MANIPULATION OF GROWTH, CARCASS COMPOSITION AND FATTY-ACID CONTENT OF MEAT-TYPE DUCKS USING SHORT-TERM FEED RESTRICTION AND DIETARY ADDITIONS

Experiments are described in which 6 groups of male ducklings were fed (i) ad libitum or (ii) restricted to a maintenance feed allowance at 6 d of age for 4 d or (iii) for 5 d or (iv) to 2 d restriction, 2 d ad libitum feeding, 2 d restriction and thereafter ad libitum feeding or (v) given 0.05% theophylline at 17 d of age or (vi) 0.4 ppm cimaterol and grown to 44 d of age. Eight additional ducks were divided into two groups and given in the diet either 3.5% linseed oil or 3.5% maxepa (fish) oil at 22 of age, increasing to 7% at 36 d of age. A finisher diet was given to all groups at 17 d of age. Ducks given theophylline grew slower (66 g/d) than the controls (73 g/d) with a poorer feed efficiency. Carcass fat of ducks on cimaterol was 17.9%. This was less than ducks restricted fed (> 20.4%). Linseed oil and maxepa oil in the diet modified lipid in duck carcass, with small increases in omega 3 + 6 longchained polyunsaturated fatty acids. The amino acid composition of duck mince (g/kg) was similar to that of the chicken but when expressed as g/16 g N was generally higher than that of the turkey. Comparisons were made of amino acid patterns relative to lysine in protein tissue of different poultry species. Retention of some amino acids was calculated and compared with those for the chicken.