We are only a few weeks away from the start of the breeding season, which means the diet of the cow is crucial and mineral deficiencies in the herd need to identified and rectified.
The weather for the most of the spring has been excellent, which has meant that cows and maiden heifers have been enjoying to an energy-dense and protein-rich diet in the form of grazed grass and concentrates.
Cows that are underweight with a body condition score (BCS) of less than 2.75 need to be put on once-a-day milking to allow for condition to be built.
A high energy intake will drive milk solids, maintain BCS, and improves fertility. To ensure this energy intake, cows need to be grazing cover of 1,400kg of dry matter (DM)/ha, which is the best quality grass possible as the grass is at the three-leaf stage.
Post grazing residuals need to be between 4-4.5cm to make sure cows are achieving good clean outs but not getting pinched on intakes, and cows should be supplemented extra feed if grass is in short supply, in a timely fashion.
Diet impacting fertility
At this stage, well-fed herds will be eating 18-19kg DM of of high quality pasture, however, these pastures contain a high level of crude protein nitrogen (N), which milking use with feed energy to make milk protein.
However, when there is surplus N in the diet of the cow, milk urea levels can rise and it should not impact the fertility of the herd under good management.
That good management involves applying fertiliser N in a little-but-often manner in the lead-up to breeding and during the breeding season.
N application should not be overloaded under drought conditions. Feeding a 12% crude protein nut is a suitable option for feeding cows during the grazing season, especially if grass quality is good and cows are grazing consistently at optimal covers.
Feeding a high energy concentrate with 12-14% crude protein can help reduce nitrogen surplus in the diet and minimise environmental nitrogen losses, and will further reduce the nutrient balance of the farm.
Mineral deficiencies
Phosphorus (P) deficiency can cause issues with fertility and lead to low conception rates and this deficiency can be identified through the cows’ behaviour, if they are licking stones and exhibiting depraved appetite, farmers need to react.
Blood tests should be completed about three weeks prior to the start of breeding, as this allows for any mineral issues to be dealt with before it all kicks off.
In order to achieve a compact calving pattern, and maximise the six week in-calf rate, checking the mineral status of cows will be increasingly more important.
To achieve the best fertility and monitor cow health, farmers potentially should be looking at using blood tests more regularly on farms.
Farmers should blood test 7-10% of the herd and identify what minerals and trace minerals are deficient.
Extra P may need to be added to the water troughs, as mineral blocks or ration boluses will not correct a P issue, according to Teagasc.
Trace minerals such as copper, cobalt, iodine, selenium, manganese, and zinc are needed in small quantities, but will have an impact on fertility if they are lacking in the diet.
Feeding minerals above requirements is expensive and will not boost fertility if no deficiency exists, which highlights the importance of blood testing to know what you are dealing with and how to rectify any deficiency.
