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Feed restriction cause reduction in feed intake and average daily gain, but increase feed efficiency. Amino acids reduction can increase feed intake and average daily gain without affecting feed efficiency. Often, studies of feed restrictions and reductions in AA allowances have been focused on performance and carcass traits, and few have looked at their influence on pig feeding behaviour. This trial aims to study the feeding behaviour of group-housed pigs fed individually from single-space feeders and subjected to feed restriction alone or in combination with a reduction in the dietary indispensable AA content. Ninety-six barrows were housed in 8 pens and individually fed either ad libitum (AL) or a restricted diet (RF) from 47 to 145 kg body weight (BW). The amount of feed given to RF pigs was close to their expected voluntary intake, but it was limited to proportions of 0.33, 0.66 and 1.00 of the estimated daily amount of feed in 3 time intervals, 00:01 to 8:00, 8:01 to 16:00 and 16:01 to 24:00 h, respectively. From 86 kg BW, the pigs in 4 of the pens were fed diets with conventional standardized ileal digestible AA content (CAA), while the pigs in the other pens received diets (LAA) in which the proportions of dietary indispensable AA were lowered with respect to CAA by 0.91 from 86 to 118 kg BW and by 0.82 from 118 to 145 kg BW. Automated feeders monitored individual feeding behaviour. Data were analysed by pig and feeding phase with a 2 × 2 factorial design.
Over the whole experimental period, feed restriction resulted in a decrease in daily feed intake (7%), the number of visits (27%) and the time spent feeding (14%), but an increase in feed consumption per visit (20%) and feeding rate (10%). The reduction in AA increased daily feed intake (7%), tended to increase feeding rate (14%). It was observed a high, negative, non-linear relationships between feed consumption per visit and visit frequency (R2 = 0.989 to 0.876), between visit duration and visit frequency (R2 = 0.648 to 0.695), and between feeding rate and time spent feeding in a day (R2 = 0.802 to 0.707), and positive linear relationships between visit duration and feed consumption per visit (R2 = 0.614 to 0.570). The individual feeding rate during growing was positively correlated with that during finishing (R2 = 0.458).
It was concluded that pigs try to adapt their feeding pattern to compensate for a reduced feed allowance or nutrient restriction, for example by increasing their feeding rate, which may reflect the pigs’ increased feeding motivation. However, the results of present experiment show that a change of feeding rate is not the only strategy that pigs adopt to reach their desired feed intake.
Carcò, G., Dalla Bona, M., Carraro, L., Latorre, M. A., Fondevila, M., Gallo, L., & Schiavon, S. (2017). Influence of mild feed restriction and mild reduction in dietary amino acid content on feeding behaviour of group-housed growing pigs. Applied Animal Behaviour Science.https://doi.org/10.1016/j.applanim.2017.09.020