Why the pre-breeding period is critical for a successful breeding season
It is widely recognised that one of the key factors underpinning farm profitability is fertility performance. Farmers are well aware of the consequences of poor fertility: increased labour, higher AI usage, fewer replacement heifers generated, less milk produced, increased calving interval, and spread in calving pattern.
Comprehensive research from University College Dublin identified two of the most influential factors that affected fertility performance on seasonal calving dairy farms to be calving spread and the quality of heat detection. Putting a focus on the drivers of these two key factors prioritises certain farm-management decisions, which will have the greatest impact on making improvements this year.
Calving pattern
A compact calving pattern is driven by high submission rates alongside high conception rates, both of which have inter-related components. For a cow to be submitted for service she must be cycling, and the farmer must have a reliable method of heat detection.
For cows to be cycling, nutrition, energy, and health are top priorities after calving. Energy balance in early lactation is likely to be one of the most important nutritional issues affecting subsequent fertility. Setting farm goals around transition management of cows in order to limit the extent and duration of negative energy balance in early lactation requires regular assessment of body condition score (BCS) to ensure 90 per cent of the herd is calving down with a BCS between 3-3.25.
Nutrition and animal health
In relation to achieving high conception rates, there are three elements of importance including the cow, the bull, and the farm-management practices. Cows must be at least 42 days calved, healthy and not have lost more than half a BCS post calving. In terms of health status, reducing the risk posed to herd fertility performance by infectious diseases such as leptospirosis, bovine viral diarrhoea (BVD) and infectious bovine rhinotracheitis (IBR) should be part of every pre-breeding programme. Leptospirosis infection in dairy cows is associated with reduced fertility performance, poorer conception rates, abortions, and stillbirths (Dhaliwal, 1996) as well as the zoonotic risk of transmission to humans and infection of farm staff. The prevalence of antibodies to leptospirosis in unvaccinated Irish dairy herds is high at 79 per cent (Leonard, 2004) demonstrating a high level of exposure to infection. This justifies vaccination as a control strategy for every dairy herd in the country. Vaccination for leptospirosis with Leptavoid-H should be done as a primary course with two doses four to six weeks apart completed over two weeks from the planned start of mating with an annual booster thereafter. Leptavoid-H is the only vaccine licensed to protect against both strains of Leptospira hardjo.
Vaccination strategies
BVD is a very costly disease that results in significantly impaired fertility performance due to abortions, embryonic losses and infertility. The prevalence of BVD in Ireland has been decreasing year on year but the biosecurity risk of BVD for each herd in terms of cattle purchases, boundary fences, personnel and equipment must be assessed on a farm-by-farm basis.
Vaccination with Bovilis BVD can help protect the unborn calf from infection. A primary course consists of two doses, four weeks apart given a month before breeding with a single booster prior to breeding each year thereafter. Both Leptavoid-H and Bovilis BVD can be given at the same time, minimising the handling and labour involved with administration. IBR is known for causing respiratory illness in cattle but there is a body of evidence demonstrating negative reproductive outcomes such as poor conception rates and abortions (Graham, 2013) following infection also. Complete and regular herd vaccination for IBR using Bovilis IBR Marker Live is instrumental in a herd’s IBR control programme. Vaccination reduces both clinical signs and viral shedding in the case of primary infections (Animal Health Ireland).
Vaccination strategies for IBR, leptospirosis and BVD proactively tackle risk associated with infectious pathogens known to reduce herd fertility while maintaining a high health status for breeding. Each farm is different so talk to your vet now and make a plan that will mitigate the risk in your herd.
Heat-detection methods
Effective and practical methods of identifying individual cows in heat are essential to good breeding management. Optimal herd observation of 20 minutes, five times a day, result in heat detection rates of 90-95 per cent (Crowe, 2018). This approach requires a high level of labour, skill and commitment which can be in short supply on farms today especially considering the advantages of accurate heat detection technology as an alternative. Cow monitoring systems such as SenseHub cow collars or ear tags, measure activity, rumination and eating time to build a profile of cow behaviours. Changes in activity associated with oestrus are quickly detected and notification of heat onset is delivered to the app where a timeline for optimal service is generated. Research demonstrates there is ample room for improvement in this area as the range in heat detection rates on farms of just 30-70 per cent of cows showing oestrous behaviour usually being detected (Crowe, 2018). As heat detection feeds into submission rates and overall reproductive performance, improvements here through technology are win-wins for farmers through reducing labour and eliminating the inconsistency of manual cow observations.
Covering the basics well in the pre-breeding period sets up the herd for successful reproductive performance. Through monitoring of BCS, nutrition, vaccination programmes and improved heat detection, huge gains can be made in reproductive efficiency and overall farm profitability. Have a conversation with your vet to discuss last year’s breeding season and what areas you can try improving for this year’s season.
References
The influence of cow and management factors on reproductive performance of Irish seasonal calving dairy cows. Elizabeth A Lane, Mark A Crowe, Marijke E Beltman, Simon J More. Animal Reproduction Science Vol 141, Issues 1-2, September 2013, 34-41.
Bovine herpes virus-1 (BoHV-1) in cattle – a review with emphasis on reproductive impacts and the emergence of infection in Ireland and the United Kingdom. Graham. Irish Veterinary Journal 2013, 66:15.
Reduced conception rates in dairy cattle associated with serological evidence of Leptospira interrogans serovar hardjo infection. GS Dhaliwal, RD Murray, H Dobson, J Montgomery, WA Ellis Veterinary Record (1996) 139, 110-114.
Prevalence of antibodies to Leptospira interrogans serovar hardjo in bulk tank milk from unvaccinated Irish dairy herds. N Leonard, John F Mee, S Snijders, D Mackie. Volume 57 (4) April, 2004 Irish Veterinary Journal.
Reproductive management in dairy cows – the future. MA Crowe, M Hostens, G Opsomer. (2018) Irish Veterinary Journal, 71(1).
Animal Health Ireland. https://animalhealthireland.ie/programmes/ibr/