Effects of vitamin A on growth performance and tissue retinol of starter White Pekin ducks

A dose-response experiment with 8 supplemental vitamin A levels (0, 500, 1,000, 1,500, 2,500, 3,500, 7,000, and 14,000 IU/kg) were conducted to examine the effects of vitamin A on growth performance and tissue retinol of starter White Pekin ducks. A total of 512 one-day-old male Pekin ducks were randomly divided into 8 treatments and each treatment contained 8 replicate pens of 8 ducks. All these ducks were reared in raised wire-floor pens from hatch to 21 D of age. At 21 D of age, growth performance and retinol concentration in plasma and liver were measured. Among all ducks, the birds fed basal diet with no supplemental vitamin A had the lowest weight gain, feed intake, and plasma and liver retinol (P < 0.05). As supplemental vitamin A increased, weight gain and feed intake increased quadratically (P < 0.05) and plasma and liver retinol increased linearly or quadratically (P < 0.05). The weight gain and plasma retinol showed broken-line response to increasing supplemental vitamin A (P < 0.05). According to broken-line regression, the minimum supplemental vitamin A requirements for weight gain and plasma retinol were 2606 and 4371 IU/kg, respectively. It was concluded that vitamin A deficiency could lead to a reduction in growth performance and tissue retinol retention and plasma or liver retinol was available biomarker to assess duck vitamin A status.