Management of browse plants as drought fodder for sheep: a preliminary study

Abstract

Two experiments were designed to provide practical guidelines to improve the effective use of browse plants as ruminant feed, especially during dry summers. The effects of planting stock and cutting management on forage yield and quality of Tangoio hybrid willow (Salix matsudana x alba), Kinuyanagi willow (Salix kinuyanagi) and erect dorycnium (Dorycnium rectum), a small leguminous shrub, were determined over one summer from 1- and 3-year-old trees. Experiment 1 was arranged as a 2×2 factorial with 2 species and 2 planting stock in 5 randomised complete blocks. Experiment 2 was also arranged as a split plot design with cutting heights allocated to main plots and species × frequency to sub-plots in 3 randomised complete blocks. At the hill country site (Ballantrae), the yields of Tangoio (66 g DM/tree) and Kinuyanagi (27 g DM/tree) were low, owing probably to the low soil nutrient status and the harsh climatic conditions. Poor regrowth after the summer harvest at Ballantrae suggested that willows can be utilised only once during the growing season in such environments. At the lowland site (Aokautere), Tangoio was higher yielding (P<0.05) than Kinuyanagi, with erect dorycnium the lowest yielding. Erect dorycnium was ineffective as drought fodder in the Manawatu owing to its relatively low yield. Tree forage digestibility and total nitrogen content were higher in Tangoio than Kinuyanagi (P<0.05) but were not affected by stock type and cutting height. Harvesting twice during the growing season increased the edible forage yield by 27% (P<0.05). Total condensed tannin content was higher in Kinuyanagi than Tangoio, a possible disadvatange. Unrooted stem cuttings were as productive as rooted cuttings (P>0.05) and are cheaper to establish. Tangoio and Kinuyanagi have potential as drought fodder in addition to their traditional roles in soil conservation and rehabilitation. Keywords: browse, cutting management, Dorycnium rectum, multipurpose trees, planting stock, Salix kinuyanagi, Salix matsudana x alba