Synchronous Least-Cost Ration Formulation for Lactating Barki Ewes using Nonlinear Programming

Least-cost procedures do not always produce the most practical rations for ruminants. The aim of this work was to incorporate the concept of synchronizing ruminal energy and protein digestion in the traditional leastcost procedure, in order to produce more appropriate and practical rations for lactating Barki ewes. The degree of dietary nutrient synchrony is measured using the synchrony index (SI) reported by Sinclair et al., (1993). In a preliminary study, degradation kinetics of seven commonly used feedstuffs were estimated using nylon bag technique. The observed patterns of crude protein (CP) and organic matter (OM) degradability of feedstuffs were largely varied and greatly depend on the rumen outflow rate (fraction/h). We developed a new userfriendly software application ‘Lacto-sheep’ based on the C# language and the. NET Framework 4.0 to facilitate the processes of ration formulation. Simplex and Hybrid local search solvers in Microsoft Solver Foundation 3.1 have been used to solve both linear and nonlinear programming models, respectively. Example synchronous least-cost ration (SLCR) and least-cost ration (LCR) formulations of 35.46 kg (body weight) lactating ewe based on the NRC recommendation is presented. SLCR and LCR showed two different patterns of N/OM release within a day. The calculated SI was about 0.87 and 0.60, respectively. As cost is often a limiting factor in the traditional least cost ration formulation therefore, LCR did not contain any source of protein-rich sources. We conclude this synchronous least-cost procedure is more appropriate to produce practical rations.