Insight into cattle genomics for vets

01 November 2015, at 12:00am

RICHARD GARD reports on the latest developments in identifying the genetic potential of bulls and heifers and how much veterinary involvement might be required

THERE is a great deal of concern about the underperformance of UK dairy herds. For some years there has been an increasing emphasis on disease and welfare, not just yield and financial margins.

Breeding for better performance has always been a major aim for the dairyman and from three years ago the use of genomics testing for young bulls has meant the genetic merit of a bull is analysed and becomes part of the selection process.

There are major advantages for bull selection. It takes approximately five years to test a bull to proven status using the daughters’ data.

Instead of waiting for daughters to be proven, the bull with known genetic traits can be offered on the test outcome alone. The reliability is lower than the daughter recording, but the benefits of superior bulls can be realised much sooner.

Not only is the new technology available for bulls but also for the female line. A few weeks ago NMR announced the availability of a testing service to identify the genetic potential of heifers (Genetracker).

Rapid progress

Developments are moving rapidly and the potential to align the bull, offering improved genetics, with the heifer that would benefit from specific traits, is an exciting advance for disease reduction as well as production.

The industry code is the Profitable Lifetime Index. Assessing £PLI is seen as the way forward for cows and herds.

But where do the veterinary surgeon and the veterinary practice fit into this new area of assessment and consultancy? Visiting the practice exhibitors at the South West Dairy Show has provided an insight into veterinary activity and genomics.

It is interesting that information about genomics is included in the Bovine Reproduction course at Liverpool and delivered by Marco Winters, AHDB Dairy head of genetics.

Marco is also one of the quoted sources from information provided by Genus ABS, so it appears that the breeding companies and the veterinary surgeons are singing from the same hymn sheet. There is a strong veterinary interest in genomics. Just how this is to be realised in practice is not so clear.

The number of dairy farmers carrying out detailed assessments of the genetic merit of their herd and having on-farm discussions about genomic bull choice is privately assessed at 15% of herds.

This may be highly subjective, but it would appear that it certainly isn’t 50%. The number of herd managers discussing genomics with their vet is considerably lower than 15%. There are issues that may account for this.

For veterinary surgeons to become more involved there needs to be a clear benefit to the farmer from veterinary input. Genetracker currently reports on 21 type traits, five yield traits, four health traits and two calving traits. Feed efficiency and disease resistance traits are to be added to the analysis.

Selection tool

Genus ABS is offering a genetics choice to improve the ability of a herd to be less susceptible to metritis, ketosis and mastitis. This is incorporated within a TransitionRight genetic selection tool targeting the disease risks occurring in the first 30 days of milk production. Selection of bulls that offer reduced disease is based on a database of 20 million cow records from commercial herds worldwide.

At the show, Synergy Farm Health staff were encouraging farmers to complete a short questionnaire on their awareness and use of genomics. In another building, Shepton Farm Vets discussed the application of its database of some half-a-million service and clinical records.

It is encouraging that practices are looking at the genomics scene and linking breeding with disease incidence. A few short conversations quickly established that developments are in hand and veterinary activity will be increasing with genomics.

One of the pointed observations, as the next batch of cattle were being brought into the judging ring, was that with genomics cows and bulls would no longer be selected on appearance.

The general theme is that it is impossible to tell which animals are carrying the best genetics just by looking at them or their pedigree.

Following on from that is the notion that all animals, particularly heifers, should be tested, not just a selected few.

There is a view that, in the future, the skinny ugly cow that is less prone to disease and provides greater profitability over the handsome, fullbodied, long-backed examples that appear in the breeding catalogues may be favoured.

It is fairly clear that production data from the daughters of bulls allow a greater degree of confidence in the reliability of a particular bull enhancing the performance of cows in a herd. Andrew Rutter, breeding programme manager at Genus ABS, indicates that farmers “should always select bulls that suit their system”. This includes the contract that the farmer has for his milk, with increasing demands for welfare as well as milk quality and volume.

As time goes on, and progeny testing of bulls is shown to match the genetic potential, a greater degree of confidence in genomic testing will be available. Currently farmers are advised to mix proven bulls with genomic bulls within their breeding programme.

All appears straightforward with production and genomics but there is concern, from veterinary surgeons, about the selection of bulls based on disease data collected from farmers.

A difficult area

Disease recording has always been a difficult area for herd health programmes. Automated systems for all milk, like cell counting, are easier to incorporate but metritis, for example, is seen as a real challenge and likely to be under- or overestimated.

The collection of data on-farm is becoming easier with the use of mobile systems and facilities. Being able to update and interrogate herd records in real time allows disease information to be linked to breeding and fertility. It would be a short step to also link to the sire.

It is strongly felt that the veterinary practice is in a good position to enhance the development of genomics in relation to disease.

One of the basic levels of engagement that has been refined and developed by veterinary practices is herd fertility.

Fertility work is recognised as the largest area of activity for veterinary surgeons with dairy herds and this difficult topic needs an increasing level of veterinary technical involvement, not less.

Within a fertility programme there are steps that may not need a veterinary arm, but it is the presence on-farm and the detailed awareness that has a direct benefit for the farmer. Engagement with breeding companies over genomics seems an obvious development.

One of the areas also highlighted is training. Apart from the efforts of Liverpool it does not appear that training sessions for cattle veterinary surgeons about genomics are available. Open meetings for farmers that have included vets take place, but there are aspects of genomics that some vets would like to explore from the veterinary perspective.

Clinical and subclinical conditions that occur with dairy and beef cattle are a specialised area and a great deal of effort, by veterinary practices, takes place to develop disease control that can be adopted by farmer clients. Closer co-operation between all parties would provide greater confidence in the role of genomics to overcome disease.

Huw Lloyd, technical services director (huw.lloyd@genusplc. com), has indicated that he would be interested to hear from fellow veterinary surgeons who would like more information and discussion regarding the use of genomics and TransitionRight genetics.