Organic acids in liquid feed for pigs - palatability and feed intake
Organic acids Fermented liquid feedAcetic acidLactic acidAcidifiersPalatabilityGrowth performanceHealth statusPig
Fermented liquid feed is well known for its health promoting effects on piglets. High levels of lactic acid are desired in the feed together with low levels of acetic acid and certain biogenic amines. Limits for acetic acid have been suggested to be 30-40 mmol/kg to avoid a decreased palatability of the feed; however, few studies have been performed. The purpose of this trial was therefore to examine which levels of lactic acid and acetic acid that can be accepted in a fermented feed without affecting the feed intake and thus the weight gain of the pig. A total of 60 pigs (Yorkshire/ Hampshire) were used in a trial during two weeks, between 9-11 weeks of age. The trial was divided into two parts with 30 pigs in each. In the first trial, lactic acid was supplemented to the pig´s diet at levels of 0, 75, 100, 150 and 200 mmol/kg. In the second trial, acetic acid was added to the feed at levels of 0, 10, 50, 100 and 150 mmol/kg. The growth performance of the pigs was measured and a behavioral study was performed. No significant differences in feed consumption or daily weight gain could be seen between any of the levels of acetic or lactic acid. The only significant difference with lactic acid was found for feed conversion rate (FCR) between treatment L2 (100 mmol/kg) and L4 (200 mmol/kg) which had a significantly more efficient FCR on 1.77 and 1.80 respectively compared to the control group (0 mmol/kg) which had a FCR on 2.07 kg (p=0.016). There was also a significant difference in FCR between the pigs fed acetic acid (p= 0.027). The control group (0 mmol/kg) and the A2 group (50 mmol/kg) had a FCR of 2.0 kg compared to A4 (150 mmol/kg) which had an FCR of 1.77. In the behavioral study, an continues recording and one instantaneous scan sampling was performed. No differences in feeding or social behavior could be seen in the instantaneous scan sampling in either acetic or lactic acid. In the continues recording, there were some significant differences in feeding behavior in both trials but between the times of feeding and not between the inclusion levels of acids. That indicates differences in eating behavior during the day more than between the inclusion levels. Our results suggest that a fermented feed can contain lactic acid up to 200 mmol/ kg and acetic acid up to 150 mmol/ kg without affecting the feed intake or growth performance of the piglets negatively.