Physiological responses of broilers to pre-slaughter lairage: effects of the thermal micro-environment?
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Abattoirs↗
Biomedical subjects
M A Mitchell
Publications and source records attributed to M A Mitchell.
Air movement and the thermal microclimates observed in poultry lairages.
1. The thermal environment experienced by broilers during transport and a 4 h lairage period were recorded for 8 loads of birds to 2 processing plants under summer and winter conditions. 2. During the transport period the thermal environment was considered not to have been a significant challenge to bird welfare. 3. During the lairage period, over all 8 d, external ambient temperatures were in the range 4 degrees to 15 degrees C during the winter trials and 12 degrees to 29 degrees C during the summer. Temperatures amongst the crated birds for this period were in the range 16 degrees to 29 degrees C and 20 degrees to 31 degrees C during the winter and summer trials respectively. 4. Air velocity measurements at bird level indicated air movement was of small magnitude (typically < 0.1 m/s) and of variable direction, despite the large air movements around the modules with speeds of over 1 m/s. 5. The potentially stressful thermal environments observed during lairage were achieved rapidly (< 1 h) after unloading. It is considered, therefore, that the minimisation of holding time alone is not a suitable control strategy. 6. The use of water-misting sprays as a control strategy in one lairage was observed to lower the temperature throughout the lairage but raised the humidity, which might offset the temperature advantage to the birds' thermoregulatory ability. 7. More closely controlled environments for broiler lairage facilities are suggested, with further work to increase air movement at bird level.
Air Movements↗
Interaction of age, strain, sex and food restriction on plasma creatine kinase activity in turkeys.
1. Plasma creatine kinase activity was determined at 4, 8, 12, 16, 20, 24, 28, 38 and 48 weeks of age in male and female traditional turkeys fed ad libitum, in male and female turkeys of a sire-line fed ad libitum or restricted to 0.5 during rearing and subsequently to 0.8 of sex-specific ad libitum-fed body weight, and in sire-line males fed ad libitum to 18 weeks and 0.8 of ad libitum body weight thereafter. 2. Plasma creatine kinase activity was low in traditional turkeys and increased rapidly after 12 weeks of age in males and females of the sire-line of turkeys. 3. Food restriction decreased the activity of plasma creatine kinase. 4. There was no difference in plasma creatine kinase activity between the sexes during rearing. After the onset of lay, the activity in plasma from females decreased at 38 weeks of age and rose dramatically in restricted females at 48 weeks when the birds had ceased laying. 5. The changes in plasma creatine kinase activity in females were associated with concomitant changes in ovarian activity as reflected in altered plasma triglyceride concentrations.
Aging↗
Influence of high dietary vitamin E supplementation on egg production and plasma characteristics in hens subjected to heat stress.
1. The effects of different dietary concentrations of vitamin E (alpha-tocopherol acetate) were investigated in 2 experiments on laying hens exposed to chronic heat stress at 32 degrees C. 2. In the first experiment, egg production and plasma concentrations of calcium and egg yolk precursors were measured in 24 hens before, during and after a stress period of one week and fed on diets containing 10 or 500 mg vitamin E/kg. 3. In the second, larger experiment, egg production and food intake were measured in 300 hens housed in 2 temperature-controlled rooms and fed on diets containing 10, 125 or 500 mg vitamin E/kg. Birds in room 1 were stressed from 24 to 28 weeks of age and those in room 2 from 32 to 36 weeks. 4. In experiment 1, egg production and egg weight were significantly higher (72.6 vs 51.2%, P < 0.05 and 66.6 vs 63.1 g, P < 0.005 respectively) during and after the period of stress in the group given 500 mg vitamin E/kg. Plasma concentrations of calcium, vitellogenin (zinc) and VLDL (triglyceride) were also higher in this group. 5. In experiment 2, egg production was significantly higher (65.4 vs 56.2%, P < 0.05) during and after the period of heat stress in birds in room 1 fed on the diet containing 500 mg vitamin E/kg. Egg production was also higher (49.9% vs 44.7%) on this treatment during the stress period in room 2, though the difference was not significant (P < 0.10). Egg weight and food intake were unaffected by treatment in either room. 6. It is concluded that dietary supplementation with extra vitamin E can, at least in part, alleviate the adverse effects of chronic heat stress in laying hens, perhaps by maintaining the supply of egg precursors in plasma.
