Product quality, feed intake and efficiency, animal health and environmental footprint were missing in current breeding indices, but would be vital in the future, Berry told the Australasian Dairy Science Symposium in Hamilton in November.
The dairy industry should be developing the traits that would be important to the sector in the next 30 years, he said.
If the benefit to the industry was significant, scientists could work out how to measure and select for them. The economic importance would be what drove genetic selection in the future, he said.
“If you name it, we can breed for it, if the economics say it’s important enough.”
The future traits that would be important to the New Zealand dairy industry would be determined by its markets, environmental regulations and its future farm systems.
For example, product quality was critical to Ireland and NZ because both exported a large percentage of their milk supply to key international markets.
Current milk tests measured fat, protein, lactose, casein and milk urea nitrogen. Using this same test, geneticists could predict traits such as saturated fatty acids with 100% accuracy.
“The real cool thing about this is it’s free because every single sample is subjected to this. We have access to a biological sample of a cow twice per day.”
It also appeared that geneticists could predict cow energy balance, feed efficiency, feed intake and even methane emissions, Berry said.
Feeding animals differently depending on their genetics or managing animals because of their inherited health risks was an exciting possibility.
Residual feed intake was also an area of real interest. Nutrigenomics was not a new concept, with experiments showing animals with superior genetic merit for milk production yielded a greater milk production response to concentrate input compared to animals of lower genetic merit for milk production.
“We’ve actually been doing it. We have genetically selected the cows in the US that are good responders to the concentrate and the opposite in NZ.”
But with genomics, they could offer faster and more accurate identification of these animals, he said.
In regards to animal health, there was a possibility of being able to identify high-risk cows that would need CIDRS or dry cow therapy, which could cut costs to farmers.
The field of genomic selection was finding the best bulls a lot faster, through selection on traits and giving access to better quality semen. Sequencing was also finding unwanted mutations such as the hairy gene and small calf syndrome, which was a good thing, but it was also creating a new dilemma for the dairy industry, Berry said.
“We can’t just go out and cull these bulls. They could be excellent for fertility, milk production but still a carrier of these mutant gene.”
Genomic selection could give the solution with more precision breeding, by predicting the probability of the calf inheriting a mutant gene.
The sequencing data could also be used to get higher hybrid vigour through crossbreeding, he said.
“By having the sire and dam genotyped, we will be able to predict the probability of the genotype of the offspring. That could predict the genetic and performance merit of the calf. This is going to be coming down the line with contract matings soon.”
A calf inherited chromosomes from its sire and its dam and with sequencing it could be determined what genes were carried by future generations. That could offer the possibility of mating a great-grand sire to its great granddaughter and ending up with only 2-5% inbreeding.
Genetic change didn’t necessarily mean genetic gain, however.
For any new trait to be added to a breeding goal, it had to be worked out how much gain was achievable, Berry said.
People were concerned about the impact of using too many traits in the breeding goal as opposed to selecting on one trait, which provided a 100% gain.
But, if another 19 traits were included in the breeding selection, based on underlying assumptions mainly such as that they all received the same weight and were not associated with each other, there would still be a 22% genetic gain overall in the original trait.
If those traits were only given a weighting of 10% of the original trait, genetic gain in the original trait would be 91% of the original gain with just single trait selection.
There was a perception that including a low-reliability trait like residual feed intake into a breeding goal would take away genetic gain from other traditional traits, which wasn’t true, he said.
If protein yield was the most important trait and was used together with residual feed intake with a reliability of 10%, for example, there would still be a 96% gain in protein yield.
The key lesson the dairy industry had learnt from the past was genetic gain had to be achieved within a holistic breeding goal including all traits affecting profit.
Phenotypic data remained one of the key components for achieving high accuracy of selection and genetic gain, even in the genomics era.
“No matter what anybody tells you, genomics is not going to solve everything.”
There would always be a need to analyse milk samples, for example. Milk production was only 35% heritable, which meant 65% of the variation was still unexplained and farmers would still need to milk test the herd to get the results.
Genomic selection had received considerable attention as a tool to increase genetic gain, but if an appropriate breeding programme was not in place, genomic selection could have serious repercussions for gains in dairy herd profit.
Energy balance and residual feed intake, for example, were strongly positively correlated. Selection for reduced feed intake while also selecting for increased milk production would create a negative energy balance that would have negative impact on animal wellbeing and reproduction and ultimately profit.
The deterioration in reproductive performance in the global Holstein population was a reminder of the consequences of ignoring or failing to monitor certain animal characteristics, he said.
Characteristics of the future dairy cow
1. Produce a large quantity of high-value output (milk and meat)
2. Good reproductive performance
3. Good health status
4. Good longevity
5. Does not eat a large quantity of food
6. Easy to manage (easy calving, docile)
7. Good conformation (over and above reflective of health, reproductive performance and longevity)
8. Low environmental footprint
9. Resilient to changing environments.
