Loading...
Milk production per cow and per hectare of spring-calving dairy cows grazing swards differing in Lolium perenne L. ploidy and Trifolium repens L. composition
McClearn, B. Gilliland, T.J. Delaby, L. Guy, C. Dineen, M. Coughlan, F. McCarthy, B.
McClearn, B.
Gilliland, T.J.
Delaby, L.
Guy, C.
Dineen, M.
Coughlan, F.
McCarthy, B.
Citations
Altmetric:
Date
2019-09
Collections
Files
Loading...
main article
Adobe PDF, 547.74 KB
Research Projects
Organizational Units
Journal Issue
Citation
McClearn, B. Gilliland, T.J., Delaby, L., Guy, C., Dineen, M., Coughlan, F., McCarthy, B. Milk production per cow and per hectare of spring-calving dairy cows grazing swards differing in Lolium perenne L. ploidy and Trifolium repens L. composition, Journal of Dairy Science, Volume 102, Issue 9, 2019, https://doi.org/10.3168/jds.2018-16184
Abstract
Grazed grass is the cheapest feed available for dairy
cows in temperate regions; thus, to maximize profits,
dairy farmers must optimize the use of this high-quality
feed. Previous research has defined the benefits of
including white clover (Trifolium repens L.) in grass
swards for milk production, usually at reduced nitrogen
usage and stocking rate. The aim of this study was to
quantify the responses in milk production of dairy cows
grazing tetraploid or diploid perennial ryegrass (Lolium
perenne L.; PRG) sown with and without white clover
but without reducing stocking rate or nitrogen usage.
We compared 4 grazing treatments in this study: tetraploid
PRG-only swards, diploid PRG-only swards,
tetraploid with white clover swards, and diploid with
white clover swards. Thirty cows were assigned to each
treatment, and swards were rotationally grazed at a
farm-level stocking rate of 2.75 cows/ha and a nitrogen
fertilizer rate of 250 kg/ha annually. Sward white clover
content was 23.6 and 22.6% for tetraploid with white
clover swards and diploid with white clover swards, respectively.
Milk production did not differ between the
2 ploidies during this 4-yr study, but cows grazing the
PRG-white clover treatments had significantly greater
milk yields (+596 kg/cow per year) and milk solid
yields (+48 kg/cow per year) compared with cows grazing
the PRG-only treatments. The PRG-white clover
swards also produced 1,205 kg of DM/ha per year more
herbage, which was available for conserving and buffer
feeding in spring when these swards were less productive
than PRG-only swards. Although white clover is
generally combined with reduced nitrogen fertilizer use,
this study provides evidence that including white clover
in either tetraploid or diploid PRG swards, combined
with high levels of nitrogen fertilizer, can effectively
increase milk production per cow and per hectare