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DIMCONC (d)
CVUFA (%)
MILK FAT SATURATION AND REPRODUCTIVE PERFORMANCE IN DAIRY CATTLE
DISCUSSION
The aim of this study was to detect associations between fertility parameters in
dairy cows and the level of UFA in bulk tank samples as a proxy for the dietary fatty acid
profile on that herd. Milk fat typically contains about 30% UFA, of which the main
proportion are 18:1 FA (20-30%), followed by 16:1 and 18:2, both representing about 1-
3% of FA (Jensen, 2002). There is considerable interest in increasing the UFA as it
contains more saturated FA compared to plant oils which could harm long-term health
of consumers (Dewhurst et al., 2006). The level of UFA is affected by animal factors such
as breed (Soyeurt et al., 2006; Schennink et al., 2008), stage of lactation and parity
(Kelsey et al., 2003), subclinical mastitis (Auldist et al., 1996) but the largest variation is
accounted for by ruminant nutrition as reviewed by many (e.g. Glasser et al., 2008;
Schmidely et al., 2008).
147.5
145.0
142.5
140.0
137.5
135.0
132.5
130.0
5
6
7
127.5
8
125.0
30 30.5 31 31.5
UFA (%)
Figure 5. The effect of the percentage of unsaturated fatty acids in the bulk tank (UFA), its coefficient of
variation (CVUFA), and the interaction between both on days in milk to conception (DIMCONC) based on
8247 first inseminations on 90 Belgian herds in 2008 and 2009.
In Belgium over the last decade, producers have been encouraged by dairy
industries to produce milk with a more unsaturated FA profile, mainly by feeding
extruded linseed. As herds participating in this specific project were paid depending on
the UFA content of the bulk tank milk samples, UFA content was determined
continuously on all Flemish herds providing the possibility to link UFA to herd fertility
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