Effects of date of autumn closing and timing of winter grazing on herbage production in winter and spring

Abstract

Growth of grass herbage in Ireland is highly seasonal with little or no net growth from November to February. As a result, feed demand exceeds grass supply during late autumn, winter and early spring. At low stocking rates [£2 livestock units (LU) ha )1 ], there is potential to defer some of the herbage grown in autumn to support winter grazing. This study examined the effects of four autumn-closing dates and four wintergrazing dates in successive years on the accumulation of herbage mass and on tiller density in winter and subsequent herbage production at two sites in Ireland, one in the south and one in the north-east. Closing swards from grazing in early and mid-September (north-east and south of Ireland respectively) provided swards with >2 t DM ha )1 and a proportion of green leaf >0AE65-0AE70 of the herbage mass above 4 cm, with a crude protein (CP) concentration of >230 g kg )1 DM and dry matter digestibility (DMD) of >0AE700. The effects of autumn-closing date and winter-grazing date on herbage production in the subsequent year varied between the two sites. There was no significant effect of autumn-closing date in the north-eastern site whereas in the south earlier autumn closing reduced the herbage mass in late March by up to 0AE34 t DM ha )1 and delaying winter grazing reduced the herbage mass in late March by up to 0AE85 t DM ha )1 . The effects of later grazing dates in winter on herbage mass continued into the summer at the southern site, reducing the herbage mass for the period from late March to July by up to 2 t DM ha )1 . The effects of imposing treatments in successive years did not follow a consistent pattern and year-to-year variation was most likely linked to meteorological conditions.

Can Festulolium, Dactylis glomerata and Arrhenatherum elatius be used for extension of the autumn grazing season in Central Europe?

“…The OMD values recorded in grasslands in the Czech Republic were comparable with OMD values reported by Hennessy et al (2006) in Ireland. The OMD values of Hennessy et al (2006) were determined by the in vitro method with using the rumen fluid, while we used the pepsin-cellulase method. Compared to the previous years, Festulolium had the highest NDF content while the NDF content in Arrhenatherum elatius was the lowest.…”

“…A general statement can be made that swards with the preparatory cut in June (1PU) had biomass production higher than swards with the last preparatory cut in July (2PU) at the end of the growing season. Hennessy et al 2006. In spite of the fact that Festulolium had the lowest content of crude proteins (CP), it had also the lowest content of crude fibre (CF), mainly in October.…”

The effects of simulated summer‐to‐winter grazing management on herbage production in a grass–clover sward

“…This is most likely due to higher senescence rates in the undefoliated treatment over this time period. Higher losses of herbage due to senescence (0·41–0·71 t DM ha −1 ) were previously recorded for the November–February period from grass‐only swards with a Early (20 September) FIN in Ireland (Hennessy et al ., ). The current experiment had relatively low HM over winter, which could explain the lower amounts of senescence (Carton et al ., ).…”

“…Another important aspect of grazing management during autumn–winter is the final grazing (closing) date. This is the primary determinant of pre‐grazing herbage mass (HM) in early spring (Roche et al ., ; Hennessy et al ., ; Ryan et al ., ). However, carrying swards with high HM for long periods over winter has been found to increase shading of clover leaves and stolon growing points, which can result in lower sward clover contents in early spring (Laidlaw and Stewart, ; Laidlaw et al ., ).…”

The effect of introducing a winter forage rotation on CO2 fluxes at a temperate grassland

“…In northwest European temperate grasslands such as those in Ireland, dairy cattle are usually housed indoors and fed on grass or cereal silages with concentrate supplements over the low productivity winter period (Hennessy et al, 2006). The practice of outdoor winter feeding on forage crop rotations, such as cereals or brassicas, has demonstrated agronomic benefits such as higher dry matter yield and improved animal body condition compared to purely grass-based winter feeding systems (Keogh et al, 2009).…”