Effect of carbonated water on arterial pH, PCO2 and plasma lactate in heat-stressed broilers

1. The effects of tap (TW) or carbonated (CW) water on arterial pH, partial pressure of carbon dioxide (PCO2) and plasma lactate were determined in heat-stressed broilers. Water treatments were infused directly into the crop at a rate of 0.4 ml/min kg BW. 2. Heat stress increased body temperature (Tb) and respiration rate (RR) but both were higher in birds given CW after 4 and 5 h than in TW-infused controls. However, PCO2 was lower and arterial pH and plasma lactate were higher in TW-infused birds after 4 and 5 h of heat stress than in CW-infused birds. Hematocrit was also higher in CW-treated birds after 4 and 5 h of heat stress than in TW controls. 3. The results indicate that CW is capable of attenuating changes in blood pH and PCO2 in heat-stressed domestic fowl. The lower pH in CW birds after 4 and 5 h of heat stress may have suppressed plasma lactate concentrations in these birds.     

Behavioural and physiological responses of three chicken breeds to pre-slaughter shackling and acute heat stress

1. The aim of this study was to compare the behavioural and physiological responses to hanging and acute heat stress in three different chicken breeds. Chicks were obtained from a slow-growing French 'Label Rouge' line (SGL), a fast-growing standard line (FGL) and a heavy line (HL). The SGL, FGL and HL birds were slaughtered at their respective market ages of 12, 6 and 6 weeks, in an attempt to achieve similar body weights. Before stunning, birds were either shackled by their legs on the moving line for 2 min (shackling stress: SH) or placed in a room at 35 degrees C and 60% of humidity for 3.5 h and then shackled for 2 min (acute heat stress plus shackling: H + SH) or subjected to minimal stress by shackling for 10 s before stunning (control group: C). 2. Bird physiological responses to the three pre-slaughter treatments were estimated by measuring blood corticosterone, glycaemia, creatine kinase activity, acid-base status and electrolyte concentration as well as lactate content and glycolytic potential in the breast (Pectoralis major) and thigh (Ilio tibialis) muscles. Behavioural responses to shackling stress were evaluated by measuring wing flapping duration, straightening up attempts and vocalisations. 3. Blood corticosterone was higher in SH and H+SH groups than in the C group, regardless of genotype. The struggling activity on the shackle line differed among chicken breeds. It was more intense and occurred more rapidly after hanging in the SGL birds than in both other breeds. Furthermore, SGL struggling activity was not affected by hanging duration while it increased with hanging duration in FGL and HL birds. 4. Wing flapping duration was negatively correlated with blood pH, bicarbonate concentration and positively correlated with breast muscle lactate content, indicating that struggling stimulated antemortem glycolysis activity in breast muscle. Acute heat stress affected blood Ca2+ and Na+ concentration and increased glycaemia and glycolytic potential of thigh muscle. 5. Both acute heat stress and shackling before slaughter were experienced as stressful events by all types of birds.     

Effect of long-term heat exposure on peripheral concentrations of heat shock protein 70 (Hsp70) and hormones in laying hens with different genotypes

1. The effect of long-term, moderate heat stress (30 to 32 degrees C) on heat shock protein 70 (Hsp70) concentration in mononuclear blood cells and plasma concentrations of 3,5,3'-triiodothyronine (T3) and corticosterone in laying hens was investigated. 2. Three groups of 48 hens each (Ethopian line [Angete Melata, Na], New Hampshire [NH], F1 cross [Na x NH]) were divided into an experimental group (24 each) and a control group (24 each, ambient temperature 18 to 20 degrees C), respectively. All hens were kept in individual cages up to an age of 68 weeks and performance data were recorded. 3. Blood samples were taken from the wing vein of 12 hens from each group at weeks 22, 38, 51 and 65 (12 hens x 3 lines x 2 treatments). Mononuclear blood cells were isolated and Hsp70 concentrations were determined by Western Blot analysis with a monoclonal anti-Hsp70 antibody. T3 and corticosterone were measured with commercially available ELISA and RIA kits, respectively. 4. The moderate heat stress caused significantly increased Hsp70 levels compared with the control groups in weeks 51 and 65. However, the responses of the lines were not uniform at different ages. 5. In contrast, T3 levels were significantly decreased in stressed birds regardless of line and age. There was no effect of treatment and line on corticosterone levels during the experimental period. 6. Our results indicate that Hsp70 and T3 levels are affected by mild heat stress applied over a long period but are both involved in independent mechanisms of acquisition of thermotolerance. Further investigations are necessary to clarify whether the observed differences in Hsp70 response between the genotypes are indicators for differences in thermotolerance.     

