Oxidative status during late pregnancy and early lactation in dairy cows

Serum antioxidant enzyme activities and oxidative stress parameters as possible biomarkers of exposure in veal calves illegally treated with dexamethasone

Low doses of the synthetic glucocorticoid dexamethasone (DEX) are often illegally used, alone or in association with steroids and beta-agonists, to improve meat performances in cattle. As it is known that oestrogens and beta-agonists may generate reactive oxygen species (ROS) and induce oxidative stress, the effects of illicit DEX protocols on the antioxidant status and oxidative stress parameters were measured in veal calves. Ten cross-bred male veal calves were given DEX (0.4mg/day administered per os, for 23days or 2mg pro capite, injected intramuscularly on days 14 and 21 after the beginning of the oral DEX administration). Five further animals were used as controls. Blood samples were withdrawn before (T(0)), and 4 (T(1)), 10 (T(2)), 14 (T(3)), 21 (T(4)) and 28 (T(5)) days. Antioxidant enzyme activities (AOEs), the serum antioxidant capacity (SAC) and ROS were measured in sera. Calves orally treated showed a significant increase of both glutathione peroxidase isoforms (P<0.05) and SAC (P<0.05), too. Antioxidant enzymes have already been used as biomarkers (BMs) of response, measured in target or in surrogate tissues. Our results suggest glutathione peroxidase and SAC as possible BMs of illicit oral low-dose administration of DEX in cattle.

Effects of age and reproductive stage on certain serum biochemical parameters of chios sheep under greek rearing conditions

The aim of the present study was to determine the normal ranges of the most commonly used serum biochemical parameters of sheep reared under Greek breeding conditions, as well as to test for the effects of the age and reproductive status of the animals on the normal values of these parameters. In total, 200 clinically healthy Chios sheep from 10 farms were used in the experiment. For the determination of the effect of age 150 sheep were assigned in three groups. Group A consisting of 50 lambs aged 2-6 months (mean +/- SD: 4.15 +/- 1.08), group B of 50 non-pregnant ewes into lactation aged 1-3 years (mean +/- SD: 2.12 +/- 0.86) and group C of 50 non-pregnant ewes into lactation aged more than 3 years (mean +/- SD: 5.98 +/- 1.66). For evaluating the effect of reproductive status 50 pregnant ewes in dry period were used, 15-30 days before the expected day of lambing (group D), along with the 100 non-pregnant ewes into lactation of groups B and C (group E). Blood sampling was performed once, in dry ewes from December to January, and in lambs and lactating ewes from March to May. The results showed that of the 14 biochemical parameters determined in serum, six were significantly affected by the age and eight by the reproductive stage of the animals.

Relationship of body condition score and oxidant stress to tumor necrosis factor expression in dairy cattle

The relationship between body condition score (BCS) with measures of oxidative status and TNF-alpha production was examined in 16 mid-lactation dairy cows. Cows were selected based on either a normal (2.5-2.7) or a high (> or =3.5) BCS using the standard five-point scaling system. The metabolic status of all cows was determined by plasma nonesterified fatty acid levels (NEFA). Plasma samples or white blood cell lysates also were analyzed for indices of oxidant stress and for the expression of TNF-alpha. Cows with a high BCS had significantly lower NEFA levels when compared to normal BCS cows and the over-conditioned animals were not in a state of negative energy balance. No significant changes in lipid hydroperoxide levels, glutathione peroxidase activity, or the ratio of reduced (GSH) to oxidized (GSSG) glutathione was detected with respect to BCS. However, high BCS cows did have a significantly lower overall antioxidant potential and reduced TrxR activities when compared with the normal BCS cows. Changes in the oxidative state of over-conditioned cows were accompanied by a significantly higher expression of TNF-alpha. Results from this study suggest that cows with a high BCS can experience oxidant stress in the absence of altered energy status. Increased TNF-alpha expression may be related to the pro-oxidant state of over-conditioned cows and possibly be a contributing factor to the enhanced susceptibility to disease in high BCS dairy cattle.

