Using Mobile Ad Hoc Networks (MANETs) for monitoring bovine animals potentially offers high increase in the profitability of cattle production. In this paper we propose a formal model for the cattle monitoring system. Then we formulate the requirements for the MANET routing protocol for such systems. We identify a suitable MANET routing protocol that satisfies these requirements and adapt it to our scenario. We propose optimizations to this protocol that utilize heterogeneity of the power constrains of the wireless nodes. More precisely we make a trade-off between the power utilized by animal mounted devices and fixed sinks where they upload the collected and processed data. We also save energy on flooding based route discovery for the cost of graceful degradation of data delivery time by utilizing passive detection of temporary availability of sink routes. Finally we show in the simulation that the proposed approach is feasible and the proposed optimizations considerably decrease the energy consumption and increase scalability in terms of density and number of wireless nodes. This is important considering size and range of stocking densities of modern farming enterprises.