Effects of feed withdrawal before delivery on pork quality and carcass yield.

A total of 270 pigs from a Yorkshire/Duroc/Landrace 3-way cross, reared under an ad libitum feed regimen, were delivered for slaughter after fasting (with access to water) for 24 and 0 h (Exp. 1), 16 and 0 h (Exp. 2) and 24, 16 and 0 h (Exp. 3). The interval between delivery and slaughter was 4-5 h. Feeding until delivery resulted in a lower pH at 45 min post mortem in the longissimus muscle. Ultimate pH values of longissimus and semimembranosus muscles were higher after feed restriction for 24 h. However, the incidence of dark, firm and dry (DFD) (pH > 6·2) was also increased after fasting in Exp. 1. Assessment of meat quality in samples taken from the longissimus at 20 h post mortem showed that, in comparison with feeding until delivery. Hunter L(∗) (Lightness)-values and drip loss decreased and firmness improved by prolonged fasting (24 h). Fasting for 16 h did not reduce drip loss, but colour was improved (lower Hunter L(∗)-values) in Exp. 3, although not in Exp. 2. Feeding until delivery resulted in better meat quality in Exp. 2 than in Exp. 1 and 3. A significant reduction in dressing percentage as a result of fasting was only found in Exp. 1. There appears no economic disadvantage in restricting feed for 16 h prior to delivery. Although the incidence of DFD may also increase, a fasting period of 16-24 h is recommended to reduce pale, soft and exudative (PSE) muscle, while losses in carcass yield are minimized. Other advantages of fasting are discussed.