23 Nov 2015
Peter Edmondson
Job Title
Figure 4. The Beef HeathCheck report allows the farmer and vet to assess liver fluke and pneumonia problems.
The Cattle Association of Veterinary Ireland (CAVI) conference was held in Mullingar right in the middle of the country in early October. There were almost 200 vets present and it is always a very social affair that involves many late nights and a lot of craic.
This is the first of two review articles about the meeting.
Doreen Corridan works for the Munster Cattle Breeding Group and is one of the leading fertility experts on grass-based milk production.
She pointed out efficient grass-based systems in Ireland can yield profits of €600 (£430) per cow per year at a cost of production at 18 Euro cents/litres at today’s low milk price. This compared to profits of €1,500, or more than £1,000, per cow in 2014.
Large differences can be seen in production from grass and many of these differences are due to genomics and fertility. Moorepark is the Irish Dairy Research Centre and it runs two groups of cows; one elite and the other average. The groups are fed the same, milked by the same people and so on.
The difference for the in-calf rate for the elite and average herd for the 12-week in-calf rate is 95% versus 78% and this is entirely due to the genetic effect. The same has been shown in some work on Irish maiden heifers where the elite group had a conception rate to first service 20% higher than the average group, and the six week in-calf rate was 30% higher, Dr Corridan said.
For grass-based dairy herds it’s important to ensure calving coincides with grass production. If you have cows or heifers that calve late there is significant loss of production. Figure 1 shows this effect clearly where the Moorepark elite herd calves earlier than average cows in the same herd. Again, this shows the impact of good genetics as this is the only different factor between the two groups of cows. This data has been built up over a number of years.
Fertility drives production. You need good genetics to maximise milk solids production and for fertility. You want to maximise the age of cows as it’s the older cows that produce the most milk and are the most profitable.
There is a real benefit from genomic testing for fertility and milk solids on maiden heifers if only a proportion is being retained in the herd. You want to keep those that are well above average rather than hoping they are going to be good performers based on their parents’ history. Figure 2 shows the average heritability between the dam and sire, shown by the straight line. The genomic results shows the true picture that some of the offspring are better and some worse. Genomic testing in Ireland currently costs just over £20. Stock bulls can also be tested genomically so you know you are using a bull that is really going to add value.
Genetics can contribute 50% of change in performance in most populations. Genetics creates potential, management realises it and disease destroys it. Genetics is the make-up and phenotype is what we see. It’s relatively easy to add to good genetics but it’s very difficult to breed out bad genes, for example, reduced fertility from high-yielding dairy herds, when you are trying to improve fertility performance.
The economic breeding index (EBI) began in 2000 in Ireland and is now starting to be used by some UK farmers. Irish farmers have the advantage of one coordinated database – the Irish Cattle Breeding Federation (ICBF) – while UK farmers have fragmented databases. The Irish database records everything and is a one-stop shop linked into the milk recording scheme data. Farmers, vets and breeding companies can all access this data.
Initially, the EBI was all focused on production, but now it’s one third production and one third fertility, with the final third made up from health, cell counts, beef traits, ease of calving and so on.
AI catalogues show the extra value an individual bull can add. For example, using bull HZB, Ballydehob Pat adds €332 (£235) extra income per daughter per year. These benefits are equally divided between production, fertility and longevity. It shows his daughters produce an extra 36kg of milk solids and the calving index is shortened by nine days. Farmers can choose what traits they wish to add. The correct bull selection can add significant value to dairy profits and production (Figure 3).
Beef Health Check is a new initiative to assess liver and lungs at slaughter. Vets at the abattoir enter the information on to a screen and this information goes straight into the ICBF database, so simple. This information gives farmers invaluable feedback on fluke and pneumonia and builds up information from specific bulls and disease prevalence (Figure 4).
