Field study on fermentative profiles of swine liquid feed in Northern Italy

Liquid feed is the main feeding practice for finishing pigs in Northern Italy and is increasingly becoming a reference for sows and piglets (Lizardo, 2003). The objective of this field survey was to characterize the fermentative profile of different liquid feeds according to the main ingredients used in Northern Italy.

In order to monitor the fermentation profile of different types of liquid feeds used in fattening pigs in Northern Italy, and the possible effect of different ingredients on the fermentation, 75 samples of soup taken from 64 farms between March 2014 and November 2015 were analyzed. No samples were taken during the summer to avoid an extreme heat possible bias on fermentation. All samples were taken in the last phase of fattening (100- 160 kg) and were tested for dry matter (DM), pH at sampling and 6 hours after, ethanol, volatile fatty acids (VFA: acetic acid, propionic acid) and lactic acid. Analyses were done on samples frozen after 6h. Soups were classified into 4 groups according to their composition besides water: dry feed (WATER), dry feed + high moisture corn (HMC), dry feed + whey (WHEY), dry feed + HMC + whey (HMC + WHEY). The addition of a lactic acid bacteria (LAB) based inoculant (Pediococcus acidilactici MA 18/5M) was also considered.

pH of the soup at sampling and 6 hours later was the lowest (P< 0.001) for WHEY diets. In addition, pH 6h was numerically lower when LAB was added, regardless of the components. WATER diets showed the lowest (P< 0.01) ethanol level, and diets with whey showed the highest (P< 0.01) lactic acid level. Acetic acid tended (P< 0.1) to be the lowest in WATER diets. The addition of LAB had an effect on ethanol (P< 0.1) and propionic acid (P< 0.05) with the highest level of the two compounds when it was added. Lactic acid was numerically higher when LAB was added. A negative correlation (P< 0.01) between lactic acid and pH after 6h, a positive correlation (P< 0.01) between lactic acid and acetic acid, and a positive trend (P< 0.1) between lactic acid and ethanol were identified, all the correlations regardless of the components. No year effect was depicted.

These results suggest that the composition of a liquid diet affect the quality of the feed. pH is strongly affected by the use of whey but it can be partially controlled by addition of LAB to ensure a better hygiene of the feed. Production of volatile fatty acids as a source of energy from the diet is also a positive effect of the addition of LAB. Mortality was not affected by diet profiles. The impact of soups composition on animal performances should be further studied on a larger number of farms.

Disclosure of Interest: None Declared.