Production

Weaning big influence over feed efficiency

Jon Condon, 27/05/2011

 

Best-practice management of young cattle at weaning can deliver dramatic improvement in their feed conversion efficiency performance later in life, a producer seminar in Tamworth was told recently.

Consultant veterinarian Dr Rick White from Livestock Central told a gathering of Westpac Agribusiness beef clients that while genetics played a strong part in feed efficiency performance, producers could also influence feed conversion potential in their cattle through nutritional management at weaning.

In some cases feed efficiency could be halved (lower is better) in cattle that were appropriately managed during early growth.

While the industry had done well over the last 40 years in selecting animals for growth rate, the same had not yet occurred for efficiency in weightgain, Dr White said.

There was still a need to develop better genetic selection tools for feed efficiency, but in the meantime producers themselves could create efficiency gains in their cattle simply by the way they were managed.

Dr White, pictured above left with Westpac Agribusiness Head of Beef Specialisation, Mark Middleton, suggested feed efficiency improvement of 40 to 50 percent was ‘certainly possible’ within herds over a four or five year timeframe, simply by introducing best practice management.

Compare this with potential improvement in feed efficiency using currently available genetic selection tools, alone, which Dr White estimated as capable of delivering 15-20pc improvement within a herd over five years, at best.

“Ideally, producers should be doing both: using the genetic tools that are out there by all means, but also through pursuing the major gains in feed efficiency that can be picked up very quickly by changing management.”

One of the critical backbones of achieving FCE improvement was through weaning practises, where a significant difference could be made to the animal’s performance by setting them up right at the weaning stage, to allow them to express their full genetic potential.

Dr White said some of the concepts involved with supplementation and the strategies used to wean animals represented a departure from some traditional practices applied in southern Australia, and this caused a sense of unease in some producers because it might be considered ‘unnatural.’

“If producers are going to early wean, they have to do it properly,” he said.
The most profitable stage to wean a calf at was as soon as they were heavy enough – around 150kg. The ideal ‘time’ to wean was as soon as they get to that bodyweight, ideally about four months of age.

“So why is that bodyweight important? Because once a calf hits 150kg, its rumen is big enough to eat enough feed every day to continue to sustain good growth rates, on reasonable quality pasture,” Dr White said.

“If it’s lighter than that, it can still be weaned, but it’s not going to sustain good growth rates on reasonable pasture, and is more likely to need supplementation.”

While there appeared to be considerable variation happening in weaning weight and age between herds, Livestock Central in its consultancy work around Australia saw a lot of weaning happening around 200-250kg, at six to ten months of age, averaging seven months.

“Firstly, weaning at around 150kg saves feed,” Dr White said.

“Milk production is an inefficient way to grow a calf weighing above 150kg. It takes about 40 percent more feed to produce milk to grow the calf, as it does to separate the cow and calf and graze them separately, for exactly the same growth rate.”

Secondly, the earlier the calf is weaned, the more ability the producer had to influence its rumen development, which stays with the animal permanently.

“But there are obviously also benefits in early weaning in terms of fertility in the female herd.

Delayed weaning practises, particularly in poor years, draws down body condition in females, which is ultimately responsible for fertility decline in cows,” he said.

“But if we then do the right thing with that calf when it is weaned, we get a second, additional benefit.”

Producing animals that are more feed efficient not only deliver a benefit in the paddock at home, but also further down the supply chain.

“They do not have to remain on feed as long at the feedlot, which costs less, and if the animals sustain less respiratory disease, this reduces treatment cost and mortality from respiratory disease. That means we are producing something the lotfeeder wants more of,” he said.

Three issues determined the feed efficiency of the rumen:

  • rate of absorption of nutrient, affected by surface area created by the development of thousands of finger-like projections from the inner wall, called papillae
  • extent of blood supply delivered through the presence of capillaries that transport the absorbed nutrients away, and
  • muscular contraction, used to churn the contents of the rumen to satisfy the rumen bugs.    

“The development of the rumen happens over the first two to eight months of life, after which, its architecture (the development of the papillae, blood capillaries and muscle contraction capacity) is set for life,” Dr White said.

The type of diet that an animal was exposed to during that early phase directly influenced the level of rumen development achieved in each animal.

“Careful management of the weaning process is critical in maximising rumen development, and thus lifetime feed conversion efficiency, and productive and reproductive potential,” Dr White said.

The main trigger in the developing rumen for high levels of surface area (papillae) development, blood supply and muscle development was the most efficient fatty acid, called propionate.

“The more propionate the animal can make, the more feed efficient it becomes later in life,” Dr White said.

 

Pictured below: Rumen epithelium from two calves, both eight months age, showing dramatically different rumen development. The one on left is from an early weaned calf, the one on the right, not weaned. Click on the picture for an enhanced view

  • Westpac will host a second production efficiency workshop through Livestock Central in in Roma on May 30-31.
  • Livestock Central is a leading provider of ruminant nutrition, production and project management and education services to Australian livestock industries. Dr Rick White can be contacted for more information on weaning strategies for optimum feed conversion on (08) 8391 1700. The business is not connected in any way with the Beef Central.com website. 

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