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Benzoic acid (BA) has long been used as a food preservative due to its antibacterial and antifungal effects. Supplementation to pig diets has also been shown to inhibit microbial free amino acid degradation and to control yeast growth in fermented liquid feed. However, although BA has been authorized as a feed additive for grow-finisher pigs at inclusion levels of 0.5% - 1% in the diet, the effect of dietary inclusion of BA in fresh liquid feed for grow-finisher pigs on feed quality and the resultant effects on pig growth remain unclear. The aim of the present study was to compare the effect of four dietary inclusion levels of BA (0kg/t, 2.5kg/t, 5kg/t and 10kg/t) on the microbial quality of liquid feed and on the growth of grow-finisher pigs. It was hypothesized that BA would have an antimicrobial effect in liquid feed, thereby limiting spontaneous fermentation and improving feed microbial quality. Furthermore, it was hypothesized that increasing dietary BA inclusion would improve growth and feed efficiency in liquid-fed grow-finisher pigs. Two-hundred and sixteen pigs with a starting weight of 30.0kg (± 7.43 SD) were used in the experiment. The four dietary treatments were: (1) Basal diet + 0kg/t BA (0kg/t BA), (2) Basal diet + 2.5kg/t BA (2.5kg/t BA), (3) Basal diet + 5kg/t BA (5kg/t BA), (4) Basal diet + 10kg/t BA (10kg/t BA).
As a result, concerning the microbial quality of liquid feed, lactic acid bacteria (LAB) counts in the mixing tank were similar across treatments but were lower in the troughs for the feed supplemented with 10kg/t BA than for all other treatments. The pH of the 10kg/t BA treatment was also lower than that of the other three treatments. Dietary benzoic acid inclusion did not affect average daily gain, average daily feed intake, feed conversion efficiency, final live-weight, carcass weight or carcass quality during the experimental period.
Therefore, it could be concluded that BA may limit the growth of LAB in liquid feed and stabilize feed pH. However, its inclusion in the diet does not improve the growth performance or carcass quality of grow-finisher pigs.
O’Meara FM, Gardiner GE, O’Doherty JV, Lawlor PG. Effect of dietary inclusion of benzoic acid (VevoVitall®) on the microbial quality of liquid feed and the growth and carcass quality of grow-finisher pigs. Livestock Science. 2020: 104043. https://doi.org/10.1016/j.livsci.2020.104043