Optimal dietary concentration of vitamin E for alleviating the effect of heat stress on egg production in laying hens.

1. The effects of different dietary concentrations of vitamin E (alpha-tocopherol acetate) were investigated on laying hens exposed to chronic heat stress at 32 degrees C from 26 to 30 weeks of age. 2. Diets containing 5 dietary concentrations of vitamin E (a control diet containing 10 mg alpha-tocopherol/kg or this diet supplemented to contain 125, 250, 375 and 500 mg alpha-tocopherol/kg) were fed to 335 birds. Half of the birds received the supplemented diets for only 4 weeks before the heat stress period (short supplementation duration, SSD) and were fed on the control diet for a further 12 weeks. The remaining birds were fed on the supplemented diets throughout the experiment, 4 weeks before, 4 weeks during and 8 weeks after the heat stress period (long supplementation duration, LSD). 3. Egg production was significantly higher during (80-6 vs 68.9%, P<0.02) and after (75.3 vs 62.7%, P<0.02) the period of stress in the LSD group fed on the diet containing 250 mg vitamin E/kg compared with the group fed on the control diet. LSD birds given 375 and 500 mg vitamin E/kg also had higher egg production than control birds during heat stress but the differences failed to reach significance (74.6 vs 68.9% and 77.1 vs 68.9% respectively). In the SSD groups, mean egg production of the birds given the diets supplemented with 125 mg vitamin E/kg or more was significantly different from the control group after heat stress (70.3 vs 62.7%, P<0.05). Egg weight and food intake were similar in all the groups. 4. Plasma and liver vitamin E concentrations were proportional to the vitamin E intake before the stress period, dropped during heat stress in the SSD groups but were maintained at concentrations closer to those observed before heat stress in the LSD groups. 5. It is concluded that a dietary supplement of 250 mg vitamin E/kg provided before, during and after heat stress is optimum for alleviating, at least in part, the adverse effects of chronic heat stress in laying hens.     

Subclinical ammonia toxicity in steers: effects on blood metabolite and regulatory hormone concentrations

The effects of subclinical NH3 toxicity on circulating and regulatory hormone concentrations were investigated in seven Hereford steers. Ammonium chloride (NH4Cl) was infused via a right jugular vein catheter at a rate of 12 mumol NH4Cl.kg BW-1.min-1 for 240 min. This was preceded (PRE) and followed (POST) by saline infusions of 120 and 180 min, respectively. Blood samples were taken at 20-min intervals via a left jugular vein catheter. Metabolite and hormone concentrations during NH4Cl and POST periods were compared to PRE values using the Student's t-test procedure. Plasma NH3 was elevated rapidly (P less than .001) and peaked at 503 micrograms/dl 220 min into NH4Cl infusion. Plasma urea-N and glucose increased (P less than .001) 39 and 12%, respectively, during NH4Cl infusion and remained elevated 180 min POST. Whole blood L-lactate concentrations peaked (P less than .05) at 18% above PRE between 160 and 240 min into the NH4Cl infusion and gradually returned to PRE values, whereas pyruvate levels were not altered (P greater than .10). Plasma nonesterified fatty acids peaked (P less than .001) at 94% above PRE levels 40 min into NH4Cl infusion, thereafter declining to PRE concentrations. Whole blood acetoacetate and beta-hydroxybutyrate concentrations were not altered (P greater than .10) by NH4Cl administration. Plasma insulin concentration decreased (P less than .05) 26 to 46% during NH4Cl infusion and increased (P less than .05) 89 to 122% during POST. Plasma glucagon levels were not altered by NH4Cl infusion, so molar insulin:glucagon ratio changes resembled those of insulin. Plasma epinephrine, norepinephrine and dopamine did not vary (P greater than .10) with treatment. These results support the hypothesis that the hyperglycemia observed during hyperammonemia may result from an under-utilization of glucose by insulin-sensitive tissues.     

