How much grass silage will maize replace?

By Alan Ryan B.Agr.Sc, TMR Area Sales Manager, Dairygold Agri Business

Maize silage yield varies year to year from lows of 18T (Tonne) per acre to highs of 25T per acre. This year maize is looking good so strong yields are expected.

Assuming maize silage yields 20T per acre and is 30% DM then every acre of maize has the potential to feed 6 cows over a 3 month winter.

The number of cows fed across the winter by differing areas of a 20T per acre crop of maize silage (assume maize is the only forage available):

Area		3 Months	4 Months	5 Months
10	acres	56	42	33
15	acres	83	63	50
20	acres	111	83	67
25	acres	139	104	83
30	acres	167	125	100
40	acres	222	167	133
50	acres	278	208	167

How does maize silage compare to grass silage?

	DM %	CP%	UFL
Maize Silage 33% starch	25-35	6-8	0.93
Maize Silage 30% starch	25-35	6-8	0.87
Maize Silage 25% starch	25-35	6-8	0.83
Grass silage 75 DMD	18-35	10-13	0.85
Grass silage 70 DMD	18-35	10-13	0.79
Grass silage 65 DMD	18-35	10-13	0.72

To get the best from your maize silage keep if for your freshly calved cows. It works well with grass silage when being fed 50:50 or as a buffer once cows go out to grass. As maize is lower in protein you will need to use higher protein balancer feeds.

Concentrates required by freshly calved cow’s milk 25ltrs on Maize silage and Grass silage:

Grass silage 65 DMD	8.5kg Post calver gold 18%
Grass silage 70 DMD	7kg Post calver gold 18%
50% Grass Silage (70 DMD) + 50% Maize silage (30% starch)	6kg Balancer gold 29%

Allows for 0.3 BCS loss in early lactation

Can I feed maize to my dry cows?

Yes, however you will have to feed straw to control energy intake and a high protein source like soya to ensure protein intake are adequate. This is a poor use of god quality maize compared to keeping it for your freshly calved cows.

Example diets for dry cows, dried off in a condition score of 3:

Grass Silage only		50% Grass silage + 50% Maize silage
	Kg Fresh		Kg Fresh
Grass silage (70 DMD)	40	Grass silage (70 DMD)	15
		Maize Silage (30% Starch)	12
		Straw	2
		Soya	1

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You have two options:

How much grass silage will maize replace?

How does maize silage compare to grass silage?

Concentrates required by freshly calved cow’s milk 25ltrs on Maize silage and Grass silage:

Can I feed maize to my dry cows?