The Challenge of Expensive Replacements

This survival model is a common replacement heifer selection method. Expose all the heifers and retain those who breed early in the breeding season and sell the failures as yearlings. Makes practical sense, a replacement with all the genetic potential in the world is of little use if she is open and those who breed early likely fit your production system.

Considering a replacement heifer is a 10+ year investment and requires 2 years of expenses without income from the day we wean her, is the survival model the best we can do?

The survival model allows for marginal performers to enter the herd because a non-pregnant genetically superior heifer can never catch up after that first unproductive breeding season. Fifty pounds is the difference in genetic potential for weaning weight when comparing the top 5% and bottom 95% of heifers in the American Angus Association database. So a pregnant replacement can wean 50 lbs less calf every year thereafter and still be equal to an exceptional female that fails to breed the first season. Zeros are hard to overcome when figuring averages.

So far we have compared a survival model where open and pregnant is the determining factor in retention. In reality we apply more selection pressure to most commercial herds as few expose every heifer born. For many the next selection criteria is born early in the calving season. Yet we rarely explore why they were born early, just that they were.

Is early calving a sign of high genetic potential, no it could be quite the opposite. Imagine a cow that weans the smallest, slowest growing calf in the herd. All things being equal one would expect her to calve early as she has more energy to put toward reproduction while the high producing cows are dedicated to feeding the current generation and breed later once peak milk production passes.

Early calvers are more likely to be older cows who didn’t have to devote resources to attaining mature size as three and four year olds. In this case the retained genetics are being sourced from older generations rather than advancing the newer genetics from your youngest cows who calve later because they are still growing.

Historically early born calves were selected to ensure heifers were 65% of mature weight by the start of the breeding season. This ensured a high percentage of females were pubertal by the start of the breeding season. Genetic progress and improved nutrition has reduced age at puberty providing greater flexibility to replacement selection.

As the cattle market starts its cyclical turn in favor of the cow-calf producer the cost of the replacement prospects are going up with weaned calf prices. Using the recent Cattle-Fax update that suggests $25-35/ cwt higher fall calf prices, a weaned heifer calf will cost you about $150 more in opportunity cost than last year.

Combine this 10% increase in opportunity cost with a year of high input costs and scarce forage resources.Perhaps replacement heifer selection should go beyond turning out a bull with the oldest heifers and waiting to see what happens.

Historically these more expensive replacements are most productive during the cyclical lows in the cattle cycle. Iowa State published an excellent heifer retention strategy document in 1997 comparing dollar cost averaging and steady herd size replacement strategies. The approach was simple: spend the same dollars on replacement prospects each year, retaining less when they are expensive and more when prices are low, or keep the same head count regardless of the cost. Dollar cost averaging increased ROI while reducing overall investment and cow costs.

The one challenge with this model was the variable herd size. The experiment started with 100 cows, expanded to as large as 160 head and shrunk to a low of 80 head. This system poses a pasture management challenge but results in a well timed buy low, sell high strategy.

Getting heifers bred the first time while not easy is much simpler than successfully rebreeding those first-calf females. The percentage of first-calf heifers who rebreed in a defined breeding season may be one of the best indicators of herd reproductive efficiency. With the heifer’s breakeven point well beyond the first and second calves, the ability to select for long-term reproductive success is a trait we should all focus on.

That said, few commercial cattlemen realize we have genomic tools available today to select for longevity before the first breeding season begins. For heifers who calve first at two years of age the difference in number of calves over the next seven calving events is 2.7 calves when comparing the top 20 and bottom 80 percentiles for reproductive efficiency.

Both heifers fit the survival criteria of calving at two years of age yet the number of calves over their lifetime was markedly different. For those who suggest the 20th and 80th percentiles are too extreme, the difference between the 25th and 50th percentile is 0.5 calves.

For those who want to continue to use the survival model as the first selection method consider testing the bred heifers and then marketing those with lower lifetime reproductive potential to reduce the first calf heifer fallout. Marketing heifers with known lower lifetime reproductive potential likely doesn’t create the reputation most cattlemen seek. One could argue the same for keeping heifers without knowing.