Oxidative responses in ferret macrophages

Although the basic function of T and B lymphocytes in ferrets has been known for some time, the function of mononuclear phagocytes has not been described in this species. The present study has characterised basic oxidative responses in ferret macrophages, and has investigated the effects of endogenous and exogenous modulators of macrophage function on oxidative capacity in vitro. Macrophages derived from the blood or lungs of ferrets were shown capable of generating the reactive oxygen intermediate (ROI) molecules superoxide and hydrogen peroxide, and secreting a lysosomal enzyme (acid phosphatase), in response to appropriate stimuli. A T cell supernatant (derived from mitogen-stimulated peripheral blood lymphocytes) was able to activate both blood- and lung-derived macrophages for enhanced ROI production, while specific ROI inhibitors (superoxide dismutase and catalase) were able to partially ablate ROI activity. The accumulation of nitrite in culture supernatants, as an indicator for the production of reactive nitrogen intermediates, could not be demonstrated by ferret macrophages derived from either tissue source. In contrast to the enhancing effects of TCS on the oxidative function of blood-derived macrophages, exposure to bacterial LPS caused marked suppression of ROI and lysosomal enzyme production by these cells. Finally, the generation of superoxide anion, following phagocytosis of live or heat-killed Mycobacterium bovis or zymosan, indicated that ROI production in response to phagocytic stimulation was relatively weak in ferret blood-derived macrophages. These results are discussed in relation to the study of immune function in a novel species, and with particular reference to research into tuberculosis (Tb), since ferrets are important wildlife vectors of bovine Tb in New Zealand.     

Analysis of first gastric compartment fluid collected via percutaneous paracentesis from healthy llamas

OBJECTIVE: To evaluate the safety and efficacy of percutaneous paracentesis for fluid collection from the first gastric compartment of healthy llamas and to describe characteristics of that fluid. DESIGN: Prospective study. ANIMALS: 10 healthy adult llamas. PROCEDURE: Physical examinations were performed prior to sample collection and for 14 days afterwards. A CBC was performed prior to sample collection and 5 days later. A 16-gauge, 7.5-cm stainless steel needle, positioned approximately 20 cm caudal to the costochondral junction of the last rib, was pointed in a dorsocraniomedial direction and pushed through the abdominal wall into the lumen of the first gastric compartment. Fluid was aspirated and analyzed immediately for color, odor, consistency, pH, methylene blue reduction (MBR) time, protozoa, and bacteria. RESULTS: Fluid samples were obtained from 9 of 10 llamas. Mean volume was 4.1 ml, mean pH was 6.67, and mean MBR time was 173 seconds. Odor was slightly acidic, color was light brown-green to light yellow-green, and consistency was moderate. Small protozoa with variable iodine staining and gram-negative bacteria were commonly detected. With few exceptions, results of physical examinations and CBC remained within reference ranges. CLINICAL IMPLICATIONS: Fluid samples from the first gastric compartment can be successfully obtained by percutaneous paracentesis. Fluid characteristics were similar to those of fluid collected via orogastric tube in llamas and cattle.     

Pulsed Doppler assessment of left ventricular diastolic function in normal and cardiomyopathic cats.

Left ventricular (LV) diastolic function was evaluated in 16 cats with primary hypertrophic cardiomyopathy (HCM) using pulsed Doppler (PD) assessment of transmitral flow and isovolumic relaxation time. Data obtained was compared to data from 12 healthy, adult, research cats. Compared to normal cats, the HCM group showed significantly (p value less than 0.05) reduced early LV inflow velocities (mean +/- standard error [SE], peak velocity of 0.70+/-0.04 m/s versus 0.54+/-0.04 m/s and integrated velocity of 0.48+/-0.08 m/s versus 0.37+/-0.03 m/s); a reduced rate of deceleration of early inflow (mean+/-SE, -12.0+/-1.0 m/s2 versus -5.1+/-1.1 m/s2); prolonged isovolumic relaxation time (mean +/- SE, 45.7+/-3.3 ms versus 76.0+/-3.1 ms); and increased atrial systolic flow velocities (mean +/- SE, peak velocity of 0.29+/-0.04 m/s versus 0.48+/-0.04 m/s and integrated velocity of 0.21+/-0.03 m/s versus 0.34+/-0.03 m/s). The results suggest that PD provides a noninvasive method of identifying and quantifying functional diastolic impairment in cats with HCM.     

