Evaluation of different dietary lipid supplements on oxidatively generated biomarkers in periparturient dairy goats

Evaluation of different dietary lipid supplements on oxidatively generated biomarkers in periparturient dairy goats. Bellagamba Federica1, Busetto Maria Letizia1, Caprino Fabio1, Invernizzi Guido1, Moretti Vittorio Maria1, Savoini Giovanni1. 1 Dipartimento di Scienze e Tecnologie Veterinarie per la Sicurezza Alimentare, Università degli Studi di Milano, Via Trentacoste 2, 20134 Milano, Italy The study of biomarker of oxidative stress in ruminant is a field of research recently explored [1]. Consequences of high-fat diet and lipid peroxidation on the health of ruminants and quality of their products have been considered and discussed [2]. This study aimed at analyzing the impact of different dietary lipid supplements on oxidative stress status in 26 periparturient Alpine dairy goats. At day 130 of gestation (about 20 days before kidding), goats, chosen homogeneous for parity and milk yield in previous lactation, were housed in single boxes and fed the same diet. Goats were divided in three experimental groups and assigned one of the identical experimental diets just differing in lipid sources: a dietary protected fish oil (FO) group, rich in n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFAs); a dietary calcium stearate (ST) group, rich in 16:0, 18:0 saturated fatty acids (SFAs) and a dietary control group (C), without any supplement. Experimental fatty acid enriched diets (FO and ST) were both formulated to administer 30 g/day and 50 g/day of fatty acid before and after kidding respectively. Blood samples (98 samples) were collected weekly starting from day 130 of gestation until 21 days of lactation; serum and plasma were obtained after sampling and stored at -80° C until the analysis. Analytical determination of malondialdehyde (MDA) by high performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA) assessment of 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodGuo) have been carried out in serum samples. Since the 8-oxodGuo derives after the ROS attack to DNA, this DNA-adduct is widely used as specific marker of oxidative damage. This DNA adduct can be measured in tissues, serum and urine and often used as prognostic factor in cancer lesions and degenerative diseases. MDA is the most abundant individual aldehyde resulting from lipid peroxidation and commonly employed in studies involving oxidative alteration of lipids. Gas chromatographic determination of plasma fatty acid has been also determined. The same sampling from animals fed without any supplements (C group) has been considered as control and analysed. Data were processed by analysis of variance (ANOVA) and values presented as mean  SEM. data were subjected to a Student–Newman–Keuls post hoc test for homogeneous subsets, and a P value of ≤ 0.05 was considered as significant. MDA and 8-oxodGuo resulted both highest in FO group (822.02±50.45 μmol ml-1 and 1.83±0.24 ng ml-1, respectively), and the 8-oxodGuo levels in serum from FO group were statistical different (P ≤ 0.05) from other groups. Dietary lipid supplements produced remarkable change in plasma fatty acid (expressed as g/100g total FAs) and particularly, n-3 LC-PUFAs, 20:5 n-3 (2.06 %), 22:5 n-3 (1.94 %) and 22:6 n-3 (1.61 %), in FO group resulted significant different (P ≤ 0.05) from ST and C groups. In ST group plasma 18:0 fatty acid was the highest value (19.20 %) and significant difference from FO (17.47 %) diet group. The n-6 LC-PUFAs (20:3 n-6; 20:4 n-6) as well as linoleic acid were not different at statistical level. MDA and 8-oxodGuo did not show any significant difference amongst different times of sampling; otherwise the interaction with sampling was evident on fatty acid of plasma, with a significant (P ≤ 0.05) increase of EPA (20:5 n-3, 3.9 %) and DHA (22:6 n-3, 2.25 %) in FO diet after 21 days of supplementation. Aiming to focus on metabolic variation of peripartum status, we analysed MDA and 8-oxodGuo in serum, as well as plasma fatty acid in samples from 2 until 7 days after kidding. The results did not produce any significance difference at statistical level, however the highest value of 8-oxodGuo was found just in peripartum period of goats receiving FO diet. The present study confirms that modification of dietary fatty acid composition derived from the utilisation of different dietary lipid sources in feed formulations can have appreciable impact on oxidative DNA damage also in ruminant specie and produce valuable variations of plasma fatty acid. Otherwise, no evidence of a significant increase of serum MDA concentrations has been verified. References [1] Celi P. Immunopharmacology and immunology (2011) 33(2): 233-240. [2] Durand D., Scislowski V, Gruffat D., Chilliard Y., Bauchart D. EAAP Pubblication (2005) 112:137-150, Wageningen Academic Publisher.