The CAFRE dairy herd at Greenmount campus in Antrim consists of around 180 dairy cows and is used to demonstrate best management practice and use of technologies to the industry.
The herd is compact autumn-calving, so particular attention is given to ensuring cows receive a consistent supply of high-quality forage to maximise the production of milk solids and maintain the calving pattern.
Traditionally, this was achieved through the production of three cuts of grass silage and the inclusion of alternative forage crops, such as maize or wholecrop wheat silage.
This year however, the grass silage was ensiled in a four-cut system at five to six weekly intervals between the end of April and mid-August.
There is evidence to suggest this will maximise the yield of utilisable forage energy and help to optimise feed efficiency and milk output.
Shown in Table 1 is a summary of grass silage analysis data collected to-date.
It highlights that forages have high dry matter (DM) contents (greater than 25%), ME above 11 MJ/kg DM and intake values greater than 100.
There is still some maize silage available from last winter, and the high starch value of this crop is useful for enhancing milk protein production. The 2021 crop was harvested in early October and samples will be taken shortly to assess feed value.
Also shown in Table 1 is the forage analysis for wholecrop wheat silage and grass silage specifically made for dry cows.
The grass silage was produced without any slurry or compound fertiliser.
Winter feeding plan
Plans for winter feeding were set in motion back in August, when the body condition score of each cow was assessed. The majority were in target condition, with scores of 2.5 to 3. Those below target either received additional concentrate in late lactation or were dried off early.
A team at CAFRE, along with Mary Jane Robinson from Thompsons Feeds, have developed a winter feed plan, with particular attention to dry and early lactation groups.
Cows in the herd are normally dry for around six to eight weeks and spilt into two groups (far off and close up).
The far off cows receive dry cow silage and dry cow minerals. Those within four weeks of calving are moved to a close up group and offered a total mixed ration (TMR) of dry cow silage, wholecrop wheat silage, straw, soya, pre-calver concentrate and anionic salts.
The dietary cation-anion balance (DCAB) of this mixture has been estimated to be around 79 meq/kg DM, which is within target (50-100 meq/kg DM). The lower the DCAB, the lower the risk of milk fever.
In 2020/21, 2% of cows had milk fever, which was below the target of 3% – 5%. There have been no major difficulties to-date this autumn, with over 50 cows calved so far.
All cows within four to five days of calving are moved into a maternity group and continue to be offered the close-up diet.
After calving, animals go into a startup group with a diet of first- and third-cut silage, maize silage, glycerol, megalac and concentrate blend.
Mixing first cut with later cuts will ensure a consistent supply of first-cut silage throughout the winter.
As shown in Table 2, in-parlour concentrate is increased from calving until 21 days-in-milk (DIM), at which point cows receive a minimum of 4kg/cow/day.
Those that justify being fed more will receive it from this stage onwards.
The feed plan is altered after 80 DIM, when the minimum feed rate is reduced and cows are fed according to yield.
Levels of milk produced from forage have initially been set at maintenance (M) + 8l/cow/day and M+ 6l for first-lactation heifers.
These figures are based on silage analysis results and forage intakes from previous years. Intakes, forage quality and levels of production will be monitored closely to ensure targets are being met.
With increasing concerns about the sustainability of using imported feedstuffs such as soya, we have looked at the potential for utilising other protein sources within the diet and how we can optimise the protein that is fed.
During 2020/21, a reduction in the inclusion rate of soya within the blend, and setting the overall protein content of the diet to 16% DM, showed no ill effects.
The plan going forward is to feed concentrates with less soya and use other protein sources to a greater degree.
Regular updates on herd performance will be available on the CAFRE website.