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When we think about bulls that have made a big impact on the Irish dairy herd over the last 20 or 30 years, bulls such as Galtee Merci, Oman, Ruud and to a lesser extent Hugo and Dano have made a huge impression. A disproportionate number of cows in Ireland are sired by these bulls. So they are iconic bulls and farmers who are into breeding are glad to have their bloodlines.
Farmers often ask if we will ever see the like of them again? But a better question is should we ever see the like of them again? The big game-changer in the Irish breeding programme since 2009 has been the introduction of genomics. By reading a bull’s DNA and combining it with a parental average, geneticists can predict to about 60% accuracy how that bull’s daughters will perform.
This has increased the rate of genetic gain, as rather than waiting for a bull to have heifers on the ground and milking before the reliability of his proof increases, farmers are now selecting more young bulls with higher reliability and EBI.
In turn, their sons are genomically tested and the top ones enter the breeding programme for the following year.
In 2017, about 70% of all AI bulls used in the dairy herd had a genomic proof. Between 2005 and 2010 (before genomics), the rate of EBI gain in Irish herds was €5/year. Over the last three years, and taking account of changes to EBI, the rate of gain has shot up to €13/year.
Because the rate of gain is increasing much quicker than before, a high-EBI bull in one season is being replaced by a higher-EBI bull next season. So bulls are not lasting long at the top of the active bull list. But this is not a bad thing as they are being replaced by higher-EBI bulls. As a consequence, the days of one or two bulls dominating the list for years is gone.
Teams
So if genetic gain is increasing much quicker than before and if bulls are being replaced at the top of the EBI list nearly every year, why are we encouraged to pick teams of bulls? The issue is reliability. Those iconic bulls mentioned at the top all have reliability figures of 99%, even when they were at their peak usage. Effectively, they did what they said they would do.
But the young genomic bulls at the top of the lists now only have reliability figures of around 60%. This means that there is wide enough room for variation in how their offspring will actually perform. While the average performance of a group of bulls won’t differ much, there will be movement within the group.
Some bulls’ EBIs change more than others, both up and down. The EBI of a young genomic bull can change by up to €110. If a farmer used a lot of one bull that dropped a lot in EBI the EBI of the heifer calves born in the next season will be adversely affected and it will seriously set back the rate of genetic gain in that herd.
Andrew Cromie of ICBF says: “We have been advising farmers to use teams of bulls since genomics was introduced. By and large farmers have taken on board the advice and are using more AI bulls on their farm. But the problem is they are not using these bulls equally, with an over reliance on one or two bulls which I see as a very risky strategy.”
For this season, the ICBF is advising farmers milking up to 100 cows to use seven bulls equally across the herd. For herds greater than 150 cows, 10 bulls should be used equally and for very large herds up to 14 bulls should be used.
The reason the number of bulls should increase is because in large herds there will be more animals born to a bull that drops in EBI. However, proportionately, the effect on the herd will be the same.
Picking the team
Put yourself in Joe Schmidt’s shoes when picking your team of bulls. Pick a panel first. To get on the panel, they must be high-performing players, so the bulls must have a high EBI. Then pick the team based on what the opposition is like. In this case, the opposition is your herd of cows. You want to pick a team that is going to improve the herd. If for example, the herd is low in protein, then you should be picking bulls that are high in protein, and so forth.
By picking a panel first, you are making sure that all the bulls used will be high-EBI. It’s from within the panel that you pick bulls that are strong on certain traits. But don’t get too hung up on this. By their nature, nearly all high-EBI bulls are well balanced in all traits.
However, there are some traits that make up a low proportion of EBI which some farmers find more important than others. For example, the maintenance sub index makes up 7% of EBI. But in large herds or on challenging farms where cows are doing a lot of walking, farmers are finding that cows with a high EBI for maintenance are more robust and hardy. Essentially, they use the maintenance sub-index as a proxy for other traits not currently in the EBI that they find desirable.
Managing teams
With more AI bulls being used, it can get confusing as to what bulls to use on what cows. It can also increase the workload on the person doing the AI. If there are seven cows to be inseminated on a farm, it’s highly likely that there could be seven AI bulls to be used. This increases complexity and workload for already busy AI technicians and DIY operators.
The best policy is to assign bulls to cows in advance. The sire advice programme on Herdplus will do this for you. The new programme assigns bulls to cows proportionately, so bulls are not being overused. It also gives an option of two other bulls that can be used on that cow without the risk of inbreeding.
Bulls can be assigned to cows using sire advice in advance of the breeding season and this information will be sent to the technician’s handheld device. Farmers who use a technician or do it themselves should print off the sire advice recommendations with the three bulls assigned to cows.
Depending on the number of cows to be served on a given day, three or four AI bulls can be picked, instead of seven or 10 first-choice bulls on sire advice.
Basically, you pick the three or four most common first-choice bulls that are also second or third choice for some cows. Write down the cows that are to get each bull and the technician can load up three or four AI guns at a time and inseminate those cows.
Daughter proven
Despite the rapid rise in genomics, daughter-proven bulls still have a place on Irish farms. Only bulls with a daughter proof and high reliability for calving ease should be used on heifers. Only bulls with more than 90% reliability and less than 2% calving difficulty should be used.
Daughter proven bulls can still be used across the herd. But while the reliability of their proofs will be higher, their EBI’s will be substantially lower at about three or four years behind the EBI of the genomic bulls.
SHARING OPTIONS: