Feeding maize silage is not the key to producing ‘healthier’ milk
Take Home Message: Feeding maize silage will increase intake and milk output, but has little effect on milk fatty acid composition
Despite some beneficial changes associated with the replacement of grass silage with maize silage, the overall effects on milk fatty acid composition would not be expected to substantially improve long-term human health.
That was just one of the findings of a trial work, carried out by scientists in England and Finland, to discover the effect of replacing grass silage (GS) with maize silage (MS) as part of a total mixed ration on animal performance and milk FA composition.
“We also found that the role of forages on milk fat composition must also be balanced against the increases in total milk and protein yield on diets containing higher proportions of maize silage,” said Reading University’s research assistant Kirsty Kliem.
“Even though extensive research has examined the role of nutrition on milk fat composition, there is less information on the impact of forages on milk fatty acid (FA) composition,” she said, explaining the rationale behind the study.
Eight multiparous mid-lactation cows were used in the trial, which comprised four treatments that fed stepwise replacement of GS with MS (0, 160, 334 and 500g/kgDM) in diets containing a 54:46 forage-to-concentrate ratio on a DM basis.
And the team found that replacing GS with MS increased the DM intake, milk yield and milk protein content.
“Among other findings, we discovered that incremental replacement of GS with MS in the diet enhanced linearly the proportions of fatty acid intake, decreased the concentrations of fatty acid 16:0, but had no effect on the total milk fat saturated fatty acid content,” said Ms Kliem.
“Inclusion of MS altered the distribution of trans-18:1 isomers and enhanced total trans monounsaturated fatty acid and total conjugated linoleic acid content.
“And milk total n-3 polyunsaturated fatty acid (PUFA) content decreased with higher amounts of MS in the diet and n-6 PUFA concentration increased, leading to an elevated n-6:n-3 PUFA ratio,” she added.
Download_paper (pdf)
Full details: Kliem KE, Morgan R, Humphries DJ, Shingfield KJ and Givens DI: “Effect of replacing grass silage with maize silage in the diet on bovine milk fatty acid composition.” Animal 2: 1850-1858.
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