Nick Barradale BVSc MRCVS, Molecare Veterinary Services
There is no doubt seasonal block calving systems have cemented their place on the grasslands of the South West, and rightfully so, but these systems work for good reason; their cows match their system and visa-versa.
The concern with seasonal conversion is financial loss while shoe-horning an all year round system into a block and then lacking fertility, allowing that block to slip. Elongation over coming years then undoes all the expenditure and effort. Some out there would look at the NZ or Irish Fr crosses, with or without Jersey genetics and think they are lesser cows than the modern Holstein but they are grass cows that yield well from grazing and little additional feed. They milk from low cost feed while maintaining conception rates to AI of 50%+, out performing high yielders on yield/cost per hectare, especially when accounting for ensiling and labour costs.
Essential fertility key performance indicators (KPIs) for seasonal systems concentrate on financial implications of the block; fertility cull rate and front loading potential.
Top herds will outperform these guide figures but missing these targets are associated with lost potential revenue. The KPIs that are financial indicators are the 6 week in-calf rate and empty rate. The block must remain front loaded to give cows the chance to recover and then conceive early in the next fertility block otherwise the empty rate will rise. Carry-overs are an option as are out of block calvers but this just adds pressure to the next block.
The key to front loading is maximising the 3 week submission rate; you must give cows the opportunity to hold early with optimal early heat detection. The concern with the ‘wrong cow’ for the system is that heat display may be absent or poor, hugely reducing 3 week submission rate.
Further to this issue, conception rates of 55-60% are a big ask of a cow at grass, unless it is genetically programmed to manage. Poor submission/heat detection rate combined with poor conception rates equal frustrating block performance.
Additional things to consider to optimise fertility KPIs:
Heat detection plan; technique and man power
Transition ration and management; rumen fill, protein supply, water quality/availability
Fresh cow ration; energy and protein provision, DMI potential, grass break management
Periparturient disease; manage clinical and sub-clinical milk fever and energy balance in cows to avoid RFMs, Metritis and Whites
Mineral supplementation method; Copper, Selenium and Iodine, Partial DCAB
Infectious disease management; BVD, Lepto, IBR
Genetics; long term management plan to refine herd over years
Purchase policy; large heifer groups are great but can come with disease issues such as BVD and Johnes
Staffing and protocoling; ensure management is manageable when it is needed
Grass platform and environment; can farm and grazing be adapted to cope with the whole herd doing the same thing at the same time?
The best guidance we have found over recent years is the experience of our clients. They have fantastic support networks in the form of farming COOPs that share knowledge regularly. Conversion takes time and can be very successful but must be mapped out with financial and environmental planning.