Umami Sensory Stimulation Improves Nutrient Digestibility in Pigs

Umami in pigs is a taste that helps the animal to identify protein sources through the stimulation of the pT1R1/pT1R3 receptor present in oral tissues and along the gastrointestinal tract, where it acts as a nutrient sensor. Performance benefits have been previously described with the use of a high-intensity umami additive (HIU) based on Maillard reaction products. Interestingly, these benefits were not necessarily linked to an increased feed intake, while an improvement in feed efficiency was reported. To further investigate possible mechanisms explaining these results, a study was performed aiming to investigate the effect of a HIU (LUCTA, SA, Spain) added to pig feeds on nutrient digestibility. Twelve pigs ((LW x LD) x Pietrain, initial BW= 22 ± 0.3 kg) were individually fitted with a T-shaped cannula in the distal ileum. After surgery recovery (two weeks), pigs were fed for 14 days with a mash starter diet (18.6% CP, 1.30% Lys, 12.7MJ/kg ME) with HIU (HIU group, 1000 mg/kg, n=6) or without HIU (CONTROL group, n=6) added. Chromic oxide (0.5%) was included in both diets as an inert marker. Animals were placed in individual metabolic cages during the collection period. Ileal contents were collected during 8-h per day throughout the last 3 days, homogenized, freeze-dried and analyzed for the determination of dry matter (DM), gross energy, nitrogen (N), chromic oxide and amino acid content (except for Trp, Met and Cys). The apparent ileal digestibility (AID) was calculated and data were analyzed as a one-way ANOVA with diet as a fixed effect using Tukey-adjustments (SAS, v.9.4). Results showed improved AID values (P < 0.05) in the HIU group for DM (72 vs. 77%, SEM=1.1), energy (74 vs. 79%, SEM=1.0), N (80 vs. 85%, SEM=0.9), and some indispensable amino acids (shown in table 1). Therefore, it is concluded that the addition of a HIU based additive may improve nutrient digestibility in pig diets.

Table 1. Apparent ileal digestibility of indispensable amino acids in pigs fed a diet with a high intensity umami (HIU group, n=6) or without HIU (CONTROL group, n=6) added.

Item (%)	CONTROL GROUP	HIU GROUP	SEM	P value
Arg	85	88	0.7	0.045
His	82	85	1.0	0.077
Ile	82	86	0.9	0.014
Leu	84	87	0.9	0.024
Lys	87	91	0.7	0.002
Phe	84	88	0.9	0.027
Thr	83	86	0.9	0.037
Val	81	85	0.8	0.002