Interaction between ascites susceptibility and CO during the second half of incubation of two broiler lines. Effect on embryonic development and hatching process

1.?Because CO₂ during the second half of incubation is known to influence air cell and blood gases, and embryo development, it is postulated that post-hatch development and ascites sensitivity could also be influenced.

2.?An ascites susceptible (A) and an ascites resistant (E) broiler line were incubated under standard incubation or high CO₂ conditions (up to 4%) from embryonic day (ED) 10 onwards. The embryonic development and the hatching process of these two lines were compared when incubated under standard or high CO₂ conditions from over the second half of incubation.

3.?The A line, selected for high post-hatch growth rate, exhibited a higher relative embryo weight from ED10 until ED16, which was supported by a higher air cell pCO₂, lower air cell pO₂, higher corticosterone and thyroid hormones and earlier hatching time.

4.?Incubation under high CO₂ increased air cell pCO₂, retarded yolk consumption, and decreased glycogen concentration in the liver at hatch. Hatchability decreased in both lines when incubated under high CO₂, due to an increased late mortality of embryos that died before IP.

5.?These results suggest that the development and metabolism of CO₂-incubated embryos differ from control incubated embryos.     

A comparison of the effects of carbon dioxide and medical air for abdominal insufflation on respiratory parameters in xylazine-sedated sheep undergoing laparoscopic artificial insemination

AIMS: To determine if abdominal insufflation with medical air will improve oxygenation and ventilation parameters when compared to insufflation with CO₂ in xylazine-sedated sheep undergoing laparoscopic artificial insemination (AI).

METHODS: Forty-seven sheep underwent oestrus synchronisation and were fasted for 24 hours prior to laparoscopic AI. Each animal was randomised to receive either CO₂ or medical air for abdominal insufflation. An auricular arterial catheter was placed and utilised for serial blood sampling. Respiratory rates (RR) and arterial blood samples were collected at baseline, after xylazine (0.1?mg/kg I/V) sedation, 2 minutes after Trendelenburg positioning, 5 minutes after abdominal insufflation, and 10 minutes after being returned to a standing position. Blood samples were collected in heparinised syringes, stored on ice, and analysed for arterial pH, partial pressure of arterial O₂ (PaO₂), and CO₂ (PaCO₂). The number of ewes conceiving to AI was also determined.

RESULTS: Repeated measures ANOVA demonstrated temporal effects on RR, PaO₂, PaCO₂ and arterial pH during the laparoscopic AI procedure (p<0.001), but no difference between insufflation groups (p>0.01). No sheep experienced hypercapnia (PaCO₂>50?mmHg) or acidaemia (pH<7.35). Hypoxaemia (PaO₂<70?mmHg) was diagnosed during the procedure in 14/22 (64%) ewes in the CO₂ group compared with 8/23 (35%) ewes in the medical air group (p=0.053). Overall, 15/20 (75%) ewes in the CO₂ group conceived to AI compared with 16/22 (72.7%) in the medical air group (p=0.867).

CONCLUSIONS AND CLINICAL RELEVANCE: There were no statistical or clinical differences in RR, PaO₂, PaCO₂, pH, or conception to AI when comparing the effects of CO₂ and medical air as abdominal insufflation gases. None of the sheep experienced hypercapnia or acidaemic, yet 42% (19/45) of sheep developed clinical hypoxaemia, with a higher percentage of ewes in the CO₂ group developing hypoxaemia than in the medical air group. Based on the overall analysis, medical air could be utilised as a comparable alternative for abdominal insufflation during laparoscopic AI procedures.     

Gas composition in controlled atmosphere stunning affects turkey meat quality traits

1. Investigations were made into the breast and leg muscle energy metabolism, and the quality of breast meat of turkeys after controlled atmosphere stunning or stun-killing (CAS) with various gas mixtures. In addition, the effect on meat quality of an increase in the chilling rate of turkey breast meat after hypercapnic or anoxic stun-killing was studied.

2. A total of 35 turkey toms within two replicate pens were individually stunned during consecutive weeks using one of 4 CAS methods. The stunning gases tested were high CO₂ concentration (60% CO₂ in air), high N₂ concentration (98% N₂,?2), a mixture of 76% N₂ and 24% CO₂, and a biphasic method (first minute in mixture containing 40% CO₂, 30% N₂, and 30% O_2; followed by two minutes in a mixture containing 60% CO₂ in air).

