A crop of wholecrop wheat is a useful addition in a total mixed ration (TMR) for dairy cows, and can be used to limit the negative impacts of a wet grass silage, Mike Burns from Lallemand Animal Nutrition told farmers at a Fane Valley forage event on Tuesday.
Describing wholecrop as an “insurance policy that can be used to balance the ration,” he pointed out that in most multi-cut grass silage systems in NI, one of the cuts often ends up wet, and therefore is potentially less palatable, with lower intake values. A nutritionist can counter that with a wholecrop silage, said Burns.
The alternative to wholecrop is to grow a crop of maize, and if quality is good, it can lead to higher milk production. But it is a crop limited to only the most favourable parts of NI.
When cutting wholecrop, the advice from Burns is to remove it when the crop is still green, and when the grain is squeezed it is like soft cheddar cheese.
“The optimum dry matter is 35% - 42%,” he said. He also recommends the use of a crop-specific inoculant designed to inhibit yeasts and moulds. The ensiled crop can be fed from 15 days onwards.
According to Matthew Armstrong from Fane Valley, a second forage will increase dry matter intakes, and ultimately milk yields. He said that the optimum inclusion rate with grass silage is around 30% to 50% on a dry-matter basis.
However, wholecrop or maize will also cost more to grow, which may negate some of the milk yield benefit, although the anecdotal evidence from farmers is that cows with higher dry matter intakes tend to have fewer health and fertility issues.
The Fane Valley event on the farm of Leslie and Timothy Andrews outside Tempo in Co Fermanagh, also focused on the importance of reseeding to maximise production from grass swards.
According to David Little from Germinal, the starting point for any reseed should be a soil test to establish pH, phosphorus (P) and potassium (K) status. “Soil fertility is the key to keeping perennial ryegrass in swards,” he said.
He advised farmers to make sure whatever seed they are buying is on either UK or Ireland recommended lists, and when assessing each variety to not just look at yield and persistency, but also D-value.
“It pays to do a bit of homework. Make sure the mix is suited to your field and your system,” he said. On heavy ground, the varieties in the mix should be mainly diploid, with some Timothy also potentially included. Tetraploid varieties tend to have slightly higher yields and D-values, but have more open growth, so are less suited to wetter land.
By far the most popular Fane Valley mix is Killyleagh, which is made up of the tetraploid, AberGain, along with two diploid varieties, AberZeus and AberWolf.
When it comes to cultivation, Little said that ploughing is still the method that creates the most reliable conditions. But, with modern machinery, there is a tendency for fields to be ploughed too deeply, and power harrows to be used to create a fluffy seedbed.
“Roll and roll again pre-sowing – the firmer the better,” said Little.
He pointed out that many farmers, particularly in the east, now prefer to direct drill into swards.
Tetraploid grasses have larger seeds so are more suited to direct drilling. The sward should be grazed tightly pre- and immediately post-sowing. If it has been burned off, it should be left up to three weeks to allow the existing material to rot away.
Soil pH is the first priority
Given the high cost of chemical fertiliser, and the fact that the use efficiency of N, P and K drops when applied to soils with pH below 6, lime should be the top priority in grass swards, maintained Gary Spence from Fane Valley.
He said that the target pH should be between 6.2 and 6.5. At a pH of 6.5, N, P and K are all 100% available for growth.
To increase soil pH, most farmers tend to opt for conventional ground limestone. However, once the pH is corrected, there is potentially a role to maintain pH by using granulated lime products.
Spence recommends applying 150kg per acre annually, or every second year. It works out at a cost around £18/acre.
“The granulated lime is finely ground, and that is very important. It will give you a rapid lift in pH,” he said. He also cautioned against using any alternative lime products that take a long time to dissolve into the soil.