Effects of diets with Amaranthus dubius Mart. ex Thell. on performance and digestibility of growing rabbits

Abstract

The effects on performance and digestibility in growing rabbits were studied by comparing 3 diets containing increasing inclusion rates of amaranth (Amaranthus dubius Mart. ex Thell.): 0 (A0), 160 (A16) and 320 g/kg (A32 diet). Diets were formulated isoproteic and isocaloric to meet the nutrient requirements of growing rabbits. One hundred and thirteen weaned New Zealand White rabbits (mean±standard deviation weight: 760±102 g), individually caged, were randomly assigned to one of the 3 experimental diets. Rabbits were fed ad libitum from 35 to 87 d of age, and health status and performance traits were onitored. The coefficients of total tract apparent digestibility of the diets were measured between 42 and 46 d of age in 12 rabbits per treatment. Amaranthus dubius contained 209 g/kg dry matter (DM) of crude protein and 398 g/kg DM of neutral detergent fibre. There were no significant differences between treatments in weight gain (mean 21.6 g/d) and live weight at the end of the fattening period (mean 1883 g). Daily feed intake was higher (P<0.05) in A0 than in A16 and A32 diets (85.4 vs. 73.7 and 69.9 g/d, respectively), and feed conversion rate improved with increased inclusion of A. dubius in the diet (from 3.84 to 3.28 for A0 and A32 diets, respectively; P<0.05). Health status was not affected by the amaranth inclusion rate. Total tract apparent digestibility showed high values, with no differences among diets except for ether extract. Thus, A. dubius could be considered as an alternative source of protein and fibre for rabbit feeding in tropical and subtropical regions.