Influence of pig substitution on milk yield, litter weights, and milk composition of machine milked sows.

This study was conducted to 1) determine milk yield of sows that were machine milked up to four times daily; 2) determine the effect of pig substitution on milk yield; 3) assess litter weight changes for sows that are milked; and 4) determine milk composition. Eight sows were milked four times daily to d 51 postpartum. Sows either maintained their own litter or had a week-old replacement litter to replace 25-d-old pigs. Individual gland milk yields were obtained on random days throughout lactation, and different diameter and weighted teat cups were rotated so that all glands received all combinations. Composite milk samples were analyzed for fat, protein, and somatic cells. Milk yields peaked at about 19 d postpartum and declined to 45 d postpartum in sows with their own litter, whereas milk yields peaked earlier and had a more dramatic decline after fostering of a younger litter. Litter weights were 17.1 +/- 1.0 kg at farrowing with 13.6 +/- .6 pigs born alive. Final litter weights were 34.4 +/- 11.7 kg for sows with replacement litters and 74.4 +/- 13.5 kg for sows with their own litters, and numbers of pigs weaned were 6.5 +/- 1.3 and 9.7 +/- 1.5, respectively. Milk fat was influenced by route of oxytocin administration (6.53 +/- .12 for i.v. vs 7.21 +/- .19% for i.m. administration; P < .05). Milk fat percentage was highest on d 2 and declined to 13 d postpartum. Milk protein was influenced by time of day of milking (lowest at the fourth milking, 5.57 +/- .11%) and followed a pattern similar to that for milk fat. Milk protein was affected in a linear manner by milk yield, with highest protein associated with lowest milk yields. Somatic cells in milk were influenced by litter replacement (P < .05) and oxytocin administration (P < .01). There was a linear increase in somatic cells from about 8 x 10(6) cells/mL milk at d 2 to more than 12 x 10(6) cells/mL milk at d 51 postpartum. These results show that pig replacement affects the amount of milk obtained. Moreover, milk composition changes throughout lactation. However, milk removal from sows has a severe impact on litter weight gains, and in systems where sow's milk is needed for commercial purposes, pig supplementation is necessary.     

Effect of the ratio between essential and nonessential amino acids in the diet on utilization of nitrogen and amino acids by growing pigs.

