Factors influencing pasture productivity in Atlantic Canada

Abstract

Most pastures in Atlantic Canada are classified as permanent and contain primarily native species. Well-managed native swards have the potential of supporting profitable animal output. Productive cultivars of cool-season perennial grass species such as timothy (Phleum pratense L.), orchardgrass (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.), reed canarygrass (Phalaris arundinacea L.) and legumes such as white clover can increase pasture productivity in the region and ameliorate seasonal fluctuations in dry matter yield associated with native swards. Improved swards gradually revert to native species, partly because forage cultivars and mixtures are not assessed for persistence under grazing.Soil acidity and deficiencies in soil nutrients were shown to reduce herbage yield, legume content of the grazed swards and mineral content of the herbage, all of which may adversely affect livestock performance. High concentrations of K, observed in swards heavily fertilized with N, are likely to cause problems in the metabolism of Ca and Mg in lactating ruminant livestock grazing such swards.Supplemental pasture crops, including annual ryegrass (Lolium multiflorum Lam.) and Brassica species, extend the productive grazing season from approximately 4 to 7 mo, and permit the production of large quantities of biomass close to the barn.Rotational grazing and forward creep-grazing techniques at high stocking rates can improve the number of animal grazing days and average daily gains. Previous experience with grazing and exposure to pasture species before and during weaning appear to influence grazing behavior and species preference of newly weaned livestock. The use of previous grazing experience may help create the desired pasture sward or improve the efficiency of sward utilization by the grazing animal. The high rainfall climate of the Atlantic region, which promotes good herbage production, also encourages heavy and prolonged infestations of infective free-living stages of gastrointestinal parasites on pastures. Permanent pasture is the main source of initial herd infection, which then spreads to newly seeded pastures. Strategic treatments of grazing livestock with anthelmintic drugs are recommended to minimize the impact of these parasites on the productivity of grazing livestock in this region. Key words: Pasture, Atlantic Canada, productivity, grazing management, fertility management, Brassica spp., grasses, legumes