Three studies evaluated the effects of added dietary salt on growth performance of pigs weighing 7 to 10, 11 to 30, and 27 to 65 kg. In experiment 1, 325 pigs were used with 5 pigs per pen and 13 pens per treatment. Pigs were fed a diet (0.39% Na and 0.78% Cl) for 7 d after weaning, then randomly assigned to diets with either 0, 0.20, 0.40, 0.60, or 0.80% added salt for 14 d. All diets were corn-soybean meal-based with 10% dried whey. Calculated Na concentrations were 0.11, 0.19, 0.27, 0.35, and 0.43% and calculated Cl concentrations were 0.23, 0.35, 0.47, 0.59, and 0.70%, respectively. Increasing salt increased (linear, P < 0.05) average daily gain (ADG) and gain to feed ratio (G:F). For ADG, the linear, quadratic polynomial (QP), and broken-line linear (BLL) models were competing with the breakpoint for the BLL at 0.59% salt. For G:F, the BLL reported a breakpoint at 0.33% while the QP indicated maximum G:F at 0.67% added salt. In experiment 2, 300 pigs were used in a 34-d trial with 5 pigs per pen and 12 pens per treatment. Pigs were weaned at 21 d of age and fed a phase 1 diet (0.50% Na and 0.67% Cl) for 11 d and then a phase 2 diet (0.35% Na and 0.59% Cl) for 14 d. Then pens of pigs were randomly assigned to corn-soybean meal-based diets containing 0.20, 0.35, 0.50, 0.65, or 0.80% added salt. Calculated dietary Na concentration were 0.10, 0.16, 0.22, 0.28, and 0.34% and calculated Cl concentrations were 0.23, 0.32, 0.41, 0.50, and 0.59%, respectively. Overall, ADG and G:F increased (quadratic, P < 0.07) with increasing added salt. For ADG, the QP and BLL had similar fit with the breakpoint for BLL at 0.51% added salt. For G:F, the BLL model predicted a break point at 0.35% added salt. In experiment 3, 1,188 pigs were used in a 44-d study with 27 pigs per pen and 11 pens per treatment. Pens of pigs were randomly assigned to corn-soybean meal-based diets containing 0.10, 0.33, 0.55, or 0.75% added salt. Calculated dietary Na concentrations were 0.10, 0.19, 0.28, and 0.36% and calculated Cl concentrations were 0.23, 0.36, 0.49, and 0.61%, respectively. Overall, there was no evidence to indicate that added salt above 0.10% of the diet affected growth. In conclusion, the BLL models suggested to maximize ADG for 7 to 10 and 11 to 30 kg pigs was 0.59% (0.34% Na and 0.58% Cl) and 0.51% added salt (0.22% Na and 0.42% Cl), respectively. There was no evidence that growth of 27 to 65 kg pigs was improved beyond 0.10% added salt (0.11% Na and 0.26% Cl).

Sodium metabisulfite (SMB)-based feed additive efficacy was evaluated in three nursery pig growth experiments where pigs were fed diets containing low deoxynivalenol (<1.5 mg/kg; DON) concentrations. Pigs were weaned at approximately 22 d of age and randomly allotted to pens with one pen of 27 gilts and one pen of 27 barrows per feeder; thus, feeder was the experimental unit. In experiment 1, a total of 2,268 pigs were used in a 35-d trial with 21 feeders per treatment. Experimental treatments included a control diet or the control with 0.50% SMB-based Product 1 (Defusion; Provimi, Brookville, OH) fed in phase 1 and 0.25% fed in phases 2 and 3, then all pigs were fed a control diet for the last week of the study. Pigs fed Product 1 had greater (P < 0.05) ADG, ADFI, and G:F compared with pigs fed the control diet from days 0 to 28. However, from days 28 to 35, the opposite response was observed with pigs fed the control diet having greater ADG and G:F than pigs previously fed Product 1. Despite this response, pigs fed Product 1 were heavier (P < 0.05) on day 35 than control-fed pigs. In experiment 2, a total of 4,320 pigs were used in a 42-d trial. Pigs were fed a control diet or diets with SMB-based either Product 1 or Product 2 (NutriQuest, Mason City, IA) at different concentrations and durations. Among the various treatments, Product 1 or Product 2 concentrations ranged from 0.50% initially to 0.25%, 0.15%, or none the last week of the study. Overall, pigs fed either of the additives at the highest concentrations and for the longest period of time had greater (P < 0.05) ADG and ADFI compared with pigs fed the control diet, with those fed lower concentrations or shorter durations being intermediate. In experiment 3, a total of 2,808 pigs were used in a 28-d trial with 13 feeders per treatment. All pigs were fed a common diet for 7 d after weaning. Pigs were then fed either a control diet (without any SMB-containing product) or a diet containing Product 1 (0.50% and 0.25% from days 0 to 21 and 21 to 28, respectively) or SMB (0.50% and 0.25% from days 0 to 21 and 21 to 28, respectively) or 0.25% SMB from days 0 to 28. Overall, pigs fed Product 1 or high-SMB diets had greater (P < 0.05) ADG compared with pigs fed low-SMB or control diets. In conclusion, results of these experiments indicate that in diets with low DON concentrations, these SMB-based products increased ADG compared with control diets.

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A total of 26 lactating sows (DNA 241, DNA Genetics, Columbus, NE) and litters were used in a discovery study to evaluate the effects of Calsporin, a direct-fed microbial containing Bacillus subtilis C-3102, on fecal microflora of nursing pigs. The treatments consisted of providing a daily oral dose of Calsporin or a placebo control to piglets during the nursing phase. Sows were randomly assigned to treatments based on farrowing date, parity, and initial BW. The treatments were applied individually to piglets once a day from d 2 after farrowing and equalization until weaning on d 19. Sow BW, sow ADFI, piglet BW, piglet weight gain, litter size, and mortality were recorded on a weekly basis until weaning. Fecal scoring was conducted to categorize the consistency of the feces using a numerical scale from 1 to 5. Also, fecal samples were collected directly from the rectum of the piglets and pooled by litter for microbial analysis. Fecal scoring and microbial analysis were performed on d 2 after birth, and after 1 or 2 weeks of treatment. As expected, and not a primary objective of this study, there was no evidence for differences among treatments on sow and litter performance (P > 0.085). There was no evidence for differences on fecal score at the beginning of the trial and after 1 or 2 weeks of Calsporin supplementation (P > 0.358). Microbial analysis revealed an increase in levels of total Bacillus sp. (P < 0.001) and a decrease in total aerobes (P < 0.026) in litters treated with Calsporin. There was no evidence for differences in number of Lactobacillus sp., Enterococcus sp., Clostridium perfringens, Enterobacteriaceae, and total anaerobes between control-and Calsporin-treated litters (P > 0.05). In conclusion, once per day supplementation of Calsporin to nursing pigs resulted in slight changes in fecal microflora, but there was no influence on nursing pig fecal consistency.