Easier to chew maizes will help to drive up feed intakes

Christopher Chaine, representing maize breeding company RAGT, says the research team is concerned the energy value of maize is irrelevant unless it also has ‘intake appeal’.

“We have been experimenting to investigate this and have shown variety choice can have a significant effect on intake levels,” he says.

Trials using maize varieties from the same maturity class have seen intakes ranged between 13.9kg and 16.9kg per day. When samples were checked non-digestible fibre (NDF) levels were found to vary, partly explaining the difference.

But a further study where samples of different varieties were selected, all with the same NDF and starch contents, there was still a marked variation in intake levels.

“We believe about half the variation is down to NDF but the other half stems from the ‘friability’ of the plant tissues, which is their resistance to breakdown by chewing,” says Dr Chaine, explaining the lower the inherent resistance of larger particles to breakdown by chewing, the more easily forage is evacuated to the rumen, driving intake.

“It seems the biochemical determinants are polyphenolic compounds, which bind lignin, cellulose and hemicellulose in cell walls.”

RAGT scientists are working to find molecular markers for genetic friability, allowing plant breeders to select new lines with high intake potential early in the breeding programme.

“Taking NDF and improved friability together we believe we can add a further 3kg per day to the maize intake of dairy cows, which could make an appreciable difference to the cost of feeding regimes,” says Dr Chaine.

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