Breeding policy for the Teagasc Johnstown Castle Herd

Background

The Teagasc Johnstown Castle Dairy Herd in Wexford comprises 153 high EBI Holstein cows plus followers, run on a total farm area of 73 ha (54 grazing ha). The herd calves in a 60% autumn block and a 40% spring block. The herd has hosted a diverse range of experiments over many years, including winter milk feed-to yield and grazing trials, and more recently some work on multispecies swards, methane-reduction additives and alternative feed protein sources. It is often the case that 4-5 mini-herds run side-byside on their own independent systems.

Perhaps as a result, visiting groups often ask whether we have a policy of breeding cows to suit a particular system. On the contrary, we have placed a strong focus on breeding a flexible, robust cow type that can produce high levels of milk solids and go back in calf across a range of systems. The sire selection policy for winter and spring sections of the herd is identical, targeting a balance of milk solids and fertility traits through EBI sub-indices. Increasingly, we are putting more emphasis on health, carbon efficiency and management aspects of the index (Table 1). We do not set specific targets for type traits, however the herd has developed to be of medium size, with good functional locomotion and udders, and a capacity to hold body condition through early and peak lactation.

We have observed over the years that milk sub-index, and not milk kg/milk volume per se, has been the best predictor of lifetime daily milk value for the herd. We also see, as shown in Figure 1, that milk fat and protein content, are driven by the EBI values for each. As such, our selection policy has been to select for high milk sub-index based on increasing milk solids while holding milk volume steady. For example, the 2022 heifers (Table 1) will outperform the current herd for milk sales value based on the milk sub-index, with milk volume being of less relevance. This is consistent for the winter and spring herds alike. The herd is fully genotyped and results used to increase rate of genetic gain.

Performance

Annual milk solids sold per cow has improved also due to improved fertility performance, from approximately 483kg milk solids sold in 2013, to 569kg milk solids sold per cow in 2022. This herd average breaks down as 605kg milk solids for the winter group and 518kg milk solids for the spring calving group, reflecting differences in feed system and annual concentrate input. Milk solids percentages are very similar for the spring and autumn cohorts (4.44% and 3.68% on average), so the principal difference in total output is due to milk volume (7426 v 6370kg). As a result, from a nitrates perspective, our spring herd/system, if operating in isolation, would be in Band 2, and our winter herd/system would be in Band 3 in a similar context, but with identical genetic profiles. This illustrates that feed system has a major bearing on herd banding category and that genetic merit for milk volume has only a partial impact; the same trend is apparent on commercial herds. Our future breeding policy will remain consistent with breeding for milk sub-index targets as a result.

Fertility performance of both calving-season groups is usually similar, with >80% calving in 6 weeks in each block and typical empty rates of 10-12% after 10 weeks breeding. Average calving interval is 370 days. We do not carry/recycle cows between calving seasons as a rule. Over time, and in tandem with breeding for higher fertility sub-index, this has helped to improve the baseline fertility in the herd as lower merit cows have removed themselves as empty cows at the end of breeding. It is clear from analysis of herd data over time, and indeed from various across herd-analyses, that selecting based on EBI has driven much of this progress. Of course, like any herd there are a few ‘outlier’ cows that break the mould, but the trend over large numbers of cows over multiple years is clear. Average lactation number of cows culled has increased to 4.1 lactations from 2.9 lactations per cow culled in 2013. This greater cow longevity has increased the opportunity to use more high DBI beef bulls across the herd due to a lower requirement for replacement stock.

Bull selection decisions Autumn 2022

For the autumn 2022 season, 9 bulls were selected for the herd; 3 were daughter proven and 6 were genomic sires. The average milk sub-index of the bull team was €121, coming from 35.5kg combined solids. Milk kg (+115kg) on average was close to the current herd average, and ranged from +14 to +200 in the bull team. We expect the daughter crop to average 3.96% protein and 4.72% fat based on how the EBI figures currently predict actual performance for the herd. Fertility is good in the herd at present but the bull team will improve genetic merit further. The bull team will also increase merit for health, maintenance and carbon traits, which will drive efficiency and produce easy-care cows. High DBI bulls with good carcass characteristics were used on the lower EBI/lower performance cows.

Selected cows

While the emphasis for the herd is on consistent improvement of the average performance, and indeed providing a suitable quality cow for systems experiments, visiting groups frequently enquire about the ‘best’ or ‘ideal’ cow in the herd. Picking two examples, FB 2282 is a typical mature cow in the winter group. With an EBI of €250 (Milk €102/Fert €82), this cow has consistently delivered high milk solids output with good calving interval and low SCC across multiple lactations. Importantly, a problem-free cow that has gone largely unnoticed in the yard. On the spring side, FB2689 is typical of the spring calving mature cows. With an EBI of 201 (Milk €85/Fert €80), this cow has lifetime milk protein content of 3.93% and lifetime average of 580kg milk solids annually, from a typical concentrate input of 500-800kg. Again, a cow that works in the herd relatively unnoticed. These are two simple examples, but demonstrate the breeding objective of high solids for the system, consistency in calving date, and good health and functionality.