To measure the concentration of serum amyloid A (SAA) protein in horses a sensitive and highly reproducible sandwich (ELISA) was established, using affinity purified SAA antibody. Results of the ELISA were found to have a high correlation (r = 0.95) with those of the single radial immunodiffusion test. Equine SAA concentration was measured by use of this ELISA. In clinically normal horses, the concentration of SAA was high immediately after birth to 2 weeks of age. After that, SAA concentration had periodic fluctuations in the range of approximately 10 to 30 microgram/ml. Mean (+/- SD) concentrations of SAA in foals (less than or equal to 12 months old) and adult horses (greater than or equal to 18 months old) were 21.23 +/- 12.20 and 14.93 +/- 9.07 microgram/ml, respectively. In mares during the perinatal period, SAA concentration remained stable within the reference range before parturition. It increased quickly after delivery, and reached a peak value of 101.29 +/- 98.82 microgram/ml on postpartum day 3, then began to decrease, at postpartum week 2, to the reference range by the end of postpartum month 1. In horses with experimentally induced inflammation, SAA concentration increased quickly and reached approximately four- to 40-fold increase over the pretreatment value on day 1 and remained high on days 2 to h after treatment. It then returned to the baseline value by 2 to 4 weeks in association with disappearance of local signs of inflammation. The SAA concentration was high in most horses with clinical signs of inflammation. It was concluded from these data that this ELISA is sensitive and reliable for measuring SAA in horses.

To measure the concentration of serum amyloid A (SAA) protein in horses a sensitive and highly reproducible sandwich (ELISA) was established, using affinity purified SAA antibody. Results of the ELISA were found to have a high correlation (r = 0.95) with those of the single radial immunodiffusion test. Equine SAA concentration was measured by use of this ELISA. In clinically normal horses, the concentration of SAA was high immediately after birth to 2 weeks of age. After that, SAA concentration had periodic fluctuations in the range of approximately 10 to 30 microgram/ml. Mean (+/- SD) concentrations of SAA in foals (less than or equal to 12 months old) and adult horses (greater than or equal to 18 months old) were 21.23 +/- 12.20 and 14.93 +/- 9.07 microgram/ml, respectively. In mares during the perinatal period, SAA concentration remained stable within the reference range before parturition. It increased quickly after delivery, and reached a peak value of 101.29 +/- 98.82 microgram/ml on postpartum day 3, then began to decrease, at postpartum week 2, to the reference range by the end of postpartum month 1. In horses with experimentally induced inflammation, SAA concentration increased quickly and reached approximately four- to 40-fold increase over the pretreatment value on day 1 and remained high on days 2 to h after treatment. It then returned to the baseline value by 2 to 4 weeks in association with disappearance of local signs of inflammation. The SAA concentration was high in most horses with clinical signs of inflammation. It was concluded from these data that this ELISA is sensitive and reliable for measuring SAA in horses.

Six horses were subjected to 3 hours of low-flow ischemia and 3 hours of reperfusion of the large colon. After induction of anesthesia, the large colon was exteriorized through a ventral midline celiotomy. Colonic blood flow was measured continuously, using Doppler ultrasonic flow probes placed on the colonic arteries supplying the dorsal and ventral colons and was allowed to stabilize for 15 to 30 minutes after instrumentation. Low-flow ischemia was induced by reducing colonic arterial blood flow to 20% of baseline (BL) flow. Colonic mucosal, seromuscular, and full-thickness blood flow were determined on a tissue-weight basis by injecting colored microspheres proximally into the colonic artery supplying the ventral colon. Reference blood samples were obtained at a known flow rate from the colonic artery and vein at a site more distal to the site of injection. Left ventral colon biopsy specimens were harvested at BL, 3 hours of ischemia, and 15 minutes of reperfusion. Blood and tissue samples were digested and filtered to collect the microspheres, and dimethylformamide was added to release the colored dyes. Dye concentration in blood and tissue samples was measured by use of spectrophotometry, and tissue-blood flow was calculated. Data were analyzed, using two-way ANOVA for repeated measures; statistical significance was set at P < 0.05. Doppler blood flow decreased to approximately 20% of BL, whereas microsphere blood flow ranged between 13.7 and 15.5% of BL at 3 hours of ischemia. Doppler-determined blood flow increased immediately on restoration of blood flow, reached 183% of BL at 15 minutes of reperfusion, and remained at or above BL throughout 3 hours of reperfusion. This reactive hyperemia was also detected, using the colored microspheres; blood flow increased to 242 and 327% of BL at 15 minutes of reperfusion in the mucosal and seromuscular layers, respectively.

