hI-con1

The objective was to determine if the introduction of androgenized steers or females in oestrus has luteolytic effects during the advanced luteal phase (Day 12-13 of the cycle, Day of ovulation = Day 0) in heifers by analysing the changes in corpus luteum (CL) size and perfused area together with progesterone (P4) secretion. Experiment 1 (EXP1) was carried out in May (autumn) with 12 Angus and Angus X Hereford heifers and experiment 2 (EXP2) in September (spring) with 20 heifers of the same breed. Procedures for both experiments were the same. Firstly, oestrus was synchronized in heifers, then, transrectal colour doppler ultrasonography was performed daily from Day 10 to Day 12 of the cycle in all animals. On Day 12 in the afternoon, animals were allocated to two experimental groups (control and biostimulated) and maintained separated (minimum distance: 1000 m) until the end of each experiment. In EXP1, two androgenized steers were introduced into the biostimulated group (BAS) and compared with unstimulated control group (CON1). In EXP2, 20 animals were separated into control group (CON2) and biostimulated group (BHE), in which 4 oestrous heifers were introduced on Day 12 in the afternoon, and 4 more on day 13. The oestrous heifers were injected with 2 mg i.m. of oestradiol benzoate every 12 h until the end of the experiment to maintain the receptiveness. In both experiments, from Day 13 until the day on which detectable luteal blood flow (irrigation) disappeared, colour doppler ultrasonography was performed every 12 h in both groups. Blood samples were collected from all heifers every 12 h from Day 10 to the day in which irrigation disappeared. In EXP1 there was no effect of treatment on CL volume. The BAS had less CL's perfused area than controls 0.09 ± 0.02 cm² vs 0.16 ± 0.02 cm², respectively (p = 0.015), less percentage of perfused area (2.4 ± 0.4% vs 4.2 ± 0.4%; p = 0,011), and lower progesterone (P4) concentration than CON1 (2.7 ± 1.0 ng/mL vs 5.8 ± 0.9 ng/mL respectively; p = 0.046). On Day 14.5 of the cycle, the BAS tended to have a lower concentration of P4 than the CON1 (p = 0.06) and on Days 15.5, 16, 16.5, 17, 17.5, 19.5 the P4 concentration was lower in BAS than in CON1 (p < 0.05). In EXP2 there were no treatment effects in any of the studied variables. Overall, it was concluded that the introduction of androgenized steers during heifers' advanced luteal phase of heifers advanced the luteolytic process. However, the introduction of oestrous heifers had no effect on luteal activity.

This study compared changes in brachial-ankle pulse wave velocity (baPWV) after concentric (CON) versus eccentric (ECC) cycling. It was hypothesized that baPWV would increase after the first ECC bout (ECC1) because of muscle damage, but not after the second ECC bout (ECC2), and would decrease after CON. Fifteen young (aged 20–30 years) men performed 2 bouts of 30-min ECC (ECC1 and ECC2) at 60% of maximal CON power output and 2 bouts of 30-min CON at the same intensity as that of ECC (CON1), and at the same oxygen consumption as that of ECC (CON2) every 2 weeks. Oxygen uptake during the cycling was recorded, and baPWV was measured before and at 0.5, 1, 24, and 48 h after each cycling bout. Maximal voluntary contraction (MVC) torque and muscle soreness of the knee extensors were assessed before and at 24 and 48 h after each cycling bout. Changes in these variables over time were compared among the 4 cycling bouts by 2-way repeated-measured ANOVA. baPWV decreased (P < 0.05) 8% from the baseline (1119 ± 116 cm/s) at 0.5 h after CON1 (1028 ± 126 cm/s), but no significant changes were evident after ECC1, ECC2, and CON2. MVC torque decreased 10% from the baseline at 24 h after ECC1, but no significant changes were evident after CON1, CON2, and ECC2. These results did not support the hypothesis, and suggest that minor muscle damage induced by eccentric cycling does not affect arterial stiffness.