Will a high EBI herd deliver better fertility? Yes is the answer so far in Cork

The Elite high EBI herd in the Teagasc Kilworth farm is outperforming the lower EBI herd this year, especially in fertility performance.

The Next Generation herd trial at the Teagasc Kilworth farm is trying to measure the fertility and milk performance of the highest EBI genetics (€244) available in Ireland. This Elite herd is being compared to a more typical National Average herd of €133 EBI.

When I called this week, there wasn’t much to separate the herds in terms of current milk yield. However, the fertility performance results for 2014 had just been collated and the Elite herd had much better fertility performance in 2014 compared with the national average herd.

As well as the genetic trial, there is a feeding system trial also going on at the same time. The idea is to see if the EBI genes perform any better or worse depending on what is the diet.

Both genetic herds are divided into three groups on three different feeding treatments. The three Elite herds (EBI €244) on average are yielding 18.0 kg, at 4.94 F%, 3.96 P% (1.57 kg MS/day), with two of the herds on zero meal and one herd on 4kg of meal with grazed grass.

The national average herds were yielding slightly higher milk volume at 19kg at 4.59% fat, 3.69% protein (1.55kg MS/day) on the same feed.

So far this year, the Elite cows have milked more (319kg MS v 299kg MS), but following on from last year’s fertility, there is a calving date difference between the herds. The Elite cows calved earlier (14 Feb), which really means there isn’t that much between the herd on milk solids produced to date.

Fertility difference

In terms of fertility performance, the Elite herd had a six week in-calf rate of 77% compared to 60% for the national average herd. The 12-week in calf rate is 95% for the Elite herd and 78% for the national average herd.

In cow numbers, this means of the 90 Elite cows on trial, there are only five cows not in calf after 12 weeks of breeding. In fact, most of them were in calf after ten weeks of breeding. That’s very good fertility.

The national average herd has 45 cows and there are ten cows not in calf after 12 weeks of breeding, which is a long way back for herds that are managed the very same way. The majority of cows milking this year are second calvers, with about 33% first calvers in each herd.

Breeding plans

The breeding season this year ran from April 26 to July 19 (12 weeks) – six weeks AI and six weeks natural service. Farm manager Aidan Brennan said: “We are very pleased with the results this year after a slightly disappointing result overall last year. The trial is really beginning to show the difference in fertility EBI stacks up in the field as well as on paper. The EBI fertility sub index of the Elite herd is €169, compared to €63 for the national average herd.”

Feeding trial

The two genetic lines are managed on one of three seasonal pasture based systems.

The three management systems are: (1) intensive grazing to 4-4.5cm and 200kg of meal; (2) high stocking rate with tight grazing to 3.5cm and 200kg of meal; and (3) high stocking rate with grazing to 4 to 4.5cm, and 1.2t of meal. Currently, the high-meal cows are on 4kg of meal and grazed grass, while the rest are on zero meal and just grazed grass.

Condition score difference

There is quite a difference in condition score between the feeding systems and between the herds. The national average herds on no meal could be described as thin and skinny (BCS 2.6), while the Elite herds on the same feeding systems look more comfortable (BCS 2.9). So far this year, the cows on the grass system have had 190kg of meal per cow.

Kennedy’s comment

It is early days for this long-term trial, but we are beginning to see differences between the Elite and the national average cows.

There are two things of note – (1) the Elite cows on the grass-only treatments are much fatter than the national average cows on the grass treatments and they seem more comfortable on the grass system.

(2) The fertility of the Elite cows this year was very good. Last year was bad over the whole herd, but this year the Elite are beginning to push away. Imagine if you had 100 Elite (high EBI) cows in your herd and had 80 of them calved within six weeks, with only five cows not in calf at the end of ten weeks breeding. You wouldn’t need many replacements to stay milking 100 cows.

It is also important to note that while the high EBI cows are not outperforming the low EBI cows on milk solids they indirectly will do this with better fertility from one year to the next. It will be interesting to follow this herd for the next couple of years.

The Next Generation herd was assembled during 2012 at the Dairygold Research farm. In-calf heifers, maiden heifers and heifer calves were sourced from commercial dairy herds.

The Next Generation Herd provides a “forward view” of the implications of the national breeding programme and how EBI sits with future management conditions.

The herd is situated at the Dairygold Research Farm in Kilworth. The herd contains two distinct genetic groups. There are 90 Elite (extremely high EBI; €244 – top 1%) and 45 Control (national average EBI; €133) Holstein Friesian milking cows.

The entire herd comprised first lactation animals in 2013. Mean calving date was February 12. The Elite heifers had a lower milk volume (-173 kg), but substantially higher milk composition (+0.26 fat % and +0.17 protein %). The net effect was 6kg more milk solids yield (fat plus protein) from the Elite heifers (345kg for the Elite vs 339kg for the Control).

Submission rate in the first three weeks and six week in-calf rate averaged 89% and 71% for the Elite, and 82% and 61% for the Control cows, respectively. Final in-calf rates were 85% and 77%. The final in-calf rate results were disappointing.