3. The birds stunned with N₂ displayed the highest initial reduction in muscle pH, but after 4?h post mortem there were no differences in pH values associated with the various CAS methods.

4. The CAS method alone had no statistically significant effect on the quality of turkey breast muscle when the chilling speed was rapid (0°C for 4?h, followed by storage at 4°C). When the chilling rate was slowed (20°C for 4?h followed by storage at 4°C), a significant decrease in cooking loss and in Warner-Bratzler shear force was recorded for birds stun-killed with CO₂.

5. This study shows that anoxic stun-killing with N₂ had no adverse effects on meat quality despite the rapid post mortem pH decrease. The CAS with N₂ allows rapid cooling of carcases without the risk of cold shortening, whereas with CO₂-stun-killing of turkeys, the rate of chilling should be slower. Concerning meat quality, all the CAS methods tested were suitable for stunning turkeys.     

The air space and embryonic respiration. 3. The balance between oxygen and carbon dioxide in the air space of the incubating chicken egg and its role in stimulating pipping

Blocking the respiratory exchange through the shell over the air space by coating the shell with paraffin was attended by a sharp decrease in the oxygen content and a moderate increase in the carbon dioxide content of the air space. Before the parafoetal period the paraffin‐coated air space contained 6.4–8.5 per cent O₂ and 7.2 per cent CO₂. In normal eggs the composition of the gas mixture was 14.2 per cent O₂ and 5.6 per cent CO₂. During the parafoetal period the air space of paraffin‐coated eggs contained 4.6–6.5 per cent O₂ and 7.3–7.7 per cent CO₂ as compared with 9.0 per cent O₂ and 6.6 per cent CO₂ in the controls. Shortly before pipping the O₂ content was 5.2 per cent and the CO₂ content 9.1 per cent in the paraffin‐coated eggs and 8.6 per cent O₂ and 8.1 per cent CO₂ in the controls.

It has been shown that the time of pipping is accelerated by a decreased O₂ content as well as by an increased CO₂ content in the air space. The stimulating effect of CO₂, however, was about twice that of O₂.

The deviations from the mean pattern of gaseous exchange through the shell over the air space and the allantoic shell in normal eggs was linked with the duration of the parafoetal period. It was shown that the egg shells were pipped earlier when the respiratory quotient on the air space side was greater, and on the allantoic side smaller, than the mean. This relation was due to the fact that the parafoetal period was positively and linearly dependent on the O₂ intake through the air space and the CO₂ output through the allantois, but not on the CO₂ output through the air space and the O₂ intake through the allantois. It was shown that the differences between the eggs in the level of gaseous exchange were not the result of differences in egg shell porosity but of differences in the ability of the lungs to take up O₂ and the allantois to give off CO₂.

After blocking the gaseous exchange through the shell over the air space about two‐thirds of the CO₂ output and about one‐quarter of the O₂ uptake originally established through this part of the shell appeared to be taken over by the allantois. The total O₂ uptake therefore fell more than the CO₂ output after this treatment with the result that the respiratory quotient rose.

It was shown that the length of the parafoetal period in both normal eggs and eggs with a paraffin‐coated air space was dependent on the nature and magnitude of the gaseous exchange through the shell over the air space and allantoic shell during this period.     

Colostral Transfer in the Goat of Antibodies Against Corynebacterium Pseudotuberculosis and the Antibody Status of Kids During the First 10 Months of Life

Serum and colostrum samples from goats at parturition and serum samples from their kids at 3 days and at 4, 7, 10 and 12 weeks after birth were examined for the presence of antibodies to Corynebacterium pseudotuberculosis hemolysins. The hemolysis inhibition test (HIT) was used. High correlation was found between titre values of antihemolysins in serum and colostrum of goats at parturition (correlation coefficient r = 0.83; P < 0.01). Intermediate correlation was found between antihemolysin titre in colostrum of goats and in the sera of their kids 3 days old (r = 0.56; 0.01 < P < 0.05). Furthermore, titre values for 3 day-old kids showed high correlation with the antihemolysin titres when the kids aged 4 and 7 weeks (r = 0.76 and 0.85, respectively; P < 0.01). Antihemolysin titres decreased linearly in kids from 3 days to 10 weeks old. Calculated half life of antibodies was 12 days. Most of the kids had detectable antibodies up to the age of 5–6 weeks. None of the kids were seropositive at 2½ months of age.Serum samples collected monthly from a group of kids chosen at random, aged 7–10 months, contained antibodies to hemolysins in half of the animals at the first testing. At the age of 10 months 14 out of 15 kids were seropositive. Thus, most of the kids from this herd were exposed to G. pseudotuberculosis antigens during summer and autumn of their first year of life.Prophylactic measures against caseous lymphadenitis is briefly discussed.     

