A question of fertility

Anne Lee

Just get on with it because we need this – yesterday, was the catch cry from farmers at the Pasture Summit’s Future Cow workshop

They were talking about fertility in the national herd, with farmers reinforcing the urgency with which they want genetic researchers and breeding companies to pursue the shortcoming that both directly hits profitability and is deemed to be the single greatest hindrance to overall genetic gain.

New Zealand Animal Evaluation Limited (NZAEL) manager at DairyNZ Jeremy Bryant said he heard their concerns and assured them there were moves afoot to address them and improve the data quality feeding into indices used to give bulls’ fertility rankings.

A research trial carried out last year that had expected a 10% difference in fertility between a high-fertility group of cows and a low-fertility group based on fertility breeding values found there was in reality a 40% difference in their six-week in-calf rates.

If animals are staying in the herd longer, just like humans living longer, it will mean a greater focus needs to go on animal health issues and confirmation, udder support, legs and feet.

The high-fertility line had a 10-15% empty rate while the low-fertility line had cows with a 45% empty rate.

It showed there was huge variability in fertility as a trait despite its low heritability, proving it was well worth pursing in breeding programmes but more importantly it indicated there was a problem with the quality of data used in the indices.

Jeremy Bryant – better data quality needed from farmers to improve fertility index.

Bryant said information coming from progeny test evaluations appeared to be accurate but as reproofs start coming in from data entered by farmers there’s a systematic drop in that accuracy.

“There’s 25% of the data being recorded we could throw out overnight – it’s just flawed,” he said.

For example, farmers entering 200 cows’ calvings in a block and recording them all as having calved on one date rather than the actual calving date.

Calving date is a metric used to inform the fertility index so straight away that interferes with accuracy.

Accurate parentage data was also a must.

Bryant said about 50% of the drop in accuracy with reproofs coming from data recorded in the national herd was due to parentage errors.

LIC New Zealand markets general manager Malcolm Ellis said a high-use bull with 30,000 daughters across the country may have about 9000 daughters recorded as his that aren’t.

Failure to accurately record when and why a cow was culled also played a part in lowering the accuracy of the fertility index.

Bryant said having 1000 herds where data recording was accurate would give quality bull evaluations.

“And maybe, and I think this is what we should consider, is we should give incentives to those farmers who are doing this well, discount them and not treat everyone the same, because they’re driving rates of genetic gain,” he said.

Teagasc Moorepark dairy genetics and breeding researcher Donagh Berry said in Ireland they’ve set a target that within five years every single bovine animal born will be DNA-verified for parentage and to give genomic proofs.

Donagh Berry – a focus on cow health traits and accentuating positive characteristics of milk from grass-fed cows.

“Think about that from a unique selling point,” he said.

Berry and Bryant agreed cow longevity in the herd wasn’t good enough in either NZ or Ireland.

Irish cows stay in the herd for an average 4.2 lactations and NZ cows 4.5 lactations.

Failure to get in calf is the major reason for her leaving the herd.

In Ireland 24% of eligible heifers fail to calve and make it into the milking herd.

While farmers thought fertility was declining in NZ, Bryant said it was actually improving albeit at just 0.1% per year.

While some may call that a glacial rate it’s better than it had been.

Before 2002 from which time fertility has been included in BW, overall fertility was declining at an alarming rate, Bryant said.

Including it had been no mean feat given there is a moderate negative association between milk production and fertility.

Berry pointed out, though, that at the current rate getting to the national six-week in-calf target would take decades.

In fact for the latest season the average six-week in-calf rate was 66% so if we relied on current rates of genetic gain it would take close to 100 years to get to 78%, Bryant said.

But he defended the NZ position somewhat in that major management changes, with the abolition of inductions and the move to significantly shorter mating periods (14 to 10 weeks), were having a big impact on empty rates and calving rates.

And he assured farmers changes were coming within a year to the fertility index to address the rate of improvement.

While there was plenty of light-hearted banter between the two, given the Irish had not long beaten the All Blacks, their messages were serious and Ireland had also faced significant fertility issues in its national herd.

Although fertility has low heritability, Berry said it was a myth it was not worth perusing through breeding.

Bryant agreed.

“Any trait – if we have genetic variation we can select on it and include it in an index,” he said.

Looking to the cow of 2030, Bryant said cows needed to be staying in the herd for 5.5 lactations with improved fertility driving that.

As well as fertility Berry argued that more focus needed to go on production per lifetime rather than production per lactation.

If animals are staying in the herd longer, just like humans living longer, it will mean a greater focus needs to go on animal health issues and confirmation, udder support, legs and feet.

In Ireland as in NZ there are genetic evaluations on mastitis and lameness but his year the Irish are launching evaluations for TB and liver fluke and are working on Johne’s and respiratory diseases.

Milk production breeding focus too could change or become more granular as milk payments likely shifted to recognise higher-value components of milk such as specific fats or proteins, Berry said.

NZ and Ireland’s grass-fed milk characteristics could be exploited and accentuated – such as omega three fatty acids and conjugated linoleic acid.

Ease of management is already accounted for but additional emphasis could be placed on factors such as milking speed, calf vigour in feeding straight after birth to boost colostrum intake and even polledness.

Efficiency in grazing is accounted for too in Breeding Worth (BW) and Irish Economic Breeding Index (EBI) through the selection of higher milk solids production and reduced liveweight. That method captures about 72% of feed conversion efficiency and to capture the remaining 28% geneticists are looking at how other technologies such as pedometers can be used as predictors.

Bryant warned the characteristics that aren’t well accounted for now that are “coming like a freight train” are low environmental footprint, both in terms of urinary nitrogen output and greenhouse gas emissions, and resilience to climate change.

  • Dairy Exporter magazine is media partner for the Pasture Summit 2019 event. For more great onfarm, technical and dairy farming science stories, subscribe to the monthly magazine  at https://nzfarmlife.co.nz/shop