Comparison of rapid laboratory tests for failure of passive transfer in the bovine

Background

Failure of passive transfer of maternal immunity via colostrum can occur in the bovine, and a number of blood tests have been developed to test calves for this failure. It is not clear which test is most suitable for this purpose. The objective was to examine the most commonly used tests for failure of passive transfer and to decide which is most suitable for routine laboratory use. 126 serum samples were taken from calves of dairy cows after birth but prior to colostrum feeding, and at 48 h of age. Five different tests were compared against radial immunodiffusion which is considered the appropriate reference method. These tests were serum gamma-glutamyltransferase levels, serum protein levels, serum globulin levels, an enzyme linked immunosorbent assay and the zinc sulphate turbidity test.

Results

The tests examined displayed high sensitivity but widely varying specificity. Examination of the use of different cut-off points allowed some improvement in specificity at the expense of sensitivity, but the tests which had performed best at the original cut-off points still displayed the best performance. Gamma-glutamyltransferase levels as a measure of colostrum absorption returned, in this study, the best balance between sensitivity and specificity. The ELISA used in this study and serum globulin levels displayed performance similar to the gamma-glutamyltransferase levels. Serum total protein was less successful than others examined at providing both sensitivity and specificity but may, when performed via refractometer, be useful for on-farm testing. As currently performed the poor sensitivity for which the zinc sulphate turbidity test is most often criticized is evident. Modification of the cut-off point to increase specificity is less successful at balancing these parameters than the ELISA, gamma-glutamyltransferase levels, and globulin levels.

Conclusions

Gamma-glutamyltransferase levels, ELISA testing and circulating globulin levels performed best in detecting failure of passive transfer in serum samples, although all three had some practical considerations.     

Estimation of light interception properties of conifer shoots by an improved photographic method and a 3D model of shoot structure

The spherical mean of the shoot silhouette-to-total leaf area ratio (STAR) and the shoot transmission coefficient (c) are two key structural parameters in radiative transfer models for calculating canopy photosynthesis and leaf area index. The standard optical method for estimating these parameters might introduce errors in the estimates for species with flexible shoots and needles by changing shoot inclination relative to its inclination in situ. We devised and tested two methods to address this problem. First, we modified the standard optical method by designing an apparatus that allows shoots to be photographed in their original orientation. Second, we developed a faster, model-based approach to replace photography and tested the results against the established approach. We used shoots of three pine species, Pinus echinata Mill. (needle length ~50 mm), P. taeda L. (~150 mm) and P. palustris Mill. (~300 mm). Values of the parameters simulated by the model were similar to those measured from the photographs. In our data, STAR varied about twofold among the pine species and was ~40% higher in shade shoots than in sun shoots of P. taeda. The transmission coefficient for P. taeda shade shoots was also ~40% higher than that of sun shoots of all three species. We tested the versatility of the model by employing it on shoots of two other pine species (P. strobus L. and P. thumbergiana Parl.) as well as on shoots of Tsuga canadensis L. Carr. and Picea pungens Engelm. Regardless of shoot characteristics, the model generated values of shoot structural parameters similar to those estimated with the optical method. Although species-specific and vertical gradients in parameter values are best for modeling radiative transfer in conifer canopies, our results suggest that, in the absence of adequate data, STAR can be approximated as 0.16 for a wide range of shoot structures. For applications requiring angle-dependent parameterization, our new model facilitates rapid generation of these radiative transfer parameters.     

Trends and change points in surface and bottom thermal environments of the US Northeast Continental Shelf Ecosystem

Temperature is an important factor in defining the habitats of marine resource species. While satellite sensors operationally measure ocean surface temperatures, we depend on in situ measurements to characterize benthic habitats. Ship‐based measurements were interpolated to develop a time series of gridded spring and fall, surface and bottom temperature fields for the US Northeast Shelf. Surface and bottom temperatures have increased over the study period (1968–2018) at rates between 0.18–0.31°C per decade and over a shorter time period (2004–2018) at rates between 0.26–1.49°C per decade. A change point analysis suggests that a warming regime began in the surface waters in 2011 centered on Georges Bank and the Nantucket Shoals; in following years, most of the Northeast Shelf had experienced a shift in surface temperature. A similar analysis of bottom temperature suggests a warming regime began in 2008 in the eastern Gulf of Maine; in following years, change points in temperature occurred further to the west in the Gulf of Maine, finally reaching the Middle Atlantic Bight by 2010. The spatial pattern in bottom water warming is consistent with well‐known oceanographic patterns that advect warming North Atlantic waters into the Gulf of Maine. The varying spatial and temporal progression of warming in the two layers suggests they were actuated by different sets of forcing factors. We then compared these trends and change points to responses of lower and higher trophic level organisms and identified a number of coincident shifts in distribution and biomass of key forage and fisheries species.     