Six horses were subjected to 3 hours of low-flow ischemia and 3 hours of reperfusion of the large colon. After induction of anesthesia, the large colon was exteriorized through a ventral midline celiotomy. Colonic blood flow was measured continuously, using Doppler ultrasonic flow probes placed on the colonic arteries supplying the dorsal and ventral colons and was allowed to stabilize for 15 to 30 minutes after instrumentation. Low-flow ischemia was induced by reducing colonic arterial blood flow to 20% of baseline (BL) flow. Colonic mucosal, seromuscular, and full-thickness blood flow were determined on a tissue-weight basis by injecting colored microspheres proximally into the colonic artery supplying the ventral colon. Reference blood samples were obtained at a known flow rate from the colonic artery and vein at a site more distal to the site of injection. Left ventral colon biopsy specimens were harvested at BL, 3 hours of ischemia, and 15 minutes of reperfusion. Blood and tissue samples were digested and filtered to collect the microspheres, and dimethylformamide was added to release the colored dyes. Dye concentration in blood and tissue samples was measured by use of spectrophotometry, and tissue-blood flow was calculated. Data were analyzed, using two-way ANOVA for repeated measures; statistical significance was set at P < 0.05. Doppler blood flow decreased to approximately 20% of BL, whereas microsphere blood flow ranged between 13.7 and 15.5% of BL at 3 hours of ischemia. Doppler-determined blood flow increased immediately on restoration of blood flow, reached 183% of BL at 15 minutes of reperfusion, and remained at or above BL throughout 3 hours of reperfusion. This reactive hyperemia was also detected, using the colored microspheres; blood flow increased to 242 and 327% of BL at 15 minutes of reperfusion in the mucosal and seromuscular layers, respectively. Mucosal blood flow was not different from seromuscular blood flow at any time, indicating relatively equal distribution of blood flow between these 2 layers. As determined from the venous reference samples, there was no evidence of arteriovenous anastomoses.

A series of experiments was conducted to document tumor necrosis factor-alpha (TNF) activity in serum of swine after inoculation with Salmonella spp endotoxin and after oral or respiratory tract challenge exposure with live Salmonella spp. For experiment 1, a potentially lethal dose of S typhimurium endotoxin (25 microgram/kg of body weight) was administered IV, and serum TNF activity was measured. High TNF (approx 700 IU/ml) activity at 1 to 2 hours after administration of the inoculum was associated with death, whereas lower TNF (approx 30 IU/ml) activity was associated with a general prolonged state of shock. For experiment 2, pigs were administered a nonlethal dose (5 microgram/kg, IV) of either S typhimurium or S choleraesuis endotoxin. Difference in the ability to induce porcine serum TNF activity was not observed between strains. During experiment 3, pigs were inoculated with 104 colony-forming units of S typhimurium chi4232 either orally by gelatin capsule (GC) or by intranasal (IN) instillation. A late serum TNF response (17 IU/ml) was measured at 6 weeks after IN inoculation. A serum TNF response was not detected in GC-inoculated pigs. All tissues and feces were test-negative for S typhimurium prior to the 6-week TNF response. Serum TNF activity may be related to clearance of S typhimurium after respiratory tract exposure, but it is not important to or indicative of clearance of orally presented S typhimurium in swine. During experiment 4, pigs were inoculated with 106 colony-forming units of S typhimurium chi4232 similarly as for experiment 3. Challenge exposure with this medium-size dose of inoculum induced a prolonged peak serum TNF response (37 IU/ml) between 2 and 4 weeks after IN inoculation Again, serum TNF activity was not detected in GC-inoculated pigs. Data suggest that clearance of a medium-size dose (106) of inoculum may be influenced by the prolonged higher serum TNF activity. For experiments 5 and 6, pigs were inoculated IN with 103, 106, 108.

