Expression of intestinal amino acid transporters, gut morphology, and amino acid digestibility in pigs fed proteins or free amino acids

International audienceDietary amino acids (AA) supplied as protein or in free form are digested and absorbed at different rates which can induce differences in gut physiology, like digestive and absorptive capacities, and metabolism. We compared the AA digestibility, expression of AA transporters, and gut morphology of pigs fed diets providing different forms of AA. Growing pigs (n = 30; 33.7 ± 4.1 kg) were fed one of the three experimental diets that provided AA as intact feather meal (INT), as free AA by extensive hydrolysis of feathers (HYD), or as synthetic AA with the same AA profile as HYD (FAA). Pigs were fed the same quantity of feed, energy, and AA. After 14 days, pigs were slaughtered 3 hours after feeding the experimental diet with indigestible markers. Digesta and tissue were collected from different sections of the small intestine. Jejunal digesta was used to measure AA digestibility as there was not enough ileal digesta during collection. Duodenum, jejunum, and ileum samples were analysed for expression of intestinal AA transporter genes and gut morphology. The AA digestibility from INT was lower compared to HYD and FAA (P < 0.05). Digestibility of Cys, Gly, Pro, and Thr was lower for FAA compared to HYD (P < 0.05). Crypt depth in the jejunum was lower (P < 0.01) and villi area in the ileum was higher (P < 0.05) for HYD suggesting greater surface for digestion and absorption. In the duodenum, INT expressed more PepT-1 (P < 0.01), while HYD expressed more CAT-1 (P = 0.04). Furthermore, HYD expressed more ASCT2 (P = 0.02) and CAT-1 (P = 0.04) in the jejunum compared to other treatments. The expression of these transporters along the intestine depended on the relative abundance of dietary absorbable AA. Results showed that the dietary AA form influences the expression of different AA transporters and morphology of the small intestine, which can impact AA absorption and bioavailability for peripheral tissues

Leafamine&reg;, a Free Amino Acid-Rich Biostimulant, Promotes Growth Performance of Deficit-Irrigated Lettuce

Water deficit causes substantial yield losses that climate change is going to make even more problematic. Sustainable agricultural practices are increasingly developed to improve plant tolerance to abiotic stresses. One innovative solution amongst others is the integration of plant biostimulants in agriculture. In this work, we investigate for the first time the effects of the biostimulant &ndash;Leafamine&reg;&ndash;a protein hydrolysate on greenhouse lettuce (Lactuca sativa L.) grown under well-watered and water-deficit conditions. We examined the physiological and metabolomic water deficit responses of lettuce treated with Leafamine&reg; (0.585 g/pot) or not. Root application of Leafamine&reg; increased the shoot fresh biomass of both well-watered (+40%) and deficit-irrigated (+20%) lettuce plants because the projected leaf area increased. Our results also indicate that Leafamine&reg; application could adjust the nitrogen metabolism by enhancing the total nitrogen content, amino acid (proline) contents and the total protein level in lettuce leaves, irrespective of the water condition. Osmolytes such as soluble sugars and polyols, also increased in Leafamine&reg;-treated lettuce. Our findings suggest that the protective effect of Leafamine is a widespread change in plant metabolism and could involve ABA, putrescine and raffinose