The 2020 grazing season is over for most Dairylink Ireland farmers and cows are settling into winter feed plans.

Third-cut silage was being offered to cows as a buffer feed over the past few weeks, while some grazing was still going on during the day.

However, with the proportion of early lactation cows rising in autumn-calving herds and ground conditions deteriorating on most farms, cows have been housed full-time and are being offered first-cut silage.

An overview of silage analysis results for the forages being fed to lactating cows across phase two farms is outlined in Table 1. In the case of John Oliver, second-cut silage is in front of first-cut in the pit, and it is therefore being fed to cows initially.

In general, silage quality is decent across Dairylink Ireland farms. One of the first things that jumps out from the table is the high dry matter content of all silages. This reflects the dry weather that occured during May, which was ideal for achieving a rapid wilt.

First-cut on James King’s farm is particularly dry at almost 49%. However, he reports no issues with heating or moulds and the high dry matter content explains the high intake potential value of 120.

“All silages showed good to excellent D-values and ME (metabolisable energy) concentrations,” commented Dairylink adviser Aidan Cushnahan.

“It comes from programme farmers taking the opportunity to harvest grass for first-cut at the optimum leafy stage during the fine weather in May,” he said.

Stephen Wallace and Richard Marshall were the first to mow grass during the first week of May and subsequently had the highest ME and D values. James Martin, Frank Goodman and James King cut later in the month and they still harvested a high D-value crop, which analysed over 11.1 MJ/kg DM. The table also shows that ammonia concentrations are low across the samples, which indicates that the silage crops have fermented well with little excess nitrogen.

All this combined led to relatively high predicted intake values across all programme farms, with the average value standing at 109. It means cows should be able to eat sufficient quantities of fodder, which will allow them to maintain high levels of feed efficiency.

Calculating feeding potential of silage

Dairylink farmers are being encouraged to actively monitor feed intakes to help maximise feed efficiency. To do this, monitor how much is fed out each day through the wagon, how much feed is leftover and the total cow numbers in each group.

Production from forage can be calculated from silage analysis results and information on intakes. The following example is a calculation based on Frank Goodman’s first-cut silage:

  • Silage DM intake = Fresh intake x DM %
  • Silage DM intake = 40 x 27.6 .
  • Silage DM intake = 11kg DM.
  • Silage energy intake = silage DM intake x ME content.
  • Silage energy intake = 11 x 11.2.
  • Silage energy intake = 123 MJ.
  • Energy available for milk production = silage energy intake – maintenance requirement.
  • Energy available for milk production = 123 – 75.
  • Energy available for milk production = 48 MJ.
  • Potential milk yield = Energy available for milk production/5.3.
  • Potential milk yield = 48/5.3.
  • Potential milk yield = 9l/cow/day.
  • In feed-to-yield systems, the baseline potential from forage is subtracted from actual milk yield to give the level of production that requires concentrate supplementation. Most systems are based on a concentrate feed rate of 0.45kg/l.

    So, for a cow yielding 30l from Frank’s first cut, she has 21l coming from concentrates and will require an additional 9.45kg.

    Minimum feed rates can also be set for the first 10 weeks or so in lactation. This aims to drive yield from feed, rather than feed to yield, and means that concentrate levels will not drop below a certain level, regardless of milk yield.

    Feed space affects silage intakes

    The level of production that cows deliver from fodder ultimately depends on the intakes that are achieved, and feed space is a critical factor that affects this.

    “You could have the best silage analysis in the world, but if cows don’t have enough room to eat it, they won’t produce the litres to match its potential. Cows should be allowed at least 30cm each at the feeding barrier,” Dairylink adviser Aidan Cushnahan said.

    In the example outlined below, if silage intake varies by plus or minus 1kg DM, then potential milk from silage varies by plus or minus 2l.

    The advice from Aidan is to monitor feed intake on a regular basis and to analyse silage quality more than once during the winter.

    Lower intakes among first lactation heifers also need to be allowed for in feed plans, especially if heifers are not separated from the rest of the herd.

    “A first lactation heifer would typically be expected to take around 3l less from forage than her fully grown counterpart,” Aidan said.

    Weekly round-up

  • Cows are settling into full-time winter feed plans on Dairylink Ireland farms.
  • The aim is to maximise feed efficiency by getting as much milk production from grass silage as possible.
  • Calving is progressing in autumn-calving herds.
  • Programme farmers are also finalising sire selection ahead of the winter breeding season.