Better grass quality will allow sheep farmers to cut back on creep feed this autumn

Sheep farmers should maximise growth rates from the higher-than-expected nutritional value of grass when planning diets for fattening lambs this autumn.

The seasonal dip in the nutritional value of grazing has not been as severe as witnessed in previous years.

“By late August, producers would usually expect pasture to undergo a noticeable seasonal dip in digestibility and palatability,” says David Thornton, Rumenco technical manager.

“But in contrast, last week’s fresh grass samples were analysed (see “Fresh grass analysis”) and have identified grass quality to be greater than expected for this time of year,” he says.

“Interestingly, samples from both permanent pasture and two-year-old seed ley both returned high levels of metabolisable energy and sugar, with D-values of more than 77% and a reasonable result for crude protein.”

Fresh grass analysis (week commencing 18 August)

Permanent pasture

Two-year grass ley

Dry matter (%)

16.7

18.4

Crude protein (%)

21.8

18.4

D-value (%)

77.3

80.1

Metabolisable energy (MJ/kg)

12.4

12.8

Sugar (g/kg)

186

192

For lamb producers, these results are promising and may provide alternative options for grazing as autumn approaches. “Maintaining a predominantly grass-based diet is important to maximise feed utilisation, especially when we are experiencing such a reliable growing season.”

The grass analysis results may come as no surprise to some producers who have already reported tremendous lamb growth rates of up to 300g/day this season, with lambs being two to three weeks ahead of this time last year.

“As encouraging as the results are, it is imperative that producers continue to assess the quality of grazing moving forwards,” says Mr Thornton.

“It is vital to determine the need and correct timing to supplement lambs to manage and sustain dietary intake levels and maintain growth rates.

“With the quality of grazing being so high, farmers may be reluctant to supplement diets. But to sustain growth rates and avoid losing the benefits of the season it is likely they will have to support and enhance the nutritional value of grass-based diets.”

The traditional weaning check should also be taken into consideration, too, he says. “This can have a further detrimental effect on growth rates being achieved. Managing this through supplementation is one way of mitigating any further performance impacts.”

Feed blocks

Using block nutrition this autumn will not only enable producers to make the most of grazing, it will also maximise intakes of energy, protein and micro-nutrition, which will benefit lamb development without removing the lamb’s capacity to graze.

Mr Thornton recommends supplementing lambs with a block that provides 12.5 MJ of metabolisable energy and 18% protein. “Blocks can also replace the nutrition the lambs get from the ewe’s milk post-weaning.”

Creep feed

Creep feed provides an alternative method to supplement lambs, he explains.

“Supplementing grass-based diets with creep feed may ensure a measured intake and allow for higher stocking densities.”

However, Mr Thornton reminds farmers that with the quality of grazing above what would be expected this year, sheep farmers should seek to maximise this resource.

Conversely, block nutrition provides supplementation that supports the digestive capacity of the rumen, which remains relatively small as lambs continue to develop, while still providing the additional nutrition required.

Trials performed in the east of England have collated data in support of this. The finishing capacity of 200 cross-bred store lambs was monitored to compare the performance of lambs finished on ad-lib stubble turnips and grass, with lambs finished on ad-lib stubble turnips and grass with free access to Rumevite Quality Lamb Blocks.

Results of the trial have proven that lambs supplemented with this block finished, on average, 38 days quicker than lambs reared on grass-only diets, and achieved an average daily liveweight gain of 189g – 95g/day more than finishing on forage only.

“The results of this trial are extremely promising and illustrate how supplementing lambs effectively can have a significant effect on lamb growth rates.

“Maximising the grazing resource this season will benefit lamb performance and winter feeding regimes. Using block nutrition will prove a cost-effective and efficient way to support the performance of finishing lambs and maintain early impressive growth rates.”