Sumbawa Island in Nusa Tenggara Province is one of the main cattle-producing areas in eastern Indonesia. In 2017 the cattle population in Sumbawa was around 350,000 head ( Dinas Peternakan Report 2017). Most cattle are raised in a traditional free-grazing system, where they are released to roam at will and find their own feed, which is obtained mainly from communal grassland and fallow land. Owing to the strongly seasonal rainfall in Sumbawa the production and availability of forage for cattle fluctuate during the year. While the annual rainfall is 1,400 mm, 88% falls in the months of November–April. Both availability and quality of feed in the dry season are poor. Availability of fallow land for grazing has been reduced as a result of the construction of a water reservoir, which is used to irrigate rice fields, resulting in more intensive use of land for rice and maize cultivation. In addition, communal grazing lands are being progressively invaded by weedy plants, such as