The breeding season is fast approaching on many dairy farms and Teagasc’s Dr. Joe Patton offered some timely advice on improving herd fertility performance at the recent Ballyhaise open day.
Joe outlined that there are multiple management factors to be considered to address average herd fertility performance. Progress, he said, will only be made by implementing a comprehensive herd plan based on proven practices and not through quick fix solutions.
1. High EBI
Touching on EBI (Economic Breeding Index), he said that cows with a high fertility sub-index (SI) have been shown to: cycle earlier; require less fertility interventions; have stronger active heats; higher conception rates; and less embryo mortality.
He advised farmers to target an AI bull team with a >€120 fertility SI on average. Crossbreeding to high-EBI Jersey bulls has a definite benefit where herd fertility and solids indices are currently poor.
2. Focus on submission rate
Research has shown that submission rate (the number of cows served) is a much stronger driver of six-week calving rate than conception rate to first service.
Tail paint/cards, vasectomised bulls or other electronic technologies all work well. Choose a system and implement it well, he said. Do not delay later-calved cows after mating start date – all eligible cows can be submitted for AI after 35 days calved.
3. Body condition score
Joe also mentioned that farmers should focus on body condition score (BCS), as it gives a good estimate of long-term nutrition, energy balance and has important links to fertility.
For high-conception and six-week calving rates, the target is to have cows at 3.00-3.25 at calving
and losing less than 0.5 units before mating start date.
Research has shown that where quality grass is plentiful, there is little benefit to BCS or herd fertility of increasing concentrate feeding around breeding time.
Instead, Joe suggested that farmers should consider milking thin cows once a day. However, they should be maintained on the same plane of nutrition as the milking herd (ie. fed concentrates twice daily in the parlour).
4. Mineral nutrition
The goal of dry cow mineral nutrition, he said, is to have cows in the correct calcium and trace mineral status at calving, so that problems such as dystocia, milk fever and retained placenta are minimised.
To prevent metabolic issues, ensure that cows receive adequate magnesium supplementation (0.4% of diet) and are on a low-potassium diet pre-calving.
Do not feed trace minerals beyond recommended rates; it is costly, will not improve fertility and may lead to issues with milk residues (iodine in particular).
5. Keep good records
Many problems around breeding stem from difficulties in the weeks around calving. Keep accurate records of problem calvings, downer cows or retained placentas.
If you have more than 5% of cows with these health problems and more than 5% assisted calvings (jack/vet), there is an issue in the herd that needs to be addressed, he added.
6. Intervene early
Cows that are thin, have cystic ovaries or are carrying uterine infection will not be available for breeding in the early weeks of the season, Joe explained.
Previous thinking was to allow these animals time to self-repair, but this reduces overall breeding efficiency. Anoestrus cows should be treated (e.g. CIDR protocol) one week in advance of mating start date, so that they can be bred early in the season. This principle can also be applied to late-calving cows.Also Read: What can a pre-breeding scan tell you about your herd?
7. Eliminate the dairy stock bull
Excellent genetic gain cannot be achieved by using stock bulls to produce dairy heifers. In any case, stock bulls will not have the capacity to achieve submission rate targets in the early weeks, he noted.
Use short-gestation, easy-calving beef bulls to mop up in the late season if necessary.
Diseases such as leptospirosis, BVD, IBR and salmonella pose a big risk to fertility. Formulate a herd health plan for your herd, in consultation with your vet, with the specific goal of achieving high fertility in mind.
9. Replacement heifers
Heifers are expensive to rear in any case; but the additional cost of calving at >28-30 months old is huge (close to €400/calving compared to 24 month calving).
In addition, older heifers have been shown to have poorer lifetime fertility and milk production – irrespective of breed or production system.
10. Have a defined breeding season and culling policy
Setting defined limits to weeks of breeding can be difficult when starting from a spread out calving pattern; but it is essential to drive long-term progress.
Experience on commercial herds is that empty culling rate will increase to >15% for a few years; but this can be tolerated provided high-quality replacements are coming into the herd.
In time, he said, the number of empty and late-calving cows will decline as EBI improves. For herds at average current performance, the recommendation is to limit breeding to 16 weeks initially and down to 12 weeks within three years.
Joe also urged farmers to eliminate the recycling of cows from the system up front. Driving a high submission rate moderates the impact of a shorter breeding season.