While a lot of discussion focuses on maximising growth rates and qualities of pasture, managing dry matter (DM) intake quantity and consistency is perhaps the most important, yet difficult, concept to achieve.
Adam Clay, head of technical at NWF Agriculture, says: “The grass plant itself will only have three fully viable leaves, a fourth will grow but the first will die away and lie in the base of the sward. Allowing this to happen is not only a waste but can reduce plant establishment in the base of the sward.
“For those without a plate meter, using the three-leaf method is an accurate and viable method of determining the optimum point to graze pasture. Leaving it longer than this will reduce a cow’s ability to achieve a low and clean grazing residual, which in turn will reduce pasture qualities.
“Intake is king; turning cows, particularly the high yielding animals into slightly higher grass cover, can increase grass intake per bite and therefore total grass intake in a given amount of time.”
Mr Clay says ‘turnout’ does not have to mean cows are out all the time and research has shown restricting time at pasture can improve grazing efficiency by increasing intake per bite and per minute. He explains this strategy can be used in two ways.
“One is spring turnout; restricting access time means when cows are out they are grazing, particularly if they have not received their buffer before being turned out. Limiting pasture access to about three hours per grazing, twice-a-day will ensure an efficient pasture intake without impacting too negatively on wet ground, tracks or gateways.
“Research has been mixed but tends to suggest access time being split as opposed to one prolonged period at grass, encourages intake per unit of time at grass, and milk yield.”
He explains the other way is looking at total dry matter intake (DMI) considering cows’ grazing behaviour.
“A typical Friesian/Holstein requires about 3-3.5 per cent bodyweight in dry matter intake – Jerseys and Guernseys can be slightly higher. That is about 20kg DMI but forage intake will typically be 12-14kg DMI leaving another 6-8kg DMI to be achieved either in the parlour or down the trough. That, of course, is assuming the forage intake can be achieved at pasture, which is often not the case and a further 2-4kg silage DMI may be required. The question is, when should a buffer be fed?”
"Grazing activity and intake reduce to almost zero through hours of darkness."
- Adam Clay
Mr Clay says as a part of their make-up, cows still fear a threat from predators in the night, and this is why through the hours of darkness cows remain in the herd and do not wonder to graze.
“Grazing activity and intake reduce to almost zero through hours of darkness. At sunrise searching activity peaks and grazing activity increases but the evening period prior to sunset sees the lowest searching period, highest intake and grazing activity period.
“There are also suggestions that pasture quality increases towards the end of the day, with lower proteins and fibre and higher dry matter, organic matter and water-soluble carbohydrates.
“To help achieve both high total dry matter intake and high grazing intake we can use this schedule to ensure that when we graze cows, we optimise the potential intake in the early morning when cows are hungry and in afternoon and evening grazing, while buffering through the quieter grazing period in the middle of the day.
This will limit the impact of the variation in dry matter intake at pasture, often caused by varying dry matters.
Mr Clay says there is no single answer for choosing the best buffer, and it varies depending on the first limiting factor to either production or animal health.
“Pasture is high in both protein and fermentable carbohydrates, so a choice of supplement and forage buffer to balance this is ideal.
“Maize silage or wholecrop offers a very good pasture buffer. The fermentable carbohydrates and low protein are a perfect balance for high protein pasture and should encourage a higher total forage intake and therefore lower concentrate feed rate.
“High fibre supplements and structural fibre should only be considered when rumen health or butterfats are thought to be compromised, as supplementing fibre may increase pasture substitution and limit total intake.
“If rumen health is under pressure, dung is very loose, cudding rates have dropped and butterfats are reducing, then added fibre will be required. This could come as structural fibre through straw or hay or digestible concentrated fibre such as sugar beet pulp or soya hulls.”