Maintaining Production in Late Spring
Why will some herds maintain production better than others at this time of year? Traditionally we see lactation declines of 15% or more per month from late October to Christmas. This means that a herd doing 25 litres in late October would drop to 18 litres in two months. Conversely, a herd with better control of feed intake would drop 9% per month to 21 litres.
What determines feed intake now?
Pasture offered
As pasture growth rates decline, the ability of the pastures to grow at the rate of
consumption will decline. Herds begin to eat into the residual feed bank left from
spring so that harder grazing is required to maintain intakes. Unless a substantial
residual pasture sword remains after grazing (1800kg dry matter per hectare) then it is
unlikely that cows will ad lib feed. This is obviously not feasible to do without losing
pasture quality and regrowth potential.
Pasture Quality
Once we pass mid October, rye grass tillers that have been exposed to winter soil
temperatures, will be triggered to run to seed. These need to be eaten off or cut
below the growth node, about 5cm above ground, to stop further seed head
development. Seed head development takes up energy and reduces the ability of
plants to grow new tillers. The new tillers will not run to seed until next spring. The
more moisture, fertiliser, nitrogen and grazing these new tillers have, the more they
will grow. If seed head tillers still remain on the plant, these new tillers will have
limited growth.
By using cows and machinery to remove seed head tillers, pastures will be able to
respond to favourable growth conditions. Often paddocks cut for silage or topped prior
to mid October will run to seed despite this since seed head development was not
started at the time of the early cut.
High soil fertility, new cultivars and use of nitrogen if moisture is not limiting, are the
essentials to optimise pasture growth once seed head tillers are removed. Cows are
quick to tell us, by responses in the vat, what they can do with such pastures.
Other Inputs
Given that spring pasture management is being optimised, it is important to monitor
production to be aware of drops greater than anticipated. Cows will vary by 1-2 litres
per cow over a week but a sustained drop at this level must be investigated. Once
paddock quality variation, water and other potential reasons are ruled out, it is
important to assess the total feed inputs.
It is difficult to measure total pasture intake however, the residual pasture height will
give a good indication of the change in amount offered.<P>
Inputs available till mid December when early crops are ready, usually involve grain.
Protein is unlikely to be limiting in their diet except for high producing herds. Grain
can be increased slowly to 6-8kg without compromising fibre balance for cows
producing 20-25 litres. These cows will be eating 15-17kg of dry matter daily so the
grain represents up to half their diet. Depending on the type of grain and relative
fibre level of pasture, buffers or rumen modifiers may be economically justifiable at
these higher levels. The fat test and faecal consistency of the herd will be early
indicators of the need to add these to the diet.
Many farmers let seasonal conditions influence production too much in late spring. Top or heavily graze paddocks to remove seed head tillers.
Set production targets and regularly monitor them.
Take early action to fill in feed gaps as production falls. Much of our profit comes from good summer production.
Click here to view the rest of the 1999 November newsletter.