Relationship between development of intramuscular connective tissue and toughness of pork during growth of pigs.
(1/383)
We investigated changes in structures and properties of the endomysium and perimysium during development of semitendinosus muscle in relation to the increase in toughness of pork using samples from neonates to 55-mo-old pigs. The shear force value of pork increased linearly until 6 mo of age, and the rate of increase slowed down thereafter. The secondary perimysium thickened owing to an increase in the number and thickness of perimysial sheets consisting of collagen fibers, which became thicker and wavy with the growth of the pigs. This increase in thickness of the secondary perimysium was correlated significantly with the increase in the shear force value (r = .98). The endomysial sheaths became thicker and denser in the muscle of 6-mo-old pigs. Maturation of the endomysium was accompanied by hypertrophy of muscle fibers. The amount of heat-soluble collagen decreased almost linearly, indicating that nonreducible cross-links between collagen molecules were formed throughout chronological aging. We conclude that thickening of the perimysium is closely related to an increase in the toughness of pork during growth of pigs. (+info)
The effect of cyclopiazonic acid on the development of pale, soft, and exudative pork from pigs of defined malignant hyperthermia genotype.
(2/383)
Malignant hyperthermia (MH) and the mycotoxin cyclopiazonic acid (CPA) are each associated with abnormal calcium homeostasis in skeletal muscle, a key underlying factor in the development of pale, soft, and exudative (PSE) pork. To determine whether the natural presence of CPA in livestock feed ingredients contributes to the varying incidence of PSE in the pork industry, various levels of CPA (.1 to 50 mg/kg of diet) were included in the diets of market weight hogs (n = 52) of defined malignant hyperthermia genotype (NN = normal, Nn = a MH carrier, and nn = MH-positive). Animals with two copies of the MH mutation (nn) displayed improved live animal performance compared with NN and Nn animals (increased feed intake, average daily gain, and feed efficiency) but yielded lower quality loin chops as indicated by lower 45-min pH (P<.01), higher Commission Internationale de l'Eclairage (CIE) L* color coordinate values (P<.05), and higher drip losses (P<.01). The effects of CPA varied. In the first feeding trial, conducted under normal outside temperatures (2 degrees C), CPA had no effect (P> .2) on either live animal performance or meat quality. During the second trial, conducted under extreme outside temperatures (-18 degrees C), CPA-dependent reductions (P<.05) in feed intake, average daily gain, and 45-min pH in nn hogs support the possibility of interactions between malignant hyperthermia and dietary CPA on skeletal muscle calcium homeostasis and the development of PSE pork. These results suggest that this interaction may require stressful environmental conditions or the ingestion of CPA doses much higher than occur under natural conditions. (+info)
Analysis and pharmacokinetics of cyclopiazonic acid in market weight pigs.
(3/383)
The pharmacokinetic behavior of cyclopiazonic acid (CPA) was determined in market weight pigs using a competitive indirect ELISA developed for the determination of the mycotoxin in various biological matrices. Sample preparation for corn and skeletal muscle was achieved with a single extraction and recoveries of 53+/-6% over the effective range of the standard curve. The detection limit of CPA was 1 ppb in plasma, which required no extraction, and 20 ppb in corn and skeletal muscle with average intra- and interassay CV of 11 and 23%, respectively. Levels of CPA contamination in corn grown and stored in Michigan were unremarkable compared with published toxicity thresholds; the highest level of CPA found in any sample was 47 ppb. In pigs given a 20-mg i.v. bolus, CPA distributed rapidly among three compartments, with an overall volume of distribution (49 L) nearly equivalent to total body water. Cyclopiazonic acid was eliminated with a half-life of 24 h. Estimates of these pharmacokinetic parameters were supported by the achievement of steady-state plasma CPA levels within 6 d in pigs consuming a diet containing 10 ppm CPA, and by measured concentrations of CPA in plasma (410+/-44 ng/mL) and skeletal muscle (469+/-86 ng/ g). From these and other data, we concluded that the threat of CPA toxicity to livestock from consumption of cereal grains or to humans from consumption of animal products is minimal. (+info)
From a philosopher's perspective, how should animal scientists meet the challenge of contentious issues?
(4/383)
This article reviews how professional ethics can be useful in helping animal scientists meet new responsibilities. The transition to a postindustrial period in animal production signals a shift in the nature of contentious issues that animal producers face. Whereas farm income was once the most controversial issue in animal production, producers and animal scientists now face complex risk issues that have overlapping constituencies. Animal scientists need to develop a professional ethic that will stress open and active debate on these issues. Discussion of these issues must take place in the animal science classroom. The new professional ethic should be based on core values required for scientific research. However, departments and professional societies must develop institutions that will permit the values and methods of rationality and truth seeking to be applied in areas where measurement and experimental method are unlikely to resolve disputes, (i.e., to controversial issues that require public discussion and debate). Several specific proposals for such institution building are discussed. (+info)
Tenderness classification of beef: III. Effect of the interaction between end point temperature and tenderness on Warner-Bratzler shear force of beef longissimus.