Subclinical ammonia toxicity in steers: effects on hepatic and portal-drained visceral flux of metabolites and regulatory hormones

Four calves (avg wt 161 kg) were surgically fitted with indwelling catheters in the femoral artery and femoral, portal, hepatic and mesenteric veins to study the effects of subclinical ammonia toxicity on portal-drained viscera (PDV) and hepatic (HEP) net flux of key metabolites and pancreatic hormones. Hyperammonemia was induced via administration of ammonium chloride (NH4Cl; 12 mumol.kg BW-1.min-1) via the femoral vein catheter for 240 min; infusions were preceded (PRE) and followed (POST) by 60- and 180-min control periods, respectively. Blood samples were obtained from the arterial catheters, and portal and hepatic vein catheters. Net flux rates were calculated by multiplying venoarterial differences by blood flow. Arterial plasma ammonia N peaked (P less than .01) at 327 micrograms/dl; hepatic ammonia extraction increased (P less than .01) from 10 to 23% during NH4Cl infusion. Arterial plasma glucose concentrations increased (P less than .05) during NH4Cl infusion (90.5 vs 82.6 mg/dl) concomitant with trends toward a reduction in net HEP glucose output. Portal-drained visceral release of insulin did not increase (P greater than .10) during NH4Cl infusion despite the steady rise in circulating glucose concentration; however, cessation of NH4Cl infusion resulted in a 109% increase (P less than .05) in PDV insulin release at +60 min POST. Plasma L-lactate, nonesterified fatty acids, urea N and glucagon concentrations and net fluxes were variable throughout the experiment. Results tend to indicate that hyperammonemia reduced hepatic glucose output and glucose-mediated pancreatic insulin release.     

Changes in the plasma concentration of immunoreactive arginine vasotocin during oviposition in the domestic fowl

1. The plasma concentrations of immunoreactive arginine vasotocin (AVT) were measured during oviposition and shortly before ovulation of the first egg (Cl) of a clutch. Immunoreactive AVT was determined on bentonite extracts of 0·5 ml plasma samples using the method of Rosenbloom and Fisher (1974). The R‐70 antiserum used to measure AVT cross reacted with arginine vasopressin (AVP), however the fowl pituitary does not synthesise AVP.

2. Over a period of 10 to 90 min before oviposition the plasma AVT concentration was about 20 pg/ml; during oviposition it increased four‐fold.

3. Measurements made at frequent intervals showed that plasma AVT concentration increased 5 to 6 min before oviposition, reached a peak during oviposition itself and decreased rapidly in the following 5 to 6 min.

4. The surge in plasma AVT occurred on average 48 min before Cl ovulation.

     

Effects of cool and hot humid environmental conditions on neuroendocrine responses of horses to treadmill exercise

To determine the effects of exercise, high heat and humidity and acclimation on plasma adrenaline, noradrenaline, beta-endorphin and cortisol concentrations, five horses performed a competition exercise test (CET; designed to simulate the speed and endurance test of a three-day event) in cool dry (CD) (20 degrees C/40% RH) and hot humid (30 degrees C/80% RH) conditions before (pre-acclimation) and after (post-acclimation) a 15 day period of humid heat acclimation. Plasma adrenaline and noradrenaline concentrations pre-acclimation were significantly increased compared with exercise in the CD trial at the end of Phases C (P<0.05) and D (P<0.05 and P<0.01, respectively) and at 2 min recovery (P<0.01), with adrenaline concentrations still elevated after 5 min of recovery (P<0.001). Plasma beta-endorphin concentrations were increased at the end of Phases C (P<0.05) and X (P<0.01) and at 5 and 30 min recovery (P<0.05) in the pre-acclimation session. Plasma cortisol concentrations were elevated after the initial warm up period pre-acclimation (P<0.01) and at the end of Phase C (P<0.05), compared with the CD trial. A 15 day period of acclimation significantly increased plasma adrenaline concentrations at 2 min recovery (P<0.001) and plasma cortisol concentration at the end of Phase B (P<0.01) compared with pre-acclimation. Acclimation did not significantly influence noradrenaline or beta-endorphin responses to exercise, although there was a trend for plasma beta-endorphin to be lower at the end of Phases C and X and after 30 min recovery compared with pre-acclimation. Plasma adrenaline, noradrenaline, beta-endorphin and cortisol concentrations were increased by exercise in cool dry conditions and were further increased by the same exercise in hot humid conditions. Exercise responses post-acclimation suggest that adrenaline and noradrenaline may play a role in the adaptation of horses to thermal stress and that changes in plasma beta-endorphin concentrations could be used as a sensitive indicator of thermal tolerance before and after acclimation. The use of plasma cortisol as a specific indicator of heat stress and thermal tolerance before or after acclimation in exercising horses appears limited.     

