Boosting milk yield
Boosting milk yield
By Marianne Curtis
REDUCING time cows spend away from pasture and using a concentrate additive which reduces grass protein degradability will boost milk yield from grass.
These are the research findings of British Grassland Society scholar Lynn Wilson at SACs Crichton Royal Farm, Dumfries. Speaking at the Societys AGM, she explained the importance of maximising grass intakes for cows yielding more than 25 litres/day.
"To fulfil maintenance requirements and produce 30kg milk/day, a cow would need to eat 19.6kg dry matter of grazed grass, which is equivalent to 100kg freshweight. Thats a lot of grass."
Grass intake depends on how long a cow grazes, her biting rate – which is 60 bites/minute and bite mass, she said. "Cows will not graze for more than 11 hours. To ensure grazing time is maximised, it is important to ensure as little of their time as possible is spent standing in yards before and after milking."
In dense leafy swards, it is possible for cows to consume 0.5gDM with each bite, which would support yields of 30 litres/day without loss of condition, according to Miss Wilson. "However, bite mass is often less than this, meaning supplementation is required."
Concentrate supplements used in her research were designed to maximise grass intake. In one trial cows were fed 6kg of two different concentrates with the same energy content based on either fibrous ingredients, such as wheat feed and citrus pulp, or cereals. "There was no difference in yield between the two types of concentrates."
In a second trial, a sugar/mineral additive was included in concentrate which boosted yield by 1.5kg milk/day, according to Miss Wilson. "The additive worked by reducing the degradability of grass protein, so cows ate more grass and produced more milk." *