Effect of betaine as an osmolyte on broiler chickens exposed to different levels of water salinity

Abstract. This trial was conducted to examine the effect of betaine on performance, humoral immunity, small intestinal morphology and blood osmotic pressure parameters of broiler chicks consumed different levels of water salinity. Total of 520 day-old broiler chicks (Ross 308) were used with 2×4 factorial arrangement in completely randomized design. Experimental treatments were consisting of 2 levels of betaine supplementation (0 and 1.5 g/kg) and 4 levels of total dissolved solids (TDS) (250, 1 500, 3 000, 4 500 ppm). In this trial daily feed intake (DFI), daily weight gain (DWG) and feed conversion ratio (FCR) were recorded on days 14, 28 and 48. Small intestinal morphology was evaluated at the age of 28. Humoral immunity was assessed by evaluation of antibody titre against sheep red blood cells (SRBC) and also Newcastle and influenza antigens. At the end of the experiment, blood was taken and concentration of plasma Na, K, Cl and haematocrit blood percentage was determined. Results showed that DWG significantly decreased and FCR increased in 4 500 ppm of water TDS in growing, finishing and whole period of broilers production (P<0.05). Furthermore increased plasma Na and blood hematocrit percentage observed in 4 500 ppm of water salinity (P<0.05). Betaine significantly increased DFI during growing phase (P<0.05). Betaine supplementation substantially increased antibody titre against influenza and also bursa of fabricius relative weight (P<0.05). Additionally, betaine inclusion increased villi height in ileum (P<0.05). In conclusion, increasing trend of water TDS affect chickens performance and betaine supplementation is able to improve antibody titre against influenza.