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Aims: Studies were carried out to investigate the survival of Salmonella Typhimurium and Salmonella Derby in pig slurry during summer and winter seasons. Methods and Results: Pig slurry samples collected from a commercial fattening house were inoculated with a broth culture of Salmonella Typhimurium and Salmonella Derby, each at a level of log10 5·0 CFU ml−1 and log10 2·0 CFU ml−1. At the higher inoculum level, S. Typhimurium and S. Derby survived for 34 and 23 days, respectively in the summer, and 58 and 46 days, respectively in the winter. Survival at the lower inoculum level for S. Typhimurium and S. Derby was 19 and 16 days, respectively, in the summer and 24 days for both in the winter. Conclusions: The survival of S. Typhimurium and S. Derby observed in this study indicates that a 2-month holding period of pig slurry, prior to land spreading, may be adequate if separate storage facilities are provided. Significance and Impact of the Study: Despite difficulties correlating laboratory studies with on-farm conditions, pig slurry may not represent a major source of transmission of Salmonella spp. in the farm environment in Ireland.

Four experiments were undertaken to examine the effect of feeding postweaning diets as dry pelleted feed, fresh liquid feed, acidified liquid feed, and fermented liquid feed on pig performance from weaning (26 d) to harvest. In Exp. 1 (n = 12 replicates) and 2 (n = 10 replicates), the treatments were 1) dry pelleted feed and 2) fresh liquid feed. In Exp. 1, 2 kg of starter diet (16.7 MJ of DE/kg and 1.6% lysine) per pig and 5 kg of transition diet (16.7 MJ of DE/kg and 1.5% lysine) per pig followed by a weaner diet (14.0 MJ of DE/kg and 1.36% lysine) were offered to 27 d after weaning. In Exp. 3 (n = 8 replicates), the treatments were 1) dry pelleted feed, 2) fresh liquid feed, and 3) acidified liquid feed. In Exp. 4 (n = 8 replicates), the treatments were 1) dry pelleted feed, 2) acidified liquid feed, and 3) fermented liquid feed. In Exp. 2, 3, and 4, 3 kg of starter diet (16.1 MJ of DE/kg and 1.74% lysine) per pig and 6 kg of transition diet (15.3 MJ of DE/kg and 1.5% lysine) per pig followed by a weaner diet (14.0 MJ of DE/kg and 1.36% lysine) was offered to 27 d after weaning. All treatments were balanced for boars and gilts and diets were offered for ad libitum consumption. Acidified liquid feed was produced by adding lactic acid to the liquid feed so that its pH was decreased to 4.0. Fermented liquid feed was produced by adding an inoculum of Lactococcus lactis subsp. cremoris 303 (1.3%, vol/wt) to the first mix. In Exp. 1, ADG from weaning to d 27 after weaning was 338 and 286 g/d (SEM = 10; P 0.05) and DM gain/feed was 865, 755, and 789 g/ kg (SEM = 14.5; P < 0.001) for dry pelleted feed, fresh liquid feed, and acidified liquid feed, respectively. In Exp. 4, ADG was 361, 389, and 347 g/d (SEM = 13.2; P = 0.11) and DM gain/feed was 888, 749, and 733 g/ kg (SEM = 15.8; P < 0.001) for dry pelleted feed, acidified liquid feed, and fermented liquid feed, respectively, during the period from weaning to d 27 after weaning. It is concluded that although feeding acidified liquid feed may have some merit in the first 27 d after weaning, this benefit is lost in the subsequent period. No benefit arose from feeding fresh liquid feed or fermented liquid feed. Growth performance from d 28 after weaning to harvest was not improved by any liquid feed treatment.

The effect of n−3 fatty acid-enriched diets (in the form of 0.5% linseed oil with either 1.5% sunflower oil or 1.5% olive oil) and α-tocopheryl acetate supplementation (200 mg/kg feed) on lipid oxidation (thiobarbituric acid-reactive substances, TBARS) and cholesterol oxide products (COPS) in cooked pork was investigated. Longissimus muscle was studied. Meat from pigs fed 0.5% linseed oil-enriched diets had a higher proportion of n−3 fatty acid than meat from pigs in other dietary groups in neutral (P < 0.0001) and polar lipids (P < 0.0001), and a 20% reduction in the n-6:n- 3 ratio was observed. α-Tocopheryl acetate supplemen- tation increased (P < 0.05) monounsaturated fatty acids in polar lipids and increased (P = 0.0001) α-tocopherol levels in muscle. α-Tocopherol concentration in muscle was affected by dietary fat (P < 0.05). Groups receiving diets enriched with sunflower oil had significantly higher α-tocopherol levels (P < 0.05) in muscle than those groups receiving olive oil-enriched diets. Num- bers of TBARS were significantly (P < 0.05) lower in the group fed supplemental olive oil than in those fed sunflower oil. Dietary linseed oil increased (P < 0.05) lipid oxidation principally at the initial period of storage in cooked pork. Overall, dietary α-tocopheryl acetate supplementation significantly increased (P < 0.001) lipid stability and decreased (P < 0.05) total COP pro- duction across the dietary groups. α-Tocopherol was a more effective antioxidant for decreasing TBARS val- ues in cooked meat when adding sunflower oil to the diets instead of olive oil.