Calving is now in full swing on most farms, and it can be a stressful time for both the cows and farmers. If a good dry cow programme was put in place, complete with body condition score (BCS) monitoring and good nutrition, minerals and management, some of this stress has been alleviated.
A cow in early lactation cannot physically eat enough to support her energy requirements, so she enters into negative energy balance (NEB). Her energy demands exceed her supply, and body fat or body condition is converted into energy that supports her milk yield.
The amount of condition lost during this period will go a long way in determining the performance and fertility of the animal. Dry matter intake needs to be measured and encouraged to minimise the BCS loss associated with negative energy balance post-calving.
Body condition score
Body condition has an influence on cow health, milk production, fertility and lameness. Cows should be at a BCS of 3 to 3.25 at calving and lose no more than 0.5 BCS units in the first three weeks post-calving.
Each condition score unit represents approximately eight percent of mature cow body weight, so for a cow weighing 600 kilograms, that would be approximately 48 kilograms. Mobilising a lot of body condition post-calving can also lead to other metabolic issues, such as milk fever and ketosis, which can compound other problems.
The first three weeks post-calving are vital to a long and successful lactation. The rumen needs to adapt to a much stronger ration, and the cow’s intakes need to almost double. A key focus in maximising her intake and performance post-calving is to supply all of the cow’s protein, energy and fibre needs using top-quality forages and concentrates.
More than 50 percent of the cow’s diet post-calving is comprised of grass silage, so the cow will always struggle for energy. The use of a secondary forage such as maize has been shown to increase energy, reduce concentrate level and boost overall intake.
The level of protein in the ration will drive intake and increase peak milk yield. The main source of protein should always be soya. For high-yielding herds, a secondary degradable protein source is recommended, such as distillers grains or rapeseed meal.
Feeding more than the cow’s requirement for protein in early lactation will look good from a milk yield perspective, but in the absence of energy and intake, a higher protein diet can strip body condition from the cow at the expense of fertility and milk protein later on. Care should be taken when diets with over 17 percent protein are prescribed. Higher levels of protein can make the overall ration expensive, and there is an energy cost to breaking down excess protein.
As we adjust the cow’s rumen to more concentrate and push for higher milk yields, it becomes important to use straw as a source of fibre in the diet. We generally look for over 30 percent neutral detergent fibre (NDF) content. In mixed diets, chopping this straw to four to six centimetres is key. Cows will need to chew the cud for around 10 hours a day, so we should see at least 60 percent chewing, whether that be in a shed or in the paddock.
Rumen function can also be enhanced by using yeast-based products such as Yea-Sacc® in your concentrate or mineral feed. Trials carried out at grass have shown better rumen function through a more stable pH, which leads to higher utilisation of feeds, increased yields and less mobilisation of body reserves.
Correct mineral and vitamin supplementation post-calving is essential and often underestimated. Minerals play a key role in every process that occurs within the body, and deficiencies can lead to substandard performance. While we associate mineral nutrition with coat colour and fertility, it also plays a vital role in milk yield and milk protein production, and in strengthening the cow’s immunity.
When we are feeding minerals, we should focus not just on the number on the bag, but also the form of those minerals. Organic-based minerals such as Bioplex® and Sel-Plex® have been proven to maintain health and reduce somatic cell count, while improving conception rates and udder health.
l Management tips for early lactation:
l Allow one feed space per cow post-calving.
l Give freshly calved animals, especially heifers, at least 48 hours to increase intake in a low-stocking environment before being let out to grass.
l Manage your silage pit to avoid heating and mouldy silage.
l Keep feed at the barrier fresh and palatable, and free from heating.
l Mixed diets should be about 40 to 45 percent dry matter, so water might need to be added to some dry silage this year.
l Water supply is very important. Cows need good access to clean water, which is sometimes taken for granted.