Abstract
Abstract. Milk production, milk composition, milk fatty acid profiles, and antioxidant status of Simmental cows supplemented with non-protected sunflower oil were studied. Ten Simmental cows in mid-lactation were appointed for change over feeding trial with one of the diet applied: the control (WSO) diet consisted of 26 % corn silage, 33 % perennial ryegrass haylage, and 41 % concentrate in dry matter (DM), and the experimental diet (SO) consisted of control diet supplemented with 2 % of unrefined sunflower oil per cow and day. The cows were kept in indoor housing system with feeding and milking system two times daily and ad libitum water supply. The milk production and standard milk components remained unchanged during the study. The partial modification of fatty acid composition was remarked with the significantly higher linoleic and conjugated linoleic acid (CLA) (cis-9, trans-11 C 18:2) concentration and significantly lower palmitic acid during the SO treatment. The blood gluthathion peroxidase (GPx) activity significantly increased and the thiobarbituric acid reactive substances (TBARS) concentration decreased significantly in the SO treatment. The non-protected sunflower has a perceptible effect on the milk fatty acid composition in Simmental cows of our research. The lower index of lipid peroxidation and higher GPx activity in blood of cows during the SO treatment could be a consequence of the antioxidant components that are normally present in the unrefined vegetable oils. The enzyme activity reflects appropriate functioning of the antioxidant defence of cows that emphasise importance of well balanced diet during the unsaturated fatty acid supplementation.
Highlights
The fatty acid composition of milk in Holstein Friesian cows has been extensively studied in various nutritional trials with the aim to increase the proportion of some favourable fatty acids and decrease the unfavourable fatty acids in milk (GEISSLER et al 1994, LIEBETSEDER 1996, PRECHT and MOLKENTIN 1997, DHIMAN et al 1999, STANTON et al 2000, SECCHIARI et al 2003, REGO et al 2005)
The ingredients and chemical composition of the diet and fatty acid composition of sunflower oil are presented in Table 1 and Table 2
We had determined the changes in milk fatty acid profile
Summary
The fatty acid composition of milk in Holstein Friesian cows has been extensively studied in various nutritional trials with the aim to increase the proportion of some favourable fatty acids and decrease the unfavourable fatty acids in milk (GEISSLER et al 1994, LIEBETSEDER 1996, PRECHT and MOLKENTIN 1997, DHIMAN et al 1999, STANTON et al 2000, SECCHIARI et al 2003, REGO et al 2005). Less data are available concerning the Simmental cows’ fatty acid composition under the certain feeding conditions. The use of unprotected vegetable oils and whole grains in the dairy cows’ diet may have a limited effect on the fatty acids composition in ruminants. An increase in polyunsaturated fatty acids (PUFA) in the diet could possible change the pattern of rumen microbe metabolism, and change the fatty acid synthesis in milk and adipose tissue of ruminants (LIEBETSEDER 1996, SZUMACER-STRABEL et al 2001, HOLLO et al 2005, DANNENBERGER et al 2006). There are some concerns regarding the feeding PUFA to animals and possible lipid peroxidation consequences if the antioxidant elements are not sufficiently present in the organism. The effect of feeding regimes on lipid and on protein oxidation in dairy cows is still unknown. In order to produce high quality milk by animal diet manipulation, our objective was to identify possible effects of non-protected sunflower oil on the milk
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