Feed disappearance, production, skin lesions and predicted environmental outcomes from different lactating sow feeding strategies

Prolific sows require high feed intake to avoid weight loss and support piglet growth. We compared three lactational feeding strategies (n = 137 sows) on two farms on production measures, skin lesions and predicted environmental outcomes. All sows were fed from feed curves, based on the stage of lactation. Type of delivery varied across strategies, either restricted to the daily allotment at three fixed feeding times (RESTR); restricted to the same allotment at the same times but with a two-hour time window each (SLOTS); or sows had continual access to feed up to 200 % of their daily allotment (ADLIB) from day 6 on. SLOTS and ADLIB sows gained access to feed by triggering a sensor in the trough. Data were analysed using linear mixed models. Sows in the ADLIB strategy had the highest feed disappearance during the last 15 days of lactation (FD_L15D) (p = 0.01), as well as highest coverage of metabolized energy (p < 0.001) and predicted environmental outcomes (N & P excretions; p < 0.001). No differences were seen for daily piglet mass gain, sow weight loss, piglet skin lesions and sow shoulder lesions. While the FD_L15D of ADLIB was highest, the increase in feed allowance could have occurred too late in lactation to see any effects on piglet body mass gain or sow weight loss. Allowing sows more choice during feeding promises to increase feed intake and may help to improve existing feeding strategies. However, additional research is needed regarding long-term impact of ad-libitum feeding and the significance of farm differences.