Evolution of the earliest horses driven by climate change in the Paleocene-Eocene Thermal Maximum

Body size plays a critical role in mammalian ecology and physiology. Previous research has shown that many mammals became smaller during the Paleocene-Eocene Thermal Maximum (PETM), but the timing and magnitude of that change relative to climate change have been unclear. A high-resolution record of continental climate and equid body size change shows a directional size decrease of ~30% over the first ~130,000 years of the PETM, followed by a ~76% increase in the recovery phase of the PETM. These size changes are negatively correlated with temperature inferred from oxygen isotopes in mammal teeth and were probably driven by shifts in temperature and possibly high atmospheric CO(2) concentrations. These findings could be important for understanding mammalian evolutionary responses to future global warming.     

Carbon and nitrogen dynamics in a forest soil amended with purified tannins from different plant species

Tannins are purported to be an important factor controlling nitrogen cycling in forest ecosystems, and the ability of tannins to bind proteins in protein-tannin complexes is thought to be the primary mechanism responsible for these effects. In this study, we examined the influence of well-characterized tannins purified from five different plant species on C and N dynamics of a forest soil A horizon. Tannic acid, a commonly used and commercially available hydrolyzable tannin (HT), and cellulose were also included for comparison. With the exception of tannins from huckleberry (Vaccinium ovatum), the amendments increased respiration 1.4-4.0 fold, indicating that they were acting as a microbial C source. Tannic acid was significantly more labile than the five purified tannins examined in this study. All treatments decreased net N mineralization substantially, through greater N immobilization and decreased mineralization. The six tannins inhibited gross ammonification rates significantly more than cellulose. This suggests that added tannins had effects in addition to serving as an alternative C source. Tannins purified from Bishop pine (Pinus muricata) were the only tannins that significantly inhibited potential gross nitrification rates, however, rates were low even in the control soil making it difficult to detect any inhibition. Differences in tannin structure such as condensed versus HTs and the hydroxylation pattern of the condensed tannin B-ring likely explain differences observed among the tannin treatments. Contrary to other studies, we did not find that condensed tannins were more labile and less inhibitory than HTs, nor that shorter chained tannins were more labile than longer chained tannins. In addition to supporting the hypothesis that reduced N availability in the presence of tannins is caused by complexation reactions, our data suggests tannins act as a labile C source leading to increased N immobilization.     

Breed and sex differences in the temperament of calves in a cow-calf operation.]

Behavioural traits related to temperament were studied in German Angus (Aberdeen Angus x German dual purpose breeds) and German Simmental cattle. Temperament was defined as the animal's behavioural response to handling. 498 calves (279 German Angus, 219 German Simmental) were tested with two different restrain tests. The animals were tested three times individually during a fixation procedure (days of live: 5, 19, 33) or weighting (days of live: 62, 138, 193). LSQ-means were calculated with a model including breed, year and sex as fixed effects and the sire as a random. Furthermore a regression on the age of the calf was included. Behaviour of the animals were recorded. Significant differences in the recorded parameters were found between the breeds on day 19 and 33 for one test and day 62 for another test. German Angus and male calves were less difficult to handle regarding the different parameters. Both tests could be used to show differences between the breeds.     

Measurement of cardiac troponin I utilizing a point of care analyzer in healthy alpacas

Background

Myocardial disease in camelids is poorly characterized. Nutritional (selenium deficiency) and toxic (ionophore toxicity) myocardial disease have been reported in camelids. Diagnosis and management of these and other myocardial diseases might be enhanced by evaluating cardiac troponin I (cTnI) concentrations. No information about cTnI reference intervals in camelids is currently available.

Hypothesis/Objectives

(A) To determine cTnI concentrations obtained using a point of care i-STAT^®1 analyzer (Heska Corporation) in healthy alpacas; (B) to compare alpaca cTnI concentrations between heparinized whole blood and plasma samples and between 2 different storage conditions (4 °C for 24 h or −80 °C for 30 days); (C) to examine assay reproducibility using the i-STAT^®1.

Animals, materials and methods

23 healthy alpacas were evaluated. Blood and plasma samples were analyzed by the i-STAT^®1 within 1 h of collection. Aliquots of plasma were stored at either 4 °C for 24 h or −80 °C for 30 days, and then analyzed. Assay reproducibility was determined by comparing 2 plasma or whole blood cTnI concentrations measured on the same sample over a 10 min period.

Results

Analyzer-specific plasma cTnI concentrations in clinically normal alpacas had a median of <0.02 ng/mL (range: <0.02 ng/mL to 0.07 ng/mL). Plasma and whole blood concentrations showed good agreement. Storage did not affect cTnI concentrations (p > 0.75). Plasma cTnI concentrations had coefficient of repeatability of 0.02 ng/mL.

Conclusions

The i-STAT^®1 can measure cTnI in alpacas on both plasma and whole blood and provides similar values for both samples. Storage at 4 °C for 24 h or −80 °C for 30 days does not affect estimates of plasma cTnI. Evaluation of cTnI might be of value in assessing cardiac disease in this species.