The effects of temperature on the silage microbiology and aerobic stability of corn and vetch-grain silages

Abstract

The purpose of the current work was to extend the study of the effect of temperature on silage microbiology, with or without formic acid, and on the aerobic stability of corn and vetch-grain silages.

The silage samples were ensiled in 1.0-l anaerobic jars, with and without formic acid, at room (20°C) or elevated temperatures (30–37°C). After 45 days of ensiling, the silages were subjected to an aerobic stability test at room (20°C) and elevated (30–37°C) temperatures. The most intensive deterioration occurred at 30–37°C. Samples incubated at 30–37°C had the highest yeast and mould count, most prolific CO₂ production.

The finding of the current study suggests that formic acid may decrease mould growth in silage samples. Unfortunately, formic acid does not reduce aerobic deterioration rate of silages. Applying a 5 g/kg formic acid on corn and vetch-grain silages was not very effective at high temperatures.     

Test protocol of an enzyme‐linked immunosorbent assay (ELISA) for the detection of antibodies against bovine leukosis virus

Summary

In this communication the test procedure is described for an indirect enzyme‐linked immunosorbent assay (ELISA) for the detection of antibodies against bovine leukosis virus (BLV). Test sera are incubated in polystyrene microtiter plates sensitized with a partly‐purified preparation of BLV. Bovine antibodies are detected with anti‐species immunoglobulin conjugated to the enzyme horseradish peroxidase, followed by the addition of the enzyme substrate.     

Association of partial pressure of carbon dioxide in expired gas and arterial blood at three different ventilation states in apneic chickens (Gallus domesticus) during air sac insufflation anesthesia

ObjectiveTo test whether partial pressure of CO₂ in expired gas (PēCO₂) predicts the partial pressure of CO₂ in arterial blood (PaCO₂) in apneic chickens during air sac insufflation anesthesia at three different ventilation states. Secondary objective: To determine the PēCO₂ at which apnea occurs during air sac insufflation anesthesia.Study designRandomized cross-over study.AnimalsTwenty-three healthy male white leghorn chickens.MethodsChickens were anesthetized via mask with isoflurane in oxygen and an air sac cannula was placed in the right abdominal air sac. Delivery of isoflurane in O₂ was transferred from the mask to the air sac cannula. The birds were maintained at a surgical plane of anesthesia and apnea was induced by adjusting gas flow; the PēCO₂ at apnea was recorded. The birds were then paralyzed and gas flow was adjusted to achieve three different PēCO₂s in random order: 43 mmHg (5.6 kPa) [hypoventilation]; 33 mmHg (4.3 kPa) [normoventilation]; and 23 mmHg (3.0 kPa) [hyperventilation]. After maintaining the target expired isoflurane concentration (EIso; 1.85 or 1.90%) and PēCO₂ for 15 minutes, arterial blood gas analysis was performed to determine the PaCO₂. The chickens were euthanized at the end of the experiment.ResultsBased on Bland-Altman comparisons, PēCO₂ was not strongly associated with PaCO₂ during the three ventilation states. The PēCO₂ at which apnea occurred varied {median (minimum, maximum): 35 (30, 48) mmHg [4.6 (3.9, 6.2) kPa]}.ConclusionsMeasured PēCO₂ cannot be used in a simple linear fashion to predict PaCO₂ in birds during air sac insufflation anesthesia. The PēCO₂ at which apnea occurs during air sac insufflation anesthesia is not predictable.Clinical relevanceArterial blood gases should be used to monitor CO₂ during air sac insufflation anesthesia to verify appropriate patient ventilation.     