BOARD-INVITED REVIEW: Intrauterine growth retardation: Implications for the animal sciences1

Intrauterine growth retardation (IUGR), defined as impaired growth and development of the mammalian embryo/fetus or its organs during pregnancy, is a major concern in domestic animal production. Fetal growth restriction reduces neonatal survival, has a permanent stunting effect on postnatal growth and the efficiency of feed/forage utilization in offspring, negatively affects whole body composition and meat quality, and impairs long-term health and athletic performance. Knowledge of the underlying mechanisms has important implications for the prevention of IUGR and is crucial for enhancing the efficiency of livestock production and animal health. Fetal growth within the uterus is a complex biological event influenced by genetic, epigenetic, and environmental factors, as well as maternal maturity. These factors impact on the size and functional capacity of the placenta, uteroplacental blood flows, transfer of nutrients and oxygen from mother to fetus, conceptus nutrient availability, the endocrine milieu, and metabolic pathways. Alterations in fetal nutrition and endocrine status may result in developmental adaptations that permanently change the structure, physiology, metabolism, and postnatal growth of the offspring. Impaired placental syntheses of nitric oxide (a major vasodilator and angiogenic factor) and polyamines (key regulators of DNA and protein synthesis) may provide a unified explanation for the etiology of IUGR in response to maternal undernutrition and overnutrition. There is growing evidence that maternal nutritional status can alter the epigenetic state (stable alterations of gene expression through DNA methylation and histone modifications) of the fetal genome. This may provide a molecular mechanism for the role of maternal nutrition on fetal programming and genomic imprinting. Innovative interdisciplinary research in the areas of nutrition, reproductive physiology, and vascular biology will play an important role in designing the next generation of nutrient-balanced gestation diets and developing new tools for livestock management that will enhance the efficiency of animal production and improve animal well being.

Oxidants and antioxidants in disease: oxidative stress in farm animals

Important infectious diseases in farm animals, such as pneumonia and enteritis, are thought to be associated with the so-called oxidative stress, i.e. a chemical phenomenon involving an imbalance in the redox status of the individual animal. The specifics of oxidative stress and how it may result in disease or be prevented are complex questions with no simple answers. However, the considerable literature on the subject suggests that many researchers consider oxidative stress-related mechanisms to be important early events in disease development. A particularly intriguing aspect is that, at least theoretically, oxidative stress should be easily prevented with antioxidants yet the use of antioxidants as therapy remains controversial. The present knowledge on oxidative stress in farm animals is the topic of this review.

Plasma malonaldehyde (MDA) and total antioxidant status (TAS) during lactation in dairy cows

Metabolic profiles are widely used to monitor health, reproductive status and nutritional status. In the last few years, the evaluation of oxidative stress has contributed increasingly to our knowledge of the fundamental mechanisms involved in metabolic disorders, especially important in dairy cows, in which lactation imposes great physiological demands on the body's homeostatic mechanisms. The aim of the present study was to evaluate oxidative status in healthy cows during lactation (from lactation onset to peak lactation) using two parameters: (i) plasma levels of malondialdehyde (MDA) and (ii) total antioxidant status (TAS). Our results confirm that nutrition can influence the characteristic metabolic changes occurring between lactation onset and peak lactation. In addition, the combination of MDA and TAS can provide complementary information about the metabolic status of the cow. Thus, the proper metabolic adaptation to the onset of lactation, showed by metabolic profiles, contrasts with the high levels of free radicals which cause lipid peroxidation and high MDA values (68.99+/-33.64 microm/L) which is maintained only for a short period of time. In this moment, the antioxidant system can cope efficiently with lipoperoxide production. The most remarkable fact was the great inter-individual variations observed in MDA that might be studied in further investigations. When the animal reaches peak lactation, metabolic status is stabilized, and this is reflected by antioxidant status with mean values of 28.87+/-5.33 microm/L for MDA and 0.154+/-0.002 mmol/L for TAS values.