An empty mare at the 14-day scan is always disappointing, and it becomes all the more frustrating for farms as the breeding season begins to wind down. Mares who struggle to get in foal, particularly older mares, need all the help they can get to ensure conception.
In a project supported by AgriFutures Australia, a research team from the University of Sydney, the University of Newcastle and Charles Sturt University are trialling a potential secret weapon for studmasters: niacin.
An energy boost
More accurately, it’s the end product of niacin, or vitamin B3, that is of interest to researchers; nicotinamide adenine dinucleotide (NAD) is produced by the cells in the body, and research in other mammals has demonstrated just how necessary a role it plays in fertility.
“There’s mounting evidence in other species, including humans and mice, that the levels of this important factor NAD decline as we advance in age,” said University of Sydney’s Professor Christopher Grupen.
The Head of the Gamete and Embryo Technologies Group at the University of Sydney’s School of Veterinary Science, Prof Grupen has been conducting research into reproductive technologies for over three decades and is the principal investigator for the inter-university research team.
Professor Christopher Grupen | Image courtesy of ESA SRB 2013
“NAD is a key regulator of many cellular processes, including energy production, the immune response, and DNA repair,” he said. “Studies in humans and mice have shown that the NAD decline can really impact female fertility. The mouse studies have gone even further and have shown that it affects the quality of the eggs that they ovulate.”
“NAD is a key regulator of many cellular processes, including energy production, the immune response, and DNA repair.” - Professor Christopher Grupen
Just as stallions over the age of 15 are more at risk of testicular degeneration, mares in the same age bracket face lowered fertility as the quality of their eggs declines. The research team hypothesised that maybe the results from trials in mice could be reproduced in horses; more NAD could lead to better quality eggs and a greater chance of a successful conception.
Straight to the source
“NAD is produced in cells and there’s different metabolic pathways that can produce it,” said Grupen. “There are several forms of niacin and the form we used is nicotinic acid, which is taken up by the cell quite readily.”
The first question that faced researchers was: how much nicotinic acid would be needed to see an effect?
The initial trial in late 2023 involved supplementing nicotinic acid into the feed of a group of Standardbred mares aged 15 or over, then collecting blood and follicular fluid to work out how well it was absorbed. The study herd was separated into groups; a control group receiving no supplement, one group receiving 1.5g nicotinic acid per day, and one group receiving 3g nicotinic acid per day.
Niacin | Image courtesy of Chemistry World
In mares fed the supplement, changes in the levels of metabolites - which indicate the transformation of niacin into NAD - could be detected using mass spectrometry.
“We were quite amazed by the metabolite changes, especially in the follicular fluid,” said Grupen. This was promising - it confirmed the nicotinic acid could get to its intended destination and be converted into the essential NAD. This mirrored results from laboratory research.
“We were quite amazed by the metabolite changes, especially in the follicular fluid.” - Professor Christopher Grupen
“In our previous in vitro studies looking at the quality of eggs from pigs, when adding factors like nicotinic acid or niacin for two days, we found that there were slight improvements in the quality of the eggs,” Grupen said.
As a result, the research team hypothesised that the window needed for supplementation was relatively small.
“The fluid in the follicle that surrounds the egg undergoes massive expansion in the lead up to ovulation. There's a huge increase in volume, and essentially the factors found in the follicular fluid derive from what's circulating in the blood.”
So, we can promote more NAD production in a mare’s eggs, but what does this mean when it comes to conception?
Putting it to the test
The next step of the research is currently underway; the research team has engaged a number of studs in the Hunter Valley as part of a wide scale study into whether increasing NAD production has a positive effect on conception rates in the field.
“We’ve partnered with a number of studs in the Hunter Valley and tried to recruit as many mares as possible, because if it's only a small beneficial effect, we need large numbers of animals to be able to detect that,” Grupen said.
“(We have) recruit(ed) as many mares as possible, because if it's only a small beneficial effect, we need large numbers of animals to be able to detect that.” - Professor Christopher Grupen
“Half of the mares in the study receive the supplement, half of them don’t, and then studs will be collecting their breeding data as normal all the way through to foaling. Then we will do the analysis at the end of the season.”
Mares selected for the study are 15 years or older, and are receiving the supplementation as an oral paste for four to eight days leading up to ovulation.
Mare and foal at the AgriFuture Thoroughbred Program | Image courtesy of AgriFutures Australia
“We're hoping that a targeted supplement for at least four days will be beneficial,” said Grupen. “Maybe the egg needs longer than that to improve in quality. It’s not disrupting the studs’ operations, they can continue their normal monitoring of the mare’s cycle and start supplementing when the mare approaches ovulation.
“If we get results showing it’s beneficial, we will then discuss with AgriFutures about the next steps for sharing this information with industry, so breeders can benefit from the protocol.”
Low risk, high reward
The hope is that supplementation will lead to a higher incidence of pregnancy in the study group, and a lower number of cycles needed to achieve it.
“It would improve the welfare of the animals, as well as reduce the cost and time spent by management to get these mares in foal,” said Grupen. “If you can get the mare to conceive on her first or second mating, then it’s much less stress on her.”
“It would improve the welfare of the animals, as well as reduce the cost and time spent by management to get these mares in foal.” - Professor Christopher Grupen
If the results are promising enough, there could be a gap in the market to develop a marketable supplement for breeding operations, with the research to back it.
“The good thing about niacin is that we know it's very safe, it's tolerated very well by the horses, and if it is in excess, it's cleared from the body pretty quickly in the urine,” Grupen said.
“The frustrating thing with a lot of supplements is that the companies that produce them often claim there's a lot of benefits, and usually it's a mixture of factors with no studies about the specific benefits. To do these studies properly and show that a specific compound will lead to clear benefits means we'll overcome that confusion.”
And what’s more, Prof Grupen believes that niacin could become one of the most important facets of a farm’s management toolkit.
“I’ve been doing research in this space for 30 years and this is probably one of the most exciting advancements I've seen,” he said. “I don't want to preempt the fertility trial results, as we've got no idea yet whether it's only going to be a slight improvement or whether it's more exciting than that, but I think this is going to be a really important story, especially for fertility in older mares.
“I’ve been doing research in this space for 30 years and this is probably one of the most exciting advancements I've seen.” - Professor Christopher Grupen
“I am hopeful that in five years’ time, everyone will understand the importance of this as a supplement.”
And while the focus in this study has been on older mares, Prof Grupen ventured that there could be benefits for mares who have poor reproductive histories for different reasons.
“We're just looking at one piece of the puzzle, so maybe it will have beneficial effects for immune response and general health as well,” he said.
