COMMINUTION OF ROUGHAGES BY RED-DEER (CERVUS-ELAPHUS) DURING THE PREHENSION OF FEED

The chewing behaviour of red deer (Cervus elaphus) during eating and t he effectiveness of chewing on feed comminution was studied in two exp eriments. In Expt 1, deer were fed long or chopped lucerne (Medicago s ativa) hay, and feed intake and chewing activity were recorded. In Exp t 2, the rumen was emptied and test meals of fresh chicory (Cichorium intybus cv. Puna), lotus (Lotus corniculatus cv. Grasslands Goldie), r yegrass (Lolium perenne cv. Ruanui) forage and long lucerne hay were g iven, chewing activity recorded and the ingested forage quantitatively removed from the rumen. In Expt 1, the chopped hay was eaten more qui ckly than long hay (11.4 v. 8.3 g dry matter/min), and required fewer chewing bites per g dry matter eaten. In Expt 2, the four forages were consumed at similar rates (mean 4.3 g organic matter/min) and there w as no significant difference in the chewing required to consume either total organic matter (OM) or cell wall OM. Deer chewed more quickly w hen eating lucerne hay than when eating lotus, and it was estimated th at a greater number of chewing bites were required to form a bolus of lucerne hay than to form a lotus bolus. The proportion of ingested OM which was comminuted so as to pass a 1 mm sieve (efficiency of chewing ) was greater for lotus (0.485) and lucerne hay (0.518) than for chico ry (0.267). The efficiency of chewing ryegrass (0.366) was intermediat e and not significantly different from any other forage. For all forag es, the main effect of chewing during eating appeared to be the releas e of cell contents, rather than the comminution of cell wall. Physical breakdown to particles which passed a 1 mm screen but were retained o n an 0.25 mm screen was low for fresh forages (0.074-0.086) but was sl ightly higher for lucerne hay (0.127). Deer reduced feed particle size during eating with a similar efficiency to sheep, but were less effic ient than goats. It is suggested that the chewing effort associated wi th forage consumption by red deer is related to the need to form a bol us. The amount of chewing may be as much influenced by the physical ch aracteristics of the forage (e.g. leaf size and shape) as by its chemi cal composition, and the extent of comminution during eating may be de termined by the processing needed to form a bolus and the resistance o f the feed to bolus formation.