Grass Fed Seed Stock – The Numbers

Rhino’s Beef™  Beating the Odds – 158,793 to 1

We breed to enhance overall efficiency,  efficiency on grass,  meat tenderness, manageability, and calving ease in grass-fed Angus cows.  Value assessments for our breeding stock is based, in part, on genomic testing.  (These are not genetic tests and are not useful for genetic modification. Rather, these tests examines molecular patterns in sires and dams that anticipate particular traits  in offspring, serving as a guide in selecting breeding stock.)

Our two herd bulls’,  Doc’s and Little Boy’s,  contribution to progeny according to Zoetis Molecular Value Prediction (MVP):

Calving Ease Direct (CED): Doc, easiest 8% rank —— Little Boy, easiest 34% rank —- CED quantifies genetic likelihood of unassisted births in first-calf heifers sired by the bull tested.

Calving Ease Maternal (CEM): Doc, easiest 17% rank —– Little Boy, easiest 28% rank —- CEM quantifies genetic likelihood of unassisted births in first-calf heifers whose parent was the bull tested.

Docility (DOC): Doc, most manageable 10% rank —– Little Boy, most manageable 7% rank —— Docility quantifies likelihood of acceptable (calm) versus unacceptable (wild) temperament of offspring. More manageable dispositions are predicted by top rankings.

Tenderness (TND): Doc, most tender 63% rank —– Little Boy, most tender 3% rank — Tenderness is a measure of the amount of shear force required to slice through cooked meat samples of progeny.

The odds against two Angus bulls selected at random from the global Angus database of matching up with the numbers put up by Doc and Little Boy for maternal calving ease, manageability and meat tenderness is 158,793 to 1. (CEMa x DOCa x TNDa = Pa ….. CEMb x DOCb x TNDb = Pb…... Pa x Pb = PT…… 1/PT=158,793) (Note: Although Direct Calving Ease (CED) would have rendered another power of 10 to the overall improbability, we excluded CED because of an expected genetic redundancy between CED and CEM.  If a genetic redundancy exists between CEM, DOC and TND, then 1/PT is less than 158,793, but we are not aware of such a redundancy.)

The odds against randomly selecting two bulls like Doc and Little Boy would probably be astronomical if  we were able to assign a value for “efficiency on grass”. However, “efficiency on grass” is not one of the 18 values assigned by Zoetis.  Therefore, to evaluate “efficiency on grass”, we examine patterns in Zoetis MVP rankings.

Efficiency, Efficiency, Efficiency

We seek efficiency, not size.  Weight gains with respect to average is what we are looking for, not size alone.

To parse overall efficiency from the data, however, we compare three rankings: weight at birth, weight at weaning, and yearling weight.

It is not particularly important to us how heavy our feeder calves are at any step along the way, as long as the calves are making efficient use of the food they consume, whether it is mother’s milk, grass or hay.  As long as dietary protein is efficiently being converted into meat protein, our efficiency goal is met in feeder calves.

Likewise, we want our replacement heifers to consume their food efficiently. In general, we prefer moderately framed herd cows that calve regularly without difficulty, year after year.  However, if our replacement heifers are a little larger than average, as long as they consume their food efficiently they meet our “efficiency” criteria.  Efficient, larger framed cows produce large calves that are highly efficient on grass, resulting in large feeder calves.

Efficiency on the Cow

To glean from genetic tests  “efficiency on the cow’,  we look for rapid MVP weight gains, with respect to the global Angus average, between birth and weaning. Because these rankings are assigned for direct offspring of a bull, these rankings are independent of the mother’s milking ability in the MVP global Angus database.

Both Doc and Little Boy, in their contribution to their progeny, tend to produce calves that have a very high efficiency on the cow prior to weaning.  This is the first indicator of a calf’s ability to efficiently use dietary protein, and it is a very important phase of a calf’s life, the phase that sets the stage for all that is to come.

Doc:  BW only 14% of calves in the global angus database are smaller, WW 37% are smaller.  (By yearlings, his calves advance to  larger than average,  YW 55% of database calves are smaller.)

Little Boy:  BW 58% are smaller, WW 96% are smaller.  (As yearlings, his calves maintain their size, YW 96% are smaller)

Efficiency on Grass

The progression vs. the global Angus database from birth weight to weaning weight to yearling weight is very important to us.  To parse “efficiency on grass” from MVP tests, we particularly look at the progression, with respect to average, from weaning weight (WW) to yearling weight (YW).

In other words, we look for small birth weight calves to become medium sized calves at weaning and larger than average calves as yearlings.  By the same token, we look for average birth weight calves to become larger than average at weaning and quite large as yearlings.  That should be a repeatable pattern in calves that are efficient overall, and efficient on grass in particular.

Doc’s Efficiency on Grass

In Doc’s case,  MVP’s indicate very easy calving (CED easiest 8%) of light birth-weight calves (BW smallest 14%) that gain rapidly until weaned (WW smallest 37%) and continue to advance with respect to the average until weighed again as yearlings (YW 55% are smaller).  These are very favorable indicators for overall efficiency, and for efficiency on grass in particular.  Doc is an outstanding bull for first-calf heifers (CED easiest 8%) and, considering his other traits,  a superior bull for mature cows as well.