Dr Corridan told delegates genomics have overcome the need to wait for progeny testing bulls to see if they are going to make progress. Genomics speeds the whole process forwards. With traditional breeding, 50% of genes come from the dam and sire and so there is only 25% reliability of traits, which is not very accurate. Genomics takes into account what is actually there and is significantly more accurate. DNA has four bases and three billion sequences. Remember 99.9% of human DNA is identical and so it is very small differences that account for variation. Genomics uses DNA data to supplement pedigree information.
The link between genomics and disease is not fully developed, but in two or three years will come on stream. For example, some bulls do not throw daughters with cystic ovaries. The same is true for liver fluke, mastitis and lameness. There is significant bull variation and once this is known it could have a very significant impact on future health.
In the future, the EBI will change and the disease element will increase in weighting. For those who doubt the importance of disease weighting, remember women who have the BRAC1 and BRAC2 gene have 5 times the risk of breast cancer and 10 to 30 times greater risk of ovarian cancer.
The effect of oestrus detection in seasonal calving herds is very different to that of an all-year herd. With seasonally calving herds it’s essential to get lots of animals pregnant as soon as you start serving. The number of mounts increases with the number of cows that are bulling. One cow bulling means an average of 11 mounts, 37 if 2 cows are bulling and 50 or more mounts if there are 3 or more cows bulling at the same time.
The importance of good and accurate heat detection cannot be overemphasised as you want the majority of spring calving cows calved within a six-month period. Use of vasectomised bulls can be very useful. They work 24/7, never complain and don’t go on strike. It is essential they have a chin ball marker and the farm staff are trained to accurately identify cows that are bulling.
Vasectomised bulls work best in their second season when they are more experienced and accurate in how they work – less teenager behaviour. Farmers often complain they are less active in the second season, but this is because they are more experienced. Just look at the marks you often find all over cows with a newly vasectomised bull; they try to mount cows in every way possible.
The effects on fertility following the use of a vasectomised bull were shown with an increase in heats picked up at three weeks increasing from less than 50% to more than 70%. However, the risk of having a vasectomised bull needs to be taken into account.
There is a presumption bulls are fertile but Irish work has shown between 2% and 5% of bulls are infertile and between 10% and 25% are subfertile. The impacts of this on seasonal calving pasture-based or any dairy herds cannot be underestimated. Bull testing is a service vet practices should be offering. It’s important to explain to farmers why this is important and why the bulls should be tested.
Practical recommendations from this paper were to consider using genomic testing for sweeper bulls or for maiden heifers if only a proportion were going to remain in the herd and to consider the use of vasectomised bulls.
Michael Diskin from Teagasc discussed fertility in suckler cows and focused on some of the key points to get maiden heifers pregnant so they calve early, ideally two to four weeks before the cows. If they calve late this will be a trend for the future.
The body condition score at calving is critical to get good calf growth rates. Body condition scores should be monitored for the final third of pregnancy as these frequently can change quickly and farmers can get caught out.
Conception rates for suckler cows in the correct condition average between 65% and 75%, far higher than for dairy cows. As an aside, Dr Diskin pointed out when inseminating cows the conception rate was 65% when the semen was deposited into the uterus, 50% mid cervix and only 35% when the semen is deposited at the entrance to the cervix. A useful reminder for those carrying out DIY AI.
Again, superior suckler cows and heifers has to be a goal and you should aim for eight lactations with an average of six lactations being achieved. You want heifers to calve down at 24 months of age and so at the prebreeding stage they should be 60% to 65% of final bodyweight, at breeding 65% to 70% of final weight and 85% at first calving. You want the heifer to have done most of her growing by the first calving so the maximum amount of energy goes to milk production.
It’s interesting that nutrition post-calving is far less important for calf growth rates compared to body condition score. Heifers and lactation two cows should calve down with a condition score of 3.0 while older cows can be 2.5.
The Irish cattle vets are hosting the World Buiatrics Congress in Dublin from 3 to 8 July next year. They are expecting more than 3,000 cattle vets from all around the world and this will prove to be a great five days of education and entertainment. It is being held in the middle of Dublin, ideal for sightseeing.
Visit www.wbc2016.com for more information.
