PSII-20 - Feeding behavior of pigs fed dietary amino acid levels adjusted according to the circadian rhythm

Abstract: Pigs are diurnal animals that presents feed intake during daylight hours, with feeding peaks in the early morning and late afternoon. However, it is possible that the concentration of amino acids (AA) in the diet throughout the day changes the pigs’ meal pattern. Therefore, the objective of this study was to evaluate the feeding behavior of growing-finishing pigs subjected to adjustment of the concentration of AA in the diet according to the circadian rhythm. Sixty-eight 25-kg (±2.67) barrows were assigned to four treatments, being a daily feeding program (DP) and three sequential feeding programs (SEQ). In DP, dietary AA concentration was adjusted daily, providing 100% of the standardized ileal digestibility (SID) recommendation for the 24-hour period. In SEQ, the daily dietary AA concentration was adjusted every 12h, providing a low AA concentration from 00:00 to 11:59 and a high AA concentration from 12:00 to 23:59. The low and high AA concentrations of the SEQ corresponded to ±20%, ±30% and ±40% of daily AA requirements. The experiment lasted 82 days and was divided in three phases. Meal pattern variables were recorded in real time by precision feeders. The information obtained was grouped into four periods: PE1, from 00:00-06:00; PE2, 06:01-12:00h; PE3, 12:01-18:00; and PE4, 18:01-23:59h. From this database, the visits to the feeder (n), meals (n), amount of time feeding (min), feed intake (g), and feed intake rate (g/min) were calculated for each period, within each experimental phase. The analysis of variance was performed considering the effects of feeding programs (FP), periods (PE), and their interaction (FP×PE), considered significant when P< 0.05. There was no interaction between FP and PE (P >0.05; Table1). The visits to the feeder were higher (P< 0.01) in PE2 and PE3 compared with PE1 in phase one and compared with PE1 and PE4 in phases two and three. The meals, amount of time feeding, and feed intake was higher (P< 0.01) in PE2 and PE3 in all phases. Regarding feed intake rate, an PE effect (P≤0.01) was observed in all phases and there was an effect of FP (P< 0.01) in phases one and three. In phase one, pigs ingested feed faster in PE3 than PE1, and in phase three feed intake rate in PE1 was lower than in the other (P< 0.01). During phase one, SEQ40 feed intake rate was lower than SEQ30, while in phase three SEQ40 showed lower feed intake rate compared to SEQ30 and DP. Pigs showed higher feeding activity from 06:00 to 18:00. The AA concentration in the diet adjusted according to the circadian rhythm did not change the pigs' meal pattern throughout the day. However, a lower feed intake rate was observed in SEQ40 group in phases one and three.