In the fields with a discussion group

The seasons change four times a year but the switch between spring and summer is the most obvious and never more so than this year.

Mild and almost tropical-like conditions since the start of May have seen an abundance of growth, both in the fields and in the ditches.

Earlier this week, the Irish Farmers Journal attended a discussion group meeting in Kilkenny and some of what was discussed is reported here.

Breeding

The host farmer started breeding on 26 April this year – about four days earlier than normal using easy-calving Limousine AI sires for the first four days before switching to dairy AI.

The thinking here is that if these cows go in calf to the Limousin bull, they will have a longer gestation, so will start to calve down at the same time as the cows bred with dairy straws on 1 May.

Ordinarily, these cows wouldn’t have been bred until the third week of breeding.

There was a bit of a discussion among the group as to whether this is a good idea. Some farmers felt that many of the cows bred to the Limousin bull will have been the best cows in the herd and the farmer has forfeited the chance of getting a replacement heifer calf from them.

Others felt that a Limousin bull, even if they are easy-calving, will affect the fertility performance of the cows that calve to them next season.

An issue the host farmer has is that his six-week calving rate is decreasing. In 2019, when the herd was still growing, he was achieving an 88% six-week calving rate.

Since then, it has gradually declined (Figure 1) and it sits at 79% this season.

Over the same time period, the EBI for fertility has increased by 14% from €63 in 2019 to €74 today. The replacement rate on the farm over the last four years has been around 18%.

Empty rate

The overall empty rate is excellent at around 5% and submission rate is usually over 90%, so the issue is low conception rate.

Nationally, the six-week calving rate is improving, up from 65% in 2019 to 67% in 2021 (national figures for 2022 have not yet been released by the ICBF).

There are obviously lots of issues at play other than EBI when it comes to achieving a high six-week calving rate such as body condition score, nutrition, heat detection, etc.

Some group members felt that it’s difficult to get a high six-week calving rate when the replacement rate drops, as the majority of heifers generally calve early in the season.

About half of the group members have invested in automatic heat detection collars, with a huge uptake in the last 12 months.

While they all commented on the labour-saving advantages of the collars, there was a bit of discussion around the timing of AI when artificially inseminating once a day.

On most of the farms, cows are automatically drafted for AI 10 hours after the onset of standing heat.

This means that, at times, some cows would not be inseminated until 34 hours after standing heat, which some farmers were a bit uncomfortable about.

The average grass growth across the group was 73kg/day and managing surplus was the order of the day. It was felt the ideal average farm cover was to be around 150kg to 180kg per cow and that if stocking rate is increased to take out paddocks for silage, they should be cut out as soon as possible to bring stocking rate back to a more sustainable level with a demand in the low-to-mid 60s.

Demand on the host farm was above 85kg/ha/day, which is fine for the moment as the farm was exploding with growth.

The group felt, however, that some of the paddocks closed for silage need to be cut out as soon as possible so as not to be caught with a high demand when growth inevitably drops.

There was a big discussion on what to do with high-clover paddocks. The clover content on the best clover paddock was estimated to be around 20% and so should be capable of producing a lot of its own nitrogen.

The farmer’s plan was to go with half-rate nitrogen on this field for the rest of the season (12/13 units/acre after each grazing).

Some felt he should cut back on nitrogen entirely and see how the field performs as its likely that all dairy farms will have to cope with using less nitrogen in the future and now is the time to learn how.

Most of the group members have cut back on nitrogen use by 20% to 30% already this year in response to rising prices and scarce supply. As a result, some felt the period of peak growth could be less this year compared to other years and predicted that grass could become stressed in a few weeks’ time.

One paddock was reseeded with multispecies 10 days ago. The field was grazed, sown with a Moore drill and then sprayed with Roundup a few days later.

The group were feeding 2kg meal on average, ranging from 1.5kg to 4kg.

On the host farm, the maiden heifers were bred after receiving two shot of prostaglandin. The first shot was given 13 days before the start of breeding and the second shot was given 11 days later, two days before the start of breeding.

All heifers were then inseminated to standing heat over three days and there are bulls running with them now.

Based on their EBI for maintenance of €21, the heifers’ mature liveweight should be 535kg (640kg minus 5kg for every €1 in maintenance). They should be 60% of their mature liveweight now, which is 320kg.

The heifers weighed 300kg recently so they are a bit behind target, which the farmer is putting down to a dose of coccidiosis as calves.

All of the group members had some cows calving in April and the question was what to do with them. Most felt that marking them and putting them on once-a-day milking makes a big difference to body condition score and the resumption of cycling activity.

Others said that in previous years they kept them separate from the rest of the herd and left a bull with them while milking once a day. While this was deemed to be successful, there was extra work in bringing in a second group for morning milking.

• Exceptionally high grass growth rates at present. Members of the discussion group had to skip over paddocks that are gone too strong.
• Average grass growth rate is 73kg/day and demand is 66kg with average farm cover at 168kg/cow.
• Six-week calving rate on the host farm has dropped from almost 90% to 79%.
• Maiden heifers slightly behind target weight, so will need good grass for the next few months.