Influence of Osteopontin in Bovine Uterine Tube Fluid on Sperm Binding and Fertilization in RCA-1 Lectin-treated Oocytes

This study was conducted to determine the effect of pre‐exposure of oocytes to Ricinus communis (RCA‐1) lectin and osteopontin (OPN) in uterine tube fluid (UTF) on in vitro sperm–egg binding and fertilization. In vitro‐matured bovine oocytes were incubated (39°C, 5% CO₂ in air) for 2 h in the following treatments: (i) 500 μl of fertilization medium (FM); (ii) 250 μl of FM with 0.25 ml of non‐luteal ampullary uterine tube fluid (NLAUTF); (iii) 250 μl of FM with 250 μl of NLAUTF and 4 μl of RCA‐1 lectin; (iv) 250 μl of FM with 250 μl of NLAUTF, a rabbit polyclonal antibody (1:200) against purified bovine milk OPN, and RCA‐1 lectin; (v) 500 μl of FM and RCA‐1 lectin. Following incubation, oocytes were washed, placed in FM with 2 μg heparin, and incubated with 1 × 10⁵ frozen–thawed spermatozoa per 10 oocytes. Oocytes used to assess sperm binding were stained with Hoescht 33342, and the number of sperm bound per zona pellucida counted. The remaining oocytes were fixed in acid alcohol, stained with 1% acetate‐orcein and observed to determine the presence of pronuclei. More sperm bound to the zona pellucida (mean ± SEM) when oocytes were incubated in treatment 3 (59.0 ± 5.5) than in treatments 2 (46.4 ± 5.6), 4 (18.1 ± 5.4), 5 (33.4 ± 5.6) or 1 (32.5 ± 5.6). More oocytes were fertilized when incubated in treatment 3 (91% ± 3.0) than in 2 (84% ± 3.0), 4 (40% ± 3.0), 5 (77% ± 3.0) or 1 (76% ± 3.0). As in previous studies, this study suggests that RCA‐1 lectin enhances binding of UTF‐derived OPN to bovine oocytes, resulting in increased sperm–egg binding and fertilization in vitro and a possible role in fertilization.     

Alternate complement pathway in porcine sera: Lysis of guinea pig erythrocytes

The hemolysis by porcine sera of unsensitized erythrocytes (EU) from nine different species was investigated. Optimal lysis occurred when porcine sera were reacted with unsensitized guinea pig erythrocytes suspended in a pH 6.5, barbital-buffered saline solution, made 0.1% in gelatin, and containing 10 mm ethyleneglycol-bis (β-amino-ethyl ether) N, N¹-tetraacetic acid and 4 mm MgCl₂ (BSG-EGTA-Mg). Results of studies with several different treatments that inhibit complement (C) induced hemolysis indicated that the alternate C pathway was involved in the lysis of EU in the BSG-EGTA-Mg buffer. The extent of lysis was decreased when porcine sera were adsorbed with zymosan, mixed with 20 mm salicylaldoxime, or heated at 50%C. However, carrangeenan treatment caused only a slight decrease in the extent of hemolysis induced. Cobra venom factor activated the alternate C pathway in porcine sera. The pattern of C component utilization resulting from lysis of EU by porcine sera indicated activation of the alternate and not the classical C pathway. Extensive adsorption of porcine sera with packed guinea pig erthrocytes at 0°C only slightly reduced its capacity to lyse guinea pig erythrocytes. Collectively, these results provided evidence that the membrane of the guinea pig erythrocyte is able to active the alternate C pathway of porcine sera without the direct involvement of specific antibody.     

Oxidative stress in the erythrocytes of cattle intoxicated with Senecio sp

BACKGROUND: Intoxication caused by Senecio sp is characterized by irreversible damage to liver cells and may be associated with oxidative stress. OBJECTIVES: The aim of this study was to evaluate the effects of intoxication by Senecio sp on lipoperoxidation, antioxidant defenses, and the osmotic resistance of erythrocytes in cattle. METHODS: Blood samples from 30 intoxicated animals (group 1) and 30 healthy animals (group 2) were analyzed. The diagnosis of poisoning by Senecio sp was based on histopathologic lesions verified through hepatic biopsy. The following biochemical parameters of oxidative stress in the erythrocytes were determined: thiobarbituric acid-reactive substances (TBARS), copper-zinc superoxide dismutase (CuZnSOD) activity, and nonprotein sulfhydryl (NPSH) groups. Erythrocyte osmotic fragility also was evaluated. RESULTS: TBARS concentration and CuZnSOD activity were significantly (P <.001) higher in group 1 when compared with group 2. The concentration of erythrocyte NPSH groups was significantly (P <.03) lower in group 1 when compared with group 2. Osmotic fragility was more pronounced in the erythrocytes of group 1 when compared with group 2 (P < .001). CONCLUSIONS: The results of this study indicate that poisoning by Senecio sp causes an increase in lipoperoxidation, oxidation of NPSH groups, and consequently, oxidative stress in bovine erythrocytes that may contribute to hemolysis. These findings may contribute to a better understanding of the mechanisms involved in cell damage in animals intoxicated by Senecio sp.     

