…but CEDAR disagrees
THE benefits of feeding a high proportion of maize silage in dairy cow diets, proven at CEDAR, have also been seen on thousands of farms, according to the centres researcher Richard Phipps.
He claims that grass silage quality in his studies, which ran from 91 to 94, did not influence the results.
"The grass silage was well fermented – except in the first year when ensiling conditions were difficult and although the ammonia N content was high it was typical of that year," says Dr Phipps. "The next two years of the study used well fermented, reasonably good quality grass silage.
"Kingshay may not have used a high enough proportion of maize to establish the true benefits of a mixed forage diet including maize," says Dr Phipps.
In the CEDAR study it was found more beneficial to offer 66% maize silage in the forage than to feed 33% maize silage.
"The subsequent use on farms has seen forage intakes, milk yields and quality increase – and producers see these benefits in margins."
He adds that the Kingshay study had no grass silage control diet and milk recorded fortnightly so there would be a higher degree of error than at CEDAR where milk yields were recorded daily. Wolverhampton-based ADAS nutritionist Bruce Cottrill agrees that there is sufficient anecdotal evidence to suggest that in most situations the response to feeding maize is beneficial.
Often there is no increase in milk fat, but protein and yield increases. But he says that the use of maize must depend on the cost of producing each forage.
And it is also possible to get no response to feeding maize on farm, he says. The responses may be low in a year when grass silage is top quality and maize silage is poorer or the starch is high but its digestion poor.
"In the Kingshay study the high dry matter of the maize could have resulted in starch bypassing the rumen – so the cow was not making use of it," he says.
• No benefit replacing grass silage with over 20% maize.
• Contradicts CEDAR work.
• Whatever the forage, high quality will get the results.