June 19, 2013
Researchers at the Department of Environment and Primary Industries (DEPI) have found changing the type and form of supplements fed to grazing cows can allow them to produce more milk solids from similar amounts of energy offered.
In turn, higher fat and protein concentrations resulted in up to ten per cent higher cheese yields when tested in a CSIRO experimental cheese factory.
Senior Research Scientist at DEPI Ellinbank, Martin Auldist, said the three-year Higher Value Milk project, had focused on checking the manufacturing quality of milk produced under a range of different feeding systems.
The program was funded by the Gardiner Foundation, Dairy Australia and DEPI.
“We wanted to ensure any feeding strategies we might recommend were not adversely affecting the quality of milk,” Dr Auldist said.
“When high amounts of supplements need to be fed, we found that switching from traditional methods of slug feeding barley or wheat in the dairy to systems that pay more attention to the composition and form of the diet, there are benefits in both the yield and manufacturing quality of the milk.
“Feeding cows a ration containing maize grain and canola meal increased milk yield and also overcame the milk fat depression often observed when high amounts of cereal grain are fed.
“Higher milk fat concentrations were observed if the diet was fed as a mixed ration on a feedpad, or as a formulated grain mix using existing infrastructure in the dairy.”
Dr Auldist and his research team also observed higher protein concentrations in milk from cows consuming the maize and canola based ration, compared to those cows that consumed similar amounts of energy as wheat and pasture silage.
“Presumably the higher protein concentrations were related to higher pasture intakes. We consistently observe that cows consuming canola-based rations are more inclined to graze when they got back to their paddock”, he said.
“Although the exact mechanisms behind these responses are still unclear, it is partly related to the improved rumen environment that results from a more slowly digestible starch source (maize).
“Essentially, high amounts of wheat give the cows a form of indigestion but the maize and canola diet maintains rumen pH at a higher level. This leads to improved digestion and drives pasture intake.”
Testing showed milk from cows fed the formulated ration produced up to ten per cent more cheese per 100kg of milk than cows fed wheat in the dairy.
“This effect was noticed across a range of supplement intakes from eight to 16 kilos of dry matter per day,” Dr Auldist said.
“What’s more we had the cheese graded by professional cheese graders at Warrnambool Cheese and Butter, who found it to be of equally high quality.”
Overall these results, reveal the potential for specific form and composition of supplements to increase milk yield and the yield of dairy products, without increasing the amount of feed.
The results have been presented to the major dairy companies and a technical manual is being prepared for distribution to industry.