Heifer development represents significant costs to the cow-calf enterprise. And, just as a heifer is ready to begin paying her way, some things can go awry:

  • She doesn't settle her first year, or she settles and has problems calving.

  • She doesn't rebreed as a two-year-old.

Jeff Cornell of Wagon Mound, NM, continually faces the dilemma of bringing a heifer into the breeding herd at the least possible expense — and getting the most out of her biological ability. Cornell is very demanding of his cows, especially the 120+ head of replacements he raises each year. He knows there's a point where costs can reach a point of no return. Even more demanding is the tough, dry environment that asks a lot of his cows.

His is a low-tech program. After fall weaning, his heifers receive 2 lbs. of cottonseed cake/head/day and grass, until they're turned out for breeding in the spring. That, and heavy, built-in, selection pressure.

Table 1. Supplement Composition*
Bypass 36% crude protein Control 36% crude protein
Cottonseed meal 33% Cottonseed meal 42%
Feather meal 17% Soybean meal 30%
Fish meal 5% Molasses 11%
Molasses 11% Ground milo 9%
Ground milo 24%
$275 per ton $235 per ton
*Supplements formulated as cubes or 33-lb. blocks feed 2-3 times weekly to provide 2 lbs./head/day.
Table 2. Delayed February Start Supplementation*
February start Bypass Control
(n=65) (n=61)
October 503 516
January 511 508
March 542 536
May 558 560
Pregnancy Rate 79% 67%
*Heifer body weights (lbs.) and pregnancy data (94-95; 96-97)

“Our philosophy is that heifers should be raised under the conditions they're expected to function in their whole life,” he says. “They're certainly not what you call ‘fat’ at any point in their life.”

Cornell selects out of “the middle” of his heifers to get a 950- to 1,000-lb. mature cow. “Bigger heifers won't stay in our program, so we get rid of them right away,” he says

The “Bypass” Boost

Researchers at New Mexico State University (NMSU) have been formalizing the practices ranchers like Cornell experience in heifer development. And, they've come up with an added twist in their recommendations for low-cost heifer development.

Dean Hawkins, NMSU professor of animal science at Las Cruces, led a long-term study in low-cost heifer development. To date, he's shown:

  • pregnancy rates of 80% with heifers developed on native range;

  • heifers average about 55% of mature weight at breeding;

  • supplementation costs at less than $30/head/year; and

  • dystocia less than 5%.

The added twist is that Hawkins uses “bypass” protein to help boost heifer conception rates. Hawkins likes to use a 36%-crude protein ration (see “The Role Of Bypass” on page 44) with significant bypass protein as a supplement. In this case, it's feather meal and fish meal fed for three months of the heifer's developing life (Table 1).

While the bypass ration is more expensive than his oilseed meal-based control supplement, Hawkins delays supplementing until February, three months before breeding (Table 2).

“We know we're getting some stimulatory effect on reproduction with the bypass protein,” he explains.

From breeding turnout until end of breeding, the heifers go back onto the control supplement. By June, they become just “cows on grass.”

Hawkins breeds NMSU's Corona, NM-based herd of moderate-framed English crossbred heifers in May using artificial insemination (AI) for one synchronized cycle. Then the bulls go in for 45 days.

Another key is that cattle are exposed to “rested” grass pastures at key times. When breeding begins, they're on fresh pasture.

Table 3. Cumulative Body Weights and Pregnancy Rates*
Bypass Control
(n=122) (n=117)
October 510 515
January 512 519
March 543 547
May 565 573
Pregnancy Rate 80% 66%
*Heifer body weights (lbs.) and pregnancy data (all years)

“We keep plenty of grass in front of the heifers,” Hawkins says. “It won't work without the grass,” Hawkins says. “Nor do we put any more resources into the heifers under this program than the mature cows.”

His philosophy is that “optimal” might be better than “maximal” management — realizing that anything near a 100% pregnancy rate, even if possible, isn't always profitable.

One key is that Hawkins' heifers are closer to 13-14 months of age at breeding than the customary 12 months under a more intensive development program.

“Compared to a feedlot heifer, you might consider ours fed under a ‘restricted’ regime,” Hawkins says. “But they're not restricted nutritionally. We won't ‘buy’ energy — that's what the grass is for, but we do depend on compensatory gain,” he adds.

Selection Pressure Is Critical

Like Cornell's program, the NMSU regime places tremendous selection pressure on heifers for puberty and pregnancy.

