Lysolecithin Improves Broiler Growth Performance through Upregulating Growth-Related Genes and Nutrient Transporter Genes Expression Independent of Experimental Diet Nutrition Level

SIMPLE SUMMARY: Lysolecithin derived from hydrolysis of soy lecithin has been widely used as emulsifier in the feed industry to improve growth performance of farm animals for some time. The components of Lysolecithin have proved to have multiple functions, but the real mechanism of action of Lysolecithin on growth promotion in the animal is still unclear. To investigate how it works, we executed this trial. The results show that, besides improving growth performance of broilers, supplementation of Lysolecithin also improved ileal digestibility of amino acids. Further studies found that nutrient (amino acids and fatty acids) transporter genes in the small intestine and growth-related genes in the liver and muscle of broilers were significantly upregulated by supplementation of Lysolecithin independent of experimental diet nutrition level. Upregulating the nutrient transporter gene and growth-related gene expression of the host might be the action mechanism of lysolecithin on growth promotion in animals. By understanding its mechanism of action, researchers can develop new feed additives with better function and lower cost to promote the growth of farm animals and meet the ever-growing need for animal protein in the future. ABSTRACT: We investigated the effect and interaction of lysolecithin (LPL) and nutrition level on growth performance, nutrient ileal digestibility, expression of growth-related genes and nutrient transporter genes in broilers. A total of 1280 one day old Ross 308 mixed sex chicks with an average body weight 42.23 ± 2.4 g were randomly allotted into 2 × 2 factorial arrangement (20 replicates per treatment and 16 chickens per replicate) with two types of diet (Normal nutrition treatments starter, grower and finisher diets with ME of 3000 kcal/kg, 3100 kcal/kg and 3200 kcal/kg, respectively, and CP level of 22%, 21%, and 20%, respectively; high nutrition treatments diets with 50 kcal/kg ME and 0.5% CP higher than normal nutrition treatment at each stage). Two levels of LPL supplementation (0 and 500 mg/kg) were also employed. From day 21 to day 35 and full stage of the experiment, the birds fed a high nutrition (HN) diet had a greater body weight gain (BWG) and lower feed conversion ratio (FCR) than those fed a normal nutrition (NN) diet (p < 0.05). Besides, lysolecithin increased BWG significantly (p < 0.05). The birds fed a diet with LPL revealed increasing fat digestibility compared to birds fed the basal diet (p < 0.05). LPL significantly increased the ileal digestibility of amino acids, including Ile, Thr, Phe, His, Arg, Tyr, Glu, Pro, Gly, Ala (p < 0.05). No interaction was found between LPL and nutrition level in BWG, FCR and nutrient digestibility. In HN diet, the genes expression of myogenic differentiation 1 (MYOD1), myogenin (MYOG), cluster of differentiation 36 (CD36), fatty acid-binding protein (FABP1), cationic amino acid transporter 1 (CAT1) and Y + L amino acid transporter 1 (y+, LAT1) were significantly elevated via LPL supplementation (p < 0.05). In NN diet, LPL significantly increased the genes expression of growth hormone (GH), insulin-like growth factor 1 (IGF1), MYOD1 and y+, LAT1 (p < 0.05). In conclusion, upregulating the nutrients transporter gene and growth-related gene expression of the host, independent of nutrition level changes, may be the action mechanism of lysolecithin on growth promotion in animals.