Set for Life

November 1, 2011 11:52 AM
Set for Life

Preweaning growth rate determines lifetime performance

There’s nothing more important in the life of a calf and her future productivity than the quality and quantity of colostrum she receives in her first hour outside the womb.

When you couple excellent colostrum management with an enhanced calf feeding program that doubles the birth weight by weaning, you are gaining nearly $200 per heifer more profit. And that doesn’t account for earlier age at first calving (up to 70 days) and better survival rates (8%).

Many dairy producers, however, believe that slow-starting calves can catch up through compensatory growth. Not true. "Most neonates, including preweaned calves, do not have compensatory gain mechanisms," says Mike Van Amburgh, an animal scientist and calf specialist with Cornell University. "Effects of early-life restrictions [such as poor immune response or below-normal growth] are difficult to overcome."

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The importance of colostrum can’t be overstated. "Calves with failure of passive transfer from colostrum have decreased average daily gain, delays to first calving and decreased milk and fat production during first lactation," says Fernando Soberon, a Ph.D. graduate student who works with Van Amburgh.

For each unit of immunoglobin G (IgG) concentration above 12 mg/ml (measured 24 to 48 hours after colostrum feeding), there is an 18.7 lb. increase in mature equivalent milk. Calves with failed passive transfer also have 50% less feed efficiency.

The reason for this poor productivity is not fully understood. But current research points in the direction of calves having to partition energy away from growth in order to mount an immune response.

Calves are born with about 4% body fat, but only half of that can be mobilized to provide extra energy. "This gives the calf up to four days of fat reserves depending on the ambient conditions," Van Amburgh says.

"Once fat reserves are depleted, the calf has to rely on either dietary intake or body protein to generate heat and mount an immune response if nutrient intake is below maintenance requirements," he says.

So the key to getting calves started right is giving them at least 4 qt. of clean, high-quality colostrum within an hour of birth and a second feeding eight to 12 hours later. "Minimizing the bacterial load of colostrum is probably one of the major management concerns with many farms," Van Amburgh adds.

Research from 1994 shows that enhanced calf feeding programs ulti-mately result in more milk production at maturity. Of nine studies that compared traditionally fed calves with calves receiving up to 50% more nutrients through liquid feed, eight showed a positive milk production response. When the results are aver-aged over all nine studies, including the one study with no response, calves on enhanced programs average 1,500 lb. more milk.

The Cornell University dairy herd, which has been on an enhanced feeding program for 10 years, has data on more than 450 calves through their third lactation. "We found a lifetime milk effect of preweaning average daily gain of over 6,000 lb. of milk depending on preweaning growth rates," Van Amburgh says.

"This suggests that colostrum status and preweaning nutrient intake have a great effect on lifetime milk yield and account for more variation and can achieve more progress in milk yield than genetic selection."

In other words, genetic selection generally yields 150 lb. to 300 lb. more milk per generation. Proper calf feeding and management can produce three to five times that!

The key, Van Amburgh and Soberon believe, is that calves double their birth weight, or at least grow at a rate to double their birth weight, by weaning at 56 days of age. To do that requires more groceries than traditional feeding programs.

The Cornell feeding program feeds for 1.5% of body weight dry matter from day 2 to day 7, and then 2% of body weight dry matter from day 8 to day 42. A 28:15 or 28:20 protein-to-fat milk replacer mixed at 15% solids is used. Free-choice water is also offered, and starter is offered from day 8 forward.

"At that feeding rate, we are offering twice the traditional industry standard nutrient amounts," Van Amburgh says. But even this feeding rate will not provide enough nutrients for growth when the ambient temperature falls below about 60°F. Remember, the calf’s thermal neutral zone is 68°F to 82°F.

While these enhanced preweaning programs cost more, the cost is offset by feeding heifers fewer days before calving. Total costs per heifer raised are nearly identical.

The benefit comes in higher survival rates of the enhanced fed calves and a younger age at calving. That translates to fewer replacements needed, faster herd growth or more heifers to sell.

In a traditional calf feeding program, you need about 76 heifers per 100 cows to maintain herd size. Survival rates are better with the enhanced feeding program, decreasing the nonperformance rate from 10.2% to 7.5%. So rather than needing 76 heifers to maintain herd size, you need only 74 with the enhanced feeding program. And when you lower calving age from 24.5 months in the traditional program to 22.2 months in the enhanced program, you need only 68 heifers per 100 cows.

When you combine these effects with $200 additional income per heifer in milk production, your return on capital invested in the heifer program shoots up.

Van Amburgh and colleague Jason Karszes estimate the return on capital is slightly less than 1% under traditional rearing programs. But returns climb above 7% with enhanced feeding and management programs. These numbers are based on improved profitability of $211 per heifer, a $15 milk price and an assumed income over feed cost of $10.50.

Colostrum Care

Using frozen colostrum is an easy and convenient way to get colostrum into newborn calves quickly.

But take care in thawing it, says Jim Roth, an Iowa State University veterinarian. Using a microwave to thaw colostrum could destroy cytokine cells.

Cytokines such as interleukin and interferon are key in helping calves mount an immune response in the first few days of life. Colostrum contains large numbers of these single-cell molecules.

Cytokine molecules, however, are more fragile than antibodies. "If you use a microwave to thaw frozen colostrum, you’re probably destroying the cytokines," Roth says. Warm-water baths, though slower, are less likely to cause damage.

Colostrum also contains maternal cells from the calf’s dam. These cells allow the newborn calf to activate an immune response faster than calves that receive colostrum which doesn’t contain these maternal cells, says Amelia Woolums, a veterinarian with the University of Georgia.

Simply freezing colostrum will destroy maternal cells. "You need fresh colostrum to give these maternal cells," Woolums says. Fresh colostrum is always the first choice.

"However, if you have frozen colostrum with high antibody [IgG] levels, feed it over fresh colostrum with low levels of antibodies," she says.

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