Three completely randomised design experiments examined the effects of the inclusion of three seaweed species (Ruppia sp., Ulva sp. or Chaetomorpha sp.) into the diet on digestibility and nitrogen balance in Barbarine sheep. Diets were composed of oat hay ad libitum supplemented with 600 g of concentrate. Seaweeds were incorporated into the concentrate at increasing levels (0, 200, 300 or 400 g seaweed kg−1 concentrate, dry matter (DM) basis) in replacement of other ingredients. Feed intake and water consumption were increased (P 0.001) organic matter digestibility from 0.637 with the control diet to 0.599 with the diet containing 400 g Ulva kg−1 concentrate. In all the experiments, nitrogen balance was positive and there were no differences among levels of seaweed supplementation in N retention or daily weight gain. These results suggest that seaweeds such as Ruppia, Ulva or Chaetomorpha can be incorporated into sheep concentrates up to 30% (DM basis) without adverse effects on feed digestibility or growth performance.

The authors are grateful to the contribution of the director and the workers in the livestock industry of Tabarka (North of Tunisia). Special thanks to Mr. Boussbiaa and Mr. Mabrouk for their involvement.

9 páginas, 5 tablas.