Thesis submitted in fulfilment of the requirements for the degree of Magister Technologiae: Agriculture in the Faculty of Applied Sciences at the Cape Peninsula University of Technology / Conjugated linoleic acid (CLA), a fatty acid (FA) present in the meat and milk of ruminant
animals, is considered a functional nutrient for humans. The interest in CLA is attributed to its
many health benefits, such as having anti-carcinogenic, anti-atherogenic, anti-diabetic and
anti-adipogenic effects. Dairy products are a rich natural source of CLA, and preliminary
research indicates that the levels in milk can vary based on cattle breed and feeding system.
The Fleckvieh is a popular dual-purpose breed recently introduced to the Western Cape. It is
used in crossbreeding programs with Holstein and Jersey herds to increase fertility and beef
production. Holstein and Jersey cattle are the two most common South African dairy breeds,
but little information is available on the effect of crossbreeding on FA content and CLA levels
in the milk. The primary objective of this study was to compare milk FA composition and CLA
content of these two dairy breeds and their respective Fleckvieh crosses. A second objective
was to investigate the effect of lactation stage on CLA levels. Jersey (J) and Fleckvieh x
Jersey (F×J) cows were kept in a pasture-based system (PBS) for the duration of the study.
Holstein (H) and Fleckvieh x Holstein (F×H) cows were housed in a feedlot system and fed a
total mixed ration (TMR) for the duration of the study. The FA and CLA content of feeds from
these two feeding systems were also analysed and compared. All cows used in the study
were housed at the Elsenburg Research Farm of the Western Cape Department of
Agriculture.
Milk samples were collected every 35 days from the cows in each feeding group, starting 10
days after calving. Samples were kept in a freezer at -20 °C until laboratory analyses. The
total number of milk samples collected was 1044. The milk FA composition and CLA in
particular were determined by gas chromatography. Differences between groups were
statistically analysed by two-way repeated measures of analysis of variance (ANOVA).
Results show that milk CLA levels are higher in Fleckvieh-crossbred cows when compared to
purebred cows. The higher CLA content of milk from Fleckvieh crossbred cows demonstrates
the feasibility of using Fleckvieh bulls in South African crossbreeding programs, and are also
an indication that genetic selection for increased CLA content is possible. The analysis of
lactation stage showed that milk CLA is higher during late lactation. A comparison of feed
samples from the two feeding systems revealed that pasture feeding resulted in higher
omega-3 FA in milk.
Key words: Conjugated linoleic acid, milk fatty acids profile, diet, breed, health benefits,
Fleckvieh, Holstein, Jersey, diet, pasture based system, total mixed ration system,
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:cput/oai:localhost:20.500.11838/2004 |
| Date | January 2015 |
| Creators | Sasanti, Babalwa |
| Contributors | Schmulian, A., Muller, C.J.C., Dr, Abel, S., Dr |
| Publisher | Cape Peninsula University of Technology |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | http://creativecommons.org/licenses/by-nc-sa/3.0/za/ |
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