Higher levels of CO2 during late incubation alter the hatch time of chicken embryos

1. It has been reported that the increasing CO₂ tension triggers the embryo to pip the air cell and emerge from the egg. However, the mechanism by which higher CO₂ concentrations during the last few days of incubation affect chick physiology and the hatching process is unclear. This study investigated the effect of CO₂ concentrations up to 1% during pipping, on the onset and length of the hatch window (HW) and chick quality.

2. Four batches of Ross 308 broiler eggs (600 eggs per batch) were incubated in two small-scale custom-built incubators (Petersime NV). During the final 3 d of incubation, control eggs were exposed to a lower CO₂ concentration (0.3%), while the test eggs experienced a higher CO₂ concentration programme (peak of 1%).

3. There were no significant differences in blood values, organ weight and body weight. There was also no difference in hatchability between control and test groups. However, a small increase in the chick weight and the percentage of first class chicks was found in the test groups. Furthermore, plasma corticosterone profiles during hatching were altered in embryos exposed to higher CO_2; however, they dropped to normal levels at d 21 of incubation. Importantly, the hatching process was delayed and synchronised in the test group, resulting in a narrowed HW which was 2.7 h shorter and 5.3 h later than the control group.

4. These results showed that exposing chicks to 1% CO₂ concentration during pipping did not have negative impacts on physiological status of newly hatched chicks. In addition, it may have a significant impact on the physiological mechanisms controlling hatching and have benefits for the health and welfare of chickens by reducing the waiting time after hatching.     

Influence of Aguamiel (Agave atrovirens) as a Natural Feed Additive on Cecal Fermentation Kinetics of Some Forage Species in Horse Feeding

This study aimed to evaluate the effect of different dose levels of aguamiel (Agave atrovirens) on in vitro cecal gas, methane (CH₄), and carbon dioxide (CO₂) productions of five forage species (Avena sativa [hay]), Moringa oleifera, Caesalpinia coriacea, Salix babylonica, and Eichhornia crassipes using inocula from the horse. The forage samples were incubated with three doses of aguamiel: 0, 34, and 68 μg of aguamiel/g dry matter (DM) of substrate. Cecal inocula were collected from four adult female Criolla horses (3–4 years of age and weighing 300 ± 15.0 kg) grazed on native grasses for about 8 hours without supplementation. Forage type affected (P < .001) cecal asymptotic, rate and lag time of gas, CH₄ and CO₂ productions (mL/g DM), pH and DM degradability. Aguamiel dose had linear and quadratic effects (P < .05) on the asymptotic and rate of CH₄ productions and rate and lag time of CO₂ productions (mL/g DM). Forage type × aguamiel dose interactions were significant (P < .05) for asymptotic, rate and lag time of gas, and CH₄ and CO₂ productions (mL/g DM). Forage species effects were pronounced (P < .05) on CH₄ and CO₂ productions (mL/g incubated and degraded DM) and proportional CH₄ production at all hours of incubation, except for CO₂ production (mL/g incubated DM). Aguamiel dose affected (P < .05) CO₂ production (mL/g incubated DM) and proportional CO₂ production at the incubated hours. Forage type × aguamiel dose interactions were observed (P < .05) for CO₂ production (mL/g incubated DM) and proportional CO₂ production at the incubated hours but had no impact on CH₄ production. It is concluded that addition of aguamiel to five forage species affected fermentation kinetics of gas production resulting in different in vitro cecal gas, CH₄ and CO₂ productions from these substrates.     

Hemolytic anemia,spherocytosis, and thrombocytopenia associated with honey bee envenomation in a dog

This case report describes a massive honey bee envenomation in a 14‐month‐old male Belgian Malinois dog from St. Kitts, West Indies. Acute and delayed onsets of hemolytic anemia, echinocytosis, spherocytosis, thrombocytopenia, hemoglobinemia, and hemoglobinuria developed following envenomation. The dog recovered after treatment with glucocorticoids and supportive therapy. Spherocytosis, hemolysis, and thrombocytopenia in patients with massive bee envenomation are likely due to the direct toxic effects of the primary components of bee venom, melittin and phospholipase A₂ (PLA₂). Mellitin causes hemolysis by forming large pores in erythrocytes resulting in leakage of hemoglobin and also causes spectrin stiffening and resultant echinocyte and spherocyte formation. Melittin also stimulates PLA₂, a hydrolase that causes echinocytosis and spherocytosis, in vivo and in vitro, and mitochondrial breakdown in platelets. However, delayed manifestations could be attributed to immune‐mediated mechanisms from the generation of antibodies against damaged erythrocytes and platelet membrane proteins.     

