Pushing performance on grass

With a declining milk price and increasing purchased feed costs, more dairy farmers will be looking to rear their heifers outdoors this season to try and help reduce farm expenditure. To get the best performance from youngstock and hit that key 24 month first calving target, dairy farmers are being urged not to overlook the importance of consistent supplementary feeding.

Dairy Nutrition
Cows out on grass Bowden - ForFarmers UK

With the prospect of cutting out the bedding and feed costs associated with indoor rearing, a growing number of dairy farmers will be looking to rear heifers outdoors this year. As a comparatively cheap, nutritious feed source, maximising the utilisation of grazed grass will be key to helping mitigate increasing farm costs.

However, while grazed grass is a readily available, cost-effective feed source on many dairy farms, grass alone won’t provide the long-term, sustained energy that heifers require to maintain strong growth and performance.

“I’ve talked to producers who’ve historically kept bulling heifers indoors and used AI but are now looking to turn heifers out to grass and run them with a bull,” explains ForFarmers’ Youngstock Manager, Ann Commbes. “There are others who are turning out heifers at six months of age, whereas before they would only turn them out after they’d been served. The driving motivation behind these adaptations is a need to cut costs.

“And while rearing heifers outdoors is a cost-effective option, I would urge some caution. While lots of producers do a fantastic job of successfully rearing youngstock outside, what these producers do well is not over-rely on grass. They are conscious of the nutritional limitations of grass and therefore buffer feed throughout the grazing season. To turn youngstock out and think that grass alone will meet heifers’ nutritional requirements would be a big mistake.

To achieve a 24 month first calving target, heifers need to achieve a consistent, average 0.8kg daily liveweight gain (DLWG) from birth to calving, as a minimum. And this is where farmers need to be realistic about what can be achieved from grass intakes alone.

“If we took a six-month-old heifer as an example, with a DLWG target of 0.85kg, she would need to be hitting 4.1kg DMI each day,” continues Ann. “With grass at 20% DM she would need to consume around 21kg fresh weight each day, and this would increase to 26kg fresh weight if the grasses’ DM was only 16%. That is an unrealistic amount of grazed grass we’d be expecting a young animal to consume.

“And then there’s the issue of grass quality. The grass consumed would consistently need to achieve a minimum of 12.7MJ/kg to adequately fuel heifer performance, but there are usually only a few weeks during a growing season when these high energy levels can be achieved. When you look at the figures, it quickly becomes clear that relying on grazed grass alone won’t be enough to support strong growth rates - buffer feeding is a must.”

Heifers at grass fed cake

The importance of buffer feeding has also been highlighted in data recently acquired through a ForFarmers DLWG assessment of over 800 heifers at grass.

“Half of these animals were supplemented with ForFarmers’ VITA Heifer 16% rolls and the other half were on grass alone,” continues Ann. “In the non-supplemented group, average DLWG was around 0.44kg, with daily weight gains ranging from -0.13kg to 0.67kg.

“In the concentrate fed group, with feeding rates of between 0.5kg and 1.5kg/per day, average DLWG were over double that of the non-buffer fed group, at 0.96kg.”

Cost effective feeding

While it’s clear that buffer feeding is needed to keep heifer performance on track during the grazing season, it can still be delivered in a way that complements grass utilisation and is cost effective.

“As we’ve seen, some of the key drivers for rearing heifers outdoors are related to economics,” says Ann. “While purchasing buffer feeds is a cost, if it’s fed consistently and at the right levels, we can help reduce overall feed expenditure while also maintaining heifer performance at grass. The key thing is to feed little but often.”

Farmers should utilise a low, 16% concentrate when feeding youngstock outdoors, and feed this out at a lower rate, throughout the whole grazing season.

“Some producers might look to feed 2kg per head/per day at the start and end of the growing season,” explains Ann. “If this is a three-month window in total, each animal would be fed around 180kg of concentrate, at a total cost of £77 per heifer - based on a 16% concentrate at £426 per tonne at time of writing.

“However, if producers were to feed only 0.5kg per head/per day throughout the whole six months of a grazing season, total concentrate use would only be 90kg, at a cost of around £38 per heifer. While this is a significant cost saving, we’d also expect more consistent growth rates from this group, which can make management and planning much easier to handle.”

And just as good buffer feeding is the key to success in any outdoor heifer rearing system, so too is regularly weighing livestock.

“The joy of rearing heifers indoors is that you can keep a close eye on them and carefully monitor their performance at every stage of growth,” says Ann. “When you turn heifers out it’s important that you still track performance, and this is when weighing really helps.

Gwyn Evans Plate metering

“We’d recommend weighing animals at least twice through the grazing season, so that any poorer performers can be spotted quickly. These animals can then be provided with extra supplementary feed before weight gains fall too far behind and they risk missing service and first calving weight targets.”

When considering rearing youngstock outdoors, Ann is also quick to highlight the importance of monitoring grass growth and quality, as well as water provision and farmer safety.

“You need to know how much grass will be available for heifers and how nutritious this grass is, so regular plate metering and fresh grass sampling is a good idea,” continues Ann. “Water troughs need to be within easy walking distance of animals and there needs to be plenty of them – especially if we are going to have another hot, dry summer in 2023.

“When feeding out concentrate, farmers will be working in amongst young, excitable livestock. So, they should put temporary fencing or gates in place so that they’re protected during feed out and can quickly get away from youngstock, if needed.”

While rearing heifers at grass does pose its challenges, Ann is confident that producers can successfully manage the process, if they’re realistic in their approach.

“Even though extra management and buffer feeding are required to maintain heifer performance of grass, it still represents a good, cost-effective way of raising youngstock,” concludes Ann. “The important things are not to expect too much from grass, keep on monitoring heifer performance and remember the importance of that 24 month first calving target. That’s the key goal and we don’t want anything to get in the way of achieving it.”

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