Silage analysis shows good crops with lower protein

Protein is down on the year slightly, according to the analysis of 6,495 first- and second-cut silage samples by Trouw Nutrition GB.

Both crops are dry at 35-36.5% dry matter (DM), with crude protein about 14.4% and metabolisable energy (ME) just over 11MJ/kg of DM.

On the whole, samples are very similar to last year, says Liz Homer, ruminant technical development manager at Trouw.

“Farmers who managed to get on early and had little disruption from weather, by timing it right through good planning and a bit of luck, had excellent first cuts. Later first cuts have slightly higher NDF (neutral detergent fibre) and lignin, but lower crude protein and are generally drier crops,” she says.

“Although the averages don’t look too different, quality is much more variable in later first cuts.”

See also: How to profit from a forage-based dairy-beef system

Independent nutritionist Hefin Richards says variability across the country, and between farms, highlights the importance of assessing forage at individual farm level and working out how to utilise and maximise the silage available.

“On the whole, it has been a fantastic season and most people have enough good quality silage for the winter. There was a lot of concern at the end of May/early June when it was really dry, but luckily it rained and everything grew again,” he says.

“Anybody that hadn’t harvested before then may have seen some deterioration, but most had got first cut or two cuts in before that.

“An average is an average, but every farmer should be scrutinising their own results and if their silage is not consistently where it needs to be, then looking for opportunities to make better silage in 2021. If you’re making three to four cuts, that’s three to four opportunities to get it right.”

Protein supplementation

With silage analysis results showing protein is generally lower this year, farmers may need to look at the best available sources of protein for winter feeding.

One potential cause of the lower protein silages is the extended periods of rainfall and drought this year, which both hampered grass growth and had a big impact on cutting windows, nitrogen application timings and nitrogen uptake by plants, Dr Homer says.

“Where we have a drive within the industry for lower protein, we really need to think about the sources of protein to make sure we’re not hindering the animals.”

Once farmers have analysis results of their own silage, Dr Homer says it would be key to look at nutrients, rather than just the ingredients labels, and ask questions about how that protein source would complement their own silage.

Mr Richards says while protein is expensive relative to energy feeds, it should be fairly straightforward to achieve a balance.

Cost-effective solutions will be possible such as feeding a combination of cuts together, increasing the base level of the compound fed, including slightly more rapemeal or a higher protein blend.

“Key will be good feed-out management to maximise forage intake,” Mr Richards adds.

Grass silage analysis 2020

 

Early first cut

First cut

Second cut

Third cut

Wholecrop

Number of samples

660

3,733

1,724

378

379

DM (%)

35.5

36.5

35

34.8

38.7

Crude protein (%)

14.6

14.3

14.4

14.9

8.2

Digestibility value (%)

71.5

70.3

67.3

67

71.4

ME (MJ/kg of DM)

11.4

11.3

10.8

10.7

10.23

Lignin (g/kg of DM)

33.9

35.2

37.5

37.7

48.2

Acid load

49.5

48.5

45.8

46.6

44.8

Fibre index

176.9

180.1

191.1

186.2

170.9

Regional variation

Breaking the results down into regions revealed slightly different results:

Challenges across Great Britain

 

DM (%)

Crude Protein (%)

Neutral detergent fibre (% DM)

Dynamic energy (MJ/kg of DM)

 

Nutriopt fermentable energy protein balance (NFEPB) (g/kg of DM)

Scotland first cut

37.2

13.9

44.8

6.23

4.6

Scotland second cut

29.5

14.4

47.7

6.17

11.4

Wales first cut

37.2

15

44.6

6.19

14.6

Wales second cut

36.6

14.9

46.9

6.04

12.9

North England  first cut

37.3

14.4

45.1

6.16

9.3

North England second cut

34.2

14.1

47.7

6.01

7.7

Midlands and east England first cut

38.4

13.2

44.9

6.20

-2.5

Midlands and east England second cut

39.5

13.7

46.3

6.02

2.1

South England first cut

38.3

14.5

44.8

6.18

8.5

South England second cut

39.4

15.0

47

5.98

13.4

NOTE: NFEPB = the difference between the available rumen-degradable protein and the rumen-degradable protein required for maximum microbial protein synthesis, based on the available amount of fermentable carbohydrates. If the NFEPB figure is positive, the diet is high in protein; if NFEPB is negative, the diet is high in fermentable carbohydrate.

Other highlights from the analysis results

  • Generally, well-fermented crops were seen and clamps were fairly stable
  • Fermentable carbohydrate was very high in first cut and reduced in later cuts, which were more lignified
  • In first cut, the risk of acidosis was quite high with the fibre index low, but in second and third cuts, generally rumen health was not at risk
  • Wholecrop results showed starch to be 2% lower on average and NDF slightly lower on the year. There was a lower acid load, so this could potentially be fed alongside “fiery first cuts”.