Auteur: McCarthy B., Dineen M., Guy C., Coughlan F. and Gilliland T.
Jaar van uitgifte: 2015
An experiment to investigate the impact of tetraploid and diploid perennial ryegrass swards sown with and without white clover on the productivity of spring milk production systems was established in 2012 (75%) and 2013 (25%). Four separate grazing treatments/swards were sown for the experiment: tetraploid only, diploid only, tetraploid with clover and diploid with clover. Eight cultivars (four diploid: Tyrella, Aberchoice, Glenveagh and Drumbo; four tetraploid: Aston Energy, Kintyre, Twymax and Dunluce) were sown as monocultures with and without clover. Thirty cows were allocated to each treatment after calving in February 2014. All treatments were stocked at 2.75 cows ha‑1 and received 250 kg of nitrogen fertiliser ha‑1. There was no difference in milk or milk solids yield between the tetraploid-only (4,895 and 414 kg cow‑1, respectively) and diploid-only (4,848 and 403 kg cow‑1, respectively) swards. However, incorporating clover resulted in 13.3% greater milk yield and 13.4% greater milk solids yield (5,532 and 464 kg cow‑1, respectively, and 5,506 and 462 kg cow‑1, respectively, for the tetraploid with clover and diploid with clover treatments, respectively). Pasture dry matter (DM) production was 16.8% greater on the grass-clover swards (17,400 kg DM ha‑1) compared to the grass-only swards (14,900 kg DM ha‑1).