Studies of method of conserving grass herbage and frequency of feeding in cattle. 2. Eating behaviour, rumen motility and rumen fill.

The influence of the method of conserving grass herbage and the frequency of feeding on eating behaviour, rumen motility and rumen fill was studied in growing steers. Silage and hay were offered to twelve rumen-cannulated Friesian steers (average initial live weight (LW) 128 kg) at a restricted level of intake (20 g dry matter (DM)/kg LW) either once or eight times daily. With once daily feeding, the daily intake of hay was consumed in a single large meal which lasted about 2 h, while silage was eaten in many small meals throughout the day. The proportion of the day spent ruminating was higher (0.39) for steers offered hay once daily than for those offered silage (0.28) or hay eight times per day (0.29). There was little effect of conservation method on frequency of rumen contraction, but contractile intensity (integration of frequency and amplitude) increased during the second half of the 24 h feeding cycle in steers offered hay either once daily or eight times daily, while the same effect was only observed when silage was offered once daily. Total daily contractile activity (the integration of the frequency and duration of myoelectric spike bursts) was significantly (P less than 0.05) higher in steers offered hay, compared with silage, once daily. The mean weight of organic matter in the reticulo-rumen of steers offered hay was significantly higher than for silage both with once (1593 v. 1326 g organic matter (OM)/100 kg LW, P less than 0.01) and eight (1367 v. 1160 g OM/100 kg LW, P less than 0.05) times daily feeding. The proportion of the particulate pool which was present as small (less than 1.2 mm) particles was always greater than 0.60.