麻豆传媒

Organic Agriculture Centre of Canada
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Trevor DeVries specializes in the behavior of dairy cows, and is now applying his expertise听to organic dairies.
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DeVries was born in British Columbia, a province that is perhaps better known for its fruit production than its dairies. Nonetheless, B.C. is home to around 500 dairy farms, mostly found in the Fraser Valley, as well as in the B.C. Interior and on Vancouver Island. With a family connection to the dairy industry - the dairy farm owned by his grandfather is still operated by his extended family - it should come as no surprise that DeVries developed a keen interest in animal science that was complemented by University of British Columbia's (UBC) active dairy research program. There, his PhD thesis examined the effect of bunk feed management and design on the feeding and social behavior of dairy cows.

These days, DeVries focuses his research on the feeding behavior of dairy cattle, examining the effects of housing and nutrition management on cow behavior. To do so, he observes cows as they feed, noting things like the size of their meals, how fast they eat and what they sort out of their food, and then听explores how it all relates back to the cows' health, welfare and productivity. As an associate professor at the University of Guelph's Kemptville Campus, he also has other research projects that explore topics such as the interaction between housing, cow behavior and mastitis, or the "modern" topic of robotic milking.

DeVries is also involved in a research project that is a part of the Organic Science Cluster. When he became involved in the project "Assessment of health, welfare and milk composition on organic and conventional dairy farms", it was his first foray into research on dairy farms under organic management. The project involves measurements of animal welfare, milk quality, and mastitis rates in both conventional and organic dairy farms.

"There are not as many differences as people think there are," comments DeVries when invited to point out the differences between organic and conventional management systems. "We visited many farms for our project, and one of the biggest differences that I noted is the feeding practices. You have much more forage and use of pasture in organic systems, which can translate into lower production in those herds. There is also greater variability in the approaches to production under organic management. This might be related to limited options available to treat cows, and thus the greater need to prevent certain illnesses from happening," he adds.

DeVries also considers that lower productivity may be linked to genetics. "In conventional systems, the majority of producers utilize Holstein cows, which have been bred for higher production and intake capacity, but do not graze as well. They may be genetically geared to produce more than what they can actually consume on a ration higher in forage. In organic production, there tends to be a wider variety of breeds utilized. More research is needed with these other breeds to optimize production in these systems".

The observations made over the course of DeVries' Organic Science Cluster study suggest that in the spring, after the winter feeding period, conventionally-raised cows exhibit better body condition scores than their organically raised counterparts. However, body condition scores under both management systems were equivalent after the summer.

"In larger herds, cows are not tied up in stalls. They are housed in free stalls where they can exercise and walk around. I was surprised with the percentage of cows kept in tie stalls in organic systems," comments DeVries. He goes on to confirm that the dairy cattle Code of Practice for Care and Handling recommends providing opportunities for daily exercise. "This is definitely a good recommendation, but you need the appropriate environment," observes DeVries.

DeVries also recognizes that gentle handling matters in both systems. "Proper handling of dairy cattle is a trained skill that a lot of people could improve - it is an art and skill to know how the cattle react to your behavior, how to position your body so that you could effectively move and handle them without having to be forceful at all or aggressive."

While DeVries' animal welfare research under the umbrella of the Organic Science Cluster will soon be completed, data that will be used to assess the impact of management systems on milk quality are still being compiled. "There is a variability听in the incidence rate of mastitis in both systems, and we need to do further analysis to look at what might be specific in those systems that influence those incidence rates. The rates are similar, but are influenced by different factors" adds DeVries.

This livestock scientist, who appreciates drinking a cold glass of milk and likes trying different types of cheeses, feels that he can rest assured when he knows that the cows producing these tasty and nutritious products are happy, and is working to ensure that this is the case.
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This article was written by Nicole Boudreau, Organic Federation of Canada, on behalf of the OACC with funding provided by Canada鈥檚 Organic Science Cluster (a part of the Canadian Agri-Science Clusters Initiative of Agriculture and Agri-Food Canada's Growing Forward Policy Framework).听 The Organic Science Cluster is a collaborative effort led jointly by the OACC, the and industry partners. For more information: oacc@dal.ca or 902-893-7256.


Posted April 2013