Summer growth critical to heifer performance post-calving

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Image of a Heifer

Heifer rearing is a cost many are understandably keen to reduce. But heifers also represent the herd’s future, and heifer growth should be a year-round priority.

According to figures from the Agriculture and Horticulture Development Board (AHDB), failing to hit recommended heifer growth rates and subsequently calving at 30 months of age instead of 24 months requires a typical 200 cow herd to carry an extra 22 heifers – 26% more than necessary.

The figures are based on a 20% culling rate (plus 5% calf mortality), and the burden rises to 36 additional heifers if the culling rate is closer to 35%. It’s a cost milk producers simply cannot afford, particularly given that the losses continue to mount up through a heifer’s remaining productive life.

“You’re actually better off investing the same resources into fewer animals – and more resources if necessary – to achieve the target growth rate needed to calve at 22-24 months,” states KW nutritionist Charlotte Ward. “Because heifers calving at that age have better fertility, higher milk yields and the highest survival rate over the first five years in the herd (table 1).

“In fact, one AHDB Dairy study demonstrated that heifers calving at 24 months break even half way through their second lactation, whereas those calving at 30 months won’t break even until into the third lactation.”

Prioritising heifer growth

Data from National Milk Records (NMR) show that although some herds are consistently hitting the two-year target, the average age at calving for Holstein Friesian heifers across the UK remains closer to 28 months. And the Royal Veterinary College (RVC) has reported that less than half of all live-born dairy heifers actually reach a third calving.

“Heifer growth and nutrition therefore needs to be a year-round priority…”

“Heifer growth and nutrition therefore needs to be a year-round priority, with a clear focus on consistently hitting recommended weight-for-age targets,” Ms Ward continues. “For example, heifers should reach 55-60% of mature bodyweight prior to serving, but this needs to be at 13-14 months of age.

“Serving at 15 months is too late to achieve an average 24 month calving age because heifer first conception rates typically range from 40-70%. And if heifers aren’t at 90% mature bodyweight prior to calving – equivalent to 85% mature weight post-calving – they won’t have the frame size needed to cope with the demands of lactation.”

Summer grazing challenge

Table 2 outlines the growth rates needed to meet these targets, and whilst relatively easy to achieve when cattle are housed during the winter, summer grazing poses a particular challenge. Latest figures from Trouw Nutrition show that even under ideal conditions, high quality (12.4MJ ME/kg DM) early summer grass can only support growth rates of 0.2kg/day in 100kg liveweight (LW) cattle, and 0.6kg/day in those of 200kg LW.


“The main limiting factor is dry matter intake, though once at 300kg LW cattle are potentially capable of 1.0kg/day growth on good quality grazing alone,” explains Ms Ward. “But it doesn’t take much in the way of poor weather, reduced grass growth or lower grass quality – heifers are often grazed after the milking herd or on less productive pasture – to drop that below the 0.70‑0.85kg/day target.

“So although good utilisation of grazed grass can help reduce rearing costs, supplementary feeding is essential for younger heifers and whenever conditions are less than perfect.”

Figure 1 shows the weight targets for typical Holstein Friesian heifers alongside equivalent wither height estimates – a useful alternative if there’s no access to weighing facilities. But just as critical as achieving target liveweight is to ensure supplementation is carefully targeted to produce the right type of growth.

Figure 1 – Live weight and wither height for Holstein Friesian heifers


Correct growth type

“The impact of underfeeding on growth rates is easy to see, but overfeeding, especially during pre-puberty, can also be damaging,” states Ms Ward. “Typical problems include overdevelopment of the fat pad in the udder and higher body condition score at calving, leading to increased risk of calving difficulties, reduced appetite and milk production post-calving and lower lifetime yield.”

What’s needed is good lean frame growth without excess fat deposition, and that requires the correct energy-to-protein balance in the diet, she advises. A rising plane of nutrition three weeks pre- and six weeks post serving is also critical to maximise fertility and ensure successful implantation.

“A good supply of quality protein is the key to developing height and frame without laying down excess fat. But it means that many conventional feeds, such as cereals or low protein concentrate pellets, should be avoided, as they oversupply energy and undersupply protein compared to the needs of the growing heifer.

British wheat distillers' feed image
British wheat distillers’ feed supplies both digestible fibre and high quality protein.

“More suitable are moist bulk feeds with a higher protein-to-energy ratio, such as Traffordgold wheat-gluten moist feed or draff. Alternatively, a dedicated youngstock blend like Precision Lifetime Rearer 17 will contain the protein and digestible fibre needed to correctly balance the nutrients in grass. Good ingredients to look for include sugar beet feed and British wheat distillers’ feed.”

Cost-effective feeding

According to Ms Ward, moist feeds continue to be a popular choice for supplementing grazing heifers, particularly when grass growth slows or conditions are poor. Simple to feed using troughs or ring feeders in the field, they require nothing more complicated than a tractor and loader.

“Blends are…an extremely flexible way to provide additional nutrients…”

“Blends are also cost-effective and an extremely flexible way to provide additional nutrients,” she adds. “Formulations and ingredients can be adjusted to match forage availability and quality, and nutrient levels adjusted to growth requirements.

“It’s also easy to include vitamins and minerals, which might otherwise need to be supplied as mineral licks or boluses.”

Dry feeds like blends are typically fed at around 1-2kg/head/day as required, with moist feeds offered at around 5-6kg/head/day depending on age and growth rate. If drought stops grass growth altogether, moist feed volumes can be increased by up to 50%, though additional forage (typically grass silage, haylage or straw) may also be needed.

“With dry feeds there’s a greater risk of acidosis, so take care if higher levels of supplementation are required. Dry feeds also tend to be consumed rapidly in one meal, which further increases the acidosis risk, and with heifers often grazing distant land not suitable for the milking herd, it’s not always practical to feed them more often.

“It’s easy to overlook the needs of heifers that are often ‘out of sight, out of mind’ once grazing, but the costs of poor growth, later calving and higher cull rates are substantial, even if not immediately obvious,” Ms Ward continues. “Regular monitoring, feeding and handling are absolutely critical if heifers are to enter the herd in the condition needed to perform well.”

Early growth impact

The impact of even the earliest stages of growth should also be considered when reviewing summer feed requirements, Ms Ward warns. Calves convert feed into growth most efficiently when young, so putting extra effort into colostrum feeding and management, using a good quality milk replacer and encouraging early intakes of calf starter can mean less ‘catch-up’ growth is necessary when calves finally go out to grass.

“Maximising growth in the first months of life is critical to reducing overall heifer rearing costs,” she confirms. “It’s not only the most efficient growth, but it also means less supplementation is needed during summer grazing.

“There’s also reduced risk of excess fat deposition trying to catch up and a greater likelihood of hitting target weights to calve at 22-24 months. And that means less heifers needed overall, which is a major cost saving whichever way you look at it.”

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