Un­der­stand­ing silage test re­sults

Irish Examiner - Farming - - AGRI ADVERTISING FEATURE - Daniel Hes­sion

Silage anal­y­sis is a vi­tal part of for­mu­lat­ing ru­mi­nant di­ets and is money well spent.

Test­ing your silage will give you in­for­ma­tion on the dry mat­ter, how well it is en­siled and prob­a­bly most im­por­tantly the feed­ing value.

Hav­ing your silage tested is one thing but you need to be able to un­der­stand the re­sults. Below is a de­scrip­tion of some of the com­mon terms that ap­pear on a silage test re­port.

Dry mat­ter DM%

Most for­age anal­y­sis re­sults are ex­pressed on a dry mat­ter ba­sis. This fig­ure re­lates to how much water is present in the silage. The silage dry mat­ter is also im­por­tant when as­sess­ing preser­va­tion qual­ity and pre­dict­ing in­take. Ide­ally the dry mat­ter of pit silage and baled silage should be around 25 – 30%. Once the dry mat­ter goes above this it makes it harder to en­sile and it is also prone to moulds and spoil­ing once it is fed out. Higher dry mat­ter will lead to higher in­take.


Sat­is­fac­tory ph val­ues will vary with the DM of the silage. Un­wilted silages should ide­ally have a ph be­tween 3.8 and 4.2. ph val­ues of 4.2 up to 5.0 may be ac­cept­able for wilted silages. Low ph below 4 will have low palata­bil­ity and an­i­mal in­takes will also be low.


The DMD is an ac­cu­rate and re­li­able test of for­age feed­ing value. The DMD re­sult is used to es­ti­mate the en­ergy of the silage as well as ex­pected liveweight gains and milk yields and also al­lows for cal­cu­la­tion of sup­ple­men­ta­tion rates.

Crude Pro­tein %

Crude pro­tein varies gen­er­ally from 9 to 17%. The leafier the grass was at cut­ting the higher the pro­tein % should be.


This is the amount of avail­able en­ergy that is in the feed. Like pro­tein the en­ergy value of the silage should be higher the ear­lier it was cut. Val­ues range from 9 MJ ME/ kg DM for headed out grass to 12 MJ Me/kg DM for leafy grass.

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