Effects of reduced time on pasture caused by prolonged walking on behaviour and production of Mpwapwa Zebu cattle J. Jung, J. Yngvesson and P. Jensen Swedish University of Agricultural Sciences, Department of Animal Environment and Health, Section of Ethology, Skara, Sweden Abstract In many African countries, cattle are often allowed to graze only during the daytime and the daily walk to pasture limits time for foraging. Two groups of cattle were allowed access to pasture for 9 h or 5 h associated with a daily walk of 0Æ5 h or 4Æ5 h respectively. Each treatment period lasted for 14 days in a cross-over design. Observations of behaviour were carried out for 8 days in each treatment period. When only 5 h were allowed at pasture, the animals grazed less (0Æ61 vs. 0Æ66 of time) compared with the first 5h of the 9h treatment. The average daily milk yield was 323 g (0Æ078) higher when 9 h were allowed on pasture (P <0Æ05 during the second week of treatments). There were no differences in milk yield after the end of the treatments. The daily liveweight gain was 250 g higher when the animals were on pasture for 9 h. These differences could be due to the limited time on pasture or to energy requirements for the walk to pasture. It is concluded that increasing the walking time and redu- cing time on pasture may compromise animal welfare and performance under the experimental conditions, i.e. on poor quality pastures in a warm humid climate where the main period at pasture is in the middle of the day. Keywords: Bos indicus cattle, restricted suckling, walk- ing, limited time on pasture, behaviour, production Introduction In many developing countries the increasing human population leads to a higher demand for land for crop production and pasture (Harrison, 1993). The limited access to grazing land close to the village forces the pastoralists to walk with the livestock to distant pastures. The quality of the grazing land available for farm animals may decline because of overgrazing and also the best land near the villages is increasingly used for crop production (Nicholson, 1984). In many African countries, cattle on traditional farms are only allowed to graze during the daytime, resting at night in an enclosure usually without access to forage (Bayer, 1990). As the time available for walking to and from pasture and for grazing is limited to the hours between milking, longer walking distances reduce the remaining time for grazing on pasture, because the vegetation available during walking is often unsuitable for con- sumption by the animals. Reduced time for grazing limits the productivity of cattle, depending on the degree of restriction of grazing time (Sinkovic, 1977; Bayer and Otchere, 1985; Leaver, 1986; Homewood et al., 1987). However, Bayer (1990) concluded that some restriction of grazing time is not a severe limitation, as cattle can compensate through increased grazing efficiency. Cattle that have access to pasture during daytime prefer to forage in the early and late hours of the day, with the middle of the day used mainly for resting and ruminating (Lewis, 1975; Arnold, 1985). When the animals have to walk for longer distances to and from pasture, the remaining time on the pasture is not only shorter but also occurs in the warmest part of the day. High temperatures and humidity can also limit food intake (see Arnold, 1985). Intensive exercise reduces milk yield in Bos taurus cows (Pasierbsky and Leoniuk, 1977; Thomson and Barnes, 1993; D’Hour et al., 1994; Coulon and Garel, 1996). Bos indicus steers in Kenya required 0Æ49 more food to maintain their live weight when they walked Correspondence to: Dr J. Jung, Swedish University of Agricultural Sciences, Department of Animal Environment and Health, PO Box 234, SE-532 23 Skara, Sweden. E-mail: jens.jung@hmh.slu.se Received 29 October 1999; revised 15 June 2001 Ó 2002 Blackwell Science Ltd. Grass and Forage Science, 57, 105–112 105