Effects of different crating periods on selected biochemical indices in broiler chickens

Effects of different crating periods on selected biochemical indices were monitored in a group of unsexed ROSS 308 broiler chickens aged 42 days. 120 randomly selected chickens were weighted and placed in 15 heavy duty plastic crates with reduction in floor space approx. 160 cm2/kg of body weight of broilers (average body weight was 2.75 kg). Five crates were kept for 4 hours (Group 4h), another five crates for 8 hours (Group 8 h) and another five crates for 12 hours (Group 12h). After tested periods of crating the broilers were released and blood samples were withdrawn from Vena bosilico in 24 randomly selected birds from each group (Groups 4 h, 8 h, 12 h respectively) and also in other 24 randomly selected non-crated control birds. The results of our experiment proved that duration of crating significantly influenced the stress response in broiler chickens. The duration of crating period was positively correlated with the plasma corticosterone level and negatively correlated with the lactate dehydrogenase, cholesterol, triglycerides, glucose and lactate levels in the blood of broiler chickens.     

NH_4Cl和NaHCO_3对肉用仔鸡慢性热应激的影响

３２０ 羽１ 周龄健康肉用雏鸡被随机分成４ 组, 经１ 周的适应后进行试验。组Ⅰ、组Ⅱ、组Ⅲ和组Ⅳ的日粮处理分别为： 基础日粮（Ｂ, 对照组） , Ｂ＋ ０－５ ％ ＮａＨＣＯ３ , Ｂ＋ ０－５ ％ ＮａＨＣＯ３ ＋ １ ％ ＮＨ４Ｃｌ 和Ｂ＋ １ ％ ＮＨ４Ｃｌ。试验为期５ 周。研究日粮中添加ＮａＨＣＯ３ 和ＮＨ４Ｃｌ 对慢性热应激肉用仔鸡的血液ｐＨ、ＣＯ２ 分压（ＰＣＯ２） 及生产性能的影响。结果表明： 在慢性热应激（２３ ～３５ ℃） 条件下, 肉用仔鸡未发生呼吸性碱中毒, 组Ⅱ的血液ＰＣＯ２高于对照组（ Ｐ＜ ０－０１） , 增重比对照组多９－４９ ％ ; 组Ⅲ血液ｐＨ 低于组Ⅰ和组Ⅱ（ Ｐ ＜ ０－０１） , 血液的ＰＣＯ２ 高于组Ⅰ和组Ⅳ（ Ｐ ＜ ０－０１） , 增重比对照组多８－１９％ 。组Ⅳ的血液ｐＨ 值极显著低于对照组（ Ｐ ＜ ０－０１） , 比对照组少增重２－５ ％     

Effects of litter quality (moisture, ammonia, uric acid) on development and severity of foot pad dermatitis in growing turkeys

High dietary protein is thought to increase the incidence of foot pad dermatitis (FPD) as a result of increased uric acid and secondary ammonia production in the excreta or litter. This study was conducted on female turkeys over a period of 3 wk to test the effects of water alone, and also of these end products of protein metabolism, independent of the presence of excreta, on the development and severity of FPD. The animals were allocated into four groups, with 20 birds in each, and housed in floor pens on dry, clean wood shavings (changed daily) throughout the experiment. The control group was housed continuously in its pen, whereas the other groups were additionally exposed daily (for 8 hr) to experimentally treated wood shavings, in adjacent separate boxes, enriched with water alone or water with NH4Cl or uric acid. NH4Cl and uric acid were added via water to the litter to achieve the concentrations of ammonia and uric acid in the litter as found in the excreta of turkeys (about 0.50 g ammonia and 20 g uric acid/kg). The wet litter was kept clean by removing the excreta twice daily and by changing the litter twice a week. The foot pads of all birds were examined on days 0, 7, 14, and 21 and scored externally (macroscopically). Three birds were selected from each group on days 0, 7, and 14, while the remaining 11 birds/group were sacrificed on day 21 for histopathologic assessment of foot pads. The severity of FPD was found to be markedly higher (about 3 times) on wet than on dry litter. There were no negative effects of ammonia and uric acid on foot pad lesions. The results indicate that high litter moisture is the most likely factor causing FPD in turkeys. A focus on nitrogenous irritants in the litter was not substantiated. Exposure of birds to wet litter (in the absence of excreta) for only 8 hr/day was sufficient to develop foot pad lesions. The present results suggest that a focus on the protein content of the diet as a cause of FPD may be misplaced, but all dietary factors which increase excreta or litter moisture, or both, should be considered. The prevalence and severity of FPD can be reduced by maintaining dry litter.     

