Nutrition is important for the reproductive performance of the herd. Genetic selection for higher-producing dairy cows creates challenges to meet the cows' energy and nutrient requirements in early lactation.
When cows cannot physically eat enough immediately post-calving, they experience negative energy balance (NEB). If the NEB is severe or prolonged it impairs the cow’s ability to start cycling and impacts oocyte and embryo quality, establishment, and maintenance of pregnancy. Aim to get cows in positive energy balance before, and during, mating.
How do I know if the cows are in NEB?
Reviewing the diet and gaining an understanding of feed utilisation helps answer this question. Consider if the cows are eating all the feed equally, the amount of energy in the diet, and check if feed wastage has been factored in.
Monitor body condition score (BCS) post-calving. Before mating, the cows should have stopped losing body condition and ideally be at BCS 4.5.
To help monitor the energy status of the herd, look at the protein percentage on the milk docket. The milk protein percentage is closely related to the energy balance of the cow. An easy way to think about it is the more energy in the diet, the less protein is needed by the cows as an energy source, resulting in more protein going into producing milk.
A normal milk protein graph over the season should have a NIKE tick shape, with the lowest point at peak milk and a slow increase occurring before and during mating. Seek advice if this is not what is occurring.
Pasture quality is crucial in maximising the dry matter intake (DMI) of the herd. Ryegrass heading dates tend to clash with spring mating. As pastures go reproductive, the neutral detergent fibre (NDF) levels increase. This makes pasture harder to harvest, needs longer to digest, and takes up more space in the rumen. Physical fill can limit total DMI.
The maximum DMI of pasture can be estimated from the NDF percentage. A 500 kg cow, grazing on pasture with a value of 35 percent NDF, will consume around a maximum of 19 to 20 kg of DM of pasture. If the NDF increases to 45 percent, as commonly seen in lower-quality pasture, this reduces intake to 14.5 to 15.5 kg of DM. Concentrate feeds can help to fill this gap and ensure the cows are fully fed and have the energy required for a successful mating.
Adequate trace mineral status is another important aspect of reproduction. It is recommended to check levels four to six weeks before the planned start of mating. If this has not been done, approach your local Veterinarian to check the herd.
View the range of supplementary feeds and trace minerals options at your local PGG Wrightson store.
