USE OF A PERFORMANCE SCALE IN SMALL ANIMAL RADIATION THERAPY

A performance scale (Animal Medical Center Performance Scale) for use in dogs and cats was developed by modifying the Karnofsky Performance Status that is used in people. It was then applied to 209 animals that received definitive radiotherapy. The results after a minimum of 1 year of observation after therapy indicated that survival times were significantly longer for those animals that scored 80 or higher on the scale. Further studies will be needed to determine its usefulness with specific tumor types.     

Nutritive value of forage species grown in the warm temperate climate of Australia for dairy cows: Grasses and legumes

The objective of this study was to quantify the differences in the nutritive value over 4 seasons, of 7 C₃ temperate grasses, 2 C₄ tropical grasses and 11 clover species used as forages for dairy cows. The nutritive value was assessed in terms of nutrient content and the availability of effective rumen degradable protein, rumen by pass protein, metabolisable protein (MP) and fermentable metabolisable energy.

All species were grown in plots as monocultures under conditions of non limiting nutrients and moisture and harvested by mechanical means. All species had a high crude protein content and this resulted in a high effective rumen degradable protein: fermentable metabolisable energy ratio varying from 15, for cowpeas (Vigna unguiculata) to 29 for birdsfoot clover (Lotus corniculatus), and all were above the ratio of 11 required for optimal microbial protein synthesis in the rumen of dairy cows. The calculated availability of MP varied from 105 g/kg dry matter (DM) for cowpeas to 173 g/kg DM for berseem clover (Trifolium alexandrinum) indicating that all forages would be able to meet the requirements of dairy cows producing up to 30 L/milk/day, provided they were able to consume over 19 kg DM of forage/cow/day.

Grasses had much higher hemicellulose (neutral detergent fibre minus acid detergent fibre) content than legumes. Kikuyu (Pennisetum clandestinum), a C₄ grass, had a higher proportion of hemicellulose content than the C₃ temperate grasses. Perennial ryegrass (Lolium perenne) and kikuyu had a similar metabolisable energy (ME) density (9.9 MJ/kg DM) in summer. The mean ME density of perennial ryegrass, prairie grass (Bromus wildinowii) and short rotation ryegrass (Lolium multiflorum) winter was similar at 10.6 MJ/kg DM and slightly higher than cocksfoot (Dactylus glomeratus), phalaris (Phalaris tuberosa) and fescue (Fescue arundunicea) which had a mean ME density of 10 MJ/kg DM.

All forages grown were able to satisfy MP and ME requirements of dairy cows producing up to 30 L milk/cow/day, provided they were able to consume sufficient forage to achieve this level of production.     

Soil Health and Soil Fertility Assessment by the Haney Soil Health Test in an Agricultural Soil in West Tennessee

The Haney Soil Health Test (HSHT) is a recent approach to quantify soil health by focusing mostly on soil biology. It uses a new extractant (H3A) for the extraction of plant available nutrients, a new method of soil respiration measurement (24-hr CO₂ burst) using Solvita® gel system, and a new approach in determining bioavailable carbon (C) and nitrogen (N) namely water extractable organic C (WEOC) and water extractable organic N (WEON). A soil health score is calculated by combining Solvita® respiration, WEOC, and WEON data. The objective of this study was to test the feasibility of HSHT to detect the management-induced changes in soil nutrient levels and soil health in the production systems of west Tennessee. We tested soils collected from a cover crop field trial established in 2013 on a no-till corn (Zea mays L.) – soybean [Glycine max (L.) Merr.] rotation. Compared to Mehlich-1 and Mehlich-3, H3A extracted the lowest amount of soil extractable phosphorus, potassium, calcium and magnesium. Neither the soil health score nor its component parameters showed significant differences between cover crop treatments and the control. In addition, the Solvita® CO₂ data did not provide a reliable estimation of potentially mineralizable N. Overall, the HSHT did not detect differences in soil health due to cover cropping in west Tennessee. We conclude that HSHT, though a promising concept due to its focus on linking soil biology with soil fertility and soil health, may need extensive field evaluation and refinement in contrasting soils and climates across the US.     

Feasibility of using tissue autolysis to estimate the postmortem interval in horses

Estimation of the postmortem interval (PMI) is a poorly studied field in veterinary pathology. The development of field-applicable methods is needed given that animal cruelty investigations are increasing continually. We evaluated various histologic criteria in equine brain, liver, and muscle tissue to aid the estimation of PMI in horses, which is central to forensic investigations of suspicious death. After death, autolysis proceeds predictably, depending on environmental conditions. Currently, no field-applied methods exist that accurately estimate the PMI using histology in animals or humans through quantification of autolysis. Brain, liver, and skeletal muscle from 12 freshly euthanized horses were held at 22°C and 8°C for 72 h. Tissues were sampled at T0h, T1h, T2h, T4h, T6h, T12h, T24h, T36h, T48h, T60h, and T72h. For each tissue, we quantified 5 to 7 criteria associated with autolysis, based on the percentage of microscopic field involved. Each criterion was modeled, with temperature and time as independent variables. Changes were most predictable in liver and muscle over the first 72 h postmortem. The criteria for autolysis that were present most extensively at both temperatures were hepatocyte individualization and the separation of bile duct epithelium from the basement membrane. The changes that were present next most extensively were disruption of myofiber continuity, hypereosinophilia, and loss of striation. Brain changes were highly variable. The high statistical correlation between the parameter “autolysis” and the variables “time/temperature”, indicates that autolysis is progressive and predictable. Further investigation of these criteria is needed to establish histologic algorithms for PMI.