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).     

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.     

DNA profiling reveals remarkably low genetic variability in a herd of SLA homozygous pigs.

Inbred strains of rodents have become indispensable for a wide range of biological studies. It has generally been accepted that genetic uniformity is unlikely to be achieved before 20 generations of brother x sister matings discouraging attempts to inbreed larger mammals. Nevertheless, pigs, homozygous for the swine MHC haplotype SLA b/b, have been inbred at the Babraham Institute for almost thirty years and used for immunological studies. Since the herd had not been studied at the DNA level, DNA profiling at multiple hypervariable loci was performed and surprisingly little genetic polymorphism and extremely high inter-individual resemblance were observed reminiscent of that observed in inbred strains of mice.     

Feline retinal degeneration: clinical experience and new findings (1994-1997)

A retrospective case series of 26 cats with diffuse retinal degeneration is presented. The most common presenting complaints included bumping into objects, dilated pupils, and reluctance to jump. Ophthalmic examination findings were consistent with those reported in dogs with progressive retinal atrophy. Breed predilection of the Siamese cat was observed. Cats with primary retinal degeneration presented late in the clinical course of their disease, when vision loss was severe. Early symptoms such as night blindness and secondary ocular complications (i.e., cataract and retinal detachment), reported in dogs with progressive retinal degeneration, were not observed in this study. All cats showed excellent adaptive capabilities to blindness.     

REVERSIBLE MAGNETIC RESONANCE IMAGING ABNORMALITIES IN DOGS FOLLOWING SEIZURES

Reversible magnetic resonance (MR) imaging lesions have been described in humans following seizures. This condition has not yet been reported in animals. This paper describes reversible abnormalities identified in 3 dogs using MR imaging that was performed initially within 14 days of the last seizure and follow-up imaging that was performed after 10 to 16 weeks of anticonvulsant therapy. All three dogs had lesions in the piriform/temporal lobes, characterized by varying degrees of hyperintensity on T2-weighted images and hypointensity on T1-weighted images. In one dog, contrast enhancement was evident. On reevaluation, partial resolution occurred in all 3 dogs. In a fourth animal with an olfactory meningioma, similar appearing lesions in the temporal cortex and right and left piriform lobes were identified after seizure activity. A surgical biopsy of the temporal cortex and hippocampus was performed and edema, neovascularization, reactive astrocytosis, and acute neuronal necrosis were evident. These histologic findings are similar to those reported in humans with seizures. Recognizing the potential occurrence of reversible abnormalities in MR images is important in developing a diagnostic and therapeutic plan in canine patients with seizures. Repeat imaging after seizure control may help differentiate between seizure-induced changes and primary multifocal parenchymal abnormalities.     

Feeding-induced increases in insulin do not suppress secretion of growth hormone

Secretion of growth hormone (GH) is reduced for several hours after feeding when access to feed is restricted to a 2-hr period each day. We hypothesized that increased secretion of insulin after feeding inhibits release of GH from the anterior pituitary gland. Our objectives were to determine whether: 1) alloxan prevents concentrations of insulin from increasing after feeding steers; 2) concentrations of GH remain high after feeding alloxan-treated steers; and 3) GH-releasing hormone (GHRH) stimulates greater release of GH in alloxan-treated, than in control, steers after feeding. Steers were injected iv with either saline (control) or with alloxan (110 mg/kg) (n = 4 per group). Concentrations of insulin were not different (P = 0.61) between control and alloxan-treated steers before feeding (87.5 +/- 33.6 pmol/l). However, alloxan prevented insulin from increasing (P < 0.001) after feeding (131.8 pmol/1) compared with control steers (442.0 pmol/l) (pooled SEM = 47.5). Overall, GH was higher (P < 0.05) in alloxan-treated (6.4 ng/ml) than in control steers (3.7 ng/ml) (pooled SEM = 0.7), but GH decreased (P < 0.001) after feeding in both groups. Iv injection of GHRH stimulated release of GH 1 hr before, but not when injected 1 hr after feeding (P < 0.001). In addition, net areas under the GH curve were not significantly different between control and alloxan-treated groups. We conclude that increased concentrations of insulin after feeding do not mediate feeding-induced suppression of GH secretion in steers.     

