The Milk Producer - July 2012 - (Page 34)

RESEARCH By Natalie Osborne Sorting out the issue Researchers pick apart what factors contribute to cows sorting their feed S imple tweaks to your feed ration could help reduce your cows’ sorting behaviours, improve their health and boost your bottom line. Animal and poultry science professor Trevor DeVries and his team have found carefully balanced feed ration benefits are lost if dairy cows selectively eat more of certain components, such as grains, rather than forage particles. This common feed sorting behaviour can compromise your cows’ health and milk production. The researchers are examining factors on Ontario dairy farms that contribute to cows sorting feed. They’re looking at everything from housing and management practices to how feed moisture content can influence how and what an animal chooses to eat. “Producers spend a lot of time and money trying to provide a perfectly balanced diet,” says DeVries. “But cows don’t always eat what we expect them to, and this can lead to significant variations in milk production.” Even a total mixed ration, which contains various feed components in a relatively uniform mixture, can be subject to sorting. Cows prefer eating tastier, highly fermentable grain components instead of longer forage particles that contain fibre to aid in healthy rumen fermentation. This nutrition imbalance can lead to metabolic problems such as subacute ruminal acidosis. In previous research, DeVries found cows that ate fewer forage particles had a lower rumen pH, increasing their risk of developing SARA. Researchers are taking a closer look at sorting’s effects on milk composition. In two separate, recent studies DeVries and his group determined that butterfat dropped an average of 34 | July 2012 | MilkPRODUCER 0.15 percentage points—for example, from 3.95 to 3.80 per cent—for every 10 per cent refusal of long forage particles. He believes cows that ate fewer forage particles ruminated less, contributing to lower rumen pH and lower milk fat production. Adding water to feed mixtures that Providing TMR more than once daily can reduce sorting. contain more than 60 per cent dry matter, particularly those containing dry forages such as hay or straw, can also effectively reduce sorting behaviour. However, the opposite is true for other mixtures containing only wet forages, including alfalfa haylage and corn silage. In those cases, adding water increased preferential grain product selection. Researchers believe very wet rations, combined with hot summer temperatures, can cause feed stored in silos to ferment. These forage particles would be less appealing to cows and could encourage sorting behaviour. “Liquid feeds may be more helpful,” says DeVries. “We found adding a molasses-based liquid feed supplement to wet rations reduces sorting. The sticky molasses helps bind grain and forage particles together, and it’s also high in sugar so it provides a tasty source of energy for cows.” Feeding management may also be a factor. Previous studies by DeVries and other researchers have shown providing TMR more than once a day will reduce feed sorting. This may be particularly important when providing wetter rations during hotter weather. DeVries and his group are studying commercial freestall farms in eastern Ontario to determine what effects housing styles, management practices and nutritional factors have on sorting behaviour, production and overall herd efficiency. They’re looking at variables, including TMR compositions, how often feed is provided, how frequently it’s pushed up and what time of day animals are fed. Other factors, such as stall stocking density, barn temperature and available feed bunk space, are also being considered. DeVries and his team want to understand how these different factors interact to promote or reduce feed sorting. Natalie Osborne is a student writer with the University of Guelph’s office of research. Collaborators include animal and poultry science professor Brian McBride, Dr. Karen Beauchemin of Agriculture and Agri-Food Canada and Masahito Oba, agriculture, food and nutritional science professor, University of Alberta. Funding for this research is provided by Dairy Farmers of Canada, the Canadian Dairy Commission and Agriculture and Agri-Food Canada. Liquid Feeds International Ltd. and the Ontario Ministry of Agriculture, Food and Rural Affairs provided additional support.

Table of Contents for the Digital Edition of The Milk Producer - July 2012

The Milk Producer - July 2012
Contents
Editor's Notes
DFO Chair's Message
Dairy Update
Farm Finance
DFC Promotion
Producer Profile
Research
Applied Science
Ruminations
Markets
New 'N' Noted
Back Forty

The Milk Producer - July 2012