Diet Preference, Feed Efficiency and Expression of the Sodium-Dependent Glucose Transporter Isoform 1 and Sweet Taste Receptors in the Jejunum of Lambs Supplemented with Different Flavours

SIMPLE SUMMARY: Flavours improve the sensory characteristics of the feed to increase voluntary intake of novel by-products and monotonous feeds, and improve feed efficiency, resulting in improved body weight gain. However, there is a scarcity of studies on the effect of flavour on the preference and feed efficiency in sheep raised in intensive farming systems post-weaning. Therefore, this study investigated the flavour preference in lambs and the effect of flavours on feed efficiency, sweet taste receptors and sodium-glucose linked transporter 1 gene expression in the small intestines. Eight lambs were offered 16 different commercial flavours in a grain mixture of rolled barley and ground corn to examine the preference. In the metabolic study, the lambs were randomly assigned to four treatments (sucram, capsicum, a mix containing sucram and capsicum at 1:1 ratio and no flavour for control) in a 4 × 2 cross-over design. The lambs showed a preference for capsicum, sucram and milky flavours, and disliked the liquid orange flavour. Flavours did not improve feed intake in the metabolic study, but capsicum increased the average daily weight gain per metabolic body weight. These findings indicate that flavours can be used to motivate feed acceptance and improve the weight gain in lambs. ABSTRACT: This study investigated the effect of dietary flavour supplements on the preference, feed efficiency and expression of the sweet taste receptor family 1 members 2 and 3 (T1R2 + T1R3), and sodium-glucose linked transporter 1 (SGLT1) genes in the lambs’ small intestines. Eight, five-month-old, Israeli crossbred Assaf lambs were offered 16 different non-nutritive commercial flavours in rolled barley and ground corn. Capsicum and sucram were the most preferred non-aroma flavours (p = 0.020), while milky (p < 0.001) was the most preferred powder-aroma flavour. For the metabolic and relative gene expression study, eight lambs were randomly assigned to either sucram, capsicum, a mix containing sucram and capsicum at 1:1 ratio or no flavour for control in a 4 × 2 cross-over design. The total collection of urine (females only), faeces and refusals was carried out, and T1R2, T1R3 and SGLT1 relative gene expression evaluated from the proximal jejunum biopsies. Flavour had no significant effect on the feed intake (p = 0.934), but capsicum increased the average daily weight gain per metabolic body weight (p = 0.049). The T1R3 gene was expressed highest in the mix treatment (1.7; p = 0.005). Collectively, our findings indicate that flavours can be used to motivate feed acceptance and improve the weight gain in lambs.