Measurement of protein turnover in skeletal muscle strips

Isolated porcine and bovine muscle strips were incubated in Krebs Ringer bicarbonate buffer to determine in vitro protein synthesis (PS) and protein degradation (PD) rates to validate the in vitro system for use with livestock species. The addition of 5X plasma concentrations of amino acids to the medium stimulated PS 30%. Addition of 3.5 mM leucine to a leucine-deficient buffer supplemented with amino acids decreased PD 37% and stimulated PS 24%. The addition of .1 U/ml insulin reduced PD 28% and increased PS 30%. Protein degradation was elevated in longitudinally split rat soleus and extensor digitorum longus muscles compared to their contralateral intact muscles. Muscle strips must be removed within 15 min of exsanguination because PD rates become greatly elevated thereafter. ATP concentrations declined during incubation, but the addition of ATP or creatine had no effect on either PD or PS. Neither PD nor PS was affected by the addition of transferrin, fetuin, ascorbate, dexamethasone or indomethacin to the incubation medium. However, muscle strips were sensitive to the addition of triiodothyronine (T3), PD was increased up to 75% as T3 concentration was increased, and PS rates doubled compared to controls. Serum from mature barrows or gilts had no effect on protein turnover, but the addition of 10% and 15% serum from boars increased both PD and PS. With fasted pigs a continual decline in PS occurred over 5 d, whereas PD was elevated at 3 d and then declined to rates comparable to the fed state after 5 d. These data suggest that the in vitro system has application for assessing relative changes that occur in vivo following nutritional, physiological and endocrinological manipulation.     

Immunological cross-reactivity between pseudocapsular antigens of strains of Staphylococcus aureus isolated from cases of bovine mastitis

An assay was developed to measure the degree of immunological cross-reactivity between the pseudocapsules of a vaccine (reference) strain of Staphylococcus aureus and pseudocapsules of strains of S. aureus isolated from cases of bovine mastitis. The field strains were obtained from Australia, New Zealand, Norway, the U.K. and the U.S.A. There was large variation among strains in cross-reactivity of their pseudocapsules with those of the reference strain. For 104 Australian strains, the range of cross-reactivity indices (CRI) was 6.1-63.2% (on a scale of 0-100%, with 0% being complete identity and 100% being nil identity); for 61 overseas strains the range of CRI values was 25.7-72.1%. The data indicated that pseudocapsule antigens of Australian strains were antigenically more closely related to those of the reference strain than were pseudocapsular antigens of strains from the 4 other countries.     

Influence of dietary protein on the pathophysiology of haemonchosis in lambs given continuous infections

Mixed-sex groups of three-month-old Finn Dorset and Dorset Horn lambs were given complete diets containing either high or low protein. A trickle infection with Haemonchus contortus of 200 larvae, given three times a week, began one month later for a 17 week period. Erythrokinetic, metabolic, digestibility and balance studies were conducted with the male lambs during weeks 12 to 14 of the infection. Clinical signs of haemonchosis became evident only in the low protein diet group. The infection was characterised by severe macrocytic anaemia, hypoproteinaemia, hypoalbuminaemia, reduced survival, high egg counts and a significantly greater worm burden. In the high protein diet group many lambs developed resistance to further infection in contrast to the low protein group in which no resistance developed. Live-weight gain was not affected by infection in the high protein diet group but decreased in the lambs given the low protein diet compared with uninfected controls. However, infection did not appear adversely to affect the digestive efficiency, nitrogen retention or iron absorption in either dietary group although loss of appetite occurred in the low protein group. Examination of a sample joint from the carcases showed infection was associated with a marked reduction in muscle mass in lambs given the low protein diet relative to the control animals.     

Quantitative correlation of parasitological and serological techniques for the diagnosis of Trypanosoma congolense infection in cattle

A comparison was made between serological and parasitological techniques for the diagnosis of bovine trypanosomiasis in Zambia. Overall sero-prevalence rates as determined by IFAT and ELISA were respectively 2.7-fold and 2.9-fold greater then the percentage of samples found positive with the dark ground/phase contrast buffy coat technique (DG). The results obtained by the two serological techniques were found to be closely correlated (94.2%) agreement) and titres obtained by ELISA tended to be slightly higher than those obtained by IFAT. Linear regression analysis of the results obtained by the IFAT and DG techniques revealed a highly significant correlation. This finding would permit the use of only one of the techniques in an epidemiological survey and to extrapolate the results from the regression line.     

Prevalence of Giardia in the feces of pups

Fecal specimens were collected from 117 healthy pups (79 privately owned pups and 38 pups from an animal shelter) and analyzed for Giardia. Giardia cysts or trophozoites were found in 35.9% of the dog feces.     

Pathogenesis of Mycobacterium bovis infection in American bison

Eighteen 12-month-old bison were randomly placed in each of 3 groups (6 animals/group): group-1 bison were exposed to live Mycobacterium bovis, group-2 bison were inoculated with killed M bovis in oil, and group-3 bison were noninfected controls. Six, 6-month-old, tuberculin test-negative calves were placed (pen contact) with group-1 bison 30 days after exposure to M bovis. Tuberculin skin test responses (caudal fold and/or comparative cervical) were detected in all bison in groups 1 and 2 at 2, 4, 6, 10, and 12 months. Tuberculin skin test responses were observed in 2 of 6 calves at 9 and 11 months after pen contact with M bovis-exposed bison (group 1). Statistically significant lymphocyte blastogenic responses to M bovis purified protein derivative were detected in group-1 bison exposed to live M bovis at 2 months after exposure (P less than 0.025). Significant ELISA reactions were detected in sera of bison at 2 months after exposure to killed M bovis in oil (P less than 0.005) and in bison 2 months after exposure to live M bovis (P less than 0.01). Significant tuberculin skin responses, ELISA reactions, or lymphocyte blastogenic responses to M bovis purified protein derivative were not observed in the 6 control bison. Grossly visible tuberculous lesions were observed in lymph nodes and/or lung collected at necropsy in 4 of 6 bison at 12 months after exposure to live M bovis. Microscopic granulomas compatible with tuberculosis were detected in 5 of 6 bison; M bovis was isolated from tissues of each of the 6 bison.(ABSTRACT TRUNCATED AT 250 WORDS)