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Feeding fermented liquid feed (FLF) to pigs has proven to benefit gastrointestinal health of the animals. However, growth performance data of piglets and growing pigs fed FLF are variable and often a lower feed intake compared to feeding non-FLF or dry feed has been observed. Accumulation of microbial metabolites, namely acetic acid, possibly in combination with low feed pH, has been suggested to be determinant in reducing feed intake by impairing palatability. However, this hypothesis has never been investigated. A study was carried out to determine the impact of increasing levels of acetic acid in FLF on feed intake of weaners. Three experimental FLF diets were prepared to contain varying levels of acetic acid (30, 60, and 120 mM). Twenty piglets per treatment, weaned at 4 weeks of age and housed individually, were fed the experimental diets during six weeks starting at weaning. Feed intake and body weight were registered weekly.
The results showed that high acetic acid concentration in FLF, accompanied by a slight lower pH level, tended to decrease feed intake (P = 0.09) without affecting body weight gain (P > 0.05). This discrepancy could partly be explained by the difficulty in measuring accurately feed intake on dry matter basis when feeding liquid feed to pigs. However, it has to be kept in mind that the typical concentration of acetic acid in FLF prepared with compound pig feed ranges between 20 and 40 mM. Therefore, the current data suggest that the levels of acetic acid typically measured in FLF prepared with standard compound feed would not profoundly affect its palatability, and thereby feed intake by piglets.
In conclusion, the present data indicate that acetic acid, at the concentrations measured in FLF prepared with ‘traditional’ ingredients, do not markedly affect growth performance. However, inclusion of ingredients with high levels of acetic acid or that promote high production of acetic acid during fermentation (e.g., liquid co-products) could impair growth performance of piglets.
N Canibe, AØ Pedersen and BB Jensen, 2010. Livestock Science, 133: 117-119.
