EFFECTS OF DIETARY THREONINE AND PROTEIN ON GROWTH PERFORMANCE AND CARCASS TRAITS OF WHITE PEKIN DUCK

Abstract

A 2×12 factorial experiment using 2 proteins (16.99%, 20.1%) and 12 total dietary threonine levels (0.46%, 0.52%, 0.58%, 0.64%, 0.70% and 0.76% of total Thr in low-protein diet and 0.54%, 0.60%, 0.66%, 0.72%, 0.78%, and 0.84% of total Thr in High-protein) was conducted to study the effects of dietary threonine and protein on growth performance and carcass traits of white pekin ducks from 1 to 21 days of age. Six hundred and twenty-four 1-day-old white Pekin male ducklings were randomly allocated to 36 pens with 8 birds per pen according to similar pen weight. There were 12 dietary treatments, consisting of six replicate pens. Weight gain, feed intake, and feed/gain of ducks from each pen were measured every week. At 21 days of age, two ducks were selected randomly from each pen, and slaughtered to evaluate the carcass quality. The results showed that in both the high and low-protein diets the threonine supplementation increased the feed intake, weight gain, and feed conversion ratio. Peak weight gain responses appeared in ducks fed the 0.67% and 0.79% threonine in both low and high-protein diets. Thr supplementation significantly affected feed/gain in the 2-3-week period (P≤0.05) and daily feed intake in the 3 weeks (P). Significant responses from Thr supplementation in both the low and high protein diet were observed for the leg meat, breast meat, and gizzard percentages. The optimal requirement of white Pekin ducks from 1 to 21 days of age was 0.00% for breast meat percentages. The results of our experiment are reported herein. Threonine supplementation has an impact on growth and carcass traits. An increase in dietary threonine had a significant impact on feed intake, weight gain, and feed-to-gain ratio during the 1-3-week period in both low and high-protein diets. Threonine supplementation did not have a significant impact on abdominal fat, liver, heart, spleen, and tibia percentages in both low and high-protein diets. However, there was a notable effect on gizzard percentages