Voluntary intake, digestibility, and subsequent selection of Matua bromegrass, coastal bermudagrass, and alfalfa hays by yearling horses.

Matua bromegrass (Bromus willdenowii Kunth. cv. Grasslands Matua) was introduced in 1973, but little information exists concerning its potential as a hay for horses. Thus, voluntary intake and apparent digestibility of OM, CP, and fiber components of Matua by 18 Quarter Horse yearlings (mean initial BW 354 kg; SE 5.8) were compared with alfalfa (Medicago sativa L.) and coastal bermudagrass (Cynodon dactylon L.) as hays in a randomized block design. A 15-d adjustment period was followed by a 5-d collection period during which the hays were consumed ad libitum. Voluntary intake of DM was greater (P<.01) for alfalfa (10.9 kg/d) than for the mean of the grasses, and intake of Matua (10.0 kg/d) was greater (P<.001) than that of bermudagrass (7.4 kg/d). Apparent digestibility of OM was greater (P<.001) for alfalfa (74%) than for the mean of the grasses but did not differ between Matua (64%) and bermudagrass (60%). At the end of the digestion trial, each yearling was offered each of the three forage hays during an 11-d period to determine subsequent preference and effect of previous hay experience. Yearlings preferred alfalfa over the grass hays and generally selected more Matua than bermudagrass. All yearlings consumed less of the forage species to which they had been previously exposed compared with unadapted yearlings. The Matua hay fed in this trial was palatable and met most of the nutritional needs for yearling horses.     

Evaluating wildlife tourism exposure to Florida manatees using citizen science,public interviews,and trail cameras

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Pectinolytic bacteria associated with potato soft rot and blackleg in South Africa and Zimbabwe

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Adiponectin and leptin are related to fat mass in horses

Plasma concentrations of adiponectin and leptin were measured in 23 mature Standardbred mares (age: 10 ± 3 years) and 12 weanling fillies (10 Quarter Horse/Belgian crossbreds and two Quarter Horses; aged: 4 ± 3 months) to test the hypothesis that adipocytokines are proportional to adiposity in horses. Rump fat thickness was measured using B-mode ultrasound and percent body fat (% fat) calculated using a published formula for the estimation of fatness in horses. Plasma adiponectin and leptin were determined using radioimmunoassay. In the absence of purified equine adiponectin or leptin, results were expressed as human equivalents (HE) of immunoreactive (ir) adipocytokines.Plasma ir-leptin HE concentration was positively correlated (r = 0.543; P < 0.001) with percent body fat and (r = 0.556; P < 0.001) to fat mass in all horses. The plasma ir-leptin HE concentration was lower (P = 0.03) in weanlings (1.90 ± 0.34 ng/mL HE) than in mature mares (3.47 ± 0.50 ng/mL HE). The ratio of ir-adiponectin HE to ir-leptin HE was negatively correlated (r = −0.621; P < 0.001) to percent fat and (r = −631; P < 0.001) to fat mass in all horses. The ratio of ir-adiponectin HE to ir-leptin HE was higher (P < 0.001) in weanlings (3.04 ± 0.51) than mature mares (1.03 ± 0.13). These data suggest that leptin is proportional while adiponectin is inversely proportional to adiposity in horses.     

Early Warnings for State Transitions

New concepts have emerged in theoretical ecology with the intent to quantify complexities in ecological change that are unaccounted for in state-and-transition models and to provide applied ecologists with statistical early warning metrics able to predict and prevent state transitions. With its rich history of furthering ecological theory and its robust and broad-scale monitoring frameworks, the rangeland discipline is poised to empirically assess these newly proposed ideas while also serving as early adopters of novel statistical metrics that provide advanced warning of a pending shift to an alternative ecological regime. We review multivariate early warning and regime shift detection metrics, identify situations where various metrics will be most useful for rangeland science, and then highlight known shortcomings. Our review of a suite of multivariate-based regime shift/early warning indicators provides a broad range of metrics applicable to a wide variety of data types or contexts, from situations where a great deal is known about the key system drivers and a regime shift is hypothesized a priori, to situations where the key drivers and the possibility of a regime shift are both unknown. These metrics can be used to answer ecological state-and-transition questions, inform policymakers, and provide quantitative decision-making tools for managers.     

Method to determine effect of antibiotics at residue levels on R-factor transfer

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