Abstract
Lipid peroxidation can be described as a process under which free radicals attack carbon double bonds of omega-3 and omega-6 fatty acids. Whereas the end products of this process are reactive aldehydes, such as malondialdehyde (MDA). Lipid peroxidation leads to adverse changes in the nutritional value of milk; therefore, higher degree of antioxidant protection (DAP) ensures higher stability of dairy products by effecting their high antioxidative potential. Therefore, the purpose of this study was to demonstrate the relationship between the DAP and the level of MDA in high-performance Polish Holstein-Friesian cows in peak of lactation. Sixty-three Polish Holstein-Friesian cows were selected to the experiment according to: parity (all in the 2nd lactation), phase of lactation (peak of lactation), cytological quality of milk (somatic cell count < 150 thousand/ml) and without diagnosed metabolic diseases. The data obtained were analyzed statistically by two–way ANOVA, and Tukey’s post-hoc test. After analysis of performance the cows were divided into 3 groups (twenty one cows in each group) based on milk yield and MDA concentration. The study revealed a significant effect of the lactation performance of cows on MDA levels in milk (P ≤ 0.01). The highest concentration of MDA (61.137 nM/mL) was shown in milk of cows yielding between 50.00 and 55.80 kg/day. The highest concentration of fat was found in milk in which the MDA level ranged from 48 to 86 nM/mL. Whereas, the inverse relationship was demonstrated in case of protein concentration. The highest level of protein was found in cows with MDA levels in the range of 18–28 nM/mL (P ≤ 0.01). The lowest MDA level (in the range of 18–28 nM/mL) was associated with the highest concentration of vitamin E, β-carotene, total antioxidant status (TAS) and DAP, measured in both milk and plasma. The obtained results show that lipid peroxidation leads to adverse changes in the nutritional value of milk; the highest DAP (7.89 x 10−3) was found in the cows with the lowest MDA concentration in milk.
Highlights
Lipid peroxidation is a biological lipid oxidation, chain and free radical process, that results in the formation of peroxides of omega-3 and omega-6 fatty acids
The increase in production should be viewed with concern because: the increase in milk yield has been accompanied by declining fertility, increasing locomotive and metabolic problems and declining longevity [32]
Cows producing large amounts of milk are more likely to be exposed to free radicals and to free radical peroxidation processes which result in MDA production [34]
Summary
Lipid peroxidation is a biological lipid oxidation, chain and free radical process, that results in the formation of peroxides of omega-3 and omega-6 fatty acids. This reaction consists of three stages: initiation, propagation, and termination; typical steps of free radical reactions and reinitiation. MDA modifies the physical structures of cell membranes and is indirectly involved in the synthesis of protein, DNA, and RNA. Ayala et al [5] reported, that the thiobarbituric acid (TBA) test is predicated upon the reactivity of TBA toward MDA to yield an red adduct; this test was first used to demonstrate autoxidative degradation of fats
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