Date of Award
Master of Science
Jim O'Neal, John Hitchcock
Three feeding trials were conducted utilizing 346 crossbred market hogs from the October 1983, January 1984 and April 1984 farrowings at The University of Tennessee Agricultural Experiment Station (Blount Farm), Knoxville, Tennessee to determine the effect of dietary salt on the performance of growing-finishing swine. Consideration was also given to the relationship between vitamin and trace mineral levels and dietary salt in respect to performance.
Finishing trial I consisted of 90 crossbred market pigs divided into 3 weight groups with the average pig weight being 145, 170 and 177 pounds. Experimental diets fed contained .5, .3 and .1 percent sodium chloride. No significant differences in performance as measured by average daily gain (ADC) and gain:feed were found throughout the trial. No significant weight group by dietary sodium chloride level interactions were found and pigs fed the .1 level performed as well as the pigs fed the .5 level of sodium chloride. This suggests that dietary sodium chloride can be reduced without affecting performance during the last 6 weeks of the finishing period.
Growing-finishing trial II consisted of 112 crossbred market hogs creep fed a .25 percent salt diet and alloted on the finishing floor by an average pig weight of 100 pounds. Experimental diets consisted of 2 level of salt and 2 levels of vitamin trace mineral premix .2, .35, .5 and .75 percent respectively. Average daily gain (ADC) during the first 42 days was significantly (P < .01) improved when .35 percent sodium chloride was added. However, this difference was not maintained throughout the trial as performance was similar at the termination of the experiment. This tends to indicate that during the early part of the finishing period .2 percent salt was inadequate to support maximum growth, but during the remainder of the period pigs were able to compensate and overcome the earlier growth depression. Feed: gain was similar but pigs receiving .2 percent salt tended to require slightly more feed than those pigs receiving .35 percent salt. The main effect of vitamin trace mineral level suggested the average daily gain (ADG) was significantly (P < .01) improved by adding 150 per cent of the NRC requirement levels of vitamin and trace minerals at both 42 days of the experiment and over the entire finishing period. There was a significant (P < .05) interaction between level of sodium chloride and vitamin trace mineral level in this study. Pigs receiving the .2 percent level of salt performed significantly better (P < .05) when they received the higher level of vitamin trace mineral both at 42 days and over the entire experiment. Whereas, pigs receiving .35 percent sodium chloride did not benefit by the addition of higher levels of vitamins and trace minerals either at 42 days or over the entire trial period. Feed:gain values were similar but indicated no beneficial effect of adding higher vitamin trace mineral levels when the diet contained .35 percent salt. These results suggest a critical balance exists between level of dietary sodium chloride and the level of vitamin trace mineral in the diet. When salt levels are marginal or barely adequate higher levels of vitamin trace mineral are important, whereas when higher levels of salt are fed no benefit is evident from the addition of additional vitamin trace minerals.
Growing trial III consisted of 144 crossbred market pigs grouped by litter in the farrowing barn. Pigs were creep fed diets containing 2 levels of salt and 2 levels of potassium chloride .5, 2.5, .196 and .333 percent respectively. Average daily gains (ADC) were similar but tended to improve when potassium chloride was added to diets containing .25 percent salt. Results related to creep feed consumption per pig were not significantly different but would suggest that pigs which received .25, percent sodium chloride in the diet required more feed than pigs fed .5 percent salt or in potassium chloride supplemented .25 percent salt diets. These results suggest lower salt levels than .5 percent can be utilized but additional potassium chloride may improve pig performance. Further research is need to delineate the relationships between sodium and potassium in diets of nursing pigs.
Underdown, H. Jack, "Effect of dietary salt levels on the performance of growing-finishing swine. " Master's Thesis, University of Tennessee, 1985.