K.A. Cummins

Ammonia emissions from field-simulated cattle defecation and urination.

Atmospheric ammonia (NH(3)) is a concern because of its environmental impact. The greatest contribution to atmospheric NH(3) comes from agricultural sources. This study quantified NH(3) volatilization from cattle defecation and urination on pasture under field conditions in Auburn, Alabama. Treatments consisted of beef feces, dairy feces, dairy urine, and a control. The experiment was conducted during four seasons from June 2003 to April 2004. Fresh feces or urine was applied onto grass swards, and NH(3) volatilization was measured up to 14 d after application using an inverted chamber method. Dairy urine was the only significant source of NH(3). Ammonia nitrogen (N) loss differed among seasons, ranging from 1.8% in winter to 20.9% during the warmer summer months. Cumulative volatilization was best described in this experiment by the equation % NH(3)-N loss = N(max) (1 - e(-ct))(i). The highest rate of NH(3) volatilization generally occurred within 24 h. This study suggests that NH(3) volatilization from cattle urine on pasture is significant and varies with season, whereas NH(3) volatilization from cattle feces is negligible.

Effects of steroids on the olfactory function of the dog

Twenty-four (24) mature, mixed breed, healthy dogs weighing from 14.6 kg to 27.6 kg were used to study the effects of various steroids on the olfactory function of the dog using olfactory detection threshold as an index. Two odorants were used, viz; benzaldehyde and eugenol. Of the various steroids used, only dexamethasone produced classical signs of Cushings syndrome in the dogs. However, all dogs that received either dexamethasone alone or hydrocortisone plus DOCA exhibited a significant elevation in the olfactory detection threshold for both odorants without any observable structural alteration of the olfactory tissue using light microscopy. On the other hand, neither DOCA, hydrocortisone alone, nor any of the vehicles used in the study significantly altered the olfactory function of the dogs. The results show that Cushings syndrome can be experimentally produced in dogs using exogenous steroids and that this condition diminishes the olfactory capability of the dog without producing classical signs of the disease.

Effect of dietary fat source and exercise on odorant-detecting ability of canine athletes

Eighteen male English Pointers (2-4 years of age, 23.94+/-0.54 kg body weight) were allotted to three diet and two physical conditioning groups to evaluate the effect of level and source of dietary fat on the olfactory acuity of canine athletes subjected to treadmill exercise. Diet groups (6 dogs/diet) consisted of commercially prepared diets (minimum of 26% crude protein) containing 12% fat as beef tallow (A), 16% fat provided by equivalent amounts of beef tallow and corn oil (B), or 16% fat provided by equivalent amounts of beef tallow and coconut oil (C). This dietary formulation resulted in approximately 60% of the total fatty acid being saturated for diets A and C, while approximately 72% of the total fatty acids were unsaturated in diet B. One-half of the dogs within each dietary group were subjected to treadmill exercise 3 times per week for 30 min (8.05 km/h, 0% grade) for 12 weeks. All dogs were subjected to a submaximal exercise stress test (8.05 km/h, 10% slope for 60 min) every four weeks beginning at week 0. Olfactory acuity was measured utilizing behavioral olfactometry before and after each physical stress test. Non-conditioned (NON) dogs displayed a greater decrease (P<0.05) in olfactory acuity following exercise, while physically conditioned (EXE) dogs did not show a change from pre-test values. A diet by treatment interaction (P<0.10) was detected over the course of the study. NON dogs fed coconut oil had decreased odorant-detecting capabilities when week 4 values were compared with week 12 values. Feeding a diet that is predominately high in saturated fat may affect the odorant-detecting capabilities of working dogs. Additionally, these data indicate that utilization of a moderate physical conditioning program can assist canine athletes in maintaining olfactory acuity during periods of intense exercise.

Drinking Rates of Stressed One-Month-Old Striped Bass: Effects of Calcium and Low Concentrations of Sodium Chloride

Abstract Drinking rates for striped bass Morone saxatilis were measured in freshwater and in water with a physiologically hypotonic concentration of NaCl (5 g/L). Fish were 27 d old (posthatching) and had recently completed larval development. Drinking rates were determined without allowing fish to adjust to test conditions because problems with survival of young striped bass often occur when they are stressed. In water with 5 g NaCl/L and 3.7 mg Ca2+/L, a combination of ions lethal to stressed striped bass at this stage of development, mean drinking rate (±SE) was 4.7 ± 0.3 μL· g–1 · h–1. This drinking rate was significantly higher than the mean drinking rate (1.8 ± 0.2 μL · g–1 · h–1) in water with 5 g NaCl/L and 100 mg Ca2+/L. Drinking rate in ion-poor water (5.8 mg Na+/L and 3.7 mg Ca2+/L) was only 0.38 ± 0.05 μL · g–1 · h–1. Drinking rates measured for 1 h or 3 h did not differ significantly, indicating that changes in drinking rates occurred quickly. High drinking rates may contribute to the death o...

Potassium flux in juvenile striped bass (Morone saxatilis): influence of external concentrations of sodium chloride and calcium.

Whole-body influx and efflux of K+ were determined for 25-day-old striped bass,Morone saxatilis, in conditions that simulated harvesting fish from ponds. During the first 5h in fresh water with combined high NaCl (80 mM) and low Ca2+ (0.12 mM) concentrations, a combination that is acutely lethal to this age of striped bass, K+ influx for fish in 0.07 mM K+ was 21±1.7 (SEM) compared to 3.4±0.33 nmol g−1 h−1 for fish in water with low Na+ (0.25 mM) or high Ca2+ (2.5 mM) concentrations. Influx of K+ was inhibited during the first few hours after fish were placed in flux chambers. Potassium efflux as percentage of42K lost per hour was two-fold higher from fish in the high Na-low Ca treatment compared to fish in low concentrations of Na+ or high concentrations of Ca2+. Potassium efflux was probably much greater than influx, but exact values for efflux could not be calculated from the data available. Survival of fish in water with high Na-low Ca was not increased by addition of KCl to the water, indicating that the net loss of K+ was probably not the cause of death.