Semi-starvation is not acceptable
Spring-calving programmes are now resulting in very busy schedules on farms throughout Ireland. The weather has been extremely mild and grass growth rates have left an excellent carpet of grass on farms. However, the inordinately high rainfall has left ground saturated.
Some farmers have put freshly calved cows out on grass day and night, with a concentrate allowance of 2kg/day.
This system mainly lends itself short-term to low-cost milk production, but what are the long-term implications?
There are very few farms visited at present that will tolerate the soil damage created by strip-grazing cows on early spring grass. Grass dry matters are currently low. It is impossible to meet the demands for maintenance and production from grazed grass without shedding excessive weight post-calving.
The overall target for bodyweight loss should not exceed 0.5kg/day for the first six weeks post-calving. This is equivalent to 0.5 body condition score (BCS). Cows that loose greater than 0.5 BCS have poorer rates of uterine involution and a slower return to normal heat cycles.
In the New Zealand grass-based milk production systems, cows may lose more weight post-calving. With a flush of grass supply, there is compensatory gain and cows return to normal heat cycles. Cows failing to start to cycle are induced using PRIDs or CIDRs.
This system of semi-starvation is not acceptable on animal welfare grounds. It is essential that the cows' feed requirements for energy and trace elements are met to allow 0.5 BCS loss in the period of negative energy balance.
The genetic potential of your cows for milk production will dictate the concentrate supplementation required in the period of negative energy balance. Trace-element supplementation has to be based on the differential between that supplied in the diet and that required for maintenance and production.