A series of experiments was conducted to document tumor necrosis factor-alpha (TNF) activity in serum of swine after inoculation with Salmonella spp endotoxin and after oral or respiratory tract challenge exposure with live Salmonella spp. For experiment 1, a potentially lethal dose of S typhimurium endotoxin (25 microgram/kg of body weight) was administered IV, and serum TNF activity was measured. High TNF (approx 700 IU/ml) activity at 1 to 2 hours after administration of the inoculum was associated with death, whereas lower TNF (approx 30 IU/ml) activity was associated with a general prolonged state of shock. For experiment 2, pigs were administered a nonlethal dose (5 microgram/kg, IV) of either S typhimurium or S choleraesuis endotoxin. Difference in the ability to induce porcine serum TNF activity was not observed between strains. During experiment 3, pigs were inoculated with 104 colony-forming units of S typhimurium chi4232 either orally by gelatin capsule (GC) or by intranasal (IN) instillation. A late serum TNF response (17 IU/ml) was measured at 6 weeks after IN inoculation. A serum TNF response was not detected in GC-inoculated pigs. All tissues and feces were test-negative for S typhimurium prior to the 6-week TNF response. Serum TNF activity may be related to clearance of S typhimurium after respiratory tract exposure, but it is not important to or indicative of clearance of orally presented S typhimurium in swine. During experiment 4, pigs were inoculated with 106 colony-forming units of S typhimurium chi4232 similarly as for experiment 3. Challenge exposure with this medium-size dose of inoculum induced a prolonged peak serum TNF response (37 IU/ml) between 2 and 4 weeks after IN inoculation. Again, serum TNF activity was not detected in GC-inoculated pigs. Data suggest that clearance of a medium-size dose (106) of inoculum may be influenced by the prolonged higher serum TNF activity. For experiments 5 and 6, pigs were inoculated IN with 103, 106, 108, or 109 S choleraesuis chi3246. A measurable, yet statistically nonsignificant, serum TNF response was observed for all doses. Pigs inoculated by GC with 108 S choleraesuis chi3246 had similar results. High does (> 106) of live S choleraesuis were associated with clinical signs of endotoxic shock. Clearance of S choleraesuis, or lack thereof, did not correlate with serum TNF activity.

Twenty-four horses were randomly allocated to 3 groups. Horses were anesthetized, subjected to a ventral midline celiotomy, and the large colon was exteriorized and instrumented. Group-1 horses served as sham-operated controls. Group-2 horses were subjected to 6 hours of low-flow colonic arterial ischemia, and group-3 horses were subjected to 3 hours of ischemia and 3 hours of reperfusion. Baseline (BL) samples were collected, then low-flow ischemia was induced by reducing ventral colonic arterial blood flow to 20% of BL. All horses were monitored for 6 hours after BL data were collected. Blood samples were collected from the colonic vein and main pulmonary artery (systemic venous (SV) for measurement of plasma endotoxin, 6-keto prostaglandin F1alpha (6-kPG), thromboxane B2 (TXB2), and prostaglandin E2 (PGE2) concentrations. Tumor necrosis factor and interleukin-6 activities were measured in colonic venous (CV) serum samples. Data were analyzed, using two-was ANOVA, and post-hoc comparisons were made, using Dunnett's and Tukey's tests. Statistical significance was set at P < 0.05 Endotoxin was not detected in CV or SV plasma at any time. There was no detectable tumor necrosis factor or interleukin-6 activity in CV samples at any time. There were no differences at BL among groups for CV or SV 6-kPG, PGE2, or TXB2 concentrations, nor were there any changes across time in group-1 horses. Colonic venous 6-kPG concentration increased during ischemia in horses of groups 2 and 3; CV 6-kPG concentration peaked at 3 hours in group-3 horses, then decreased during reperfusion, but remained increased through 6 hours in group-2 horses. Systemic venous 6-kPG concentration increased during reperfusion in group-3 horses, but there were no changes in group-2 horses. Colonic venous PGE2 concentration increased during ischemia in horses of groups 2 and 3, and remained increased for the first hour of reperfusion in group-3 horses and for the 6-hour duration of ischemia in group-2 hors.

