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The two critical measures of silage


With a lot of dairy-beef animals now indoors, grass silage will contribute to a high proportion of the diet of animals over the course of the winter period. Balancing this silage with the correct quantity/quality of concentrate is key to achieving the desired levels of winter weight gain.

When it comes to silage, there are two critical measures - feed quantity and feed quality, Tommy Cox, DairyBeef 500 advisor discusses. Nationally, silage quality of around 65% dry matter digestibility (DMD) is the norm, this however, is not the case on the farms of the DairyBeef 500 participants. Calf-to-beef systems require superior quality silage, as animals have to perform at every stage of the production system. Given this, a strong emphasis on both making excellent quality silage and verifying its feed value is placed amongst the DairyBeef 500 farmers.

Silage analysis is currently ongoing on all DairyBeef 500 farms; the results to date are positive, with the majority of the silage testing with a DMD of 70 or greater. This is the type of silage that is required on these farms, otherwise high levels of concentrate supplementation will be needed.

Without completing a silage analysis, farmers are in the dark as to the quality of their winter feed. Completing silage analysis is critical to ensure that the nutritional requirements of stock are met and that the desired level of performance is achieved over the winter. Visual assessment alone is not adequate to determine silage quality. A laboratory test will provide accurate information on silage nutritive value and preservation and allow informed concentrate feeding decisions to be made. Table 1 gives the key parameters tested and the desired target in each area.

Silage samples must be taken carefully to ensure correct results. A period of 5-6 weeks should elapse between ensiling and sampling. A long core sampler should be used with 3-5 cores taken from well-spaced points on or between diagonals on the pit surface. Alternatively sample an open pit by taking nine grab samples in a ‘W’ pattern across the pit face. When testing bales, a number of samples from each batch are needed to get a representative sample.

Table 1: Key information provided from silage analysis 

Unit of measureMeaningLowHighQuality best when
Dry matter (%) Feedstuff less water content 13-17 40-55 Medium
pH Measure of acidity 3.4-3.7 4.5-5.5 Medium to low
Ammonia - N (% N) Indicator of grass N content at cutting 4-7 15-25 Low
NDF (% DM) Measure of forage fibre and intake potential 42-47 55-65 Moderate to low
DMD (%) Measure of quality 55-65 76-80 >72
ME (MJ/kg DM) Energy content (linked to DMD value) 8-9 11-12 High to moderate
UFV (unit/kg DM) Energy content (linked to DMD value) 0.6-0.7 0.89-0.96 High
Crude Protein (% DM) Measures N as an indicator of true protein content 7-9 15+ Moderate to high
Ash (% DM) Indicator of soil contamination 5-6 12-15 Low to moderate

 Feeding plan - Jarlath and Austin Ruane

Jarlath and Austin Ruane run a dairy calf to beef and lowland sheep system near Claremorris, Co. Mayo. The Ruanes are doing an excellent job in terms of silage quality. Last year, first cut silage on the farm was harvested on May 14 and resulted in a crop with a DMD of 76.7. A week delay in harvesting this year’s first cut has had an impact in terms of quality with a reduced, but still respectable, DMD of close to 72 achieved.

The feeding plan on the farm this winter is to provide weanlings and finishing animals with this high-quality, first-cut baled silage. Alongside this quality silage, weanlings will receive concentrates at a rate of 1/kg/head/day of a 16% protein ration. This will ensure that the target ADG of 0.6kg is reached over the housing period, while finishing stock will receive 5-6/kg/head/day of a 14% maize-based ration, with store cattle receiving 1/kg/head/day until Christmas.

Table 2: Guideline daily feeding rates based on silage quality (DMD)

Animal typeTarget ADG66 DMD68DMD70DMD72DMD74DMD76 DMD
Weanling 0.6kg/day 1.8kg 1.5kg 1.2kg 0.9kg 0.6kg 0.4kg
Finishing steer 1kg/day 7.0kg 6.0kg 5.5kg 5.0kg 4.0kg 4.0kg
Finishing heifer 0.9kg/day 7.0kg 6.0kg 5.5kg 5.0kg 4.0kg 4.0kg

Feed quantity 

The saying ‘you’re better looking at it than looking for it’ is particularly relevant to silage quantity. No matter how much silage one has in the yard, completing a fodder budget is a worthwhile task. Completing a fodder budget is a two-part process; it involves working out how much feed you have on your farm and working out how much feed you need. All farmers in the DairyBeef 500 Programme have completed a fodder budget using PastureBase Ireland, and the situation across the board is generally ok, with all having adequate levels of forage available on farm.

On a recent visit to Co. Clare farmer Michael Culhane, a fodder budget was completed. Inital results show that there are adequae levels of feed for the farm for the winter, but there is not a massive buffer available should the spring turnout be delayed. In total, the farm has a stockpile of 149.18t of dry matter silage, while the total winter demand is estimated at 142t of dry matter.

On farms where a fodder deficit is identified, it is imperative to act early to avoid a situation where silage stocks run out completely. There are two options available to farmers in a deficit situation - either reduce their demand or replace what is needed with alternative feed.

The options availabe for reducing demand on the farm include selling store cattle or putting finishing animals on stronger meal feeding levels to achieve an earlier finish.  There are also alternative feed options such as buying silage, ration or alternative forages, but these all come at a significant cost.

This article first appeared on Agriland, as part of the winter beef series.