Abstract 593

Nefzaoui,-A; Marchand,-S; Vanbelle,-M

Universite Catholique de Louvain, Lab. Biochimie de la Nutrition, B - 1348 Louvain-la-Neuve, Belgium.

Proceedings of the International Colloquium on Tropical Animal Production for the Benefit of Man. 1982, 309-314; 22 ref. Antwerp, Belgium; Prince Leopold Institute of Tropical Medicine.

Under simulated drought and feed shortage conditions in Tunisia, 3 groups of 20 pregnant Barbary ewes had freely for 6 months rations containing 0, 35 or 70% olive pulp (as DM) in place of half or all of bran, also molasses 26, urea 2 and minerals 2%; 300 g straw was supplied daily. With 70% pulp ewes lost weight and birthweight of lambs, showing 25% mortality, was reduced. Testing on Thibar wethers indicated a negative effect of pulp on digestibility, especially of crude cellulose. In a crossover trial with 10 wethers, feed was of barley 83, field beans 15 and minerals 2%, or with 10-40% olive pulp incorporated at expense of barley. Digestibility of the ration was not impaired by use of up to 20% pulp. In a third trial 6 Texel sheep with rumen cannula had hay and 200 g concentrate daily. Olive pulp was ensiled alone or with 2-8% ammonia or 4-8% NaOH (1 kg pulp plus 0.5 litre solution), then lyophilized before testing of digestibility in situ. NaOH increased and NH3 in large doses reduced production of acetic and lactic acids, but butyric acid and (with NaOH) NH3 nitrogen were nil. With NH3 total and NH3 nitrogen increased. Among cell-wall constituents, NaOH acted mainly on hemicellulose and to some extent on lignin, about 66 and 50% being solubilized at the 8% level. NH3 did not appear to attack hemicellulose, but large doses induced delignification. Alkali treatment increased digestibility of DM by 20%.