After decades of colour-coding straws by dyeing the diluent according to breed – red for Holstein Friesian, green for Jersey, and yellow for Kiwicross – the breeding company has discovered red and green dyes cut conception.
“Last year we did a trial looking at what happened if we took out the breed stain,” explains LIC’s general manager research and development, Richard Spelman.
“Across tens of thousands of animals we saw close to a 1% improvement in conception rate from straws that didn’t have breed stain in them. That’s pretty significant. A 1% increase in conception rate is reckoned to be worth $4-$5/cow. Across four million animals, that’s $16-20 million more for the farmer,” he told Dairy News.
Dyes have been used to help technicians select the right straws in the field for as long as Spelman can remember – over 20 years – but the research team is always looking for ways to increase conception rate, testing whether different chemicals or diluents are more or less toxic to sperm, he says.
Using coloured plastics for the straws, instead of dyeing the content, was considered but the plastic used for straws has been selected as one with minimal affect on sperm viability, and a whole new set of tests would be required if coloured plastic were to be used.
“Every year we go through tests to check the plastic isn’t toxic to sperm. If we asked them to colour it we would have to go through all the testing again. Even if we just coloured the outside, it might still dissipate through to the contents.”
Instead, after last year’s findings, systems were put in place for technicians to go by labelling on straws alone, and they have been accordingly briefed for the coming mating season, Spelman told Dairy News.
This year’s LLL straws will still look yellow, even though they are undyed, as egg yolk is used in the mix.
CRV Ambreed says it has never dyed its semen but has looked at using different colour straws. “We feel it would be a bit risky to put colour in it,” marketing manager Peter Berney told Dairy News.
Given all the variables affecting conception, he suggests the 120,000 inseminations LIC made to test the dye effect would be the absolute minimum to be confident a difference as small as just under 1% was statistically significant.
“[LIC] have the ability to run all sorts of trials and look at all sorts of data and compare it across the entire national database. That’s a massive, massive advantage when it comes to this sort of thing, but that’s the way the industry is set up, and they are not doing anything wrong by doing that.”
However, Dave Hayman of Liberty Genetics, a CRV Ambreed subsidiary that’s run independently of its parent, says if LIC’s trial was prompted by an interrogation of the national database, then it should share its findings with all breeding companies. “I would expect them to come out to the industry and make it clear what the background to this is,” he told Dairy News.
Liberty’s straws are prepared by Animal Breeding Services. ABS’ bull centre manager Chris Parminter says no dye is used but the straws themselves are colour coded: green for Jersey, yellow for Kiwicross and grey for Friesian.
“LIC uses a short fat straw that’s unique to them and only available in clear plastic. They’ve got around that (up to this year) with dye.”
Spelman says the trial was prompted by LIC scientists looking at all components of the diluents for sperm toxicity, rather than any interrogation of the national database.
