Effect of dietary metabolic energy on growth performance, blood homeostasis in ducks under heat stress-related climate change

ABSTRACT

Aim: This study was carried out to investigate the effect of dietary metabolic energy on growth performance, homeostasis of blood biochemical parameters, immunoglobulin G (IgG), and corticosterone in meat duck exposed to heat stress.Methodology: A total of 320 meat ducks (Cherry valley, Anas platyrhynchos) were randomly allotted into five groups. In all experimental treatment groups, dietary crude protein content was fixed at 18%. metabolic energy level for the control group (thermononeutral temperature, 26°C) was set at 3000 kcal kg-1, while metabolic energy levels for heat stress groups were set at 2900, 3000, 3100 or 3200 kcal kg-1. Heat stress conditions were artificially induced at 36°C with relative humidity of 70% once daily (from 1100 to 1600 hr) during finisher periods (day 22 to 42). Results: Compared to control group, heat stress groups with different metabolic energy showed significant decrease in body weight gain, feed intake, red blood cell, and platelets. Heat stress groups with different metabolic energies showed significant increase in feed conversion ratio, blood lipid profiles, aspartate aminotransferase, alanine transferase, electrolytes, pH, gas concentration, immunoglobulin G, and corticosterone compared to the control group.Among heat stress groups, red blood cells and platelets were significantly higher in the heat stress group with metabolic energy of 3000 compared to those in other groups. Blood IgG and corticosterone levels were significantly lower in 2900 and 3000 groups than those in heat stress groups with metabolic energy of 3100 and 3200. Interpretation: The results of this study suggest that dietary metabolic energy 3000 kcal kg-1 level can improve the growth performance of meat duck exposed to heat stress by modulating homeostasis of blood biochemical parameters.