Highland nt821 Update:

– Current list of “carrier” & “Free” animals

March 2024
– The AHCS (Australian Highland Cattle Society) has made a decision on the nt821 gene – they will be prohibiting the registration of bulls with nt821 gene (homozygous or heterozygous), and females with 2 copies of the gene (homozygous), and that the nt821 status of an animal registered in the herdbook will be displayed (if known) on their registration certificate and the online database. This decision will need to be voted on by the membership at the upcoming AGM, and if passed, will come into effect 3 months later (there will be no effect on any registrations prior to this date).

February 2024
– The UK Highland Cattle Society informs members that they will be prohibiting the registration of bulls with nt821 gene (homozygous or heterozygous), but at this stage is taking no position on females with the gene.
– Testing cattle in Australia has slowed with caution around the position of the AHCS.

January 2024
– More and more folds are testing throughout the world and carriers animals continue to pop up.
– In Germany the testing thus far sees the gene trace back to one common bull, who’s parents were born in 1988 & 1987 respectively.
– In the USA, testing has just started this month and some carrier animals have been identified, one of which has parents that were born in 1974 and 1964 respectively (meaning that the nt821 gene has been around at least 50 years).

December 2023
– Many folds in Australia and overseas are starting to test for nt821, to gain an idea of what affect it has on Highlands, how many Highlands are affected, and how many generations it can be traced back (& to which animals).

November 2023
– 1st – nt821 found in 3 Bairnsley calves
– 11th – Bairnsley notifies the AHCS (Australian Highland Cattle Society) of the presence of the gene in Highlands in Germany & Australia for the first time.
– nt821 is discovered in Highland cattle in Scotland

October 2023
– nt821 is found in Highland cattle in Germany (first time in the world)
– 26th – UK Highland Cattle Society notified

What is the nt821 Myostatin Gene – A Summary?

Myostatin is a protein that inhibits muscle cell growth. The “double-muscle” genes (of which nt821 is the most well known) block myostatin and therefore allow muscle cells to grow.

Normal, “wild-type” animals do not have a myostatin gene. One copy (herterozygous) in cattle is essentially unrecognisable when compared with cattle that do not have the gene. Two copies of the gene (homozygous) in beef cattle sees significantly more muscle mass, although this varies between breeds because of the effects of other genes. This suggests a recessive (or partially recessive) mode of inheritance.

It is found in many British breeds (Shorthorn, Red Angus, Black Angus, Red Polls, Speckle Park), as well as European breeds of cattle. These breeds began to discover the gene in there cattle around 2010 and their breed societies have put into place regulations to manage the presence of the gene, and in some cases to educate only, to allow breeders to breed towards or away from the gene.

It was first tested for, and found, in Highland cattle in Germany in October 2023.

The History of the nt821 Gene

The nt821 gene was discovered in 1977, however, “double muscling” in cattle has been observed since the early 1800’s (first seen in Durham cattle, the animal that Shorthorns were derived from).

There are currently 21 known “double-muscling” genes (of which nt821 is probably the most well known), of which 6 can currently be commercially tested for (at Neogen Genetics).

The Belgian Blue breed started around 1850 (& the herd book in 1919), is the most well known double muscled breed, with 98% of the herd book being homozygous for nt821 (& various other myostatin genes). They have been selectively bred for extreme muscling over the last century since their inception.

What Does the nt821 Gene Do in Cattle?

It varies with the breed of cattle and sex (other genes are known to affect myostatin function as well), but what has been shown in multiple other breeds –

The negatives (in the homozygous animal) –

Increased muscle mass (in skeletal muscle only – increased number of muscle cells in each muscle – approximately twice as many)
Reduced intramuscular fat (& slightly reduced subcutaneous & abdominal fat)
Reduced connective tissue in muscle (related to increased tenderness)
Slightly decreased bone density (5-9%)
Slightly reduced internal organ size
More likely to have calving difficulty (because of slightly narrowed bony pelvic diameter in homozygous females)

The positives

Increased retail beef yield (carcass dressing percentage) & a leaner carcass (with similar or improved meat tenderness)
Slightly improved feed conversion ratios (except after 18 months of poor feed, when they show slightly more growth and fertility problems)

What does the nt821 gene do in Highland cattle?

This is currently poorly understood, but how it manifests is known to vary from breed to breed. It appears to have been around for 50+ years and thus far has not raised any eyebrows. This question will likely be answered in the next 12 months as we identify heterozygous and homozygous animals, but for our experiences in our own fold, please read below.

The nt821 gene is also seen in dogs, mice, humans.

Our Experiences at Bairnsley

nt821 Homozygous Cattle

We only have one homozygous heifer (born May 2023) here so the smallest of sample sizes – she is thick (a bit coarse / lacks femininity), and well muscled for sure, but nothing like a Belgian Blue!

Currently, we do not know of any other proven homozygous Highland cattle, but no doubt, more will show up.

nt821 Heterozygous Cattle

Our experiences agree with the research in that Highlands with one copy of the nt821 gene are essentially just like any other Highland (maybe marginally better than average muscling, but no more than what is seen in other well fleshed lines without the gene), with no other differences in physical characteristics, fertility or calving ease.

nt821 Free Cattle

This is 99.9% of Highlands and these animals express greater or lesser degrees of muscling depending on their genetic make-up. Their muscle pattern may vary, and selection for more or less flesh happens innately within the breed depending on a breeder’s goals (beef production, show cattle, F1 cross females, or just pets).

What have Other Breed’s Societies Done?

This information has been gathered from online resources, herd book regulations and personal communications with members of other breed societies.

Australian Shorthorn Association
– Recommended to test but not required (thought that homozygous animals will have negative selection pressure anyway in this “balanced breed”)

Australian Angus Society
– Optional to test for a panel of 6 myostatin genes (with Neogen), but it is not one of the 9 “genetic conditions” that Angus Australia lists as unwanted conditions in their breed.

Australian Red Angus Society
– Optional testing for a range of genetic mutations, including myostatin genes (at the breeders expense).

Australian Speckle Park Society
– Testing for nt821 gene & recording in the online pedigree database (homozygous animals can not be registered). Accepted as a breed in 2006, they run a closed herd book so the gene was there prior to this time – from either the Angus or Shorthorn lines)

Australian Red Poll Association
– Optional testing of nt821, and result can be recorded on societies online pedigree database.

American Shorthorn Association
– All bulls (post 2018), and all animals imported from the UK, all ET calves are required to be tested (& these test results are noted on the online pedigree database) (Paid for by the society)

UK Aberdeen-Angus Cattle Society
– Allows registration of carrier nt821 animals (one gene)

UK South Devon Society
– Compulsory testing of bulls for nt821, with recording in the online pedigree database.

List of Animal Test Results (& sources)

The NSW DPI performed a 20 year study comparing black Angus females with low muscling to those with high muscling and those that were heterozygous for nt821 and found no differences in fertility, calving ease, calf weights or weaning weights. However, after 18 months of poor nutrition, the nt821 heterozygous cows performed slightly worse than the other cows for fertility characteristics.

CSIRO and other research groups in Australia have looked into the heterozygous nt821 state and found a 2-6% increase in retail beef yield, with decreased marbling and normal to increased tenderness.