Twenty-four horses were randomly allocated to 3 groups. Horses were anesthetized, subjected to a ventral midline celiotomy, and the large colon was exteriorized and instrumented. Group-1 horses served as sham-operated controls. Group-2 horses were subjected to 6 hours of low-flow colonic arterial ischemia, and group-3 horses were subjected to 3 hours of ischemia and 3 hours of reperfusion. Baseline (BL) samples were collected, then low-flow ischemia was induced by reducing ventral colonic arterial blood flow to 20% of BL. All horses were monitored for 6 hours after BL data were collected. Blood samples were collected from the colonic vein and main pulmonary artery (systemic venous [SV]) for measurement of plasma endotoxin, 6-keto prostaglandin F1alpha (6-kPG), thromboxane B2 (TXB2), and prostaglandin E2 (PGE2) concentrations. Tumor necrosis factor and interleukin-6 activities were measured in colonic venous (CV) serum samples. Data were analyzed, using two-was ANOVA, and post-hoc comparisons were made, using Dunnett's and Tukey's tests. Statistical significance was set at P < 0.05 Endotoxin was not detected in CV or SV plasma at any time. There was no detectable tumor necrosis factor or interleukin-6 activity in CV samples at any time. There were no differences at BL among groups for CV or SV 6-kPG, PGE2, or TXB2 concentrations, nor were there any changes across time in group-1 horses. Colonic venous 6-kPG concentration increased during ischemia in horses of groups 2 and 3; CV 6-kPG concentration peaked at 3 hours in group-3 horses, then decreased during reperfusion, but remained increased through 6 hours in group-2 horses. Systemic venous 6-kPG concentration increased during reperfusion in group-3 horses, but there were no changes in group-2 horses. Colonic venous PGE2 concentration increased during ischemia in horses of groups 2 and 3, and remained increased for the first hour of reperfusion in group-3 horses and for the 6-hour duration of ischemia in group-2 horses. There were no temporal alterations in SV PGE2 concentration. There was no difference in CV or SV TXB2 concentration among or within groups across time; however, there was a trend (P = 0.075) toward greater CV TXB2 concentration at 3.25 hours, compared with BL, in group-3 horses. Eicosanoid concentrations were significantly lower in SV, compared with CV plasma. Prostaglandin E2 and 6-kPG concentrations were approximately 3 to 8 and 5 to 10 times greater, respectively, in CV than in SV plasma. The increased concentrations of 6-kPG and PGE2 in CV plasma were likely attributable to their accumulation secondary to colonic ischemia. The increased values of these vasodilator eicosanoids may have a role in the reactive hyperemia observed during reperfusion. The increased 6-kPG concentration in SV plasma may represent spillover from the colonic vasculature, but more likely reflects systemic production.

Receptors for opsonins, such as complement component C3b (CR1) and immunoglobulins, Fc receptors, interact with adhesion glycoproteins in mediating immune functions. Defects in expression of the adhesion glycoproteins CD11/CD18 results in severely hampered in vitro and in vivo adherence-related functions of leukocytes. Little is known regarding the effect of leukocyte adhesion deficiency (LAD) on ligand binding and receptor expression. We investigated the binding and expression of CR1 and Fc receptors by bovine neutrophils isolated from dairy calves suffering from LAD, compared with clinically normal (hereafter referred to as normal) age-matched calves. Neutrophils were also assayed for endogenously bound IgG and IgM and for exogenous binding of C3b, IgG1, IgG2, IgM, and aggregated IgG (aIgG), using flow cytometry. Luminol-enhanced chemiluminescence (CL) production in response to IgG2 opsonized zymosan was studied, and specific inhibition of CL was used to determine the specificity of IgG2 binding. Activation of protein kinase C with phorbol myristate acetate was used to determine the effect of cellular activation on expression of CR1. A greater percentage of neutrophils from normal calves bound C3b than did neutrophils from LAD-affected calves. Receptor expression was similar. Activation with phorbol myristate acetate resulted in increased expression of CR1 on neutrophils from normal and LAD-affected calves, but expression was almost twofold greater on neutrophils from normal calves. There was no difference between LAD-affected and normal calves in percentage of neutrophils that bound endogenous IgG and IgM. A greater percentage of neutrophils from normal calves bound exogenous IgM than did neutrophils from LAD-affected calves. Receptor expression for aIgG was greater on neutrophils from LAD-affected calves than on those from normal calves.

