Maintaining fertility for July and August calvers needs to be a top priority this summer. So says KW ruminant technical manager Charlotte Ward.
According to one study, pregnancy rates between 55% and 70% were recorded for summer calvers, compared to between 85% and 92% for those calving in winter.
“With each additional day beyond a 365-day calving index costing around £2.50 per cow, even a 12-day extension due to lower fertility represents a loss of around 0.3ppl,” she explains.
Shortening day length means grazing intakes are dropping, as is grass quality. And too often buffer feeds aren’t making up the nutrient shortfall, according to Ms Ward.
“Periods of heat stress or poor weather are also further restricting intakes. The result is a loss in body condition and reduced fertility.
“Increasing the buffer’s energy density and intakes is the priority, using moist feeds like brewers’ grains or wheat-gluten moist feed, plus a molasses-based liquid feed,” she says.
“Balance energy release in the rumen with digestible fibre from soya hulls and add a protected fat if more energy is needed above that supplied by the rumen.
Ms Wards adds that excess rumen degradable protein can also negatively affect fertility: “So counter the surplus RDP in grass with feeds high in rumen-bypass protein, such as heat-treated rapeseed expeller.”