Animal Feed↗
Physiological stress and welfare of broiler chickens in transit: solutions not problems!
The rearing of large numbers of broiler chickens at geographically dispersed sites means that they have to be transported by road, over various distances, to centralized processing plants for slaughter. The birds may be exposed to a variety of stressors during transit, including the thermal demands of the transport microenvironment. The thermal environments experienced by broiler chickens during routine transport in the U.K. on a large number of commercial vehicles under a wide range of external climatic conditions have been characterized using three-dimensional thermal mapping (temperature and water vapor density). Inadequate ventilation results in heterogeneous distributions of temperature and humidity and, thus, thermal loads within the vehicle, and, therefore, the existence of a "thermal core" in which the risk of heat stress is increased. Relationships between specific physiological indices of stress and quantified thermal loads have been determined in accurate transport simulations in the laboratory. The findings have been employed to establish a predictive model of the induction of heat stress during commercial transportation, as well as to define the acceptable ranges and limits for temperature and humidity within the transport containers. These principles have been utilized in developing a monitoring system to warn of impending heat stress and in improving vehicle design to facilitate the prevention of heat stress during broiler transportation.
Animal Welfare↗
Nonuniform heating during radiofrequency catheter ablation with long electrodes: monitoring the edge effect.
BACKGROUND: Long, narrow electrodes are being considered for radiofrequency ablation of atrial fibrillation; however, preliminary work revealed coagulum formation on the electrodes and lack of lesion continuity. This may be due to the "edge effect," which concentrates radiated energy at sharp geometric gradients. It is proposed that temperature sensors at electrode edges are preferable to a single centered sensor for temperature feedback and monitoring of long electrode geometries. METHODS AND RESULTS: A finite element model was used to predict the heating properties of new long electrode geometries. Sixteen dogs with atrial fibrillation underwent left and right atrial ablation using catheters with multiple 12.5-mm coil electrodes. Electrodes with a single thermistor were compared with electrodes with dual thermocouples placed at opposite ends and on opposing sides of the electrode. Power, temperature, and impedance were recorded for all lesions, and coagulum adhesion and magnitude were noted in a subset of lesions. Finite element analysis shows uneven heating, with the main heating concentrated at the electrode edges and a propensity toward temperatures >100 degrees C with single-thermistor feedback control. Ablations with dual thermocouple electrodes achieved higher measured temperatures at lower power levels than those that used single-thermistor electrodes. Impedance rises and coagulum adherence occurred less frequently with dual thermocouple electrodes than with single, centered thermistor electrodes (176 of 395 versus 9 of 425 lesions; P<.0001; 46 of 98 versus 7 of 150 lesions; P<.0001, respectively). CONCLUSIONS: Maximum heating from radiofrequency energy occurs at the electrode edges, particularly with long electrodes. The safety of temperature-feedback atrial ablation with these electrodes is significantly improved by monitoring temperatures at the edges.
Animals↗
Sustained wide complex tachycardia resulting in myocardial injury in a patient with apical hypertrophic cardiomyopathy.
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Bundle of His↗
Atrial rhythm after atrioventricular junctional ablation.
