Abstract
ABSTRACT This study was conducted to establish dietary threonine (Thr) levels for Linwu ducks, aged 4 to 8 wk. Experimental diets formulated to contain 0.56, 0.61, 0.66, 0.71, 0.76, and 0.81% Thr fed to Linwu ducks. A total of 360 healthy Linwu female ducks with similar body weight (1183.89±3.83 g) were randomly divided into six groups, with five replicates in each group, and 12 ducks in each replicate. Samples were collected at 8 wk for the determination of growth performance, carcass traits, visceral organ indices, and serum biochemical parameters. As a result of this study, Thr level had no significant influence on the final weight, the daily gain, feed/gain ratio, and average daily intake (p>0.05). Similarly, there were no significant effects of dietary Thr on carcass traits and visceral organ indices (p>0.05). The pancreatic index was highest among all the treatments when the dietary Thr level was 0.66%. The different dietary Thr levels had no significant effect (p>0.05) on the concentration of total protein (TP), triglyceride (TG), total cholesterol (TC), glucose (GLU), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-Px), and glutathione (GSH). However, the serum MDA concentration in the 0.66% treatment was lower (P=0.068) than in the other treatments. In conclusion, Thr at 0.66% concentration may have an antioxidant activity and exert positive effect on Linwu ducks.
Highlights
Threonine (Thr) is an essential amino acid in poultry diets
Baeza & Leclercq (1998) designed an experiment to assess the effects of Thr supplementation in finishing diets used for raising Muscovy ducks and found that Thr requirement was greater than 3.5 g/kg and less than 4.5 g/kg
feed:gain ratio (F/G) was gradually reduced with the increase in dietary Thr levels; the value of F/G was minimum when the dietary Thr level was 0.76%
Summary
Threonine (Thr) is an essential amino acid in poultry diets. It is the third most limiting amino acid and plays an important role in animal growth and development (Ayasan et al, 2009; Canogullari et al, 2009; Xie et al, 2014). Thr is a typically deficient amino acid in corn, sorghum and soybean meal based rations and it becomes one of the major factors in limiting the birds’ performance (Kidd, 2000). Supplementation of Thr in the diets of broiler chicks and white Pekin ducklings was reported to improve their growth performance (Horn et al, 2010; Ayasan & Okan, 2011). Thr did not affect the relative percentages of liver, thigh, and gizzard in Ross 308 broiler chicks (Estalkhzir et al, 2013). Baeza & Leclercq (1998) designed an experiment to assess the effects of Thr supplementation in finishing diets used for raising Muscovy ducks and found that Thr requirement was greater than 3.5 g/kg and less than 4.5 g/kg
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