Relationship between periparturient diseases, metabolic markers and the dynamics of hair cortisol concentrations in dairy cows.

Hair cortisol concentration (HCC) might represent a promising marker for retrospective welfare assessment of dairy cows. The objective of the study was to explore the dynamics of HCC in diseased and healthy cows from eight-week ante partum (AP) to eight-week post partum (PP). Twenty-four pregnant cows were followed from drying off to week eight PP. Tail hair was used to measure cortisol at five different time points. The occurrence of peripartum diseases, lameness and the body condition score (BCS) were monitored on a weekly basis. Blood ß-hydroxybutyric acid, non-esterified fatty acids, calcium and insulin-like growth factor-1 (IGF-1) concentrations were measured. The temperature-humidity index (THI) was continuously recorded. The median values of HCC in all cows were 0.4, 0.3, 0.6, 0.8 and 0.5 pg/mg at weeks eight, four AP, calving, weeks four, eight PP, respectively. There was no association between HCC and the occurrence of peripartum diseases (P ≥ 0.05). A positive correlation between HCC and BCS loss (P < 0.01) and THI (P < 0.05) was observed. The occurrence of peripartum diseases was associated with low IGF-1 during the study period but no relationship was found between cortisol and IGF-1 levels (P ≥ 0.05). Brown Swiss cows showed higher HCC (P < 0.01) at weeks eight, four AP, and week four PP and lower average milk yield (P < 0.05) than Holstein-Friesian cows. In conclusion, HCC was not a suitable marker for peripartum diseases but it could reflect a stress response, which is linked to BCS loss, heat stress and breed.

Role of the Na+/K+-ATPase ion pump in male reproduction and embryo development.

Na+/K+-ATPase was one of the first ion pumps studied because of its importance in maintaining osmotic and ionic balances between intracellular and extracellular environments, through the exchange of three Na+ ions out and two K+ ions into a cell. This enzyme, which comprises two main subunits (α and ß), with or without an auxiliary polypeptide (γ), can have specific biochemical properties depending on the expression of associated isoforms (α1ß1 and/or α2ß1) in the cell. In addition to the importance of Na+/K+-ATPase in ensuring the function of many tissues (e.g. brain, heart and kidney), in the reproductive tract this protein is essential for embryo development because of its roles in blastocoel formation and embryo hatching. In the context of male reproduction, the discovery of a very specific subunit (α4), apparently restricted to male germ cells, only expressed after puberty and able to influence sperm function (e.g. motility and capacitation), opened a remarkable field for further investigations regarding sperm biology. Therefore, the present review focuses on the importance of Na+/K+-ATPase on male reproduction and embryo development.

Effects of antioxidants and duration of pre-freezing equilibration on frozen-thawed ram semen.

The objective was to evaluate the effects of various antioxidants and duration of pre-freezing equilibration on cryopreservation of ram semen. Semen samples from four rams were pooled, diluted with Tris-egg yolk extender without antioxidants (control), or supplemented with reduced glutathione (GSH: 0.5, 1.0, and 2.0 mM), superoxide dismutase (SOD: 5, 10, and 20 U/mL), or catalase (CAT: 5, 10, and 20 U/mL), and cryopreserved, immediately after thermal equilibrium was reached at 5 °C (0 h), or 12 or 24 h after equilibration. Total antioxidant capacity was determined in the in natura extenders and after addition of semen samples for various durations of processing (fresh/dilute, throughout refrigeration, and post-thaw). Plasma membrane (PI-CFDA), acrosome integrity (FITC-PNA), and mitochondrial membrane potential (JC-1) were determined in fresh/diluted, refrigerated, and post-thaw samples. Post-thaw sperm motility was assessed with a computerized analysis system (CASA). There were no significant differences in acrosome damage or mitochondrial membrane potential after refrigeration and freeze-thaw, regardless of antioxidant addition. Sperm plasma membrane integrity was worse (P < 0.05) with cryopreservation immediately after equilibration (average 20.1 ± 8.3; mean ± SD) than after 12 h of equilibration (average 42.5 ± 10.9); however, the addition of SOD and CAT (10 and 20 U/mL) resulted in no significant difference between post-equilibration intervals of 0 and 12 h. Total antioxidant activity was not different (P > 0.05) among treatments after sperm addition or throughout the refrigeration and post-thaw. In conclusion, adding GSH, SOD or CAT did not increase the total antioxidant capacity of semen, nor did it enhance the quality of the post-thaw sperm. However, maintenance of ram semen at 5 °C for 12 h prior to cryopreservation reduced membrane damage of frozen-thawed sperm.