Susan G. Low, Sarita J. Bennett
Department of Environment & Agriculture, Curtin University. PO Box U1987 Perth, Western Australia 6845
Producers use a range of perennial fodder shrub species to remediate degraded and/or non-arable areas of farms in the wheatbelt of Western Australia. Fodder shrubs have been either been left ungrazed or traditionally used to fill the autumn feed gap for sheep in Western Australia. This trial aimed to evaluate the potential of fodder shrubs to reduce the potential effects of heat stress in breeding ewes and potentially reduce the negative impact of high temperatures on conception rates for summer joining flocks.
Two sites were used, a 25 year old saltbush planting and a 5 year old mixed native shrub planting. At each site, 4 temperature loggers were placed in shrubs at heights from 0.5 to 1.5 m above the ground with a control logger located on the adjacent fence. Maximum and minimum temperatures were recorded hourly across summer, autumn and winter. There was a significant difference (p<0.001) in maximum daily temperature between loggers at both sites with daily maximum temperatures reduced when compared to the control. Maximum temperature reduced by up to 1.5oC in the saltbush and by up to 3oC in the mixed species site within seasons.
Fodder shrubs have the potential to reduce heat stress on mating ewes by reducing ambient temperature during summer joining. Mixed plantings that include shrubs that have varied mature heights provide more shade than saltbush sites. Decreasing ambient temperature may result in increased ovulation rates, increased conception and lambing rates and improved lamb survival.