The Labour Court is hearing evidence from Ballydoyle Racing Stable as it argues it should be exempt from working times regulations.
The stable has been served with a compliance notice from the Workplace Relations Commission after inspectors found alleged breaches in relation to excessive working hours.
The stable has argued it is exempt because employees are engaged in agricultural work.
It also argues grooms and exercise riders who work long hours have a special bond with the thoroughbred horses in the stables and that would suffer if there were more grooms and riders working fewer hours.
A hearing was told that although grooms at Ballydoyle sometimes work very long days, they have significant downtime during those days.
Clem Murphy, who described himself as a bloodstock consultant, said many staff at Ballydoyle take three-hour breaks from midday during the summer months.
He said he did not know all of the staff named in a compliance order on Ballydoyle but he had been told all bar one of them take the three-hour break and he had seen staff leaving the stables for their homes at that time of day.
He also said that while staff may have long days when taking horses to race meetings they had a lot of free time when at a race course.
He said their horse might have run the first race but they could be at the race course until the last race because there could be another Ballydoyle horse in the final race.
He said once a groom's horse had run its race they would be free to watch the races and meet with friends.
It was put to him that the groom remained at the disposal of the employer and could not leave the course.
Asked did that not mean the groom was at work, he replied: "If you say so."
He was asked if that meant a groom could work from 6am one day until 2am the next when attending a race meeting.
He said they loved their work.
A head groom at Ballydoyle, Robbie Manton, told the commission that he works a standard rota, which includes a day and a half off a fortnight.
He said the work day starts at 5-6am, and the work is more intense in the morning but less so in the afternoon.
He said people were free to leave after 11.45am until 3pm.
He said that it would not be the same if there were two grooms or two exercise riders for each horse as there is a bond between groom and horse and rider and horse.
He was asked about some grooms working 26 or 27 days in a row in November, which has been described as a quiet month.
He said that was by choice and that "the girls in the office are heartbroken, ringing fellas trying to get them to take their days off".
He said people often choose to come in on their days off, particularly exercise riders, as they do not want anyone else riding their horse.
He was asked if people are paid for working on their day off and said they could get overtime or time off in lieu.
Aidan O'Brien, racehorse trainer at Balyldoyle, told the court that some riders are so attached to the horses they work with that they come in on their days off to ride them.
Mr O'Brien said employing more grooms and riders to work with horses would threaten health and safety.
The WRC wants the stable to employ more staff so that they work fewer hours and have more breaks.
However Ballydoyle argues this would undermine the individual bonds between people and the horses they care for.
Mr O'Brien told the court that changing a rider increases danger as horses bond with their riders and develop a telepathic understanding.
He said he has seen so many people and so many horses injured after a change in pattern it cannot be a coincidence.
The WRC has suggested that there could be two principal riders of each horse instead of one as is the case at present.
Noel Travers, SC for the WRC, asked Mr O'Brien if a solution could be found that would allow him to run his stables while ensuring staff were given adequate breaks.
Mr O'Brien replied that all he wanted was that if someone asked if they could come in and ride their horse on their day off that he would be able to say yes you can.