Receptors for opsonins, such as complement component C3b (CR1) and immunoglobulins, Fc receptors, interact with adhesion glycoproteins in mediating immune functions. Defects in expression of the adhesion glycoproteins CD11/CD18 results in severely hampered in vitro and in vivo adherence-related functions of leukocytes. Little is known regarding the effect of leukocyte adhesion deficiency (LAD) on ligand binding and receptor expression. We investigated the binding and expression of CR1 and Fc receptors by bovine neutrophils isolated from dairy calves suffering from LAD, compared with clinically normal (hereafter referred to as normal) age-matched calves. Neutrophils were also assayed for endogenously bound IgG and IgM and for exogenous binding of C3b, IgG1, IgG2, IgM, and aggregated IgG (aIgG), using flow cytometry. Luminol-enhanced chemiluminescence (CL) production in response to IgG2 opsonized zymosan was studied, and specific inhibition of CL was used to determine the specificity of IgG2 binding. Activation of protein kinase C with phorbol myristate acetate was used to determine the effect of cellular activation on expression of CR1. A greater percentage of neutrophils from normal calves bound C3b than did neutrophils from LAD-affected calves. Receptor expression was similar. Activation with phorbol myristate acetate resulted in increased expression of CR1 on neutrophils from normal and LAD-affected calves, but expression was almost twofold greater on neutrophils from normal calves. There was no difference between LAD-affected and normal calves in percentage of neutrophils that bound endogenous IgG and IgM. A greater percentage of neutrophils from normal calves bound exogenous IgM than did neutrophils from LAD-affected calves. Receptor expression for aIgG was greater on neutrophils from LAD-affected calves than on those from normal calves. Luminol-enhanced CL of neutrophils in response to IgG2 opsonized zymosan was not different between LAD-affected and normal calves. Results indicate increased binding and expression of Fc receptors for aIgG and decreased binding and expression for C3b and IgM on neutrophils from calves with LAD. Leukocyte adhesion deficiency may be compounded by added defects in the expression and binding of receptors for opsonins, such as C3b and IgM.

Vestibulotoxic and ototoxic effects often are seen after long-term, high-dose systemic treatment with gentamicin, but toxic effects after topical use have not been reported in animals, to the authors' knowledge. Vestibular and auditory effects of twice daily otic gentamicin treatment for 21 days were evaluated in 10 dogs with intact tympanic membranes and in the same 10 dogs after experimental bilateral myringotomy. Each dog served as its own control; 7 drops of gentamicin sulfate (3 mg/ml in a buffered aqueous vehicle) were placed in 1 ear, and 7 drops of vehicle were placed in the opposite ear. Treatment and control ears were reversed after myringotomy. Vestibular function was evaluated daily by neurologic examination and behavioral assessment Auditory function was evaluated twice weekly by determination of brain stem auditory evoked potentials. Gentamicin sulfate placed in the ear of clinically normal dogs with intact or ruptured tympanic membranes, in the quantities used in this study, did not induce detectable alteration of cochlear or vestibular function. Serum gentamicin concentration after 21 days of treatment was detectable in only 2 dogs and was an order of magnitude below documented toxic concentrations.

Vestibulotoxic and ototoxic effects often are seen after long-term, high-dose systemic treatment with gentamicin, but toxic effects after topical use have not been reported in animals, to the authors' knowledge. Vestibular and auditory effects of twice daily otic gentamicin treatment for 21 days were evaluated in 10 dogs with intact tympanic membranes and in the same 10 dogs after experimental bilateral myringotomy. Each dog served as its own control; 7 drops of gentamicin sulfate (3 mg/ml in a buffered aqueous vehicle) were placed in 1 ear, and 7 drops of vehicle were placed in the opposite ear. Treatment and control ears were reversed after myringotomy. Vestibular function was evaluated daily by neurologic examination and behavioral assessment Auditory function was evaluated twice weekly by determination of brain stem auditory evoked potentials. Gentamicin sulfate placed in the ear of clinically normal dogs with intact or ruptured tympanic membranes, in the quantities used in this study, did not induce detectable alteration of cochlear or vestibular function. Serum gentamicin concentration after 21 days of treatment was detectable in only 2 dogs and was an order of magnitude below documented toxic concentrations.

