Intensive milk production system based on irrigated permanent pastures in the south of Chile. II Dry matter production, intake and a proposed test to evaluate pasture management

Abstract

In this study, dry matter (DM) production, intake, and DM conversion efficiency into milk in a closed production system with permanent grassland under irrigation are estimated. Due to errors in the estimation of DM using the direct sward clipping method (CD), the indirect net energy method was used. Along with a detailed calculation of the procedure, several options for “harvesting cost” according to the guidelines indicated by Fox et al. (1990) are presented. For this study, the factor 0.40 was applied. If one starts from actual production and calculates its ENL content, that energy produced should have been consumed. Additionally, if the DM to milk conversion curve is used during the grazing period, monthly, quarterly or average factors can be calculated. In this study, the average factor was 1.45 Mcal EN_L kg^-1 DM. By applying these concepts, it was possible to establish that the average DM production per hectare was 17,009 kg, the average daily consumption per cow mass was 16.5 kg and the average consumption per 100 kg of live weight was 3.1 kg. The consumption per W^0.75 was 0.149 kg, with a DM conversion efficiency to milk of 1.05:1. Additionally, the net energy method has a low interannual coefficient of variation (5.69%), a value that supports the validity of the result. As a measure to establish the quality of grazing management, the correlation between cow days and milk production is proposed, which in this study was 0.975.