GENOMICS ISTHE BUZZ WORD IN HOLSTEIN BREEDING AT THE MOMENT
The heifers with the highest genomic fi gures are topping the sales and the bulls with the highest fi gures are being used the most and commanding the highest price
By Thomas Hill
It is thought there are genes that are known to have an effect on feed effi ciency and that these genes have an acceptable amount of genomic reliability to allow them to be used for breeding. The genes are also known to be heritable.
If the most effi cient cows were recognised at an early age this could bring about cost savings in the long run as some potentially inferior animals could be sold. Another way that feed effi ciency as a genomic index could work is that cows could be fed more accurately if their genetic makeup was known. This could further increase feed effi ciency. There isn’t one gene that can affect feed
effi ciency, but there are thought to be several that could control a 1-2% increase in feed effi ciency. Even if breeding for feed effi ciency of the cow reduced the amount of feed needed by the cow by 1kg a day this could have a large impact on a lot of farms.
A 200-cow farm reducing the feed intake by 1kg of fresh feed a day would save 73,000kg over the course of the year. It is also thought that cows that have a higher feed effi ciency produce less methane and so, therefore, could help to reduce greenhouse gas emissions.
Another area where development is expected is the reliability of health and fertility traits. This will enable breeders to focus on traits such as herd life and fertility with more confi dence. Health traits such as life span and daughter fertility with their relatively low heritability and low genomic reliability have caused some problems for breeders wanting to use these traits, as they have been unable to do so with any level of great confi dence.
If the reliability of such traits could be improved then this would allow breeders to focus more on these traits which are sure to increase the profi tability of an
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Genomics has the potential to enable the bottom end of every herd to be eliminated
animal. Cows get in calf quicker reducing the amount of days that the cow is empty.
The quicker a cow gets in calf the more profi table she is. Empty days can cost up to £3 a day. Increasing the length of time a cow is producing in the herd will also spread the cost of rearing the animal over a longer productive period, offsetting the cost of rearing with a higher lifetime milk yield. Cows will stay in the herd longer if these traits work and this will result in a higher daily herd average milk yield. Genomics have the potential to enable the bottom end of every herd to be eliminated. This can be achieved by correctively mating with more knowledge and confi dence and reliability about the animals that are being used. Cattle with lower genomic indexes can be selectively removed from the breeding programme to enable the top end cattle to be bred from.
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This together with corrective mating can improve the profi tability of the cattle. This profi tability can be further improved by the use of traits such as feed effi ciency and, hopefully, with the improved reliability of health and fertility traits, these traits can increase profi tability also. Having knowledge of the animal’s genomic breakdown and having the confi dence that this data is reliable will enable massive gains in the genetic improvement of, not only individual herds, but also the breed as a whole. But it is unlikely there will be a total uptake across the breed for genomic testing of heifers due to the cost and due to people’s lack of trust for another index or just down to their lack of understanding of what genomics can offer.
THE JOURNAL APRIL 2015 29
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