Balance and urinary excretion of calcium, magnesium and phosphorus in response to high concentrate feeding and lactate infusion in lambs

Two experiments were conducted to investigate the influence of dietary concentrate level and iv lactate infusion on the urinary excretion and balance of Ca, Mg and P in lambs. In Exp. 1, six ruminal fistulated, crossbred wethers (25 kg) were fed diets of 0, 50 and 70% concentrate for 5-d periods (periods 1, 2 and 3, respectively) followed by 25 d on a 90% concentrate diet (periods 4, 5 and 6, respectively). Collections were made for all days except 6 to 10 and 16 to 20 on the 90% concentrate diet. Dry matter intakes increased with each increase in dietary concentrate until the initial period of 90% concentrate (period 4) when intakes were lowest. Intakes increased (P less than .05) during the latter two periods of 90% concentrate feeding compared with period 4. Rumen fluid pH decreased and rumen L (+) lactate increased with increasing concentrate intake. Blood pH and bicarbonate both decreased with increasing concentrate intake indicating a mild disturbance in acid-base balance. Plasma concentrations of Ca, Mg and P decreased with increased concentrate intake and were elevated (P less than .05) for periods 5 and 6 compared with period 4. Plasma alkaline phosphatase activity and urinary hydroxyproline excretion both increased (P less than .05) for periods 5 and 6. Four of the six animals were in negative Ca balance for the initial period of 90% concentrate feeding, but showed highest Ca retentions for periods 5 and 6. Magnesium and P balance appeared unaffected by increased concentrate intake. Disturbances in Ca metabolism appeared to be short-term and nondetrimental; the animals responded with increased growth and Ca retentions once adjusted to the high concentrate diet. In Exp. 2, four Hampshire ewes (32 kg) were used in a 4 X 4 Latin square design with treatments being saline (.9% NaCl, w/v), L (+) lactate, D (-) lactate and D, L-lactate infused iv in a saline solution to supply .6 mM/kg body weight of each isomer in 15 min. Plasma and urine samples were taken 0, .5, 1, 1.5, 3, 6 and 12 h from the start of infusion. Total urinary excretion of Ca (P less than .04) and Mg (P less than .02) were elevated for all lactate infusions as compared with saline. Total P excretion was greater (P = .06) for all lactate infusions compared with saline and was increased (P less than .05) for the D, L-lactate treatment as compared with the D- and L-lactate treatments.(ABSTRACT TRUNCATED AT 400 WORDS)     

Response of one-humped camel (Camelus dromedarius) to intravenous glucagon injection and to infusion of glucose and volatile fatty acids, and the kinetics of glucagon disappearance from the blood

The effects of glucagon injection and infusion of glucose and volatile fatty acids were studied in one-humped camels. Twenty adult male camels were divided into four equal groups. The first group was infused with physiological saline and served as a control. The second group was injected with a single dose of glucagon, the third group was infused with glucose (50%) in sterile saline, and the fourth group was infused with a volatile fatty acid (VFA) mixture. In the first, third and fourth groups, sampling was performed before the beginning of infusions (control time), and at 15, 30, 60 and 120 min post-infusion. Plasma glucagon concentrations were monitored in the second group at 5, 10, 15, 20, 30, 45, 90, 105 and 120 min after injection. For glucagon injection, glucose concentration peaked at 15 min post-injection, and tended to decrease thereafter. Plasma glucose concentrations showed significant rises above the basal value at all times after glucose infusion. VFA infusion had no apparent effect on plasma glucose concentration. After injection of glucagon, the plasma lactate concentration dropped significantly at 15 and 30 min, then increased gradually until it reached the original concentration of lactate at 120 min. However, glucose infusion elevated the plasma lactate concentration only at the end of the infusion period. A decrease in plasma lactate was observed at 60 min after VFA infusion. The present investigation provides evidence that the glucagon level in camels is higher than that in other ruminants and in man, and suggests that this is a probable species specificity, which would explain the higher level of glucose in the blood of camels than in that of other ruminants. The disappearance curve of injected glucagon had, as in other ruminants, an exponential two-compartment function. The hormone was rapidly distributed and was eliminated with a high rate of clearance.     

