Factors which affect blood variables of slaughtered cattle.

Blood was obtained at an abattoir from 4 groups of cattle. The first group was slaughtered in a conventional way, the second and third were subjected to shechita slaughter with or without the application of the captive bolt immediately after the cutting of the throat, and the fourth group of cattle was subjected to a period of recumbency prior to conventional slaughter. Blood samples were analysed for concentrations of catecholamines, cortisol, glucose, lactate and total lipids. The haematocrit and osmolarity was also determined. There were no major differences in the blood variables of cattle subjected to conventional slaughter and those of cattle which had been subjected to a period of recumbency prior to conventional slaughter. Plasma catecholamine concentrations in cattle subjected to shechita slaughter without the application of a stun, were significantly elevated when compared to any of the other groups. It was concluded that postural changes have very little effect on the blood variables, but that the application of a stun after the throat has been cut in shechita slaughter abolishes the increases in blood variables associated with shechita in the absence of stunning.

Effect of a 72 hour fast on physiological stress indicators in feedlot cattle.

Feedlot oxen (n = 15) were herded and subjected to venepuncture on a daily basis for 2 weeks. Plasma glucose, lactate, free fatty acids, total lipids, total protein, cortisol, catecholamines, osmolarity and haematocrit were compared between Days 1 and 14. Plasma glucose concentration and haematocrit decreased significantly while total plasma lipid and free fatty acid concentrations increased significantly over the 14 d. Thereafter, food was withdrawn for 72 h from the experimental group (n = 10) and the same blood variables were compared in the control and the experimental groups. Plasma free fatty acid concentrations rose, while glucose concentrations declined in the experimental group during the fasting period. It is concluded that food deprivation for 72 h in cattle cannot be regarded as a major stressor.

The response of animals to suxamethonium (succinyldicholine) and succinylmonocholine.

The time which elapses before cessation of breathing, and blood pressure and blood gas changes after the intramuscular administration of suxamethonium, or a mixture of suxamethonium and hexamethonium, is compared in immobilised African elephants (Loxodonta africana) and buffaloes (Syncerus caffer). In addition, the respiratory responses of elephants and other animals to intravenous administration of suxamethonium and succinylmonocholine are reported on, as are the effects of darting animals with succinylmonocholine. The results show that respiration is affected in a similar fashion in all species investigated. However, the characteristic gradual decrease in respiratory rate seen in elephants during culling, using suxamethonium, resembles the effects observed when succinylmonocholine is administered. It is suggested that elephants are killed by this first breakdown product of suxamethonium during culling and/or that unique acetylcholine receptors may be involved.

Evaluation of a simple plasma catecholamine extraction procedure prior to high-performance liquid chromatography and electrochemical detection.

The modified extraction method for catecholamines described in this study is reproducible, simple, rapid, economical and relatively hazard-free. This method is based on the principle that plasma catecholamines are selectively adsorbed on acid-washed alumina at pH 8.6 and then eluted at a pH between 1.0 and 2.0. No statistically significant differences were obtained by using either 0.5 or 1.0 ml of plasma with 0.5 or 1.0 ml of Tris buffer. A 15-min mixing time during the adsorption and desorption steps was found to be practical, but any standardized time up to 1 h can be used. If the washing step was omitted, the catecholamines could not be eluted from the acid-washed alumina. To prevent dilution, the alumina had to be centrifuged and not aspirated to dryness after the washing step. An amount of 50 mg of WA-4 alumina was found to be the most practical in this study. Extracted or unextracted plasma as well as catecholamine standards were stable for four months at -20 degrees C.

Blood constituent responses of animals culled with succinyldicholine and hexamethonium.

Blood constituent responses of elephants and buffaloes culled in the Kruger National Park, using a mixture of succinyldicholine and hexamethonium, were compared to those of animals culled with succinyldicholine only. The results show a decreased physiological response in the animals culled with the mixture, characterised by lower total catecholamine, cortisol and glucose concentrations. Neither a delay of up to 30 min in obtaining blood samples from culled animals, nor a delay of up to 30 min in processing samples obtained immediately after cessation of respiration, gave any significant difference in the blood constituents which were measured.

Immediate response to repeated capture and handling of wild impala.

