Soil conditions and inclement weather are two of the biggest limitations affecting the extension of the grazing season on Irish dairy farms.
Over 50% of soils in the Republic of Ireland are classified as podzols, gleysols or histosols.
These soils are slow draining and practically impervious, thereby preventing full-time turnout to pasture in early spring and late autumn, due to a high risk of poaching damage.
Teagasc researchers Michael O’Donovan and Emer Kennedy, completed a trial in order to investigate ways in which the grazing season can be extended and therefore increase the proportion of grazed grass in the diet.
Grazed grass is the cheapest feed available and it has previously been shown that as the proportion of grazed grass in the diet increases, costs of production decrease.
The trial contained four treatments of which dairy cows were given access to pasture for 22 hours; 9 hours; 2 x 3 hours and 2 x 4.5 hours respectively.
For the duration of the trial they were offered on average 1,282kg DM/ha of highly digestible grass.
No significant reduction in milk yield, milk solids yield, bodyweight or body condition score was observed when animals were allocated two three-hour periods of access to grass compared to cows grazing full-time.
By adjusting their grazing behaviour (i.e. grazing bites per minute and grass dry matter intake per bite) cows given two three-hour periods of access to grass grazed for 5.9 hours (98% of their time at pasture) resulting in
no difference in grass dry matter intake.
Cows can be retained at pasture during periods of wet weather without any poaching damage occurring due to the development of on/off grazing technologies which will lead to an increase in the number of days at grass.
On/off grazing can also be used as a strategy to allow an earlier turnout date on farms with heavy soil.