Effects of dietary protein level during rearing period and age at overfeeding on magret and foie gras quality in male mule ducks

Abstract

The aim of this trial was to study the effects of dietary protein content during the rearing period on the performance of mule ducks, according to age at overfeeding (O). Ducks (n = 612) were divided into four groups differing in the protein content in the diet offered during the starting period (S, 0-20 days; S_l vs. S_h : 150 vs. 175 g/kg crude protein (CP)) and growing-finishing period (GF; 21-67 or 81 days, depending on age at O; GF_l vs. GF_h : 133 vs. 152 g/kg CP). The relative weight of pectoral muscle was lower when ducks were fed a low protein diet during S (-5%, P < 0.01) or GF period (-6%, P < 0.001) at 68 days and higher in ducks of the S_l GF_h group (+6%; P < 0.05) at 82 days. Both foie gras and magret weights fell when ducks were fed S_l or GF_l (P < 0.05 and < 0.01). Mortality during the O period was higher in ducks fed the S_l diet and overfed at late age (7.4% vs. 0%; P < 0.01). In conclusion, a reduction in the dietary protein supply should be recommended only during the GF period for ducks overfed at a late age.

Keywords: age; dietary protein; male mule duck; overfeeding; performance.