Comparison of clinical signs and hemodynamic variables used to monitor rabbits during halothane- and isoflurane-induced anesthesia

OBJECTIVE: To characterize variables used to monitor rabbits during inhalation anesthesia. ANIMALS: 8 male New Zealand White rabbits. PROCEDURE: Rabbits were similarly anesthetized with halothane (HAL) or isoflurane (ISO) in a crossover study; half received HAL followed by ISO, and the protocol was reversed for the remaining rabbits. After induction, minimum alveolar concentration (MAC) was determined for each agent, using the tail-clamp method, and variables were recorded at 0.8, 1.0, 1.5, and 2.0 MAC (order randomized). RESULTS: Mean +/- SEM MAC was 1.42 +/- 0.05 and 2.07 +/- 0.09% for HAL and ISO, respectively. Directly measured auricular mean arterial blood pressure was 52.8 +/- 5.6 and 54.8 +/- 6.1 mm Hg at 0.8 MAC for HAL and ISO, respectively, and decreased from these values in a parallel dose-dependent manner. Respiratory frequency remained constant (range, 69 to 78 breaths/min) over the range of HAL doses but incrementally decreased from a mean of 53 (at 0.8 MAC) to 32 breaths/min (at 2.0 MAC) for ISO. The PaCO2 was similar at 0.8 MAC for HAL and ISO and progressively increased with increasing doses of both agents; PaCO2 at 2.0 MAC for ISO was significantly greater than that at 2.0 MAC for HAL (79.8 +/- 13.7 vs 54.9 +/- 4.0 mm Hg, respectively). Eyelid aperture consistently increased in a dose-dependent manner for both anesthetics. CONCLUSIONS: Arterial blood pressure, PaCO2, and eyelid aperture consistently and predictably changed in rabbits in response to changes in anesthetic doses. The magnitude of respiratory depression was greater for ISO than for HAL.     

The effects of prednisone and azathioprine on circulating immunoglobulin levels and lymphocyte subpopulations in normal dogs.

This study investigates serum immunoglobulin (SIg) levels and lymphocyte subpopulations in normal dogs in response to putative immunosuppressive doses of prednisone and/or azathioprine. The objectives were to quantify SIg levels and lymphocyte subpopulations, including Thy-1+, CD4+, CD8+ and B cells, in normal dogs both before and after the administration of prednisone and/or azathioprine at 2 mg/kg, PO, each. Eighteen beagles were divided into 3 groups of 6 dogs each. Blood samples for radial immunodiffusion assay of IgG, IgM and IgA, complete blood count (CBC)and flow cytometry were collected prior to the administration of any drugs and again after 14 d of azathioprine, prednisone or azathioprine and prednisone. Peripheral blood mononuclear cells were isolated using density centrifugation and were incubated with monoclonal antibodies reacting with CD4+, CD8+, Thy-1+ and membrane immunoglobulin. Lymphocyte subsets were quantified using flow cytometry. Azathioprine-treated dogs had no significant changes in SIg levels or lymphocyte subpopulations. Prednisone-treated dogs had significant (P < 0.05) decreases in all SIg levels, all lymphocyte subpopulations and erythrocyte numbers, and had an increase in neutrophil counts. Prednisone and azathioprine-treated dogs had significant (P < 0.05) decreases in serum IgG levels and Thy-1+ and CD8+ lymphocyte subpopulations, with an increase in the CD4:CD8. These dogs also had a significant decrease in erythrocyte number and a significant increase in the monocyte count. These findings suggest that azathioprine and prednisone in combination or prednisone alone may be useful for the treatment of T cell-mediated diseases since decreased circulating T cell levels were demonstrated following treatment. The combination of drugs or azathioprine alone may not be appropriate for treatment of acute or autoantibody-mediated immune disease, because SIg levels were minimally affected by treatment.     

Plasma myeloperoxidase level and polymorphonuclear leukocyte activation in horses suffering from large intestinal obstruction requiring surgery: preliminary results.

Myeloperoxidase (MPO) is a specific enzyme of neutrophil azurophilic granules with a strong oxidative activity. Thanks to a radioimmunoassay of equine myeloperoxidase, the authors have observed a significantly higher plasma level of MPO in horses operated for strangulation obstruction of the large intestine (n = 6) than in horses suffering from a non-strangulating displacement of the large intestine (n = 9). For the 2 groups, 3 phases were distinguished: reception (P1), intensive care (P2) and terminal phase (P3). The mean peak values of MPO for these phases were 121.6 ng/mL (P1), 168.6 ng/mL (P2), and 107.0 ng/mL (P3) for the non-strangulating group, and 242.6 ng/mL (P1); 426.0 ng/mL (P2), and 379.5 ng/mL (P3) for the strangulation group. The variations of the mean peak values of plasma MPO were significantly different between the 2 groups and between the different phases. A significant increase of the least square means of MPO was observed between P1 and P2. A significant decrease of the least square means of the number of circulating leukocytes was observed between P1 and P3. Polymorphonuclear neutrophil activation could play a major role in the pathogenesis of acute abdominal disease and endotoxic shock.