Abstract
ABSTRACTConjugated linoleic acids (CLAs) are fatty acids found in bovine milk which possess benefits for human health. This study aimed to compare fatty acid profiles, particularly CLA, of milk from grazing cows from south Chile receiving varying levels of concentrate. The study was conducted during spring of 2012 in two dairies from southern Chile. Dairy A was under low grazing intensity with high levels of concentrate (6–8 kg/cow/day); Dairy B combined low levels of concentrate (1–2 kg/cow/day) with more intensive grazing activity. Milk and blood samples were collected from 15 cows at each dairy at 30 days postpartum. Milk was analysed for fatty acid profiles, and blood for beta-hydroxybutyrate. Body condition score, parity, and daily milk yields were recorded. Pasture and concentrates were sampled for nutritional analysis. The proportion of CLA isomers in milk was 0.91% and 1.66% for Dairy A and Dairy B, respectively (p < .05). Dairy B had a lower ratio of saturated to unsaturated fatty acid and higher levels of omega-3 fatty acids than Dairy A. In conclusion, cows with increased grazing and low concentrate presented higher levels of CLA and omega-3 fatty acids than cows with less grazing and greater concentrate.
Highlights
Bovine milk represents an important source of nutrients rich in energy, high-quality protein, minerals, and vitamins for human nutrition (Gurbuz 2009)
The model for each fatty acid was corrected for body condition score (BCS), parity number (PN), MY, and BHB concentration at the time of sampling
No significant differences were observed between groups for total values of saturated fatty acids (SFAs), though palmitic acid (C 16:0) was higher in Group A
Summary
Bovine milk represents an important source of nutrients rich in energy, high-quality protein, minerals, and vitamins for human nutrition (Gurbuz 2009). Fat represents the greatest energy source provided by this milk, and fat composition is determined primarily by the nutritional composition of a cow’s diet (Bauman & Griinari 2003). Milk fat encompasses primarily saturated fatty acids (SFAs) (Jenkins et al 2008). Because of the relationship between SFA and cardiovascular disease, milk fat is considered a risk factor for human health. The presence of essential polyunsaturated fatty acids (PUFAs), monounsaturated fatty acids (MUFAs) and conjugated linoleic acid (CLA) has been associated with positive impacts on human health (Belury 2002; Benjamin et al 2015). CLA has been shown to possess hypocholesterolemic and anti-atherogenic properties (reducing the amount of cholesterol and low-density lipoprotein); to have an immunostimulant effect (increasing immune response by promoting T-cell proliferation and increasing the IgA secretion and macrophage function against certain cancers); and to have an antioxidant role and participate in the reduction of body weight by increasing lipolysis and reducing fat deposits in tissues (Benjamin et al 2015)
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