Tractor trailer emptying harvested maize© Juice/REX/Shutterstock

Initial analysis of maize silage suggests that it may not provide the immediate boost to production that many farmers are looking for.

Analysis of 600 samples taken this year by Trouw Nutrition shows that ME content is lower on the year.

While 2016 samples are much drier at 34.4% compared to 30.2% last year, the ME content is lower at 11.4MJ/kgDM (11.6MJ in 2015).

More concerning, only 31% of samples have an ME over 11.5MJ compared to 57% last year.

Trouw Nutrition GB Ruminant Specialist Tom Goatman says that many of the differences between maize harvested this year and last year can be attributed to substantially different growing seasons.

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“Last year, farmers delayed harvest in the hope that crops would eventually mature with many maturing at least two weeks later than expected. They were then hit with very wet weather, which made harvest a lottery,” he comments.

“This year, favourable growing conditions and an atypically warm September meant crops matured quicker, while the driest October for 65 years made for harvesting in near perfect conditions. However, this has implications for feed value and likely performance in the diet.”

Mr Goatman says the lower ME is partly due to lower starch content, which is a reflection of the more mature crops.

“The other factor influencing lower ME is the reduced digestibility of the vegetative parts of the plant, meaning less energy is available from the stem and leaves. NDF digestibility in the rumen is down from 61.1% in 2015 to 57.3% this year, an indication of overall plant maturity.”

What this means for cow performance

Mr Goatman explains that lower starch degradability and higher bypass starch, combined with the reduction in NDF digestibility, mean less carbohydrate energy will be available for rumen fermentation.

“When formulating diets in the early winter, farmers may not see the usual boost that maize gives to production because of the change in starch content and the impact on rumen fermentation.”

Mr Goatman suggests increasing the supply of rapidly fermented carbohydrates available from other sources, such as wheat, to ensure the diet provides sufficient quickly available energy to support effective microbial and rumen function.

He says these sources can be trimmed back later as starch degradability in maize improves to reduce diet costs.

“As maize matures in the clamp and starch degradability increases, so production from maize should increase. It will be vital to analyse clamps regularly to exploit the benefit of improved feed potential.”

On a positive note, Mr Goatman says the reduced starch degradability will help improve rumen health. 

“Lower starch degradability and reduced NDF digestibility mean less carbohydrate will be available for rumen fermentation. This, coupled with the increased dry matter content and lower lactic acid content, mean that this year’s maize has significantly lower acid load. This, combined with a higher fibre index will help support good rumen health and function.”

Early maize silage analysis (source TNGB)

 

2015

2016

Dry matter (%)

30.2

34.4

Crude protein (%)

7.9

7.3

D Value (%)

73.2

72.0

ME (MJ/kgDM)

11.6

11.4

pH

4.0

4.0

Starch (%)

31.1

30.7

Starch degradability (%)

79.4

76.8

Bypass starch (g/kg)

62.8

71.7

NDF (%)

39.2

40.0

NDF digestibility (%)

61.1

57.3

Lactic acid (g/kg)

52.9

31.7

Intake potential (g/kgML)

104.5

108.5

Acid load

49.1

41.1

Fibre Index

142.4

146.0