Atrioventricular (AV) junctional ablation followed by pacemaker implantation is an established treatment for patients with refractory paroxysmal atrial arrhythmias. The stability of the underlying atrial rhythm after AV junctional ablation is unknown. This study evaluates the atrial rhythm after AV junctional ablation in 49 patients with medically refractory atrial arrhythmias. The group included 25 men and 24 women, of whom 36 had known structural heart disease. Paroxysmal atrial fibrillation was the primary rhythm disturbance in 41 patients, whereas 8 manifested either atrial tachycardias or atrial flutter. All patients had failed therapy with > or = 1 antiarrhythmic drug. Chronic pacing modes were DDIR or DDDR, with mode switching in 15 patients and VVIR in 34 patients. After AV junctional ablation, chronic antiarrhythmic drug therapy was prescribed in only 4 patients (8%). Routine electrocardiograms (ECGs; 6.5 +/- 6.1/patient) during long-term follow-up (18.6 +/- 15.6 months) showed that 7 patients (14%) had an atrial arrhythmia detected on all ECGs, 30 patients (61%) had sinus or atrial-paced rhythms on all recordings, and 12 patients (25%) had both atrial arrhythmias and sinus rhythm documented. Sinus or an atrial-paced rhythm was present on the last available ECG in 33 of 49 patients (67%). Pacing mode was not a predictor of continued sinus rhythm. In conclusion, most patients with a history of paroxysmal atrial tachyarrhythmias will not convert to chronic atrial arrhythmias after AV junctional ablation, even in the absence of antiarrhythmic drug therapy. Use of dual-chamber pacing modes will allow maintenance of at least intermittent atrial function in these patients.
Aged↗
In vivo expression of full-length human dystrophin from adenoviral vectors deleted of all viral genes.
Adenoviral vectors have been shown to effect efficient somatic gene transfer in skeletal muscle and thus offer potential for the development of therapy for Duchenne muscular dystrophy (DMD). Efficient transfer of recombinant genes has been demonstrated in skeletal muscle using recombinant adenoviruses deleted of E1. Application of this vector system to the treatment of DMD is limited by the vector immunogenicity, as well as by size constraints for insertion of recombinant genes, precluding the incorporation of a full-length dystrophin minigene construct. We describe in this study the use of helper adenovirus to generate a recombinant vector deleted of all viral open reading frames and containing a full-length dystrophin minigene. We show that this deleted vector (delta vector) is capable of efficiently transducing dystrophin in mdx mice, in myotubes in vitro and muscle fibers in vivo. Our modification of adenoviral vector technology may be useful for the development of gene therapies for DMD and other diseases.
Adenoviridae↗
Relationships between the degree of food restriction and welfare indices in broiler breeder females.
1. Broiler breeder females were fed ad libitum, or according to a commercial food restriction programme or to gain 0.85, 0.70, 0.55, 0.40 or 0.25 of the body weight of ad libitum-fed birds. Several indices of the welfare of the birds were assessed at 3-weekly intervals to 18 weeks of age and related to body weight by regression analysis. Results for 6, 12 and 18 weeks of age are presented in detail. 2. Water intake was consistently higher in the 0.25, 0.40 and commercial restriction treatments. 3. There was a negative curvilinear relationship at each age group between body weight and the heterophil-lymphocyte ratio and plasma corticosterone concentration. 4. There was a positive relationship between the plasma concentration of creatine kinase and body weight at 12 and 18 weeks of age. The relationships between body weight and the plasma activity of alkaline phosphatase and aspartate transaminase changed with the age and there were no differences between treatments for lactate dehydrogenase. 5. The time spent resting increased with body weight at each age. The relationship between time spent preening and body weight changed with age whereas that for oral activities was similar among restricted birds at 6, and among all treatments at 12 weeks of age. At 18 weeks there was an increase in oral activities with decreasing body weight. 6. Fearfulness was positively related to body weight. The response of the comb to phytohaemagglutinin injection was similar in all treatments and the antibody titre to injections of sheep red blood cells was curvilinear. 7. A principal components analysis of all measured traits at 6, 12 and 18 weeks of age was conducted. Most of the variables were redundant but at least one from each of the different classes of welfare indices was retained at 6 and 12 weeks of age. 8. It was concluded that a body weight during rearing in the range of 0.5 to 0.85 of ad libitum might provide for optimum welfare of broiler breeder females.
Alkaline Phosphatase↗
Creatine kinase isoenzyme profiles in the plasma of the domestic fowl (Gallus domesticus): effects of acute heat stress.
