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Thursday 8 December 2016

What to do with your silage test results

Joe Kelleher

Published 19/11/2016 | 16:00

Gerry Giggins will spend a lot of time this month reformulating rations.
Gerry Giggins will spend a lot of time this month reformulating rations.

Silage analysis have been coming back at a steady pace for the past number of weeks and are reading poorer than would be expected.

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The last week of May and the first week of June was probably the best spell of weather of the year and ideal conditions for first cut silage.

However, despite this, most analysis of silage cut in this period are reading 4-5pc units lower in Dry Matter Digestibility (DMD) than you would expect.

Typically, we would expect silage cut around May 25 to be reading in excess of 70pc DMD, but this year these silage results tend to be in the region of 67-68pc DMD. In the first three weeks of May we had a huge surge in growth rates with many farms recording average growth rates in excess of 100kgs/ha.

This meant many silage fields were growing at a rate of more than 150kgs/ha and this seemed to bulk up silage crops very fast in this period which inevitably led to a high proportion of stem in the crop thereby causing the drop in DMD.

silage analysis.PNG  

Is 68pc DMD silage good enough to feed the dry cow over the winter months? If we look at table 1, we see that if a cow has a body condition score (BCS) of 3.0 or greater and is offered 68pc silage ad lib, then she will calve down at the correct BCS of 3.25 assuming she is dry for an eight-week period.

However, if she is thinner than this, then she will require some intervention of an extra few weeks dry and some supplementation also.

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If we take the example of a cow with a BCS of 2.5 who is due to calve in the first week of February, then she needs her holidays straight away.

First Calvers

John Phelan, Kilmeaden, Brendan Smiddy, Teagasc Cork East, Anne-Marie Butler, Ulster Bank, Donald Bateman, Cahir & Michael Gowen, Kilworth pictured at the launch of the Teagasc National Dairy Conference on ‘Technologies for Success’ which takes place in Rochestown, Cork on December 6 and Mullingar on December 7. Photo O'Gorman Photography
John Phelan, Kilmeaden, Brendan Smiddy, Teagasc Cork East, Anne-Marie Butler, Ulster Bank, Donald Bateman, Cahir & Michael Gowen, Kilworth pictured at the launch of the Teagasc National Dairy Conference on ‘Technologies for Success’ which takes place in Rochestown, Cork on December 6 and Mullingar on December 7. Photo O'Gorman Photography

She has only 13 weeks from today until calving, (assuming she is dried off immediately) but also needs to be fed 2kgs meal on the 68pc silage.

The other group that require special attention are the first calvers.

These heifers typically calve down at 90pc of their mature body weight and the only real opportunity they have to grow the further 10pc, is during the first winter after first calving.

To put on this extra weight they need three months dry, so if they are not dry already, then it is time to start tubing.

Regarding the use of dry cow tubes, special attention needs to be given to the milk withholding dates of the tubes you are using.

Some of the longer acting tubes last for 10 weeks in the udder and milk cannot enter the bulk tank until this period expires.

Coupled with this, the first few milkings after calving have to be kept out of the tank, with some tubes specifying that milk cannot enter the tanks for 156 hours after calving, which equates to 13 milkings.

If using any of these tubes, record keeping is vital to avoid any costly mistakes next spring.

Dry cows will also need mineral supplementation. Most of the trace elements and vitamins are included in standard minerals at the maximum legal limit.

The main difference between the better minerals and the average mineral is the inclusion rate of phosphorus and magnesium.

Ideally there should be 4pc phosphorus and 25pc magnesium, but if it does, it is going to cost more.

If you haven't analysed your silage yet, then it is time to do so now. Dry off thin cows and heifers straight away and start supplementing those that require it.

Joe Kelleher is a Teagasc dairy advisor based in Newcastle West, Co Limerick

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