Helpful tools of the trade

The Challenge of Predicting Heights in Young Cattle

When purchasing young, immature cattle, it can be very difficult to know exactly how they’ll mature. You might assume that the adult height of a calf will simply average between its sire and dam — but that’s not always the case.

 

It’s also tempting to think that the calf’s current height tells the whole story. In reality, growth is influenced by several factors, including genetics, nutrition, and developmental stage.

Many breeders have published versions of the graphic below to illustrate growth differences, but these comparisons are only meaningful once an animal has reached at least 3 years of age.

  

Taking the Mystery Out of Miniature Cattle Selection

This post is meant to remove some of the mystery from selecting miniature cattle and hopefully reduce — if not eliminate — a few of the surprises along the way.

Age Matters

All calves are small at birth, but that doesn’t mean they’ll stay small. Highlands in particular are slow developers and may continue growing until around 5 years old. In the mini cattle world, the official measurement age is 3 years, when height is recorded for classification. That said, animals can still gain another inch or two as they finish maturing.

For example: if you buy a calf whose dam is 7 years old and measures 43”, it’s entirely possible that she was 41-42” on her third birthday — officially “miniature” — but gained a bit of height with age.

Where the Measurement is Taken

Another layer of complexity comes from where the height is measured. Historically, minis were measured at the hook (hip bone). In the past couple of years, however, many breeders have shifted to measuring from the ridgeline directly above the hook, while others measure at the shoulder. In my experience:

• Ridgeline and shoulder measurements are fairly consistent with each other on mature animals but not on calves.  Calves shoulder height is almost always shorter than a ridge line measurement.  
• Hook measurements tend to be 2–3 inches shorter.

When inches make all the difference in classification, it’s important to ask sellers exactly where they are measuring from.

The Importance of Accurate Age in Predicting Size

Sometimes a cow’s birthdate is unknown or has been recorded incorrectly. Without knowing an animal’s true age, it’s nearly impossible to predict its eventual full-grown height.

With very young calves, it can even be difficult to tell the difference between a 3-month-old and a 6-month-old just by size alone. However, as cattle approach a year of age, their horn development becomes a some-what more reliable indicator. By paying attention to horn size and growth patterns in yearlings and older animals, you can make a much more accurate estimate of age — and therefore a better prediction of their final height. Note that lower percentage highland crosses often times have smaller horns.

The “miniature” height designation is different depending on WHO you talk to.  IMCBR says the animal must be under 42” at three yrs old.  Pretty much every other registry has a height differential between cows and bulls of roughly 2”… so a miniature bull in this case is anything under 44”.  

Understanding Height Predictions in Chondro vs. Non-Chondro Calves

 

When estimating the adult height of a calf, it’s important to account for whether one parent carries the chondro gene. If one parent is chondro positive but the calf tests negative, you cannot simply average the parents’ recorded heights to predict the calf’s mature size.

Instead, you must first “add back” the chondro adjustment to the positive parent’s height before averaging. For example, a bull that measures 38” with chondro would be approximately 42-44” without it. Using the adjusted height will give you a more realistic estimate of the calf’s mature size.

In general:

• Chondro-positive calves often grow to be similar in height to their chondro-positive parent, and sometimes slightly larger if the dam is the chondro carrier — but only if the non-chondro parent is truly miniature.
• Standard-sized parents bred to chondro animals can produce “mid-size” offspring — animals that are essentially standard cows with dwarf proportions. In some cases, these calves resemble full-size cattle but with disproportionately short legs.