Creatine kinase isoenzyme activities in extracts of plasma, skeletal muscle, heart and brain tissue of domestic fowls were separated by anion exchange chromatography and tissue specific distributions of the isoenzyme designated MM-CK, BB-CK1 and BB-CK2 were demonstrated. The muscle isoenzyme (MM-CK) was the predominant form in plasma (99 per cent) and its activity increased in response to an episode of acute heat stress.
Acute Disease↗
Identification of tissue hypoxia in the livers of ascitic and hypoxia-induced broilers using trypan blue.
1. The perfusion of livers with the vital dye trypan blue was performed to test for evidence of tissue hypoxia in 3 groups of young broiler chickens, namely, ascitic, hypoxia-induced and controls. 2. Hepatocytes that stained with trypan blue were considered to be dead or dying before fixation and represented damaged cells. 3. The proportion of trypan blue-stained hepatocytes in the livers of ascitic birds was slightly less than half that observed in the hypoxia-induced birds but significantly more than the proportion of stained cells observed in control birds. 4. Liver damage in the ascitic birds was also assessed biochemically by an altered enzyme profile. 5. The study demonstrated that increased trypan blue uptake in the livers of ascitic birds reared at sea-level may be the consequence of hypoxia stress caused by reduced oxygen utilisation.
Animals↗
Sources and reservoirs of Toxoplasma gondii infection on 47 swine farms in Illinois.
Field studies were conducted on 47 swine farms in Illinois during 1992 and 1993 to identify sources and reservoirs of Toxoplasma gondii infection. Blood samples were obtained from swine and from trapped wildlife. Serum antibodies to T. gondii were determined using the modified agglutination test, incorporating mercaptoethanol. Antibodies to T. gondii (titer > or = 25) were found in 97 of 4,252 (2.3%) finishing pigs, 395 of 2,617 (15.1%) sows, 267 of 391 (68.3%) cats, 126 of 188 (67.0%) raccoons, 7 of 18 (38.9%) skunks, 29 of 128 opossums (22.7%), 6 of 95 (6.3%) rats, 3 of 61 (4.9%) white-footed mice (Peromyscus sp.), and 26 of 1,243 (2.1%) house mice (Mus musculus). Brains and hearts of rodents trapped on the farm were bioassayed in mice for the presence of T. gondii. Toxoplasma gondii was recovered from tissues of 7 of 1,502 (0.5%) house mice, 2 of 67 (3.0%) white-footed mice, and 1 of 107 (0.9%) rats. Feces of 274 cats trapped on the farm and samples of feed, water, and soil were bioassayed in mice for the presence of T. gondii oocysts. Toxoplasma gondii was isolated from 2 of 491 (0.4%) feed samples, 1 of 79 (1.3%) soil samples, and 5 of 274 (1.8%) samples of cat feces. All mammalian species examined were reservoirs of T. gondii infection. All farms had evidence of T. gondii infection either by detection of antibodies in swine or other mammalian species, or by detection of oocysts, or by recovery from rodents by bioassay. The possibility of transmission of T. gondii to swine via consumption of rodents, feed, and soil was confirmed.
Animal Feed↗
Risk factors for transmission of Toxoplasma gondii on swine farms in Illinois.
Two epidemiologic studies of risk factors for transmission of Toxoplasma gondii to swine were conducted for farms in Illinois. The first study was a cross-sectional survey of swine farms from the state of Illinois pseudorabies testing program, in which farm owners or managers were interviewed by telephone regarding presence of risk factors for transmission of T. gondii on the farm. There were 123 farms surveyed that provided blood samples for at least 30 sows. The mean sow seroprevalence was 19.5% (median = 10.0%). Multiple regression analysis of the association of sow seroprevalence with outdoor housing of sows, cat access to sow areas, number of sows, open feed storage and water delivery, delayed removal of carcasses, and presence of rodents on the farm indicated that higher sow seroprevalence was associated with cat access to sows (P = 0.009) and fewer sows in the herd (P = 0.05). The second study was a field investigation of 47 swine farms (37 from the cross-sectional study). Data collection included obtaining blood samples from swine, cats, and rodents, and fecal samples from cats, heart and brain tissue from rodents, and feed, water, and soil samples for T. gondii examination. The risk of T. gondii transmission from cats and rodents to sows and finishing pigs was evaluated, taking into account housing conditions and herd size. Multiple regression analysis indicated that T. gondii seroprevalence in finishing pigs increased with more seropositive juvenile cats on the farm (P < 0.0001) and higher seroprevalence in house mice (P = 0.0023).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Substitutions and deletions in the cytoplasmic domain of the phagocytic receptor Fc gamma RIIA: effect on receptor tyrosine phosphorylation and phagocytosis.
