Production ability is top consideration for retaining heifers
Riverton – “There is only one reason to keep a heifer and that is to improve the quality and profitability of the herd,” said Scott Lake, UW Extension beef specialist.
“Less than two percent of cows in U.S. are culled every year for their structural problems,” he added. “We need to make more decisions based on performance and do a better job in culling.”
Lake sees, first and foremost, reproduction ability as the most important factor when selecting heifers.
Other traits to consider include mothering ability, good milking ability for the environment and good structure of the udder.
“We need to keep selecting for maternal traits that are going to be the foundation of the cowherd,” said Lake. “When producers start chasing growth and carcass traits and selecting more for those is when we start to see fertility go down.”
Physical traits to look for on heifers are a body condition score of 5.5 to six, a large capacity to be able to carry a large calf to term and have room for large amounts of feed, structural integrity and easy weight gaining ability.
“It’s important to select a cow that fits a producer’s environment and fits their energy resources,” stated Lake. “There is a strong correlation between the condition of the cow and how well she is going to perform.”
The number one problem with fertility of open cows is a low body condition score. Nutrition is the number one reason open cows are in anestrous – a period where a cow is not cycling.
A feminine look is also important when selecting heifers. Feminine heifers have a tendency to reach puberty faster, remain in a herd longer and be the daughters of more masculine bulls.
The time a heifer reaches puberty is also highly correlated to post partum intervals.
“When producers are making selection decisions for their herd, they want a cow that will produce a value-added calf,” stated Lake. “They have to define what a value-added calf is to them.”
Lake gave the example of a value-added calf being one that is better than the average calf in a cowherd.
Lake continued on to say just because a cow was bred and had a dinky calf doesn’t mean she should stay in the cowherd.
Some reproductive goals for heifers are to reach puberty by 12 to 13 months of age and a lot of management practices prefer to have those heifers cycling before they are bred.
“We want to be able to breed her by the time she’s of 15 months of age and calve her as a two-year-old,” said Lake. “A lot of models have shown this to be the most profitable system.”
“A lot of what keeps two-year-olds in a herd has to do with how they are managed and developed,” added Lake.
The most common way heifers are managed is to get them at 65 percent of their mature body weight by the time she is bred, a management practice called target weight – meaning a 1200-pound mature cow will need to be 750 to 780 pounds before she is bred.
“Approximately 80 percent of U.S. cowherds calve during the spring,” described Lake, “which means producers are going to be feeding their heifers a concentrate diet to get them to their target weight.”
Heifers fed on an increased plane of nutrition right after being bred have a higher conception rate than heifers turned out to pasture right after breeding described Lake.
Lake devised a heifer conception rate study that consisted of three treatment groups of heifers. All of the heifers were fed on the same nutritional plane prior to breeding and the differences in the three groups of feed lasted for 21 days.
The three feed groups consisted of a gain ration to simulate a high concentrate diet seen in a feedlot, a maintenance ration that symbolized a grass pasture turnout and a ration simulating forage from a mountain turnout.
“We saw a 20 percent difference in conception rate between cattle kept on the gain ration and the other two rations,” explained Lake. “Overall, the heifers in the gain ration had a 70 to 90 percent conception rate.”
The heifers in the other two feed groups lost weight during the 21-day trial period and had poorer conception rates.
“When this study was reconstructed in a real world scenario, the results were exactly the same,” said Lake. “A 15 to 20 percent difference in conception rate occurred between the heifers in the feedlot and the heifers that were turned out to pasture.”
Lake further noted that the gain ration treatment also contributed to a higher quality of embryo from the heifers.
Lake spoke at the Fremont County Farm and Ranch Days in the middle of February. Madeline Robinson is the assistant editor of the Wyoming Livestock Roundup and can be reached at firstname.lastname@example.org.
“Heifers born in the first cycle of calving season are going to be more fertile and have a shorter post partum interval throughout their lifetime,” commented Scott Lake, UW Extension beef specialist. “Those are the heifers that we want to pick.”
Lake suggested when selecting and developing heifers to keep 10 to 15 percent more than planned because some of them will fall out of the herd.
“Inherently producers are selecting for fertility when they select for early calving cattle because that means their mother was bred at the beginning of the breeding season,” added Lake.
Reproduction is a low heritable trait, but when selected for continuously, the effects become evident. The difference won’t show up in the next generation of calves, but over a period of time, the difference will be notable.
Lake also advised from an economic and fertility standpoint, it is not feasible to keep open two-year-olds that are unable to be bred-back with the rest of the herd, even if they had a good calf the previous year.
“We want the ones that will breed back to continue on in the cowherd,” said Lake.