In 36 growing pigs (30 to 60 kg), N balance and amino acid (AA) composition of weight gain were measured to evaluate the interactive effect of the ratio between N from essential amino acids (EAA(N)) to nonessential amino acids (NEAA(N)) and total N level (T(N)) in the diet on N retention and utilization of N, EAA(N), NEAA(N), and AA. Nine diets composed from ordinary feedstuffs and supplemented with crystalline AA were used (three EAA(N):NEAA(N) ratios of 38:62, 50:50, and 62:38 at three T(N) levels of 18.8, 22.9, and 30.0 g/kg). Pigs were fed restrictedly, at a level of 2.8 x energy for maintenance. In all diets, EAA (including arginine) supply was according to or slightly above the recommended ratios to lysine. Measurements were done in four blocks of nine pigs each. In a concomitant slaughter experiment, the AA composition of deposited body protein was determined to estimate AA utilization. The effects of T(N) and EAA(N):NEAA(N) and their interaction for N retention and utilization were significant. Nitrogen retention increased with higher T(N) in the diet. Increasing EAA(N):NEAA(N) from 38:62 to 50:50 improved N retention only at the two lower T(N) levels. Increasing EAA(N): NEAA(N) above 50:50 failed to improve N retention significantly at any of the three T(N) levels. Lowering T(N) improved the utilization of total and digested N and of EAA(N) and NEAA(N). The increase in EAA(N): NEAA(N) consistently resulted in a lower utilization of EAA(N), but this was compensated by a higher utilization of NEAA(N). The utilization of T(N) was improved by increasing EAA(N):NEAA(N) from 38:62 to 50:50 at the two lower T(N) levels and was relatively unaffected by EAA(N):NEAA(N) at the highest T(N). However, a lower utilization of N was observed at a ratio of 62:38 at a T(N) level of 22.9 g/kg. The effects were similar for utilization of individual EAA and NEAA. Utilization of alanine, aspartic acid, and glycine was close to or >100% at the highest EAA(N):NEAA(N), which was expected because all of these AA are synthesized in pigs. Also, the utilization of arginine was >100% in most of the treatments, which confirms the semiessential character of this AA for maintenance. We concluded that the required ratio of EAA(N):NEAA(N) for optimal N retention and utilization is approximately 50:50. The EAA(N):NEAA(N) is more important at lower dietary protein levels. This study indicates that EAA(N): NEAA(N) can be increased up to 70:30 without lowering the utilization of N. Thus, deaminated EAA(N) was efficiently utilized for the synthesis of NEAA(N).     

Abnormal regulation of muscle contraction in horses with recurrent exertional rhabdomyolysis.

OBJECTIVE: To determine whether abnormal regulation of muscle contraction similar to that associated with malignant hyperthermia (MH) was evident in intact external intercostal muscle cells from Thoroughbreds with recurrent exertional rhabdomyolysis (RER). ANIMALS: 5 adult Thoroughbred horses with RER and 7 clinically normal adult Thoroughbred or mixed-breed horses. PROCEDURES: Twitch time course variables and contracture responses to various concentrations of potassium, caffeine, and halothane were measured in small bundles of intact external intercostal muscle cells from clinically normal horses and horses with RER. RESULTS: Threshold for significant contracture induced by potassium depolarization was lower for RER-affected muscles, compared with normal muscles, although the relationship between potassium concentration and membrane potential were not different. Thresholds for contracture induced by caffeine and halothane were also lower for RER-affected muscles, compared with normal muscles. Lower thresholds for caffeine- and halothane-induced contractures, as well as depolarization-elicited contractures, in RER-affected muscles suggest a defect in myoplasmic calcium regulation. CONCLUSIONS AND CLINICAL RELEVANCE: Regulation of muscle contraction is abnormal in Thoroughbreds with RER. The specific defect may be attributable to abnormal intracellular calcium regulation. Knowledge of the specific defect involved in RER may lead to improved prevention and treatment of RER-affected horses.     

Effect of prepubertal feeding regimen on reproductive development of gilts.

The effect of prepubertal feed level on growth and reproductive development of gilts was investigated. At 13 wk. of age, white crossbred gilts were penned individually and assigned to the following treatments: Ad lib, ad libitum intake from 13 to 25 wk. of age (n = 64); Control, ad libitum intake from 13 wk. of age until 100 kg BW and then 90% of ad libitum intake until 25 wk. of age (n = 65); and Restricted, 74% of ad libitum intake from 13 wk. to 25 wk. of age (n = 64). Feed was formulated to primarily restrict energy intake. The study was replicated in two seasons. At 25 wk. of age, gilts were moved to group pens, approximately 16 gilts/pen, allowed ad libitum access to feed, and estrus detection was initiated. Gilts were mated at first estrus and those recycling were remated. After mating, gilts were moved to gestation stalls and fed 1.5x maintenance. At 30 d of gestation, reproductive tracts were harvested, and numbers of corpora lutea (CL) and live embryos were recorded. From 13 to 25 wk. of age, feed consumption was 258 for Ad lib, 251 for Control, and 189 kg/gilt for Restricted, and, from 13 wk. of age until 30 d of gestation, total feed consumption was 367 for Ad lib, 356 for Control, and 299 kg/gilt for Restricted gilts. Age at puberty (196 d) and pregnancy (200 d) was not affected (P>.18) by treatment. However, the rate at which gilts attained puberty (e.g., percentage pubertal at 28 d) was greatest in Ad lib (75) and least in Control (61) gilts. Number of CL and live embryos at 30 d of gestation/gilt assigned to the study was unaffected (P>.21) by treatment. Quantity of feed consumed from 13 wk. of age to 30 d of gestation per live embryo in gilts assigned to the study was 40.0 for Ad lib, 39.8 for Control, and 30.6 kg/gilt for Restricted gilts. These results indicate that moderate feed restriction of gilts during prepubertal development may increase efficiency of swine production without negative impact on reproductive performance through 30 d of gestation.     