Hepatic concentration of heat shock protein 70 kD (Hsp70) in broilers subjected to different thermal treatments.

1. The relationship between repeated thermal treatments and hepatic synthesis of Hsp 70 was studied in broiler chickens. 2. Sixty broilers were submitted to 5 different treatments (12 birds each) from day 1 to day 42. Four groups were kept in a thermoneutral environment and subjected to 0, 1, 2 and 3 heat stress episodes at 35 degrees C for 4 h per week (TN-0, TN-1, TN-2 and TN-3, respectively). The last group (HT-35) was reared at a room temperature of 35 degrees C. 3. From 39 to 42 old, the birds experienced acute heat stress at 41 degrees C. Resistance to heat stress was evaluated by the time taken for rectal temperature to increase by 3 degrees C above the pre-treatment value. Livers were collected (before and after heat stress) and Hsp70 was determined using Western Blot analysis with monoclonal anti-Hsp70 antibody. 4. Resistance to heat stress and concentration of Hsp70 were higher in those birds subjected to more heat stress episodes during the experimental period (TN-3) and HT-35. A positive correlation was observed between Hsp70 concentration and the time taken for a 3 degrees C increase in rectal temperature (r = 0.42; P<0.01). 5. Exposing birds to episodes of heat stress (35 degrees C) during rearing may improve their resistance to acute heat stress, but the previous thermal history did not seem to influence the hepatocyte Hsp70 content after exposure to more severe heat stress (41 degrees C).     

Relationship between urine ammonium ion excretion and urine anion gap in dogs.

Acidemia stimulates renal ammonia production and excretion. This adaptive response allows increased H+ secretion and generation of new bicarbonate. To determine whether a relationship existed between urine ammonium (NH4+) concentration and excretion and urine anion gap (Na+ + K(+)- Cl-), ammonium chloride (NH4Cl) was administered per OS for 5 days to induce systemic acidemia in 12 healthy Beagles. During NH4Cl administration, a strong, statistically significant (P less than 0.0001) relationship was apparent between urine NH4+ concentration measured in millimoles per liter and urine anion gap. Regression equation: urine [NH4+] = 8.2 - 0.416 x urine anion gap; r = -0.897. A statistically significant (P = 0.0001) relationship existed between urine NH4+ excretion measured in millimoles per kilogram of body weight per day and urine anion gap. Regression equation: urine NH4+ excretion = 0.74 - 0.38 x urine anion gap; r = -0.768. As urine NH4+ concentration or excretion increased, urine anion gap became more negative. Before NH4Cl administration (no systemic acidemia), a weak, but statistically significant (P = 0.015) relationship was observed between urine NH4+ concentration and urine anion gap. Regression equation: urine [NH4+] = 65.2 - 0.141 x urine anion gap; r = -0.41. However, a relationship was not evident between urine NH4+ excretion and urine anion gap before NH4Cl administration. Hence, urine anion gap is a reliable index of urine NH4+ concentration and excretion only in dogs with metabolic acidosis. In human beings with distal renal tubular acidosis, NH4+ excretion is inappropriately low and results in a positive urine anion gap.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of the gut microflora on fasting heat production in chicks

1. The influence of the gut microflora on fasting heat production in chicks was investigated. 2. Single Comb White Leghorn chicks were fed on an adequate diet from 2 to 12 d of age and then fasted for 3 d. Fasting heat production was estimated from changes in body composition and energy content of droppings from days 1 to 3 of fasting. Measurements of body temperature and plasma thyroxine concentration were also made. 3. Body fat content was consistently higher in germ-free (GF) chicks than in conventional (CV) counterparts during the starvation period, whereas no difference was found in body protein content. The GF birds had a significantly higher body temperature than the CV controls with no change in plasma thyroxine concentration. 4. It was concluded that estimated fasting heat production of chicks was increased by the absence of the gut microflora.     