Fc gamma RIIA in the absence of other Fc receptors or receptor subunits induces the ingestion of IgG-coated cells. The cytoplasmic domain of Fc gamma RIIA contains two Y-x-x-L sequences similar to those in other Ig gene family receptors plus an additional tyrosine residue not in a Y-x-x-L motif. Upon cross-linking, Fc gamma RIIA is phosphorylated on tyrosine and the cytoplasmic tyrosines, Y275 (Y1), Y282 (Y2), and Y298 (Y3), may be important for its phagocytic activity. Because COS-1 cells can serve as a model for examining molecular structures involved in phagocytosis, substitutions and deletions were introduced into the cytoplasmic domain of Fc gamma RIIA and examined in COS-1 cell transfectants for their effects on phagocytosis and tyrosine phosphorylation. Disruption of a single cytoplasmic Y-x-x-L motif by substitution of tyrosine Y2 or Y3 by phenylalanine or by removing the threonine and leucine residues within the motif inhibited phagocytosis 50% to 65%. Tyrosine phosphorylation of Fc gamma RIIA also was inhibited, although to a greater extent by the substitution of Y3 than of Y2. Replacement of the N-terminal first cytoplasmic domain tyrosine, Y1, which is not within a typical Y-x-x-L, by itself did not inhibit phagocytosis, but replacement of Y1 in mutants lacking Y2 or Y3 virtually eliminated phagocytic activity and receptor tyrosine phosphorylation. Thus, at least two cytoplasmic tyrosines, including at least one typical single Y-x-x-L motif, are required for phagocytosis by Fc gamma RIIA. The data suggest that there is a close but not a simple relationship between phosphorylation of the Fc gamma RIIA cytoplasmic tyrosines and Fc gamma RIIA-mediated phagocytosis. Y3 appears to be particularly important because its removal by truncation or replacement with phenylalanine inhibits both tyrosine phosphorylation and phagocytosis in parallel. Alterations in the 12 residue proline-containing sequence between the two Y-x-x-L motifs also reduced phagocytic activity and tyrosine phosphorylation. Thus, the specific structure of the Fc gamma RIIA cytoplasmic domain accounts for its ability to stimulate phagocytosis in the absence of other subunits.
Amino Acid Sequence↗
CC-1065 bonding to intracellular and purified SV40 DNA: site specificity and functional effects.
