intake (728 g/d) compared with the prescribed treatment (127 g/d and 570 g/d, respectively). This same effect continued in wk 2 for average daily BW gain and average daily milk intake, with ad libitum-fed pigs consuming more (P < 0.05) milk replacer (256 g/d and 1,356 g/d, respectively) compared with prescribed-fed pigs (192 g/d and 974 g/d, respectively). Over the entire 15-d feeding study, average daily BW gain (234 g/d), average daily feed intake (1,140 g/d) and milk intake-to-BW ratio (4.60) were greater (P < 0.05) in the ad libitum treatment compared with prescribed feeding (180 g/d, 830 g/d, and 3.81 respectively). Insulin concentrations were greater (P < 0.05) in the ad libitum treatment (348 µIU/mL) 30 min after feed provision compared with the prescribed treatment (190 µIU/mL). Video analysis of spatial preference within HC suggested pigs in the prescribed treatment spent more (P < 0.05) time in quadrant 4 during wk 1 (5.43% of time recorded) compared with the ad libitum treatment (3.82% of time recorded), likely due to quadrant 4 housing the feed bowl. However, all other time points had no effect on spatial preference. Overall, the type of feeding style altered growth performance and insulin concentrations within young pigs and may impact the spatial preference of pigs within their home-cage environment.