A new genetic index due to be launched by AHDB Dairy next year will help dairy producers achieve better dairy calf survival.
The loss of a calf in a dairy enterprise is one of the most painful events to deal with and instantly shatters all hopes for the animal’s future career.
Improving management at calving and for the newborn calf have always been a focus for progressive dairy managers, but what if breeders could select bulls which have progeny with a better chance of survival?
Soon they will be able to, says Prof Mike Coffey from SRUC, who has led the research, funded by AHDB Dairy, which will result in the development of a predicted transmitting ability (PTA) for calf survival (CS).
Using data from millions of animal records from the British Cattle Movement Service, the team at SRUC started to look for genetic trends.
Prof Coffey says: “First, we had to establish whether there was a sire component to CS and the answer to is yes.
“In other words, the calves of some sires are more likely to survive their first year of life than those from others.”
The fact the trait was shown to be heritable (or was passed from one generation to the next) and the variability in CS for different sires, provided the base from which a genetic index could be developed.
The heritability of CS has been found to be about 4 per cent, according to Prof Coffey. This is a similar heritability to dairy cow lifespan, a trait for which the UK breeding industry has been selecting for the past 15 years, and similar to some other traits, including female fertility, which has also seen dramatic improvement.
This all bodes well for genetic improvement to be made, according to Prof Coffey.
He says: “When a trait is heritable and there is genetic variance, the UK farming industry has an exemplary record of using the information and making genetic improvement.
“Look at female fertility index. There has been a great interest among farmers to select for it and both its genotype [the genetics for good fertility] and phenotype [the actual expression of good fertility on-farm] have been rising.
“I am confident farmers will select for a CS PTA as soon as background work is completed and figures can be published.”
But with a heritability of 4 per cent, will it be truly worthwhile?
Prof Coffey is confident genetic progress will be made, saying: “Of course good calf husbandry is the first line of attack, but if you are continually improving underlying genetics, selecting for good survival rates and making incremental improvements every year, you are giving calves a head start.”
So, what is the potential impact on the national dairy herd of improving CS?
Andy Dodd, who has delivered the AHDB Calf to Calving initiative, which focuses on best practice in calf and heifer rearing, says the scope for improvement is huge.
He says: “Research and on-farm data have shown about 14 per cent of heifer calves born alive never make it to first lactation.
“This represents a huge cost to dairy farmers and has been calculated as an extra £140 on the rearing cost of every surviving heifer.
“The AHDB Calf to Calving initiative has been focusing on management, especially in the birth to weaning period, when a lot of losses occur.
“Few lost calves ever undergo a post-mortem, so we rarely know the reason, so having a PTA will definitely help identify where there could be a genetic contribution to poor survival rates.”
The new CS index and information about how it should be used will be published by AHDB Dairy in 2018.
The new PTA for CS will be based on British Cattle Movement Service records of calf deaths between tagging and 12 months of age.
This captures a period when mortality is high, but excludes stillbirths and deaths in the first 24 hours of life – information which is harder to obtain from national records.
In contrast, the existing PTA for lifespan (LS) predicts survival of animals once they are in the milking herd.
There is a correlation between the two PTAs, indicated by a correlation coefficient of +0.4.
Marco Winters, head of animal genetics for AHDB Dairy, says: “This is a fairly low figure. It indicates there is a relationship between the two traits of LS and CS, but they are not the same trait.
“This is unsurprising, as the common causes of calf deaths, such as scours and respiratory disease, are not the same as the common reasons for cows leaving a herd, such as mastitis and infertility.
“However, there are clearly links between the two, as, for instance, both calf and cow survival will be assisted by a good immune response.”
The CS PTA should be a particular help where a bull has poor calf survival, yet his daughters which do survive go on to be long-lasting cows.
Mr Winters says: “Previously, a bull with good lactating daughter survival would not have been identified if his calf survival was poor, as this information was not captured for use in any genetic index.”
However, with the new CS PTA, one of only a few such dairy indexes in the world, the producer will have more information with which to make well-informed breeding decisions.