Effects of lasalocid on ruminal and blood metabolites in young dairy calves

Effects of lasalocid on peripheral concentration of blood ketones, plasma nonesterified fatty acids, glucose, insulin, urea-nitrogen, and volatile fatty acids and ruminal pH, ammonia-nitrogen and volatile fatty acids were examined using 16 Holstein bull calves. Ruminal cannulas were installed surgically at 5 ± 2 d of age. Calves were fed 1.8 kg milk replacer twice daily to weaning at 8 wk and a commercial pelleted calf starter once daily for ad libitum consumption to a maximum of 4.5 kg. Blood was collected once weekly for 12 wk and analyzed for β-hydroxybutyrate and acetoacetate. Blood β-hydroxybutyrate increased with increasing dry matter intake and was affected significantly by treatment post-weaning. Blood acetoacetate response was similar to β-hydroxybutyrate but without treatment effect. Plasma nonesterified fatty acids decreased with age suggesting that calves were under little stress. Plasma glucose increased to wk 5 then decreased to concentrations expected for mature ruminants. Plasma insulin responded to plasma glucose by increasing to weaning then decreased across all treatments. Plasma insulin correlated .41 to plasma glucose suggesting that insulin responds to other metabolites in addition to glucose. Plasma urea-nitrogen increased with age due to an increase in crude protein intake. Plasma total VFA increased with increasing dry matter intake and correlated .62. Plasma acetate, which composed 93 percent of plasma total VFA, correlated to dry matter intake (r = .62). Plasma propionate (r = .53) and butyrate (r = .02) were less highly correlated with DMI. Ruminal pH decreased with increased dry matter intake (r = .68). Calves fed lasalocid tended to maintain a higher ruminal pH than control calves. Ruminal ammonia-nitrogen increased across all treatments throughout the study. Ruminal VFA increased as a function of dry matter intake (r = ,74). Molar percent ruminal acetate decreased and percent propionate increased throughout the study. Percent butyrate tended to be lower for calves that received lasalocid ruminally. Data indicate that ketone body concentration resulted from alimentary ketogenesis and lasalocid decreased blood ketone levels. No protein-sparing effect was observed in this study. Both ruminal and plasma volatile fatty acids responded to dry matter intake. Lasalocid shifted molar percentages of ruminal VFA away from acetate and butyrate in favor of propionate

The impacts of environmental warming on Odonata: a review

Climate change brings with it unprecedented rates of increase in environmental temperature, which will have major consequences for the earth's flora and fauna. The Odonata represent a taxon that has many strong links to this abiotic factor due to its tropical evolutionary history and adaptations to temperate climates. Temperature is known to affect odonate physiology including life-history traits such as developmental rate, phenology and seasonal regulation as well as immune function and the production of pigment for thermoregulation. A range of behaviours are likely to be affected which will, in turn, influence other parts of the aquatic ecosystem, primarily through trophic interactions. Temperature may influence changes in geographical distributions, through a shifting of species' fundamental niches, changes in the distribution of suitable habitat and variation in the dispersal ability of species. Finally, such a rapid change in the environment results in a strong selective pressure towards adaptation to cope and the inevitable loss of some populations and, potentially, species. Where data are lacking for odonates, studies on other invertebrate groups will be considered. Finally, directions for research are suggested, particularly laboratory studies that investigate underlying causes of climate-driven macroecological patterns