Risk factors for milk off-flavours in dairy herds from Prince Edward Island, Canada.
A sudden increase in the incidence of milk off-flavours in bulk tank milk from Prince Edward Island (Canada) dairy farms in the late 1990s prompted an investigation of potential herd-level risk factors. A prospective case-control study was conducted from 2000 to 2002. Data on herd management were obtained by questionnaire and field investigation from all the 62 identified off-flavour positive farms (cases) and 62 loosely matched (for data-collection convenience) off-flavour negative farms (controls). Forty-three of the 62 cases (69%) of milk off-flavours identified during the study period were classified as "transmitted" (feed) off-flavours, and 9 (15%), 6 (10%), and 4 (6%) as "rancid", "oxidized" and "malty" off-flavours, respectively. Given this evidence and the relatively low incidence of other flavour defects in milk, only transmitted-flavour cases were considered in the analyses of risk factors. Poor air quality in the lactating cows' barn (OR = 40.8), using baled silage as the main forage (OR = 10.6), as well as feeding roughage before milking (OR = 253.3) or as a free choice (OR = 3.2) all were significantly (P < 0.05) associated with the incidence of transmitted flavours in bulk-tank milk. Clipping the hair on the cows' udder (OR = 0.07) and changing the bedding material more than once a day (OR = 0.12) were protective. The finding about feeding baled silage before milking has raised hypotheses about silage composition (in particular the off-flavour compounds or their precursors) and also about the process of silage making itself.
Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3. amounchili@upei.ca
A
A
Mounchili
J J
JJ
Wichtel
I R
IR
Dohoo
G P
GP
Keefe
L J
LJ
Halliday
D000821:Animal Feed; D000818:Animals; D016022:Case-Control Studies; D002417:Cattle; D003612:Dairying; D005260:Female; D015994:Incidence; D008414:Mastitis, Bovine / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D008892:Milk / Q000502:physiology*; D009812:Odorants; D011325:Prince Edward Island / Q000453:epidemiology; D011446:Prospective Studies; D012307:Risk Factors; D012621:Seasons; D012820:Silage; D011795:Surveys and Questionnaires; D013649:Taste