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.
Mounchili
A
A
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
Wichtel
J J
JJ
Dohoo
I R
IR
Keefe
G P
GP
Halliday
L J
LJ
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