CC-1065 is a minor-groove bonding agent capable of forming covalent adducts with the N-3 position of adenines within A-T-rich regions of duplex DNA. By examining the formation and location of CC-1065 adducts within the simian virus 40 (SV40) DNA molecule, the present study marks the first time that the precise sites of CC-1065 lesions have been identified at the level of eukaryotic genomic DNA. In naked DNA preparations, r values (moles of drug/mole of nucleotide base pair) > or = 0.0015 effected, after thermal treatment, a measurable decrease in intact supercoiled form I, as well as increases in forms II and III, indicating that both single-strand and apparent double-strand damage had occurred. A similar pattern of damage was observed in SV40-infected cells, albeit at higher CC-1065 levels. The amount of CC-1065 required to produce a 50% loss in form I was > 2-fold higher in infected cells (r = 0.029) than with purified DNA samples (r = 0.013). The appearance of double-strand damage at low drug levels suggested a high specificity of CC-1065 bonding to localized regions of the genome. The precise location of these CC-1065 adduction sites was examined by three methods: sequence analysis of the entire genome (GenBank), DNA polymerase termination assay of specific fragments of SV40, and restriction enzyme digestion analysis of the entire SV40 molecule. When sequence analysis of the entire genome was performed by examining both strands for the presence of the consensus CC-1065 binding sequence 5'-A/T-A/T-A/T-A/T-A*-3'[Reynolds et al. (1985) Biochemistry 24, 6228-6247], 294 single-strand adduction sites were predicted, compared to 20 sites where CC-1065 should bond to both strands within a 30-base-pair window and at which, when heated, a double-strand break should occur. DNA polymerase termination assay of actual adduction sites was performed on restriction fragments of SV40 DNA pretreated with CC-1065 in infected cells or in purified supercoiled DNA preparations and selected on the basis of the sequence analysis (i.e., regions 2510-2730, 3701-3920, 4400-4659, 4020-4320, and 5163-65). In general, double-strand lesions were detected in similar regions of the genome by the DNA termination assay and by sequence analysis. When restriction enzyme digestion and the DNA polymerase termination assay were compared throughout the genome, nearly identical patterns of adduct formation were observed. Interestingly, similar alkylation patterns were observed with either naked or infected cell DNA.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Interstitial collagenase is required for angiogenesis in vitro.
Human umbilical vein endothelial cells (HUVECs) invade collagen gels and establish vascular-like structures within the gel following stimulation with phorbol esters. This process was quantitated by measuring release of radioactivity from gels composed of [3H]collagen. Collagen was steadily degraded over the period of several weeks by phorbol ester-treated cells while little collagenolysis by cells not receiving phorbol ester was noted. Examination of matrix metalloproteinases (MMPs) secreted by HUVECs revealed a prominent induction of interstitial collagenase. Production of the mature forms of gelatinase A was also stimulated, as was the secretion of gelatinase B. Stromelysin was not detected. Two inhibitors of MMPs, the naturally occurring tissue inhibitor of metalloproteinases (TIMP; 10 micrograms/ml) and the synthetic, peptide inhibitor BB-94 (1 microM) were both effective at blocking HUVEC-mediated collagen degradation. Morphological examination of control, PMA-treated HUVECs, as well as PMA-treated HUVECs receiving TIMP or BB-94, revealed that MMP inhibition resulted in a block to invasion and tubule formation within the collagen gels. Similar results for MMP expression and inhibition of tubule formation in vitro were obtained with human dermal microvascular endothelial cells. Examination of collagen proteolytic fragments revealed that both BB-94 and TIMP blocked cleavage of the alpha 1 and alpha 2 chains of type I collagen and the appearance of tropocollagen fragments A and B, demonstrating that the inhibitors were acting directly upon interstitial collagenase. Our results demonstrate that interstitial collagenase is required for angiogenesis in vitro.
Amino Acid Sequence↗
Haematology and blood composition at two ambient temperatures in genetically fat and lean adult broiler breeder females fed ad libitum or restricted throughout life.
1. Genetically fat and lean adult broiler breeder females were fed ad libitum or restricted throughout life. At one year of age, comparisons of blood viscosity and haematology and changes in blood chemistry after exposure to thermal stress were conducted. 2. Whole blood viscosity was more than twice as high, and plasma triglyceride and haemoglobin concentrations were over 30% higher in fat line than in lean line females fed ad libitum or in restricted birds of both genotypes. 3. Mean cell haemoglobin concentration was higher and mean cell volume lower in fat compared with lean line females. 4. Food restriction was associated with lower plasma triglyceride concentrations, lower numbers of heterophils and monocytes and a lower heterophil-lymphocyte ratio. 5. Fat line birds had a higher blood pCO2 and lower pH than lean line birds. 6. Thermal stress was associated in ad libitum-fed birds with a rise in blood pH and a decrease in pCO2, and in restricted birds with a decline in blood pH and an increase in pCO2. 7. Blood creatine kinase activity increased in all groups under thermal stress.
Animals↗