Page 59 - BCHNews-122023-Web

New genetic mutation discovered responsible for calf recumbency
Lauren Engelking, Ph.D.
Lauren recently defended her PhD in dairy cattle nutrition and physiology at the University of Alberta. Lauren’s research assessed the interaction between nutrition, physiology, and behaviour in transition dairy cows, with an overarching focus on the role of inflammation in cows - both the harmful and beneficial sides of inflammation, and the extent to which we should interfere.
This report summarizes the presentation
by Dr. Chad D. Dechow, Associate
Professor of Dairy Cattle Genetics at
Pennsylvania State University, at the
American Dairy Science Association
Southwind
Supersire
Calves with genetics from
Southwind, Robust or Supersire
mutation originated from a recessive recumbent haplotype; calves that were homozygous for the recumbency haplotype presented with calf recumbency. Conversely, calves that were carriers of this mutation (heterozygous), meaning they only carried one ‘bad’ recessive gene, did not experience recumbency.
A genomic ‘process of elimination’ was
used in investigating bulls that had
been identified as recumbency carriers.
Future directions
Although this research has begun to inform this condition’s origin and impacts, Dechow noted that we do not yet have 100% certainty about the origin or onset of this condition. Despite the identification of the potential sire and gene this mutation originated from, researchers are still challenged by the fact that some calves survived, whereas others did not. Researchers noted that this is a more complicated genetic condition than many other conditions that have previously been investigated. It is believed this mutation may be incomplete penetrance, meaning not all calves that possess the mutation experience calf recumbency – pointing to the need for additional research to understand this. Dechow speculated that the specific herd or the environment of the herd may influence how this gene mutation affects calves; in other words, the environment the dam is in during pregnancy, and the environment the calf is born into, may impact how this gene affects calves. Overall, there are a limited number of calves that have been genotyped so far, and thus more data will be required to improve our understanding and confirm the current speculations of this mutation’s origin and implications.
Take home findings:
A mutation was identified in CACNA1s, a gene affecting calcium activity in calves that prevents calves from standing, resulting in calf recumbency, and often death. This gene mutation has been traced back to the sire, Southwind, and thus animals originating from this genetic line could be carriers, and extra consideration is required to avoid mating possible carriers.
A. Al-Khudhair2, and M. C. McClure3
2USDA Animal Genomics and Improvement Lab, Beltsville, MD, USA
3ABS, Global, DeForest, WI, USA
What’s going on with our calves?
Recently, dairy producers in North America started to notice that some newborn calves that appeared otherwise healthy were unable to stand in the days following their birth. This condition is referred to as calf recumbency; in other words, these calves were consistently lying down, and were unable to stand. Some calves appeared to recover down the road, however, the majority of calves never gained standing ability and most calves died either on their own or had to be euthanized. Veterinarians performed postmortem necropsies to evaluate what may have been the cause of this condition (and the subsequent deaths), however, no metabolic abnormalities nor a precise cause of this condition was found.
Investigating where this condition is coming from
This condition continued showing up on farms across North America, which led dairy cattle geneticists like Dr. Chad Dechow to investigate this calf
recumbency gene4c muta4on.
Calves with gene4cs from Southwind,
Annual Meeting, June 25-28, Ottawa. recumbency genetic mutation. Researchers were able to narrow the gene Robust or Supersire (ancestors of
C. D. Dechow, P. M. VanRaden2, D. J. Null2, abnormality further. Dechow and
his search down to a single mutation - a gene research team conducted a genome-wide related to calcium activity in calves was
suspected to cause this condition. Calcium
Southwind) may be suscep4ble to calf
association study where approximately 100,000 markers were used to identify the chromosome affected in these calves; the end of chromosome 16 appeared to be impacted in these calves. Next, researchers worked backwards to investigate a genetic origin of this condition. While these calves were born from different methods including IVF, AI and natural service, all calves shared a common genetic lineage. Researchers found that all calves had genetics from the bull Robust, and most calves also had genetics from the bull Supersire, a son of Robust, indicating that this was indeed a genetic condition.
Initially the mutation was thought to originate with Robust, but within a few months, an affected calf was born without Robust in its pedigree. The researchers discovered that this calf traced back to Southwind, an ancestor of Robust, suggesting instead that the mutation may have originated with Southwind, but it wasn’t discovered until Robust-sired calves were affected.
Next, Dechow and the USDA started tracking the haplotype responsible for this condition, and genetic sequencing was conducted to identify potential genes affected. The researchers found that this
is essential for muscle contractions and skeletal tissue activity, making gene mutations related to calcium activity a logical source of calf recumbency. This is further supported by research in other mammalian species that shows a mutation in this particular gene may result in degenerated muscles, the inability to stand, paralysis, or death.
What can producers do?
Producers should talk to their semen suppliers about this condition to determine suitable semen for their herds. This mutation is expected to be added to the current genotyping tests, but producers should strategize with their genetic consultants to manage their breeding programs to minimize risk. Commercial test kits have also recently become available to test for this specific mutation, allowing producers to identify which of their animals may carry this mutation and have the potential to pass the condition to their offspring. In addition, if producers encounter a calf that is unable to stand following birth, the herd’s genetic consultant should be contacted, and the calf’s lineage should be reported to improve the database and overall understanding of this condition.
CHRISTMAS 2023  WC DAIRY NEWS 59
Robust
may be succeptible to calf
J
a
yl or W i s
a
www.JAYLOR.com
LOCAL DEALERSHIP:
ISLAND TRACTOR & SUPPLY | 4650 Trans Canada Highway, Duncan, BC V9L 6L2 | 888-795-1755
JAYLOR WESTERN CANADA TERRITORY MANAGER:
WARREN BURGEVITZ | Cell: 403-473-5847 | Email: WBurgevitz@jaylor.com
h
e
s
Y
o
u
At Jaylor we have designed a TMR Mixer to work with your operation offering the effectiveness, efficiency and dependability you’ve come to expect. Our patented square cut auger consistently delivers the mix your cows require.
Thank you to all our customers; existing, new and future! We are excited to build relationships that last a life time.