Effects of exogenous lactoferrin on characteristics and functions of bovine epididymal,ejaculated and frozen-thawed sperm

The purpose of this study was to investigate effects of addition of lactoferrin on characteristics and functions of bovine epididymal, ejaculated, and frozen-thawed sperm. The addition of lactoferrin was significantly (p < .05) effective on increasing values of progressive motility, straightness, and linearity in caput epididymal sperm and values of motility in cauda epididymal sperm. When ejaculated sperm were incubated in capacitation medium, percentages of motile and progressively motile sperm decreased largely within the first period of 30 min, followed by only minor changes. However, the addition of lactoferrin significantly lessened the early decreases of these parameters and additionally promoted capacitation-dependent changes of chlortetracycline staining patterns (from F pattern to B pattern). In other experiments, when ejaculated sperm were exposed to oxidative stress with 100-µM H₂O₂, the addition of lactoferrin partially protected them from dysfunction of flagellar movement and loss of progressive movement. In final experiments with frozen-thawed samples incubated in the capacitation medium, the addition of lactoferrin effectively survived dying sperm and suppressed occurrence of sperm agglutination. These results may suggest biological and biotechnological potentials of lactoferrin for modulation of bovine sperm viability, motility, capacitation state, and preservation in vitro.     

Pulmonary ventilation in a population of hatching chick embryos

Two experiments were made to study pulmonary ventilation in the hatching chick embryo with particular reference to the part played by the air cell.

The hatchability of embryos without access to the air cell was the same as for normally positioned embryos. The lungs of about 35 per cent of the normally hatching embryos were inflated in the air cell, but 65 per cent were inflated after breathing atmospheric air. The shell was cracked but not pipped before the outer membrane was penetrated. Comparisons between different groups of normally and abnormally positioned unhatched embryos revealed that the air cell had an insignificant respiratory value, but that the mechanical advantages of the large end seemed apparent.

The time relationships between lung inflation, inner membrane perforation, pipping, yolk sac retraction, outer membrane perforation, lung discoloration and hatchability were studied. Equations were derived for the regression on time of each of the seven variables studied. Statistically insignificant differences in hatchability were observed between the 2 groups of embryos which hatched from the large or small end of the egg.

It is suggested that lung inflation occurs when a certain threshold in the respiratory movements of thoracic muscles is reached. The threshold is attained by the rising anoxia, and probably other stimuli. The chick embryo's lungs, which lack elastic recoil, respond to the threshold and start utilising air. It is doubtful whether the embryo needs the very high partial pressure of carbon dioxide in the air cell. It is feasible to believe that CO₂ is an inevitable metabolic by‐product, and that it is stored in the air cell. The air cell also serves as a resting place for the chick while retracting the yolk sac. Through evolution, however, the chick embryo may have built up a high physiological tolerance to the CO₂ which it encounters upon entering the air cell.     

Microbiological quality of organic chicken meat during refrigerated storage in air and modified atmospheres

ABSTRACT

1. The aim of this study was to assess the incidence of pathogens and the development of spoilage microflora in organic chicken meat originating from a small poultry slaughterhouse and stored for 14 days at 2°C aerobically (control) or in one of two modified atmosphere packaging systems (MAP1: 80% O₂, 20% CO₂ and MAP2: 70% N₂, 30% CO₂).

2. Campylobacter jejuni survived well during storage; and was found on the skin in 95% of samples (262/276).

3. In general, both the skin and meat samples showed a good initial microbiological quality with total viable counts of less than 3 log cfu/g in meat and approximately 5 log cfu/g on skin.

4. No difference was found between breast and thigh samples during the experiment.

5. Shelf life was limited mainly by the development of mesophilic and psychrotrophic microflora on skin which were found at 7-day storage for the control and MAP1 and 10 days for MAP2.     