The composition of blood from veld and boma (enclosure)-kept impala, obtained immediately after the animals were manually restrained, was compared to control values. Statistically significant differences existed between the values for hematocrit, lactate, glucose, and osmolarity of veld and boma-kept animals compared to control data. Cortisol values were significantly greater (P less than .05) in boma-kept animals (93 +/- 21 nmol/liter) but not in veld impala (11 +/- 3 nmol/liter). It is suggested that the high cortisol and other values measured in boma-kept impala were due to an anticipatory conditioned response in these animals which occurred prior to them actually being caught. Repeated capture and handling, over a period of several months, of boma-kept impala resulted in statistically insignificant decreases in the mean values of several variables. Although this is indicative of adaptation it is doubtful whether the animals would ever fully adapt to the procedures involved.

Remote controlled sampling of cattle and buffalo blood.

1. Blood samples were obtained from cattle and buffaloes over extended periods of time by remote controlled methods at 4-hourly intervals. 2. Initial handling of the animals and deliberate exposure to stress at the end of the experimental times resulted in increased plasma concentrations of a number of variables. 3. Between initial handling and applied stress, the concentration of all variables investigated showed little change and no evidence of rhythms. 4. The results obtained reflect true plasma composition of free ranging cattle and buffaloes at rest.

Arterial blood gas composition, consciousness and death in rabbits.

Conscious rabbits were exposed to environments with low oxygen and/or high carbon dioxide. The electroencephalogram and arterial blood pressure were recorded. Arterial blood samples were taken sequentially. Rabbits became 'unconscious' at an arterial blood PO2 of 25 +/- 1 mm Hg and PCO2 of 99 +/- 27 mm Hg, when simultaneously the environmental oxygen was decreased and carbon dioxide increased. Brain death occurred at a PO2 of 23 +/- 1 mm Hg and PCO2 of 113 +/- 32 mm Hg. Cerebral perfusion was still adequate. In rabbits, the margin between 'unconsciousness' and 'death' is narrow so far as PO2 is concerned. If these results apply generally, animals culled with muscle relaxants may perceive stress involved until shortly before death.

Plasma constituents in Nguni cows over forty-eight hours.

Plasma constituents were investigated at ninety minute intervals over a forty-eight hour period on four unrestrained Nguni cows (in small cubicles) in order to study the presence or absence of rhythms. No circadian, ultradian or diurnal rhythm was found for any of the parameters investigated. Basal values over a forty-eight hour period were obtained for certain plasma constituents. These values are of use for studies relating to the effects of stress in cattle.

Blood composition in culled elephants and buffaloes.

Blood composition of succinyldicholine culled elephants and buffaloes was compared with that of undisturbed animals shot in the brain. The results show statistically significant differences in a number of variables including plasma ACTH and cortisol concentrations. The observed changes are attributed to stress induced by a combination of herding and darting with succinyldicholine and asphyxia. Extrapolation from blood oxygen tensions suggests that this stress may be perceived for an undetermined period which is probably longer in elephants than buffaloes.

The composition of plasma and interstitial fluid of goats with swelling disease.

Angora goats may develop a characteristic ventral oedema of the subcutaneous tissue which is not unlike the 'wet-carcass syndrome' of sheep. The plasma of oedematous goats shows a lower total protein concentration, a lower colloid osmotic pressure and a lower albumin: globulin ratio than that of normal goats. Similarly, interstitial fluid of oedematous goats has a lower protein concentration, osmolality and colloid osmotic pressure than the fluid from normal but a similar albumin:globulin ratio. These results suggest that, unlike the 'wet-carcass syndrome' of sheep, the most likely explanation for the oedema is hypoproteinaemia which leads to filtration of fluid and an increased capillary permeability.

The composition of plasma and interstitial fluid of sheep with the 'wet carcass' syndrome.

Carcasses of sheep from various areas in South Africa and South West Africa (Namibia) show a wet glistening appearance immediately after slaughter. The subcutaneous interstitial fluid of these sheep has a significantly lower protein concentration and colloid osmotic pressure and a significantly higher albumin/globulin ratio than that of normal sheep. These results imply the presence of an oedema and an increased capillary permeability to protein. They suggest that histamine, or an histamine-like substance, mediates the changes.

Concentration and composition of plasma proteins in wild mammals.

Total protein concentrations from a variety of wild mammalian species were measured by the Lowry and Biuret techniques and compared with results obtained or derived by refractometry. Values obtained with the Lowry method were the highest and certain derived refractometry results, the lowest. It is suggested that the Biuret method provides the most acceptable values but that care should be exercised in using the correct standard. The percentage composition of plasma from 22 species of wild mammals is also presented and the observations discussed with relation to methodology and A/G ratio.