“Though fertility is considered generally low in heritability, it's still heritable,” he says. “If they can't get pregnant under range conditions, I don't want them on the ranch.” Hawkins admits his low-input regime draws its share of criticism. It's not for everybody.

“This program isn't for the weak of heart or the novice cattleman,” he warns. “It takes a different kind of mindset to raise heifers under these low-input conditions.”

Still, NMSU's cost per pregnant heifer was $124.67, compared to $163.25 for “high-input,” feedlot-raised heifers. These costs include the open heifers.

The catch with Hawkins' program is that it may not be best for ranchers who invest a lot of money and time into boosting genetics by synchronization, AI or embryo transfer.

Mark Petersen, NMSU ruminant nutritionist, emphasizes there's no drop-off in production or longevity as Hawkins' heifers mature.

“In fact, we're seeing that it's an advantage to bring these heifers into the cow herd. They will be better-doing cattle for the rest of their lives,” he says.

Petersen adds that the low-input regime can work without bypass protein in the diet (see Table 3). “But, you risk taking a hit on pregnancy rates.”

With seven years of data, Hawkins' findings are solid, says Clay Mathis, NMSU Extension livestock specialist. But, he adds, the results go against the recommendation that heifers be at 65% of mature weight at breeding.

“Some producers may balk at an 80% heifer pregnancy rate,” he adds. “But, the cost per pregnancy is more important than the pregnancy rate alone, especially if you consider the salvage value of open heifers.”

Cornell says that, with ranch profit margins so slim and feed costs generally being the biggest out-of-pocket expense in raising cattle, it makes sense to make maximum use of the ranch's grass resource.

“We're tough on them,” he says, “but if you do that for a few years, you end up with a pretty much trouble-free, low-labor herd.”

Editor's note — M.E. Ensminger's “Stockman's Handbook” was also referenced for this article.

Heifer Development At A Glance

Here are some highlights from New Mexico State University's (NMSU) heifer development research:

  • Highest percentage of pregnant heifers has been in the bypass-protein supplement groups.

  • Placing heavy selection pressure on heifers may be more profitable long term.

  • Advantage in pregnancy rates has occurred without dramatic changes in body weight.

  • Judicious use of sires with low birth weights has essentially eliminated dystocia.

  • Rebreeding is averaging 85% on two-year olds.

For more information, contact Dean Hawkins, NMSU professor of animal sciences, at dhawkins@nmsu.edu.

The Role Of “Bypass”

Proteins are composed of nitrogen containing compounds, namely amino acids. Dietary protein is broken down in the rumen by microbes to yield ammonia and carbon compounds (CO2+CH2). These microbes utilize the ammonia to synthesize their own body proteins.

The ruminant animal obtains its protein through digestion of the microbes that are washed from the rumen to the omasum, abomasum and lower gastrointestinal tract.

A certain percentage of the dietary protein escapes microbial digestion and travels to the small intestine, where it's digested if it is digestible. This type of protein is undegradable intake protein (UIP) or “bypass” protein, and is distinct from degradable intake protein (DIP).

As with any biological process, there's an energy loss, or “tax,” when the microbes convert protein for their growth, says Sean Firth of Nova Scotia's Department of Agriculture and Marketing, Kentville Agricultural Centre in Kentville, Canada.

Bypass protein seeks to avoid this tax by passing through the rumen undigested. It passes into the small intestine where it's absorbed directly through the intestinal wall.

The microbes can only use DIP, whereas the animal can utilize DIP and UIP. Proteins that are digestible, but aren't degraded in the rumen, are escape proteins. The degree of escape is influenced by feed composition (protein solubility), rate of passage of feed, and microbial and animal condition.

There are two significant considerations related to escape protein, Firth says. First is the energy content of the diet. The energy content determines the degree to which microbial synthesis will occur. Second, there must be an adequate supply of degradable protein to satisfy the microbial requirement.

Numerous studies demonstrate increased serum insulin concentrations in cattle fed with bypass protein, says Mark Petersen, New Mexico State University ruminant nutritionist. He's worked with bypass protein for nearly 20 years.

By changing the metabolic functions of the animal, bypass proteins increase the release of reproductive hormones — LH, FSH, or GnRH.

“Increased insulin makes the heifers more responsive to the lower quantity of nutrients,” Petersen says. “Thus, they get more out the energy supplied under low-quality feed conditions.”