Stacking the Odds

By Boyd Kidwell
Progressive Farmer Contributing Editor

As beef cattle producers move into the expansion phase, interest in artificial insemination (AI) with sexed semen is increasing. Many ranchers want to see if sexed semen is a profitable way of developing additional high-value replacement heifers.

Proponents of the approach say sexed semen can improve genetics and gives them the option of using calving ease sires, along with a high percentage of calves of the desired sex. In today's market, many ranchers want to stack the odds in favor of high-quality replacement beef heifers.

"We're coming out of a drought, and cow numbers are down. I think replacement beef females will be in high demand," said Heath Kohler, manager of the 26,000-acre Ratcliff Ranch near Vinita, Okla. "People want replacement females with known genetics from a reputable herd. We have years of carcass data on our cow herd. People know the calves out of our heifers will hit the grids and earn premiums."

CONCEPTION TRIAL

To build cow numbers for the ranch's 4,200-cow herd and for replacement heifer sales, Kohler recently worked with Genex Cooperative and the University of Missouri in a large sexed semen project. He AI-bred 300 cows using conventional and sexed semen; a year later he AI-bred another 656 cows using conventional and sexed semen. These were one-time AI cows, on a working ranch.

Conception rates in both groups were higher with the conventional semen. In the first 300-cow group, the conception rate using conventional semen was 69%. The cows bred using the sexed semen had a 59% conception rate. In the second group of 656 cows, those bred using conventional semen averaged 77% conception, and those bred using the sexed semen averaged 51%. These percentages were for cows that were in heat at the time of breeding. The researchers used heat detection patches to determine which cows were in estrus at the time of AI.

"The take-home message with timed AI is that you can achieve over 50% conception rate with sexed semen if you only inseminate the animals showing estrus. Based on what we've seen, I wouldn't recommend using sexed semen unless cows are showing estrus," said Stan Lock of Genex Cooperative.

PREGNANCY RATES KEY

AI conception rates must be strong to make sexed semen pay off in replacement heifer operations. There are fewer viable sperm in sexed semen, which is why conception rates from sexed semen run 10% to 15% lower than for conventional semen.

Sexed semen, however, is 90% effective in gender selection, reports Sexing Technologies of Navasota, Texas. This company sorts semen by X and Y chromosomes and has working agreements to sort semen with most of the large bull studs in the U.S.

Sexed semen is more expensive than conventional AI semen, but the price has recently decreased. Depending on the sire, Sexing Technologies estimates a straw of sexed semen costs $35 compared to $20 for conventional semen.

Despite the additional cost, sexed semen is only 6% of the total cost of developing a bred heifer. The initial value of the heifer at weaning and the cost of feeding her during the development phase are the major expenses.

Although bull choices are still limited, the number of AI sires with sexed semen available has jumped from zero to approximately 100 during the past five years. Bull owners can deliver their sires to facilities in Texas and Nebraska to have AI semen collected and sexed. Clean-up bulls are often used with either sexed semen or conventional semen to bring conception rates up to long-term herd averages.

GENDER DIFFERENCES

The gender difference in sales value of a replacement heifer is a major factor in using sexed semen to produce females. F1 (Brahman/Hereford or Brahman/Angus) heifers represent a good example in gender difference.

F1 females are considered the most efficient and long-lasting brood cows from Texas across the Gulf Coast to Florida. However, the half-Brahman steer mates resulting from the F1 cross are often discounted at feeder calf sales (compared to steers with less than 25% Brahman blood).

"If there's a big gender difference in value (around $150) it offsets the lower pregnancy rate," said Jim McGrann, management economist and professor emeritus at Texas A&M University. "Before a producer starts breeding with sexed semen, he needs to know the gender difference. Producers wanting F1 replacement heifers sure see a large gender value difference."

(VM/CZ)

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