Abstract. Twenty Friesian cows in four pens were arranged in a 4x4 Latin Square with a 2 x 2 factorial arrangement of treatments to evaluate the effect of barley fibre with solubles and dried distillers solubles (DDS) as a protein supplement on silage intake and milk production. Each experimental period lasted 4 wk, during which the cows were given ad libitum silage with one of the four supplements: barley (B), barley + DDS (BD), barley fibre (F) and barley fibre + DDS (FD). All the supplements were given at the rate of 7.5 kg/day on dry matter (DM) basis. In cows given DDS, 0.9 kg of barley or barley fibre was replaced by DDS on DM basis. The principal carbohydrate constituent of the B supplement was starch and of the F supplement hemicellulose.Silage DM intake was 0.38 kg/day (P<0.05) higher for cows given F diets but the total DM intake was not significantly affected by the diet given.Milk yield was 2.2 kg/day (PcO.OOl) higher in cows given F diets than B diets. But milk fat content was lower (P<0.001), and as a result milk fat yield was slightly higher (805 v. 787 g/day), with B diets. F diets were also associated with a lower (P <0.05) protein concentration in milk, but because of the higher yield, milk protein yield was 8.3 % (P<0.001) higher than in B diets. Feeding F diets increased milk lactose content (P<0.05) and lactose yield (P< 0.001) relative to B diets. Live weight gain was higher (P<0.05) for cows given B diets. DDS supplementation had no significant effect on feed intake, milk production or milk composition. Cows given DDS increased their live weight less (PcO.OI) than those fed without DDS.Despite the smaller amount of ME available for production, milk energy yield was higher (Pc0.05) in cows given F diets, indicating a shift in energy partioning towards milk instead of body tissues. Estimates of the efficiency of utilization of ME for milk production were higher for cows given F diets than for those given B diets both including and ignoring live weight change in the calculations.The results show that barley fibre with solubles, despitea lower digestibility than barley, can produce more milk and protein and a similar yield of milk fat provided that silage is given ad libitum.

Abstract. A duplicated 4x4 Latin Square experiment was conducted to determine the effects of a gradually increased level of barley fibre in the diet on ad libitum grass silage intake and milk production. Barley fibre is a fibrous ethanol-starch by-product (120 g crude protein, 550 g neutral detergent fibre (NDF) and 120 g starch/kg dry matter (DM)). The four supplements, given at the rate of 6.5 kg/d on DM basis, were barley (B) and barley of which 333 g/kg (BF), 667 g/kg (FB) and 1000 g/kg (F) were replaced by barley fibre. In addition the cows were given I kg of rapeseed meal and 0.25 kg of mineral mixture.As the proportion of barley fibre in the diet increased there was a linear (P<0.001) increase in silage DM intake. The cows ate less concentrate at the higher levels of barley fibre inclusion, so that there was a tendency for higher total DM intake only when the intermediate levels of barley fibre (diets BF and FB) were given (quadratic effect; PcO.I).Milk yield and fat corrected milk yield were not significantly affected by the level of barley fibre. However, as the proportion of barley fibre in the diet was increased, milk protein content decreased (linear effect; P<0.01), there was a trend towards lower milk fat content (linear and quadratic effect; P