In this first instalment of the series, we look at what should be the top aims of dairy youngstock rearers.

Every now and then it makes sense to step back from the day-to-day challenge of effective calf rearing and re-assess exactly what you are aiming to achieve - Could we do better? Could we rear our herd replacements more efficiently?

Whatever your rearing system, you are typically looking to achieve some key goals and meet some important growth targets, explains Dr. Jessica Cooke from Feed for Growth (Volac Milk Replacers Ltd).

She highlights the seven important aims for any dairy youngstock rearer:

Maintain a healthy calf (no mortality and minimal morbidity);
Double birth weight at weaning;
Achieve a pre-weaning daily liveweight gain (DLWG) of at least 0.7kg per day;
Achieve good starter intake to stimulate rumen development (and aid the transition from non-ruminant to pre-ruminant);
Achieve a smooth weaning transition with no setbacks;
Achieve a post-weaning DLWG of at least 1.0kg per day;
Secure a decent return on investment (by minimising cost per kg of DLWG).

“Young calves require energy and protein for healthy growth and frame development," Dr. Cooke said.

"Ensuring that both are delivered in abundance, and in the most digestible form, enables a calf to easily utilise the feed and convert it into liveweight.

According to Dr. Cooke, during the first three weeks of life, when starter feed intake is minimal, the energy available to the calf is directly proportional to the supply of milk or milk replacer.

"Consequently, some calf milk formulas are now precision-formulated to ensure they deliver the right amount of energy (from fat and sugar) to fuel growth, but not to over-supply it, because this can compromise a smooth transition onto solid starter feed.

“Depending on your growth target and the prevailing temperature, a calf’s energy intake needs to be adjusted.

"However, the best way to supply a calf with more energy is simply to feed it more by increasing the volume of milk fed or the milk formula mixing rate (solids level),” she said.

Dr. Cooke points out that increasing the fat content of a milk replacer (for example, from 17% to 20%) has a negligible effect on the overall energy supplied to the calf, compared with simply feeding more of it.

“If the fat level is increased in a milk formula, an equal amount of lactose must be removed from the formula to create ‘space’ for the additional fat (since the level of proteins and minerals are not changed)," she said.

"As a result of this formulation balancing process, there is only a small increase in the total ME supplied by the product.”

Stimulate starter feed intake

Dr. Cooke also explains that by supplying more lactose and less fat, calf milk formulas typically stimulate the earlier intake of solid feed.

“This is what you want; simply because the intake of solid feed pre-weaning - to stimulate rumen development - is key to ensure a smooth transition around weaning," she said.

"Starter feed is also cheaper than milk replacer, so getting calves to eat more starter without compromising growth rate will reduce your cost per kg of DLWG.”

Dr. Cooke highlighted recent trial work in The Netherlands with 136 pre-weaned calves fed either a 17% fat or 25% fat, 23% protein skim-based milk replacer.

Whilst both groups of calves received 50.4kg of milk powder, the calves fed the 17% fat milk replacer consumed 10.4kg extra starter feed over a 12-week rearing period.

“It’s important to get the balance of milk and starter feed right,” she stresses.

“Our work suggests the right compromise is to feed pre-weaned calves 50-57kg of a good quality 17-19% fat (anything over 20% fat can suppress starter intake), 23% protein milk replacer at the rate of 900g of milk solids per day.

"In addition, make sure palatable fresh starter feed, chopped forage (3-4cm) and water is freely available from day one.

"We also advise socially housing animals from day seven of age (either in pairs or groups)."

The Feed for Growth representative said that if farmers follow these basic guidelines, "your calves will typically double their birthweight by weaning (having grown at the rate of 0.75-0.81kg per day)".

“You will also secure a smooth weaning transition with no growth setbacks - and can expect a post weaning growth rate up to weeks 10-11 of age of 1.1-1.2kg per day.

"And achieve all this at a cost of body weight gain of €2.84-€2.96 at current average milk replacer and starter feed prices,” Dr. Cooke said.

To read more about the 'Calf Rearing: Starting Strong to Finish Stronger' series, click here.