We investigated the ability of an antibody-specific, O antigen-based ELISA to document Salmonella typhimurium herd infections by screening of milk samples. Three cattle populations, 20 herds with no history of salmonellosis, 8 herds with history of S. typhimurium episodes within the previous 7 months, and 220 herds of unknown disease status, were tested. A herd was considered ELISA positive if at least 5% of the cows had OD values > 0.3. Among the 20 herds without history of salmonellosis, only 2 herds were ELISA positive, whereas all 8 herds with a known history of salmonellosis were ELISA positive (herd specificity, 0.9 and herd sensitivity, 1.0). A significant correlation (P < 0.001) was found between the OD values of serum and milk samples from cows in the herds with a history of salmonellosis. It was concluded that ELISA testing of individual milk samples can be used for surveillance of herds for S. typhimurium infections, but further modifications are needed to test bulk tank milk samples.

We investigated the ability of an antibody-specific, O antigen-based ELISA to document Salmonella typhimurium herd infections by screening of milk samples. Three cattle populations, 20 herds with no history of salmonellosis, 8 herds with history of S. typhimurium episodes within the previous 7 months, and 220 herds of unknown disease status, were tested. A herd was considered ELISA positive if at least 5% of the cows had OD values > 0.3. Among the 20 herds without history of salmonellosis, only 2 herds were ELISA positive, whereas all 8 herds with a known history of salmonellosis were ELISA positive (herd specificity, 0.9 and herd sensitivity, 1.0). A significant correlation (P < 0.001) was found between the OD values of serum and milk samples from cows in the herds with a history of salmonellosis. It was concluded that ELISA testing of individual milk samples can be used for surveillance of herds for S. typhimurium infections, but further modifications are needed to test bulk tank milk samples.

We evaluated the single-cycle structural properties for axial compression, torsion, and 4-point bending with a central load applied to the caudal or lateral surface of a diaphyseal segment from the normal adult equine humerus, radius, third metacarpal bone, femur, tibia, and third metatarsal bone. Stiffness values were determined from load-deformation curves for each bone and test mode. Compressive stiffness ranged from a low of 2,690 N/mm for the humerus to a high of 5,670 N/mm for the femur. Torsional stiffness ranged from 558 N.m/rad for the third metacarpal bone to 2,080 N.m/rad for the femur. Nondestructive 4-point bending stiffness ranged from 3,540 N.m/rad for the radius to 11,500 N.m/rad for the third metatarsal bone. For the humerus, radius, and tibia, there was no significant difference in stiffness between having the central load applied to the caudal or lateral surface. For the third metacarpal and metatarsal bones, stiffness was significantly (P < 0.05) greater with the central load applied to the lateral surface than the palmar or plantar surface. For the femur, bones were significantly (P < 0.05) stiffer with the central load applied to the caudal surface than the lateral surface. Four-point bending to failure load-deformation curves had a bilinear pattern in some instances, consisting of a linear region at lower bending moments that corresponded to stiffness values from the nondestructive tests and a second linear region at higher bending moments that had greater stiffness values. Stiffness values from the second linear region ranged from 4,420 N.m/rad for the humerus to 13,000 N.m/rad for the third metatarsal bone. Differences in stiffness between nondestructive tests and the second linear region of destructive tests were significant (P < 0.05) for the radius, third metacarpal bone, and third metatarsal bone. Difference between stiffness values of paired left and right bones was not detected for any test.