(5/383)
The objectives of this experiment were to determine 1) whether end point temperature interacts with tenderness to affect Warner-Bratzler shear force of beef longissimus and 2) if so, what impact that interaction would have on tenderness classification. Warner-Bratzler shear force was determined on longissimus thoracis cooked to either 60, 70, or 80 degrees C after 3 and 14 d of aging from carcasses of 100 steers and heifers. Warner-Bratzler shear force values (3- and 14-d aged steaks pooled) for steaks cooked to 70 degrees C were used to create five tenderness classes. The interaction of tenderness class and end point temperature was significant (P < .05). The increase in Warner-Bratzler shear force as end point temperature increased was greater (P < .05) for less-tender longissimus than more-tender longissimus (Tenderness Class 5 = 5.1, 7.2, and 8.5 kg and Tenderness Class 1 = 2.4, 3.1, and 3.7 kg, respectively, for 60, 70, and 80 degrees C). The slopes of the regressions of Warner-Bratzler shear force of longissimus cooked to 60 or 80 degrees C against Warner-Bratzler shear force of longissimus cooked to 70 degrees C were different (P < .05), providing additional evidence for this interaction. Correlations of Warner-Bratzler shear force of longissimus cooked to 60 or 80 degrees C with Warner-Bratzler shear force of longissimus cooked to 70 degrees C were .90 and .86, respectively. One effect of the interaction of tenderness with end point temperature on tenderness classification was to increase (P < .01) the advantage in shear force of a "Tender" class of beef over "Commodity" beef as end point temperature increased (.24 vs .42 vs .60 kg at 14 d for 60, 70, and 80 degrees C, respectively). When aged 14 d and cooked to 80 degrees C, "Commodity" steaks were six times more likely (P < .01) than "Tender" steaks to have shear force values > or = 5 kg (24 vs 4%). The end point temperature used to conduct tenderness classification did not affect classification accuracy, as long as the criterion for "Tender" was adjusted accordingly. However, cooking steaks to a greater end point temperature than was used for classification may reduce classification accuracy. The beef industry could alleviate the detrimental effects on palatability of consumers cooking beef to elevated degrees of doneness by identifying and marketing "Tender" longissimus. (+info)
Stress tolerance in doughs of Saccharomyces cerevisiae trehalase mutants derived from commercial Baker's yeast.
(6/383)
Accumulation of trehalose is widely believed to be a critical determinant in improving the stress tolerance of the yeast Saccharomyces cerevisiae, which is commonly used in commercial bread dough. To retain the accumulation of trehalose in yeast cells, we constructed, for the first time, diploid homozygous neutral trehalase mutants (Deltanth1), acid trehalase mutants (Deltaath1), and double mutants (Deltanth1 ath1) by using commercial baker's yeast strains as the parent strains and the gene disruption method. During fermentation in a liquid fermentation medium, degradation of intracellular trehalose was inhibited with all of the trehalase mutants. The gassing power of frozen doughs made with these mutants was greater than the gassing power of doughs made with the parent strains. The Deltanth1 and Deltaath1 strains also exhibited higher levels of tolerance of dry conditions than the parent strains exhibited; however, the Deltanth1 ath1 strain exhibited lower tolerance of dry conditions than the parent strain exhibited. The improved freeze tolerance exhibited by all of the trehalase mutants may make these strains useful in frozen dough. (+info)
Inulin and oligofructose: what are they?
(7/383)
Inulin is a term applied to a heterogeneous blend of fructose polymers found widely distributed in nature as plant storage carbohydrates. Oligofructose is a subgroup of inulin, consisting of polymers with a degree of polymerization (DP) +info)
Pontiac fever at a sewage treatment plant in the food industry.
(8/383)
BACKGROUND AND OBJECTIVES: During a hot and humid summer period workers became ill with fever and flu-like symptoms after repairing a decanter for sludge concentration at a sewage treatment plant. The work took place over a period of 10 days in a small closed room, while another decanter was in operation and was consequently emitting aerosol to the environment, to which the workers were exposed. The aim of this study was to determine the cause of this outbreak of febrile illness so that additional cases could be prevented. METHODS: All 5 patients were seen and examined in the Department of Occupational Medicine. Furthermore 2 of the workers had recurrent illness and were examined during hospitalization. As Pontiac fever (nonpneumonic legionellosis) was suspected, antibodies to legionellae were measured in blood samples. After positive antibody titers to Legionella pneumophila were found, samples of the sludge were collected for legionellae culture. RESULTS AND CONCLUSIONS: The clinical picture agreed with that described for Pontiac fever, and positive antibody titers to L. pneumophila serogroup 1 were found in blood from all 5 patients. L. pneumophila serogroup 1 was cultured in high amounts from sludge from the decanter. It was concluded that the fever was caused by L. pneumophila emitted to the environment by the uncovered decanter. Procedures for preventing new cases were established. (+info)