Nutrition and the heart

Nutritional deficiencies (e.g., carnitine in dogs, taurine in cats) resulting in cardiomyopathy, and nutritional excesses (e.g., calories leading to obesity, sodium leading to hypertension) have emerged as important considerations in cardiology. These dietary factors may become particularly exaggerated in altered physiological and/or pathological states (e.g., pregnancy, old age, primary cardiovascular disease). Unfortunately, we do not have complete information on requirements for essential nutrients, nor do we know the precise role nutrition may play in the production of so-called old-age diseases or on the interactions among other organ systems (e.g., kidney, liver) and the heart.     

Studies of infectious laryngotracheitis vaccines: immunity in layers

Ten-week-old layer chickens obtained from a commercial source were eye-drop vaccinated with chicken-embryo-origin (CEO) or tissue-culture-origin (TCO) vaccines for infectious laryngotracheitis (ILT). Controls were not vaccinated. Approximately one-third of the layers were challenged with virulent ILT virus at 21, 40, or 60 weeks of age. Serum samples taken from the layers before challenge were used in a virus neutralization (VN) test to determine vaccination titers at those three ages. Both vaccines induced low VN titers (geometric mean titer [GMT] less than 6). At 21 weeks of age, the titers produced by the two vaccines were not significantly different, but at 40 and 60 weeks of age the VN GMT of the CEO-vaccinated group was significantly greater than that of the TCO-vaccinated group. The VN GMTs did not drop over time in either group and actually rose between 21 and 60 weeks of age in the CEO group. Both vaccines protected layers against severe challenge with virulent ILT virus, neither being significantly better than the other under these experimental conditions. Unvaccinated sentinel chickens were maintained in contact with the vaccinated layers during three intervals between 1 day and 6 weeks post-vaccination. Diagnostic tests performed on the sentinels to detect lateral spread of vaccine virus from vaccinated to unvaccinated chickens showed scattered positive results.     

Comparative microscopic lesions in reoviral and staphylococcal tenosynovitis

Experimental inoculation of 1-day-old male broiler chickens with avian reo-virus or Staphylococcus aureus caused tenosynovitis of the gastrocnemius and digital flexor tendons. Reovirus inoculation by either the oral or footpad route initiated a diffuse lymphocytic infiltration in the peritendineum, synovial membrane, and epitenon from 1 to 5 weeks postinoculation (PI). Heterophils were not a predominant feature of the inflammatory response, but when present they were localized with fibrin in and around synovial spaces. The prevalence of microscopic tendon lesions was less common with staphylococcal infection than with reovirus infection. With staphylococcus, lesions were localized to the synovial space and membranes and were characterized by heterophils and fibrin but few lymphocytes. Synovial cell hyperplasia and bursal atrophy were common in both groups. From 10 to 20 weeks PI, both groups developed progressive tendon fibrosis. These results indicate that tenosynovitis due to inoculation with reovirus or staphylococcus may be differentiated histologically from 1 through 5 weeks PI. After 10 weeks, this may not be possible, because diffuse fibrosis was the major lesion with both. Perhaps fibrosis predisposes older, heavier broilers to tendon failure and rupture.     

Canine pythiosis--isolation and identification of Pythium insidiosum

Pythium insidiosum was isolated from the subcutaneous tissue of a 1-year-old tan crossbreed dog and from the intestinal tract of an 18-month-old Samoyed male. Gomori's methenamine silver stain was superior to hematoxylin and eosin in demonstrating the organism in tissue sections. The agent was identified as P. insidiosum by zoospore formation in an aqueous yeast extract solution containing grass blades. Exoantigens produced in culture were shown to be identical to known P. insidiosum antigens by microimmunodiffusion.     

Influence of diet composition on intestinal volatile fatty acid and nutrient absorption in unanesthetized pigs

Two experiments were conducted to study the effect of the amount and nature of fiber and carbohydrates on nutrient and VFA absorption. Five Large White pigs in each crossover experiment were accustomed to a semisynthetic 14% protein diet containing 6 (LC) or 16% (HC) pure cellulose (Exp. 1) or 22% alfalfa meal (6.3% cellulose, HA) and 22% lactose and 6% pure cellulose (HL; Exp. 2). Each animal was then fitted with catheters in the portal vein and carotid artery and with a flow probe around the portal vein. Eight days after surgery, the absorption of reducing sugars (RS) and amino-N was studied for 12 h and that of VFA for 24 h after intake of a single 800-g meal. The alternate diet was then given for 7 to 10 d and a second series of samplings was performed within the same conditions. In the first experiment, added dietary cellulose decreased efficiency of absorption of RS (LC: 90.4 +/- 7.0%; HC: 81.6 +/- 3.6%) and amino-N (LC: 95.3 +/- 9.1%; HC: 70.3 +/- 2.8%; P less than .05). Daily absorption (24 h) of VFA tended to be larger when the cellulose level rose (LC: 1,184 +/- 85 mmol; HC: 1,429 +/- 216 mmol, NS) and increased (P less than .05) with the length of adaptation (21 to 28 d) to the diet, regardless of cellulose level. In the second experiment, after intake of the alfalfa diet, absorption of RS was high (97.8%), whereas absorption of amino-N (74.3%) and VFA (880 +/- 87 mmol/24 h) were low. Intake of lactose reduced absorption of RS (85.2%), did not alter absorption of N (75.9%) and increased absorption of VFA (1,181 +/- 218 mmol/24 h). Thus, the energy efficiency of the diet was lowered (P less than .05) when cellulose was added to the diet but not when alfalfa meal or lactose were added.     

