Thursday, August 18, 2022

Taking care of future herds

Calves are the future of the national herd so giving them the best possible start is vital to ensure they achieve their potential.

With calving just around the corner, there has been a good turnout of farmers looking to brush up on their calf rearing skills at the Dairy Women’s Network (DWN) Calf Rearing Expos “Today’s calf is tomorrow’s cow”.

DWN chief executive Jules Benton says the aim of the expos was for farmers to walk away from the day feeling prepared and ready for the calf rearing season.

“It’s a time that can be overwhelming so they need to be able to walk away not only with knowledge around best practice, but tools and resources they can action,” Benton says.

Around 100 dairy farmers and calf rearers attended the expo in Stratford to see what was on offer and hear guest speakers, including AgriVantage technical advisor and nutritionist Natalie Chrystal, present on how to maximise the genetic potential of calves in their early weeks for a lifetime of high performance.

Chrystal shared best practice and recent science to help calf rearers and farm owners get their calves off to the right start.

“We know that care of the newborn has the potential to dramatically impact lifetime productivity,” Chrystal says.

“We want to provide calf rearers with information to allow them to develop the best possible rearing system for their situation. The aim is to break down the science into practical application so rearers achieve the most profitable results.”

Chrystal initially asked the attendees, “What if I said to you that your heifers could produce $125 more milk in their first lactation?”

She demonstrated that farmers could achieve that goal by spending a little more time looking after their heifers. Not only from birth to weaning, but right through to their first calving.

“Farmers have an opportunity to improve their heifer raising practices and get a better return from them. What you do in the first few weeks and months of life has a long-term impact on productivity,” she says.

“We have to maximise profit. Unless we make our businesses profitable and sustainable, it’s very hard to support good animal welfare practices and environmental sustainability.”

She emphasised that there are two key short-term areas to consider when maximising profits raising heifers: minimising illness and mortality; and optimising early growth.

The long-term goal is to optimise lifetime production. In the long-term those heifers are going back into the herd and farmers must invest in those heifers in such a way that they form the foundation of their herd going forward.

Research has shown that increased bodyweight at first calving has a positive effect on first lactation milk production. The heavier the animal at first calving increases the amount of milk she produces.

She showed two studies that demonstrated that not only was there an increase in production of 4.4 -8.7 litres of milk per additional kg of live weight for the first lactation, there was a rise of 21-23 litres of milk per additional kg of live weight at the second lactation.

Heifers that achieve a greater proportion of their mature live mass at 12 months of age produce more in their first lactation and have higher cumulative three year milk yields.

“It’s not a first time productivity effect, but a lifetime productivity effect. We like to think that there’s an opportunity for compensatory growth and that they’ll make it up later on. In reality the gains made later on don’t make up for the losses in the earlier periods,” she says.

“You must think about heifer rearing continually through their lifetime rather than just at a specific point in time.”

She then fleshed out her initial statement of how gaining that extra $125 worth of production could be achieved.

“If you lose about .3kg MS for every kilogram of body weight gain; and if the upper quartile of heifers are around 18kg lighter than they should be, it works out to be around 5.5kg MS lost,” she says.

“However, the average heifer is around 52kg lighter than she should be, which works out to be around 15.5kg MS. At an $8 payout, that’s $125.”

She then illustrated an opportunity to make a significant improvement in investment in your heifers by feeding them adequately in the first two years.

“Studies have shown that if you grow your heifers faster pre-puberty, the impact on subsequent production is far greater than if you catch them up post puberty. It’s really important to get them growing as fast as possible within the first 12-15 months of their life.”

Chrystal showed that the one key to achieve that growth is to get colostrum into calves as quickly as possible after birth.

“The ability of the calf to absorb the Immunoglobulin G (IgG) in colostrum changes over time. We know that over 12 hours there is a rapid decrease in the calf’s ability to absorb it.

“Secondly we want the gold colostrum from the first milking. The longer you leave the colostrum, the quality and amount of IgG per litre decreases.”

For those that measure the Brix of their colostrum, 22% Bx is what farmers should aim for. This equates to about 50 grams of IgG per litre, so two litres of colostrum will provide the amount required.

“One aspect we don’t talk about very much is colostrum cleanliness. The ability of a young calf to absorb those immunoglobulins is affected by the bacterial population in the colostrum. The more microbes you have, the less efficient the absorption and the more colostrum you need to put into the calf.”

This article first appeared in the July 2022 issue of Dairy Farmer.

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