Optimum utilization of feed resources: model studies and farmers' practices in two villages in East Java, Indonesia

This paper presents studies on feed utilization in two Indonesian villages (Putukrejo and Kedungsalam) with large seasonal variation in availability of feeds. The model used calculates the effect of varying degrees of feed selection on the number of animals that can be fed ad libitum, the corresponding mean liveweight gain (MLWG) per animal and total liveweight production (TLWP) of the herd. Calculations assume that, if only part of the feed is used, the feeds giving the highest intake of metabolizable energy are selected first. When feeds were pooled for the whole year, 2976 AU (animal units) could be fed ad libitum in Putukrejo and 4443 in Kedungsalam, but maximum TLWP was obtained with a smaller herd size (HS; 2300 and 3800 AU, respectively), not using the poorest feeds. Without transfer of feeds from one month to another, the maximum number of AU that could be fed ad libitum each month varied from 583 to 4130 AU in Putukrejo and from 1446 to 11080 in Kedungsalam. The optimum constant HS, giving maximum TLWP for the whole year, varied with assumptions regarding transfer of feeds between seasons. With assumptions most closely reflecting farmers' practices, optimal HS was 1200 AU for Putukrejo and between 1900 and 3200 for Kedungsalam, with MLWGs of 199 and 131-159 g/AU per day respectively. This corresponded well with actual HS (1320 and 2985 AU, respectively) and actual MLWG (182 g per animal per day).