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Don’t obsess about peak milk, obsess about grass quality to drive milk solids

Don’t obsess about peak milk, obsess about grass quality to drive milk solids

Many dairy farmers have raised questions on how best to feed their cows to optimise milk production during the mid-season, especially after a challenging spring, which has tapered milk yield peaks on some farms.

Joining the recent ‘Managing grass and herd health in mid-season’ webinar, Dr Joe Patton, Head of Dairy Knowledge Transfer at Teagasc, explained how the biggest risk to milk production in the mid-season is only manifesting itself now - poor grass quality.

Pulling from the extensive bank of research in Teagasc on dairy cow nutrition, Dr Patton tracked how varying levels of nutrition in the first 11 weeks post calving affected both the milk production of cows during the mid-season period, but also through the entire lactation.

As part of this study, cows were offered a concentrate supplementation rate of 0kg/head/day, 3kg/head/day or 6kg/head/day before all being returned to the same diet for the remainder of the lactation. Although there was a slight lag time once returned, milk production of the three groups converged around weeks 16 and 17 post calving and persisted throughout the lactation.

Summarising this study, Dr Patton said: “Just because you get a high peak doesn’t guarantee you are set up for high milk production for the year. Conversely, if you got a lower peak that does not mean you can’t catch up in milk from this point forward and for the remainder of the year.”

“What’s more important for production in May, June, July and August will be grass quality on the day it is grazed in May, June, July and August.

“Don’t overly worry about the fact that the cows haven’t peaked as much as they would have, think about fixing grass quality this week, next week and the week after and you will get a milk yield response to that. Don’t obsess about peak, obsess about grass quality.”

The correct pre-grazing covers to support milk production

The topic of the correct pre-grazing covers was also discussed, with Dr Patton highlighting why 1,400kg DM/ha covers are optimal for cow performance and health and why – regardless of stocking rate – they should always be the aim.

Again delving into the Teagasc research repository, Dr Patton showed how cows receiving no concentrate grazing 1,400kg DM/ha covers produced similar volumes of milk to those on 2,000kg DM/ha being supplemented at a rate of 6kg/head/day (milk kg of 23.9kg versus 23.7kg).

Again when compared at the same covers, this time receiving 2kg/head/day of concentrate on each, the cows grazing 1,400kg DM/ha covers had a grass intake of 16.2kg and a milk production of 26.2kg, whereas cows on the 2,000kg DM/ha cover had a grass intake if 14.5kg and milk production of 19.7kg.

“The reason we talk about 1,400kg DM/ha covers and a couple of kilograms of concentrate at most is it’s the best balance of cow performance, cow health and managing to maximise the grass utilised out of the paddock,” Dr Patton explained.

On the topic of farms carrying higher stocking rates adjusting the pre-grazing yields upwards over and above 1,400kg DM/ha, Dr Patton said that this is a misunderstanding of the factors in play.

“A high stocking rate does not mean you increase the pre-grazing yield. A high stocking rate means that you reduce the [grass] allowance per cow and you supplement the difference. If you run out of grass, it’s not the pre-grazing cover, it’s a mismatch between grass growth rate and your stocking rate,” Dr Patton explained.

Elsewhere in the webinar, Grass10 Advisor, Joseph Dunphy offered tips to maintain grass quality in the weeks ahead, while Evan Hunt, Sligo dairy farmer and 2023 Young Grassland Farmer of the Year, detailed how his farm coped through the spring and the steps he’s taking to maintain grass quality through the mid-season period.

For more insights, access a recording of the ‘Managing grass and herd nutrition in mid-season’ webinar here.