Causative factors influencing epizoochorous dispersal of weed seeds by sheep and associated carcass contamination in southern Australia

Abstract

Hordeum spp. (barley grass) and Bromus spp. (brome grass) are annual weed species that achieve long-distance seed dispersal via attachment to sheep, but also lead to sheep carcass damage due to the penetration of seeds into animal tissues. Range expansion of invasive weed populations predicted as a consequence of climate change may be associated with an increase in seed contamination incidence glob-ally. An examination of Australian abattoir data (2006)(2007)(2008)(2009)(2010)(2011)(2012), along with recent weed distribution patterns, indicates carcass contamination was associated with rainfall and abundance of key annual grass weeds, primarily Bromus spp. and Hordeum spp., although other factors may play a contributing role. Significant differences in seed contamination in slaughtered sheep were noted between states and regions, with widespread contamination occurring throughout all agro-ecological zones. Abattoir, sheep age and sex significantly influenced incidence, with contamination highest in adult males. Incidence increased with mean monthly rainfall, but declined with mean elevation, and significant interactions were noted between mean monthly temperature and state, and between mean elevation and year. Results show the need for vigilant recording of seed injuries in sheep to enhance weed surveillance efforts and effective integrated weed management of contributing annual grass weeds. K E Y W O R D Sannual grass weeds, Bromus, damage, Hordeum, livestock 222 |

Winter Forage Crop Harvest Time Impacts Regeneration of the Annual Weeds Barley Grass, Annual Ryegrass and Wild Radish

“…Agronomy 2021, 11, 1700 2 of 13 Barley grass is a relatively short-lived annual that provides high-quality grazing early in the season, but its seed heads cause contamination of wool and sheep carcases. Additionally, seeds cause irritation to the mouth, eyes and nose of sheep and other grazing livestock [7][8][9][10], and it is also a host for cereal pathogens. Annual ryegrass is a desirable pasture plant, producing substantial yields of high-quality grazing, but it is also a major weed of broadacre winter crops [11].…”