Analyses of early harvested maize crops in the UK show good ruminant feed, says Trouw Nutrition GB after testing over 1,000 forage samples so far this year. However, a significant number of crops were harvested late, and so may present a nutritional challenge.
Trouw’s ruminant technical development manager Dr Liz Homer notes that early crops have produced a similar quality feed to the average recorded for 2014. “The average 2015 maize silage is 30.1% dry matter, 1.4% lower than last year, meaning that 0.7kg more freshweight will need to be fed to achieve a 5kg dry matter intake. The average ME score is higher this year at 11.6MJ, which is combined with marginally higher starch, lower NDF and lignin figures. Therefore, intake potential is virtually identical to last year too.
“Starch degradability is higher than last year, and is already as high as 2014/2015 whole season average,” she continues. “Degradability increases significantly with time in the clamp and, coupled with lower NDF content, means that farmers will need to balance the rapidly and total fermentable carbohydrate supply in the ration to reduce the risk of acidosis.”
Dr Homer says the early maize crops should support good levels of milk production provided they are well-balanced. But late harvested forages may be less digestible.
“Where late harvesting is linked to slow crop maturity, it is likely that overall starch levels will be increased as more sugars are converted to starch leading to a higher potential ME level, provided crops do not get over-ripe. However, if the stalk becomes increasingly lignified then the crop will have lower digestibility which will impact on both energy content and intakes.
“Where crops were harvested late due to the weather, increased lignification will be a serious risk and starch content may be diluted by a higher proportion of vegetative material in the crop,” she advises. “The other threat in this situation will be the increased risk of soil contamination which will make it difficult to achieve a stable fermentation.
As always, farmers should have their silage analysed for accurate feeding, as the averages mask a wide range of results, Dr Homer concludes. “With farmers looking to maximise contribution from forage and to ensure all litres are produced as efficiently as possible, maize silage will have a large role to play. Regular analysis of quality and close attention to diet formulation to maximise rumen health will be essential to exploit the potential this winter.
Early maize silage averages 2015-2016 (DM basis)
|2014/15 Season Average||2015 Early Season Averages|
|Intake Potential||g/kg 0.75||105||104.3|
|NH3-N\% Total N||\%||2.4||2.2|