It may be easier to explain away why you don’t have marbling in the herd than it is to get it. Some say that’s the origin of the popular “urban legend” in the Angus breed: high marbling potential is for “terminal” cattle, because they don’t make good mamas. You can’t have both in the same herd. But you can, as more and more commercial Angus herds across North America are proving with data and profit. Recent research suggests any theories to the contrary were simply created by those who have not made much effort to select for carcass traits and thus describe their herds as “maternal.”
“Selection for Marbling and the Impact on Maternal Traits,” a research paper by Virginia Tech Extension animal scientist Scott Greiner and graduate student Jason Smith, explores the topic.
Marbling has a slight relationship “with most of the traits that we associate with cowherd productivity,” Greiner says (see Table 1 below). Terminal and maternal traits can “coexist.”
The first step to building a productive cow is to get her bred and bred early, and scrotal circumference is an indicator of fertility The first step to building a productive cow is to get her bred and bred early, and scrotal circumference is an indicator of fertility.
Decades ago, some fairly popular and high-marbling Angus bulls happened to score low in that indicator, but that was just coincidence, according to all evidence.
Both small-scale studies and actual analysis of the expected progeny differences (EPDs) for marbling and scrotal circumference found no association between the two traits. Nor should marbling ability impact the onset of puberty.
“Age at first calving” is often used to determine if a female will get pregnant during a normal breeding season. One study indicated no relationship and another said an increase in a full unit of marbling would extend age at first calving by 10 days.
“A breeder that makes a 0.25 unit improvement in marbling EPD would be expected to increase age at first calving by less than three days,” authors Greiner and Smith state.
There is no correlation between marbling and heifer pregnancy in the Angus database.
“Angus sires are highly sought after amongst commercial producers due to their ability to excel at calving ease while they maintain or improve carcass traits,” the paper says.
The limited research highlights possible positive impacts, such as increased marbling in tandem with calf survival, lower birth weight and better calving ease.
by Miranda Reiman