Case life of seven retail products from beef cattle supplemented with alpha-tocopheryl acetate.

Packages (n = 660) of clod, strip loin, tenderloin, bottom round, eye-of-round, and top round steaks, as well as ground beef, from beef cattle fed diets supplemented with vitamin E (500 IU/d for 100 d preharvest) were compared with packages of products derived from carcasses of beef cattle fed control diets to determine the duration of acceptable muscle color during simulated retail display. In addition, the effect of storage before steak fabrication, simulating distribution time, on the acceptability of each treatment and each cut during retail display was investigated. Dietary supplementation of animals with vitamin E increased muscle alpha-tocopherol concentrations (P < .05) in all cuts. The acceptable retail display time of ground beef from vitamin E-supplemented cattle was longer (P < .05) compared to ground beef from unsupplemented cattle by 10.2, 15.6, and 17.6 h following 7, 14, and 21 d of storage in chub packages prior to final grinding and retail display, respectively. However, length of storage in a vacuum package before retail display did not have a consistent effect on retail case life of steaks. Product drip loss during retail display was not affected by storage time or vitamin E treatment. The trained panel color score during retail display of high vitamin E strip loin, bottom round, inside round, and eye-of-round steaks remained acceptable longer (P < .05) by 11.5, 25.2, 8.4, and 29.4 h, respectively, than that of control steaks. The results demonstrated that vitamin E supplementation of cattle feed can be used as a management tool to reduce the economic losses associated with beef muscle color deterioration during retail display of products.     

Evaluation of disinfectants with the addition of antifreezing compounds against nonpathogenic H7N2 avian influenza virus.

In the winter of 1997 and 1998, in the midst of the H7N2 avian influenza outbreak in Pennsylvania, producers added antifreeze or windshield washer fluid to disinfectant solutions in wash stations to prevent freezing. The purpose of this study was to determine if the addition of these products to the disinfectant solutions would have deleterious effects. Four disinfectants (two phenols, one quarternary ammonium, and one combination product: quarternary ammonium and formaldehyde) and one sodium hypochlorite detergent product currently used in the poultry industry were studied. Each product was diluted according to the manufacturer's recommendation in sterile distilled water and compared with dilutions of the disinfectants with the addition of antifreeze products (ethylene glycol or propylene glycol) or windshield washer fluid for their effectiveness in killing nonpathogenic H7N2 avian influenza virus. All products diluted according to the manufacturer's recommendation killed the nonpathogenic H7N2 avian influenza virus in this test system. The phenol products and the quaternary ammonium product were still efficacious with the addition of the antifreeze containing ethylene glycol. Both the combination product and the sodium hypochlorite detergent had decreased efficacy when the ethylene glycol product was added. When the propylene glycol product was added, the efficacy of all disinfectants remained unaffected, whereas the efficacy of the sodium hypochlorite detergent decreased. With the addition of the windshield washer fluid (methyl alcohol), all products remained efficacious except for the combination product.