Future challenges of disease in the beef cattle industry

Disease control must be part of the management system in any beef cattle enterprise where improved net returns are a constant goal. A current view of the importance of disease is reflected in the research portfolio of the Australian Meat and Live-stock Research and Development Corporation (AMLRDC), where only 14% of projects relate to cattle health problems. Our relative freedom from epidemics is partly responsible for this balance, but the profession should continue to be alert to the range of actual or potential threats to the national herds and those predisposing factors, both managerial and environmental, that influence their effects. In Australia with its crucial beef export component, several priority areas can be identified. They are (i) completion of the Brucellosis and Tuberculosis Eradication Campaign (BTEC) (ii) improved knowledge of the effects of production of subclinical disease including deficiency states (iii) better understanding of the infertility complex from conception to birth. Congenital viral infections such as mucosal disease and the arbovirus group are slowly emerging from their epidemiological obscurity (iv) constant awareness of the potential threat of exotic diseases and defensive methods available to meet them. There is a particular need to understand the epidemiology of the large tropical cattle herd, which interfaces with South-East Asia. Our comparative freedom from epidemics should not cause any relaxation of vigilance by the veterinary services in the private or public sectors. Nor should government be allowed to minimise the critical role of the veterinary profession in our defense against animal disease (v) increased liaison with our trading partners in livestock exports.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum concentrations of IGF-I in postpartum beef cows

Four experiments assessed changes in serum IGF-I under various physiologic conditions in postpartum cows. In Exp. 1, anestrous suckled cows (n = 25) were infused for 6 d with either saline or glucose at two different infusion rates. In Exp. 2, anestrous cows (n = 29) received either a saline (weaned and suckled controls) or 3 g/d phlorizin (weaned phlorizin) infusion for 3 d. Calves from the weaned groups were removed from 15 h before and throughout infusions. In Exp. 3, cycling suckled cows (n = 20) received prostaglandin F2 alpha (PGF2 alpha) when the 5-d saline or phlorizin infusion began. In Exp. 4, suckled cows (n = 20) had ad libitum access to feed or received 50% of control feed consumption from 30 to 40 d postpartum. Increasing glucose availability (Exp. 1) increased (P less than .05) serum IGF-I by 30 to 35%. IGF-I remained stable after weaning (Exp. 2) in phlorizin-infused cows (128.8 +/- 12.7 ng/ml), but increased (P less than .05) by 3 d after calf removal in weaned control cows (152.2 +/- 7.5 ng/ml). IGF-I also remained stable in phlorizin-infused cows following PGF2 alpha injection (Exp. 3), but increased in control cows by 2 d after PGF2 alpha (156.8 +/- 18.3 on d 2 vs. 133.7 +/- 9.8 ng/ml pre-injection; P less than .05) and remained elevated (P less than .05) during the periovulatory period. In cows receiving restricted feed intake (Exp. 4), IGF-I decreased by approximately 50% within 4 d of feed restriction (71.3 +/- 9.4 vs 137.4 +/- 16.6 ng/ml; P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of single or multiple sires and serving capacity on mating behavior of beef bulls

A study was conducted to determine the effect of serving capacity (SC) on sexual behavior of yearling bulls during single- and double-sire pasture matings. Approximately 60 crossbred virgin bulls were subjected to 3 SC tests, and 20 bulls were selected that were similar in age, BW, testes size and semen quality. Ten bulls were high SC (greater than or equal to 3 services/test) and 10 bulls were low SC (less than or equal to 2 services/test). Competitive order among the 20 bulls also was determined. Single-sire tests were conducted with 15 intact estrual heifers and 1 bull in a pasture for 6 h. Double-sire tests were conducted with 30 estrus-induced, ovariectomized heifers and 1 high SC and 1 low SC bull of approximately equal competitive order for 6 h. Bulls in double-sire tests had more (P less than .007) mounts than those in single-sire tests. High SC bulls in double-sire tests served more heifers (P less than .04) and had more services (P less than .04) than any other SC group and test type. There was no difference (P greater than .10) in the number of mounts or services between high and low SC bulls in single-sire tests. High SC bulls had a greater (P less than .002) percentage of mounts that culminated in a service that did low SC bulls. Conception rate was not different (P greater than .10) between SC groups in single-sire tests.(ABSTRACT TRUNCATED AT 250 WORDS)     

Natural causes of death in non-suckling grey seals (Halichoerus grypus)

Thirty-four grey seals which died of natural causes were examined. They ranged in age from aborted fetuses to adults, but suckling pups were excluded from the study. The commonest primary cause of death was pneumonia and a variety of parasitoses occurred as secondary lesions.     

Suspected fusariomycotoxicosis in sandhill cranes (Grus canadensis): clinical and pathological findings

In 1985 and 1986, large-scale natural die-offs of sandhill cranes in Texas were attributed to fusariomycotoxicosis. These birds demonstrated a progressive loss of motor control to the neck, wings, and legs. Based on necropsy and/or histopathology of 31 cranes, the most common lesions involved skeletal muscle and included hemorrhages, granulomatous myositis, thrombosis, and vascular degeneration. Serum chemistry results revealed that levels of creatinine kinase, aspartate aminotransferase, and alanine aminotransferase were above published normals. However, only alanine aminotransferase was higher in clinically affected cranes than in normal cranes collected from the same area.