We evaluated the single-cycle structural properties for axial compression, torsion, and 4-point bending with a central load applied to the caudal or lateral surface of a diaphyseal segment from the normal adult equine humerus, radius, third metacarpal bone, femur, tibia, and third metatarsal bone. Stiffness values were determined from load-deformation curves for each bone and test mode. Compressive stiffness ranged from a low of 2,690 N/mm for the humerus to a high of 5,670 N/mm for the femur. Torsional stiffness ranged from 558 N.m/rad for the third metacarpal bone to 2,080 N.m/rad for the femur. Nondestructive 4-point bending stiffness ranged from 3,540 N.m/rad for the radius to 11,500 N.m/rad for the third metatarsal bone. For the humerus, radius, and tibia, there was no significant difference in stiffness between having the central load applied to the caudal or lateral surface. For the third metacarpal and metatarsal bones, stiffness was significantly (P < 0.05) greater with the central load applied to the lateral surface than the palmar or plantar surface. For the femur, bones were significantly (P < 0.05) stiffer with the central load applied to the caudal surface than the lateral surface. Four-point bending to failure load-deformation curves had a bilinear pattern in some instances, consisting of a linear region at lower bending moments that corresponded to stiffness values from the nondestructive tests and a second linear region at higher bending moments that had greater stiffness values. Stiffness values from the second linear region ranged from 4,420 N.m/rad for the humerus to 13,000 N.m/rad for the third metatarsal bone. Differences in stiffness between nondestructive tests and the second linear region of destructive tests were significant (P < 0.05) for the radius, third metacarpal bone, and third metatarsal bone. Difference between stiffness values of paired left and right bones was not detected for any test. Four-point bending ultimate failure bending moments ranged from 260 N.m for the femur to 940 N.m for the third metatarsal bone. There was no difference in failure bending moment between the directions of applied central load for a given bone.

Growth indices were examined in 24 identically managed tanks, each containing 120 diploid juvenile rainbow trout (initial mean body weight, 9.3 g), during a 12-week study to examine tank effects associated with tank location in a multi-user research facility. Growth indices included mean body weight, feed intake, feed conversion index, and specific growth rate. The null hypothesis that tank effect had no effect on growth over the 12-week period was rejected (P = 0.038), and mean weight in individual tanks differed by as much as 18.7%. During the study, it was determined that the proximity of tanks to common-use walkways in the facility could affect growth indices. This was indicated by significant differences in the mean fish weights among blocks of tanks served by different header tanks after 4 (P = 0.001) and 8 (P = 0.024) weeks. The block containing tanks of fish with the highest mean weight was nearest to the 2 common-use walkways in the facility. Fish in this block of tanks, compared with those in other blocks, had significantly greater feed intake but no significant differences in conversion efficiency. Compensatory growth, a well known growth attribute in fishes, diminished the difference in mean weight between these blocks of tanks by the end of the study. Comparison of paired tanks within header tank blocks indicated that fish in those located nearest to walkways had higher feeding rates over the 12-week period (P = 0.048), but less efficient teed conversion (P = 0.040) than did fish in matched tanks located farthest from walkways. However, there were no differences in mean weight of fish. Results of this trial document the risks involved in identifying fish in a tank as the experimental unit when treatments are administered to the tank of fish, the latter being the true experimental unit.

Growth indices were examined in 24 identically managed tanks, each containing 120 diploid juvenile rainbow trout (initial mean body weight, 9.3 g), during a 12-week study to examine tank effects associated with tank location in a multi-user research facility. Growth indices included mean body weight, feed intake, feed conversion index, and specific growth rate. The null hypothesis that tank effect had no effect on growth over the 12-week period was rejected (P = 0.038), and mean weight in individual tanks differed by as much as 18.7%. During the study, it was determined that the proximity of tanks to common-use walkways in the facility could affect growth indices. This was indicated by significant differences in the mean fish weights among blocks of tanks served by different header tanks after 4 (P = 0.001) and 8 (P = 0.024) weeks. The block containing tanks of fish with the highest mean weight was nearest to the 2 common-use walkways in the facility. Fish in this block of tanks, compared with those in other blocks, had significantly greater feed intake but no significant differences in conversion efficiency. Compensatory growth, a well known growth attribute in fishes, diminished the difference in mean weight between these blocks of tanks by the end of the study. Comparison of paired tanks within header tank blocks indicated that fish in those located nearest to walkways had higher feeding rates over the 12-week period (P = 0.048), but less efficient teed conversion (P = 0.040) than did fish in matched tanks located farthest from walkways. However, there were no differences in mean weight of fish. Results of this trial document the risks involved in identifying fish in a tank as the experimental unit when treatments are administered to the tank of fish, the latter being the true experimental unit.