The feeding value of a perennial lupin-cocksfoot pasture compared with lucerne for sheep

Abstract

The aim of this study was to determine the feeding value of perennial lupin-cocksfoot pasture compared with lucerne for sheep. Lupin-cocksfoot and lucerne pastures sown on the 5th of December 2013 were rotationally stocked with Merino lambs over autumn (11 March – 19 May) and Coopworth hoggets over spring (5 August – 20 October) in 2014 at Lincoln University, Canterbury. The Merino lambs grew faster (32 g/day) on the lucerne in autumn because the lambs consumed more high quality leaf material in this pasture than in the lupin-cocksfoot pasture. The nutritive analyses of total herbage on offer in the lucerne and lupin-cocksfoot pastures indicated that dry matter digestibility (DMD), crude protein and metabolisable energy (ME) contents were similar in autumn. However, the DMD, crude protein and ME contents varied greatly between the separated fractions, but the nutritive value of leaves was similar for lupin and lucerne. In spring, the Coopworth hoggets grazing on lucerne had a higher growth rate (365 vs. 262 g/day), stocking rate (30.8 vs. 19.7 sheep/ha) and liveweight gain per hectare (333 vs. 177 kg/ha) than on the lupin-cocksfoot pasture. These differences were associated with greater DM yield (2520 vs. 2100 kg DM/ha), pasture allowance (3.2 vs. 2.4 kg DM/head/day) and apparent DM intake (2.4 vs. 1.8 kg DM/head/day) for lucerne than lupin-cocksfoot. The nutritive analyses in spring were consistent with the results from autumn. Sheep showed a grazing preference for the highly digestible fractions than lower quality fractions of both swards. Lupin forage is known to contain low concentrations of alkaloids making them sour-tasting to sheep. However, the sheep in this study appeared to adapt to the taste of the lupins and they consumed lupin leaf in the first few days after they were put into a paddock of lupin-cocksfoot. Therefore, this study has shown that perennial lupins are a viable forage option for where other conventional forage legumes such as lucerne cannot be grown.