Lyons Estate is the farm belonging to University College Dublin and is located close to the M7 motorway in Co Kildare. In total, there are about 200 cows on the farm but the system’s research herd consists of 60 cows. The rest of the cows are used in research trials and experiments.

The herd is run by UCD lecturers and the farm staff at Lyons Estate. Dairy lecturer Karina Pierce says the objective of the research herd is to evaluate the feasibility of a high-input/high-output grazing system where land is limiting.

Some of the 60 cows used in the study were purchased as heifers from around the country in 2014 and calved for the first time in 2015. Some second-lactation cows were also purchased and some cows from the existing herd at Lyons were also used.

The 60 cows are all spring-calving Holstein Friesians. The grazing area allocated to them for 2017 is 17.65ha, so the stocking rate is 3.4 cows/ha. A further 7ha is located away from the dairy and this is used as a silage block with three cuts taken over the year. When you include the silage area, the overall stocking rate is 2.43 cows/ha. Replacement heifers are contract-reared on other parts of the farm.

The key driver on the farm is production, with 600kg plus of milk solids per cow being the target. Last year, the herd came close to achieving this, producing 588kg of milk solids per cow having been fed on average 1.45t of meal per cow.

Despite the emphasis on production, there is still a focus on grass. The herd was turned out in early February and was out grazing day and night when I visited two weeks ago.

“When cows are at peak production we average around 34 litres per cow per day. Grass is a major part of the diet but grass alone is not sufficient to maintain these yields because they can’t eat enough of it.

“The very most we would expect is for unsupplemented cows to be able to eat around 18kg of grass dry matter per day. To achieve our yield expectations we supplement with concentrate to make sure the herd’s dietary requirement is being met so that we can fully exploit their genetic potential for production,” Veterinary lecturer Finbar Mulligan explains.

For this reason, the herd is on a fixed-rate feeding regime which varies depending on stage of lactation. This feed budget is detailed in Table 1. Effectively, the herd is on 8kg of meal per day for the spring.

Balancing this level of concentrate feeding and utilising grass at the same time is challenging, grass manager Ciaran Hearn says.

“At the moment we are falling between a few stools when it comes to grass; we are following the spring rotation planner which sets out the area that we should be grazing per day. However, the cows aren’t cleaning out their allocated area that well, even when out full-time without any silage in the diet. If we reduced the supplement they would probably eat more grass and we would have better residuals in spring but the question then is are we feeding them to their potential.”

That said, Karina says that over 4,500 litres of milk per cow was produced from forage last year, which she says is a very respectable figure.

Fertility

Fertility results from the first full year of production are mixed. As can be seen in Table 2, the submission rate and the empty rate after 12 weeks of breeding are excellent at 91% and 9% respectively.

However, the conception rate to first service was low at 43% and considerably below the target of 60%. The knock-on effect of this is that the six-week in-calf rate was low at 59%, while the target for Lyons is 70%. This is the percentage of cows that went in-calf in the first six weeks of breeding last year, and thus should calve in the first six weeks of this calving season. Heifers are not included in this figure.

“Overall the results are disappointing. While the submission rate and end of season empty rate are good, the conception rate was low, particularly for first service. There were no health effects but the weather was very bad two weeks before the start of breeding and the herd had to be housed fully for a week. This had an effect on body condition score and it is the only thing we can identify that might have led to the lower than expected conception rate,” Finbar says.

In terms of genetics, the herd is one of the highest in the country with an EBI of €155. The EBI of the herd is very evenly split between milk and fertility sub-index of €58 and €60 respectively. The maintenance sub-index is €5.40 and the health sub-index is €1.60.

Within the herd there is a comparison of strain or genetic merit for milk volume. While only the highest EBI animals were selected to join the herd, there was a difference in their predicted transmitting ability (PTA) for milk volume, with half of the herd having a PTA for milk of 250kg while the other half having a PTA for milk of 44kg.

The milk and fertility sub-index is €64 and €51 for the high and low milk herd respectively, while the fertility sub-index is at €53 and €67 for the high and low milk cows respectively.

I visited the herd in March 2016 and February 2017. At both times, the herd was out grazing day and night but leaving large quantities of grass behind, measured by UCD at between 200 and 500kg DM/ha. When being fed 8kg of meal, the cows simply could not physically eat all of the grass that was available to them.

It is easy to understand why the meal is being fed but in my view wasting high-quality pasture is never acceptable and this is the big challenge of the system, alongside making a profit with a low milk price.

Is the stocking rate too low for the amount of grass being grown? (Average farm cover was 1,100kg in February and 13t of grass was grown in 2016). Or should the concentrate feeding level be determined by the quantity and quality of grass available?

Perhaps leaving a high residual is the best way to manage grass in a high-input system, but all the research I have seen points to more profit as more grass is utilised.

It would be useful if this study could develop a metric for the more strategic use of supplementary feed for highly stocked grass-based farms, as opposed to fixed-rate feeding based on stage of lactation. To be fair, the team at UCD are interested in these questions also but feel they need to test the current system first, before looking at alternative options.

In terms of the fertility performance, while the six-week in-calf rate for 2016 is undoubtedly disappointing, we must remember that numbers are small and the herd is reasonably new. We will need a number of years’ data before we can draw definitive conclusions.

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Special focus: spring AI 2017