Little Boy’s Efficiency on Grass

In Little Boys case, MVP’s indicate moderately easy calving (CED easiest 34%) of average birth-weight calves (BW 58% are smaller) that gain very rapidly until weaned (WW 96% are smaller) and continue to gain rapidly until weighed again as yearlings (YW  95% are smaller). Again, very favorable indicators for overall efficiency, and particularly for efficiency on grass.  Little Boy, factoring in his other qualities, is a superior bull on first-calf heifers (CED easiest 34%) and a truly exceptional bull for mature cows.

Footnote – Building a Case for “Efficiency”

Vigor In Utero

While “efficiency on grass” and “overall efficiency” are not the only possible explanations for accelerated growth with respect to the global Angus population, calves sired by both Doc and Little Boy display a pattern of vigor that begins in utero and continues throughout their first year of life.

It has long been understood that birthweight is the predominant driver of calving ease.  Calves sired by both Doc and Little Boy (CED) are predicted to calve easily (top 8% and top 34%, respectively).  However Doc sired calves are in the 14th percentile for weight, well above the 8th percentile expected from calving ease. (Not a large percentage difference, but raw values on the extremes of a bell curve increase dramatically with small percentage increases.)  Similarly, Little Boy’s progeny are in the 58th percentile for weight, considerably above the 34th percentile expected from calving ease.

Maybe qualities other than “calf vigor” (such as flexibility, proportionality, head size, etc.) are responsible for calves that are markedly heavier than would be expected from CED ranks.  Nevertheless, this is the pattern we seek. If calves sired by these bulls are simply more determined to be born (not really more “vigorous”), we can live with that.  (The sire’s contribution to progeny is independent of the dam’s in the database, so the dam’s inherent birthing qualities do not offer an explanation for the sire’s MVP contribution to direct calving ease vs. expected birth weights.)

Voracious Appetite vs. “Efficiency”

As discussed previously, an accelerated growth pattern, with respect to the global population, for calves sired by both bulls begins at birth — for the first seven months (from birth to weaning) and continuing for the next five months (from weaning to yearling).

Voracious appetites alone, irrespective of efficiency, are unlikely to be responsible for birth to yearling weight gains with respect to the global population.  For instance, appetite alone would not explain the growth pattern observed before weaning, because the sire’s contribution is independent of the dam’s (regardless of the dam’s milk production or udder qualities). Possibly these calves suckling qualities allow them to obtain each very last drop of milk, but even if that is the case, there’s only so much milk available from the prototypical cow in the database.

In the special cases of Doc and Little Boy, MVP ranks for Dry Matter Intake (DMI, pounds of dry matter per day on feedlot rations) and Carcass Weight (CW), argue strongly for progeny with relatively small appetites if finished in the feedlot.

Doc’s progeny are in the lightest 45 percent (YW) as yearlings, yet they consume less than 95% (DMI) of other animals in the feedlot, producing carcasses (CW) in the lightest 33%.  Little Boy’s progeny are in the heaviest 5% (YW) as yearlings, consume less than 53% (DMI) of other animals in the feedlot, yet produce carcasses in the heaviest 16% (CW).

Intentional Breeding for “Efficiency”

In the end, we seek maximum efficiency for three things: protein in feed converted to animal  protein; carbohydrates in feed used to meet energy needs; dietary minerals used to build structure.

For every calf in the database that increasingly gains ground on the global population, another calf in the database steadily loses ground.

The random chance is small of seeing even fractional advances with respect to the population at each step along the way.  The random chance is minuscule of seeing major advances in CED>BW>WW>YW  (Doc 8%>14%>37%>55% — Little Boy 34%>58%>96>95%).

Unless this quality is intentionally sought, it is unlikely to happen on it’s own accord.   We believe that producers, grass fed or not, who intentionally breed for this quality are poised to meet the demands of the 21% century.

Furthermore, we are convinced by the preponderance of evidence that calves sired by both Doc and Little Boy make optimal use of available nutrients from birth until they are weighed as yearlings.  Call it “vigor”; call it “efficiency”; either way, it’s what we want.


A subgroup of the 18 MVP genetic traits  (MVPFL) is evaluated by Zoetis Genetics to predict the potential for generating profit if the progeny of tested animals are finished in conventional feedlots (combining MVP values for dry matter intake (DMI) , carcass weight (CW), as well as predicted USDA quality and yield grades, assuming 180 days on feedlot rations).

Again, Doc and Little Boy excelled in MVPFL ranking. Doc’s contribution to his progeny is expected to generate an average of $164 above the industry average for each finished steer he sires, ranking in the top 12%. Little Boy is expected to generate a return of $159 above the industry average for each finished steer he sires, ranking in the top 15%.

There’s a 1.8% chance of selecting two Angus bulls at random from the database with as much earning potential as Doc and Little Boy, even for a commercial beef producer.

It makes sense.  Vigorous, efficient calves should finish well on any rations.

Randomness, Breeding Programs and Seed Stock

It goes without saying that seed stock is never selected at random.  All seed stock producers aim to match this type of numbers for the given qualities they wish to enhance.  Some producers breed to enhance show qualities in purebred animals; some producers breed to enhance commercial qualities in feedlot finished beef; some producers breed non-Angus bulls to cross with Angus cows.

We breed to enhance overall efficiency, efficiency on grass, meat tenderness, manageability, and calving ease.  Based on genetic tests, there is every reason to believe that our calves will finish just as well on grain as they do on grass.

For more information on how genetic tests fit into our decision making process, refer to Herd Bull Genetics.