Just 2% of Next Generation Herd empty

After four breeding seasons, real trends are beginning to emerge on the performance of the Next Generation Herd in Moorepark. Just 2% of the elite herd were empty this year after a 12-week breeding period, bringing average empty rates over the past four years to 8%.

In comparison, the national average herd, had 18% empty this year and will average with a 19% empty rate over the past four years, even though the length of the breeding season was the same for both groups.

The 90 elite cows on the trial represent the highest EBI animals in the country. They were genotyped and purchased in 2012 as in-calf heifers along with 45 heifers with an average EBI and these represent the national average herd. All the animals on the trial are black and white Holstein Friesians.

This year’s fertility performance is the best yet, with only two cows out of the 90 elites not in calf. Farm manager Ricki Fitzgerald doesn’t know why there’s such a big difference in fertility between the elites and national average herd, where eight out of 45 cows are empty:

“In terms of management they’re both treated the same. They graze side by side and they always graze to the same residual. If one group is on meal, so is the other group. We even use the same AI bulls on both herds, so really the only explanation for the difference in fertility is to do with genetics.”

The herd was scanned last week and the six week in-calf rate for the elites was 77%, 96% of the herd was submitted for AI in the first three weeks of breeding and the pregnancy rate to this first service was an impressive 60%.

Despite having a mean calving date six days later than the elites on 19 February, the submission rate for the national average group was good and above target at 92% this year. However, pregnancy rate to first service was much lower for this group at only 37% and this is reflected in the lower six-week in-calf rate of 55% compared with 77% for the elites and 18% were empty at the end of the breeding.

Morgan O’Sullivan is the PhD student working on the trial. He says this year’s results mirror what happened in previous years, although the difference between the groups was closer last year.

“Last year the calving data showed the elites had a six-week in-calf rate of 70% and an overall empty rate of 9%. The national average herd had a six-week in-calf rate of 62% and an overall empty rate of 11%. It was more a case of the national average herd having a good year as opposed to the elites having a bad year. When it comes to fertility, the trends over the course of the last four years have been overwhelmingly in favour of the elites,” Morgan says.

As for management, Ricki uses a combination of tail paint and automated heat detection (Dairymaster Moo Monitors) to pick up cows in heat. He did three weeks of pre-breeding heat detection followed by six weeks of AI and six weeks of Aberdeen Angus stock bulls.

Milk solids

When I visited the Dairygold Farm in Kilworth last week, the Elite herd were producing 1.42kg of milk solids (MS) per cow per day while the national average were producing 1.41kg MS/cow. This is the performance for the control group. These were on zero meal and grazing the best-quality grass down to a residual of 4.5cm.

For the year to date, the elite cows have produced 387kg MS/cow while the national average cows have produced 372kg MS/cow. However, there was a difference in calving date, with the national average cows calving on average six days later than the elites.

“We try to keep calving dates the same for trial purposes, but there’s always some difference. The elites have produced more milk solids over the year and this increase is in line with their genetic potential based on their predicted difference for yield, fat and protein,” Morgan says.

Total concentrate fed to date has been 297kg. The herd is on a grass-only diet at present and average farm cover is around 1,100kg/ha. Ricki says there is enough grass on the farm to keep cows out fulltime until early November without putting in any supplement, but he said he might start feeding meal in November to stretch grass until December.

After last month’s base change in the EBI, the EBI of the elite herd fell by €84 to €180 and the EBI of the national average herd fell by €85 to €67. The relative difference is similar to before at €113 but because there was a genetic evaluation run at the same time as the base change the fall in EBI is €13 greater than the €71 fall for all animals.

Table 2 outlines the breeding performance of the main Teagasc research and demonstration farms. The results this year look good. The average empty rate on the Teagasc farms was 8%, below the Teagasc target of 10%.

The six week in-calf rate averaged 75% which is on target. The average EBI of these farms, after the base change is €124. Interestingly, all the Teagasc farms have Jersey crossbred cows with the exception of Johnstown Castle and the Next Generation Herd. Half of the Curtins and Solohead herd are Jersey crossbred while there is a higher proportion of crossbreds in Ballyhaise, Shinagh and Greenfield. The EBI of the Teagasc herds at €124 is much higher than the national average of €66. If what is happening within the Next Generation Herd trial represents what is happening at farm level, then we can take it that the average herd in Ireland still has a long way to go to improve fertility.