The rules of thumb of compensatory gain

The rules of thumb of compensatory gain

Beef
Aa

Demonstrable benefit to supplementary feeding weaners right now.

Aa

WHETHER or not compensatory gain can be relied on comes down to the balance of things like time of calving, how the season is playing out and what markets are being targeted.

However, there are some rules of thumb that research and experience has turned up every producer should know.

At current market and commodity prices, advisors say there is a demonstrable benefit to providing sufficient supplementary feed to steers from weaning to sale at a feeder weight.

Veterinarian consultant at the Mackinnon Project Ben Linn gave a comprehensive overview of production and maintenance feeding of weaners at a Meat & Livestock Australia webinar this month.

The research he presented showed that in many instances, producers who finish their own animals don't need to push them to maintain high average daily gain post-weaning during the dry season as they will catch up in the finishing phase.

But for steers marketed earlier as weaners or vealers, supplementary feeding is critical, as there is insufficient time for any reduced growth rate to be caught up and compensated.

Given current commodity prices, a strong case can be made for supplementary feeding now.

Compensatory growth is a complex but important concept to understand because maintaining a consistent growth rate is difficult in grazing situations, whether it's the wet and dry season in the north or the late winter-spring flush of green feed then dry conditions in summer, Dr Linn explained.

"What we see is if we have a nutritional restriction period there is a rebound effect where the live weight gain is faster than expected - that's compensatory gain," he said.

That begs the question should a producer provide supplementary feed to keep weaners going at a high growth rate or accept slower growth rate and then catch up.

The challenge is that feeding too hard in summer may effectively be money down the drain. Subsequent compensatory growth of the restricted cattle may erode any benefits of supplementation on top of the significant feeding expenses.

What affects compensatory gain?

The degree of animal maturity at the start of feed restriction is a big player, Dr Linn said.

The older the animal when limited feed comes in, the faster the rate of compensatory gain.

Rule of thumb number one: The earlier the restriction, the more difficult it is to fully compensate.

Dr Linn said on average cattle exposed to a feed restriction at less than six months required 14 to 18 months to compensate to 70 to 80 per cent of their liveweight.

Cattle exposed at more than six months needed only 4 to 7 months.

Rule of thumb number two: Nutritional restriction pre-weaning is not good.

This was where principles of early weaning apply during drought, Dr Linn said.

Post-weaning feeding heifers

Heifers need to hit targets of critical mating weights. A 500 kilogram mature cow would need to be at 300kg at joining.

"So in a scenario where we wean at 120kg at four months, to hit that target, the heifer would need to grow at .54kg/day," Dr Linn said.

"However, we don't need to follow a steady curve for growth - it can be restricted earlier then sped up."

Rule of thumb three: Let heifers cruise along. As long as they still maintain some growth post-weaning, heifers do not require the same level of supplementary feeding as steers. Should a spring flush (south) or wet season (north) not occur, supplementary feeding will need to be considered at a later time to ensure heifers reach critical mating weights.

Post weaning setbacks in growth do not tend to compromise reproductive performance, Dr Linn said.

"Some growth is still necessary because age at puberty is strongly dependent on body weight," he said.

"But prioritise feeding steers above heifers."

Steers

Target market is critical when weighing up the costs and benefits of feeding steers.

Steers sold as feeders, or those being finished on pasture, have time for compensatory gain to occur but weaners and vealers don't.

He presented research from Beef CRC in Rockhampton into the effect of different post weaning growth paths on long-term weight gain.

In this work, steers were split into three groups - rapid gain, slow and weight loss.

The results were average daily gain was not different for the entire trial period, however cattle in the weight loss group were 50kg lighter than the rapid cattle at finishing.

At a market price of 650 cents per kilogram carcase weight, at 51pc dressing, that is $165 less per head.

Rule of thumb number four: Do the maths. There is a need to weigh up the sale price per kilo against the cost of supplementary feeding.

"Depending on commodity prices, it can be profitable to feed at a high rate when the sale price is high, however you can save yourself money holding stock for an extra period," Dr Linn said.

It also doesn't have to be all or nothing, he said. Consider supplementary feeding the lighter portion of a mob.

The bottom line

If spring calving and selling weaners or vealers, don't look to utilise compensatory gain as you can't let them lose weight because they'll be sold before you get any compensatory gain.

If selling feeders or finishing, there is potential to utilise to achieve higher margins due to lower cost of production.

The story The rules of thumb of compensatory gain first appeared on Farm Online.

Aa

From the front page

Sponsored by