The minimum emetic dose of deoxynivalenol to swine weighing 9 to 10 kg was 0.05 mg/kg of body weight intraperitoneally and 0.1 to 0.2 mg/kg orally. There was no emesis by undosed pigs consuming vomitus from pigs orally dosed with deoxynivalenol or penned with such pigs without access to vomitus. Analysis by gas-liquid chromatography of a sample of Gibberella zeae-infected corn containing about 25% visually damaged kernels indicated 12 ppm of deoxynivalenol. Deoxynivalenol added to feed reduced feed consumption of 20to 45-kg pigs, ranging from a 20% decrease with 3.6 ppm to 90% reduction with 40 ppm. Loss in weight was associated with feed refusal. Feed refusal, however, was much greater for naturally infected corn samples than for feeds with equal concentrations of the pure compound added, indicating the involvement of an additional factor(s) in the swine refusal response.

Utilization of soybean oil (SBO) in swine starter diets and the effect of an adaptation period to SBO on performance was studied in two 4-wk experiments with pigs initially 4 to 5 wk of age. One trial was extended an additional 4 wk and apparent DE was measured during the 4th wk postweaning. Corn-soybean meal-based diets were used in which SBO was substituted for cornstarch at 2, 4 and 6% of the diet in Exp. 1 and at 3 and 6% of the diet in Exp. 2. In Exp. 2, SBO was added either initially (adaptation) or after 2 wk (no adaptation). In Exp. 1 daily gain and efficiency of feed utilization were improved (P less than .05) by adding SBO during wk 3 and 4, but not earlier. Feed intake was not affected by treatment. In Exp. 2, for the initial 4-wk postweaning period, there was no effect of SBO addition on growth rate; feed intake was depressed (P less than .05) when SBO was added at wk 3, and efficiency of feed utilization was improved (P less than .05) for pigs fed SBO without an adaptation period. The primary improvements in performance occurred in the 3rd and 4th wk postweaning, with a tendency for pigs to perform better without an adaptation period. During wk 4, pigs adapted to SBO consumed more (P less than .05) feed but tended to be less efficient (P less than .10) than nonadapted pigs. With or without adaptation, apparent DE was unaffected by SBO additions. Regardless of adaptation period, SBO additions depressed feed intake (P less than .05) and improved efficiency of feed utilization (P less than .01) for the 5- to 8-wk growing phase. In conclusion, adding SBO the first 2 wk postweaning did not improve performance; an adaptation period was not necessary for a performance response from added SBO.

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The effect of iron on the ability of sow's milk to suppress Escherichia coli was examined both in vitro and in ligated intestinal segments of neonatal pigs. Sow's milk from day 7 of lactation was diluted with NaHCO3/KH2PO4 and divided into four treatment groups: (1) diluted milk; (2) diluted milk + ferric citrate; (3) diluted milk heated at 100 degrees for 20 minutes, and (4) treatment 3 + ferric citrate. Treatment groups were tested for antibacterial activity in vitro after inoculation of 10(4) Escherichia coli (strain 263); counts after a 3-hour incubation were: 721, 9,290, 11,400 and 9,680 for treatments 1-4, respectively. The same four treatments were tested in ligated intestinal segments of 9-day-old pigs with or without the addition of 10(4) E. coli. The average total E. coli count (+10(5)) per centimeter of intestine for 16 pigs after 3 hours of incubation were: 11, 50, 84 and 249 for treatments 1-4, respectively, without additional E. coli and 14, 110, 314 and 535 with additional E. coli. The effects of exogenous iron on the in vitro anti-coli capacity of sow's milk were also examined at 3-day intervals throughout the first 21 days of lactation. Iron had a significant detrimental effect on the anti-coli capacity of sow's milk from days 6 to 18 of lactation. Iron did not have an effect on the anti-coli capacity of colostrum, which exhibited bactericidal activity, or on milk from the 21st day of lactation, which allowed good E. coli growth. Results from these studies suggest that iron reduces the capacity of sow's milk to repress E. coli concentrations both in vitro and in vivo.