Grassland management practice on Irish Thoroughbred stud farms

Abstract

Grass production and quality was monitored on ten farms over a twelve month period 2008–2009. The farms ranged in size from 40 to 230 hectares. A grazing management calendar was completed by the stud manager. Grass cover, total number of resident livestock at the beginning and end of each month and concentrate intake of the mares was recorded. Ten of the most intensely grazed paddocks on each farm were selected for monthly sampling. Grass quality (proportion of leaf, stem and dead material), composition (DM, protein and NDF) and pre, post and resident grazing heights were recorded. Data was analysed using non-parametric analysis in SPSS. Grass cover peaked in May (1,045 kg DM /ha) and was lowest in January (192 kg DM/ha). Grass cover estimates recorded in the summer were higher than estimates recorded during any other seasons of the year (P < 0.05). The horses grazed to heights ranging from 4.3 to 5.9 cm. Grass heights were higher in the pre grazing areas (6.4 cm) compared to both the resident (4.9 cm) and post grazing (3.9 cm) areas for all seasons (P < 0.05). Of the ten farms surveyed the average number of days grazing per hectare was 67. The highest proportion of leaf material was recorded during the month of April (68% leaf, 11% stem and 21% dead material). NDF content ranged from 420 g/kg in April to 526 g/kg in August. The lowest protein content was recorded in June (112 g/kg) ranging from 69 g/kg to 177 g/kg. This preliminary study provides baseline data on grass production, nutritive value and sward characteristics over a twelve month period under Irish growing conditions.