title: Changes in milk oxidative stress biomarkers in lactating dairy cows with ovulatory and an-ovulatory oestrous cycles.
abstract: This study was conducted to evaluate changes in milk profiles of oxidative stress (OS) biomarkers in dairy cows with ovulatory and an-ovulatory oestrous cycles. Thirty healthy, cycling Holstein cows averaging 60±17 days in milk, and producing 33±6kg of milk per day (the week before commencing the study) were enrolled in this study. Composite milk samples were collected thrice weekly and assayed for the following OS biomarkers: lipoperoxides (LPO), biological advanced potential, superoxide dismutase (SOD), advanced oxidation protein products (AOPP), ceruloplasmin, glutathione (GSH), β-carotene and glutathione peroxidase (GSH-Px). Milk samples were also tested for fat and protein composition and the fat:protein ratio (FPR) was categorized as low (≤1.31), medium (1.32-1.56) and high (>1.57) to evaluate their main effect and the interaction effect of FPR and the week of study on OS using linear mixed models with cow identification being a random factor. Cows with ovulatory oestrous cycles (n=20) presented significantly greater SOD levels than cows that did not ovulate ((n=10; P<0.05). On the other hand, LPO, GSH-Px and GSH concentrations were lower in ovulated cows compared to the an-ovulated cows (P<0.05). The highest level of LPO and AOPP were noted at prooestrus phase while β-carotene presented the lowest value at that phase of oestrous cycle. It could be postulated that the elevated level of milk SOD and the observed lower level of LPO, GSH-Px and GSH in ovulating cows may be an essential event preceding the ovulatory response.
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia. Electronic address: stal8977@uni.sydney.edu.au.
authors.forename: S
authors.initials: S
authors.lastname: Talukder
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia.
authors.forename: K L
authors.initials: KL
authors.lastname: Kerrisk
authors.affiliation: Dipartimento di Biomedicina Comparata e Alimentazione, Università 'di Padova, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Gabai
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Fukutomi
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia.
authors.forename: P
authors.initials: P
authors.lastname: Celi
mesh_terms: D000818:Animals; D015415:Biomarkers; D002417:Cattle / Q000502:physiology*; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D007774:Lactation / Q000502:physiology*; D008892:Milk / Q000737:chemistry*; D010060:Ovulation / Q000502:physiology*; D018384:Oxidative Stress / Q000502:physiology*; D011374:Progesterone / Q000737:chemistry / Q000378:metabolism
chemical_list: D015415:Biomarkers; D011374:Progesterone
keywords: Dairy cow; Milk; Ovulation; Oxidative stress biomarker; Progesterone