In vitro Evaluation of in vivo Fertilizing Ability of Frozen Rabbit Semen

The present work studied different spermatozoa parameters and the ability of frozen rabbit spermatozoa to fertilize, in vitro, in vivo‐matured oocytes, as a test to predict their in vivo fertility and prolificacy. Semen from rabbit bucks was frozen using two freezing protocols [in a freezer at ?30°C or in liquid nitrogen vapour (LNV)]. For the in vivo trial, females were inseminated with frozen‐thawed spermatozoa. Oocytes used for in vitro testing were recovered 14 h after ovulation induction from donors and co‐incubated with 2 × 10⁶ frozen‐thawed spermatozoa during 4 h at 37°C in Tyrode's medium under an atmosphere of 5% CO₂ in air with maximal humidity. After co‐incubation period, presumptive zygotes were cultured in TCM199 supplemented with 20% foetal bovine serum (FBS), under the same conditions described above. Although no statistical differences were observed between freezing protocols in seminal parameters [motility rate: 40 and 35%, VCL: 35 and 46 μm/s, amplitude of lateral head displacement (ALH): 1.7 and 2.4 μm, for semen frozen at ?30°C and in LNV, respectively], significant differences were noted in the fertilizing ability in vivo and in vitro. Semen frozen at ?30°C showed the highest fertilizing ability in vitro (26.7% vs 6.2 and 8.7% for semen frozen at ?30°C, in LNV and fresh semen, respectively) and the lowest fertility rate in vivo (21.7% vs 64.2% and 70.6% for semen frozen at ?30°C, in LNV and fresh semen, respectively). Sperm frozen at ?30°C seemed to be more capacitated.     

Isolation, identification, and characterization of compounds from acer rubrum capable of oxidizing equine erythrocytes

OBJECTIVE: To identify compounds in Acer rubrum that cause hemolysis or oxidation of equine erythrocytes and determine whether these toxins are found in other Acer spp. SAMPLE POPULATION: Equine erythrocytes. PROCEDURE: Washed erythrocytes were incubated with extracts and fractions of Acer spp that were separated by thin layer chromatography. Methemoglobin and hemolysis were measured spectrophotometrically. Compounds within Acer spp fractions associated with cell oxidation or hemolysis were identified by gas chromatography-mass spectrometry. RESULTS: Erythrocytes incubated separately with either A. rubrum, A. saccharum, or A. saccharinum extracts had increased methemoglobin formation, compared with extract-free control samples. Two Acer spp fractions had toxic effects on erythrocytes in vitro. A major component of the Acer fraction that caused a significant amount of methemoglobin formation was identified as gallic acid. An amount of gallic acid equivalent to that found in A. rubrum extract significantly increased methemoglobin, compared with extract-free control erythrocytes, but caused less methemoglobin formation than A. rubrum extracts did. A potential co-oxidant, 2,3-dihydro-3,5-dihydroxy-6-methoxy-4H-pyran-4-one, was found in the A. rubrum extract and may have been responsible for increasing methemoglobin formation. A second A. rubrum fraction caused methemoglobin formation and significant hemolysis. A. saccharum and A. saccharinum extracts caused hemolysis but less than the A. rubrum extracts did. CONCLUSION AND CLINICAL RELEVANCE: Oxidants in A. rubrum are also found in A. saccharum and A. saccharinum, and the ingestion of A. saccharum and A. saccharinum poses a potential threat to horses.     

Antibodies to Corynebacterium Pseudotuberculosis in Adult Goats from a Naturally Infected Herd

Serum samples taken in 3 successive years (1977, 1978 and 1979) from adult dairy goats (Norwegian breed) originating from 1 herd were examined for antibodies to Gorynebacterium pseudotuberculosis. Both bacterial agglutination test (BAT) and hemolysis inhibition test (HIT) were used. The proportion of seropositive goats increased 10–12 % during the investigation period. In 1979 all animals were seropositive to BAT and about 95 % had antihemolysins in their sera. Twenty-two of the 23 one-year old goats recruited to the herd in 1978 were seropositive. The average age-specific titres increased up to the age of 3 years, and subsequently decreased for goats aged 4–7 years. Caseous lymphadenitis is thus regarded as a chronic infection. The effect of age on the titre values was significant at the 5 % level in 1977 and 1978 when HIT was used and in 1978 when BAT was used. During the investigation period the same 36 and 40 goats were examined every year by BAT and HIT, respectively. Intermediate to high correlations between titre values for the same goats from year to year were found.Both BAT and HIT are suitable for sero-epidemiological investigations concerning infection with G. pseudotuberculosis in goats.