The College of Agriculture, Food and Rural Enterprises (CAFRE) has recently surveyed 120 dairy herds across Northern Ireland to determine the main reason for culling cows within these businesses.
The participating farms, which included CAFRE’s own dairy unit at Greenmount College, account for 15,800 milking animals.
The work has confirmed that the decision to cull a cow is driven by a number of factors.
The main results of the survey were discussed by CAFRE’s Dr. David Mackey at the recent ProCROSS open day. The event was hosted by Co. Tyrone dairy farmer, Des Kelly.
CAFRE dairy survey
The results of the survey confirm that the average age of cows was 6.1 years and the average calving age was 27.7 months. They had a productive lifespan of 3.8 years, after producing some 30,200L of milk.
The CAFRE work also confirmed that infertility is still the main reason for culling, followed by mastitis and lameness.
Across all the herds surveyed, 12% of cows are culled in their first lactation.
Mackey highlighted the concept of determining dairy cow efficiency in terms of her estimated lifetime yield of butterfat and protein per day of life.
For the current Greenmount herd, this figure comes in at 1.14kg. The average figure across the survey as a whole was 1.04kg.
As cows get older, a proportionately higher number of cows are culled for mastitis and lameness-related issues.
Mackey commented: “Achieving a good lifetime yield is about: Securing good yields per lactation; calving heifers earlier; effectively managing infertility in young cows; managing mastitis and lameness-related issues.
“Securing a reduced culling rate is also important.
“Herds with the highest lifetime yields culled fewer younger cows, especially in their first and second lactations,” he added.
“In contrast, herds with the lowest lifetime yield culled as many cows in their first lactation as the top 25% of herds achieved up to the end of cows’ third lactation.”
Future sustainability
According to CAFRE, lifetime yield is key to the future sustainability of dairying. Around 27% of cows are either culled or die in Northern Ireland, achieving lifetime yields of 30,200L.
“Lifetime yield is not about keeping more older cows, it’s about having fewer losses of younger cows,” Mackey continued.
According to Mackey, crossbreeding can be expected to increase the productive life by between 0.5 and 1.0 lactations.
This is a direct result of lower culling rates for infertility, mastitis and lameness.
David Mackey pointed out that dairy farmers in Northern Ireland should aim for a minimum lifetime yield from their cows of 40,000L.
This works out at 1kg of milk solids per kg of cow bodyweight per year. This assumes an average liveweight figure for mature cows of 700kg.