A randomised trial was conducted to determine the effects of sodium monensin on plasma metabolite concentrations, resumption of cyclicity and oestrus and milk production and milk composition of postparturient dairy cows. Cows treated with sodium monensin in a controlled-release capsule had significantly lower plasma beta-hydroxybutyrate (BHB) concentrations (P = 0.006) and tended (P = 0.07) to have significantly higher plasma glucose concentrations than untreated cows. Treatment did not significantly influence plasma free fatty acid, urea nitrogen or cholesterol concentrations. Despite higher plasma glucose concentrations and lower plasma BHB concentrations, periods from calving to first ovulation and oestrus were not reduced by treatment. This observation, with limited numbers of cows, is not consistent with a hypothesis that glucose or ketones are important metabolic regulators of pulsatile release of luteinising hormone and consequent resumption of cyclicity. While milk production and milk protein concentration did not significantly differ between groups, milk fat concentration was significantly lower for treated cows. Treated cows probably had lower dry matter intake than untreated cows as they produced 67 litres less milk per head and lost more weight than untreated cows during the study period, although weight and body condition score were not significantly affected by treatment. The lack of significance of these latter observations probably reflects the low statistical power of the study.

Objectives: To examine, 1) optimal structure of break periods to mitigate physiological heat strain during rugby league play (Stage 1); and ii) effectiveness of three different cooling strategies applied during breaks (Stage 2). Design: Counter-balanced crossover design. Methods: In 37°C, 50% RH, 11 males completed six simulated 80-min (two 40-min halves) rugby league matches on a treadmill with different break structures: regular game (RG) (12-min halftime), 1-min or 3-min "quartertime" breaks halfway through each half with a 12-min halftime break (R1C and R3C), a 20-min halftime break (EH), or 1-min or 3-min quarter-time breaks with a 20-min halftime break (E1C and E3C) [Stage 1]. Nine participants completed Stage 2, which assessed the application of either ice towels (ICE), an electric fan (FAN) or a misting fan (MST) during breaks in the E3C protocol which, in Stage 1, prevailed as the optimal break structure. Results: Stage 1: Irrespective of quarter-time break duration, reductions in rectal temperature (−0.24°C ± 0.24) and heart rate (−61 ± 10 bpm) during the halftime break were greater with a 20-min compared to a 12-min break (−0.08 ± 0.13°C, p = 0.005; −55 ± −9 bpm, p = 0.021). Stage 2: End-game rises in rectal temperature were smaller (p < 0.006) in MST (1.41 ± 0.22°C), FAN (1.55 ± 0.36°C) and ICE (1.60 ± 0.21°C) than in CON (1.80 ± 0.39°C). The end-halftime heart rate was lower (p < 0.001) in ICE (89 ± 13 bpm), MST (90 ± 10 bpm) and FAN (92 ± 13 bpm) than in CON (99 ± 18 bpm). Conclusions: Combining an extended halftime period and quarter-time breaks with MST application is the optimal cooling strategy for rugby league players in hot, humid conditions.

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