Endocrine response to lactate infusion during pentobarbitone anaesthesia

Lactic acid was infused iv in 6 Welsh ponies during pentobarbitone anaesthesia to investigate whether lactate triggers the pituitary-adrenal response to anaesthesia. Ponies were premedicated with acepromazine and anaesthesia was induced with pentobarbitone iv and maintained with pentobarbitone/oxygen for 2 h. Immediately after induction, 3% L(+) lactic acid infusion was started and adjusted to maintain plasma lactate concentration between 2 and 2.5 mmol/l. Cardiorespiratory function, temperature. PCV, plasma glucose, lactate, βendorphin, ACTH, cortisol and catecholamine concentrations were measured before, during and after anaesthesia. Hypothermia, reduced PCV, slight hypotension (minimum value 84 ± 6 mmHg 20 min after induction of anaesthesia), hyperoxia and marked bradypnoea developed during anaesthesia. No acidaemia occurred. Plasma glucose concentration increased at the end of anaesthesia. There were no changes in plasma ACTH, cortisol and catecholamine concentrations, but plasma & endorphin increased after induction until the end of anaesthesia. There was a correlation between plasma lactate and β-endorphin concentrations (P<0.001, r=0.63), which may suggest that lactate stimulates βendorphin release. Beta-endorphin was apparently secreted independently from ACTH and appears to be a sensitive marker of a stress response.     

Effects of treadmill exercise on the transfer of plasma triglyceride into the ovary of the laying fowl

1. The effects of 90 min continuous treadmill exercise on the plasma-to-ovary transfer of 14C-labelled triglycerides in laying hens were examined. 2. Exercised birds showed a 4-fold increase in plasma free fatty acid concentration, a 15% decrease in plasma glucose concentration and unchanged plasma triglyceride concentration compared with resting controls. The mean plasma-to-ovary triglyceride transfer rate was approximately halved by exercise. 3. The surface area-specific triglyceride transfer rate was greatest for oocytes weighing 0.25-1.5 g and decreased with increasing oocyte size. The lowest rates were in the small (less than 0.25 g) white oocytes. This pattern was largely unaffected by exercise. 4. Factors that might be responsible for the reduction in triglyceride transfer into the oocytes during exercise include hormonal effects on the permeability of the oocyte envelope, increased competition for plasma lipids by the working muscles and reduced blood flow to the ovary, as a result of the release of vasoconstrictors.     

热应激对巴马香猪免疫和生化指标的影响

为了探讨热应激诱发动物免疫损伤的可能机理,本研究观测了热应激对巴马香猪行为、基线免疫和血液生化指标的影响。对巴马香猪的行为观察发现热应激使其饮欲增强、活动量增大和打斗增多。结果表明:热应激使巴马香猪红、白细胞数量显著升高(P<0.05);嗜中性粒细胞百分率下降,嗜酸性和嗜碱性粒百分率上升;单核细胞百分率升高(P<0.05);热应激对巴马香猪血浆超氧化物歧化酶(SOD)、总胆固醇(TC)和白蛋白(ALB)的影响不大。血尿素氮(BUN)呈下降趋势,但差异不显著;肌酸激酶(CK)升高(P<0.05);乳酸脱氢酶(LDH)含量下降。葡萄糖(GLU)则在早期低于对照组,而后期高于对照组(P<0.05),说明热应激引起巴马香猪代谢和内分泌紊乱。     

Effects of sodium acetate, bicarbonate and lactate on acid-base status in anaesthetized dogs

Equal doses of sodium acetate, bicarbonate and lactate (6.6 mEq/L) infused intravenously over 30 min into three groups of halothane-anaesthetized dogs caused changes in acid-base status. Arterial carbon dioxide tension (PaCO2), pHa, base excess (BE) and standard bicarbonate (SB) increased. Sodium bicarbonate caused the most rapid and greatest changes. The bicarbonate group was significantly different (P less than 0.05) from the other groups at 15 and 30 min after the start of infusion for pHa, BE and SB. The greater effects of bicarbonate are due to its production of alkalinization without a requirement for metabolism; acetate and lactate require oxidation to be effective. The acetate and bicarbonate groups were not statistically different at 45 min after the onset of drug infusion, but both had significantly higher SB and BE mean values than the lactate group. All measurements made after 45 min revealed no significant differences among groups. Thus, after the earlier differences noted above, the three alkalinizers caused similar effects on acid-base status. PaCO2 was elevated in all groups, but there were no differences among groups. Cardiovascular effects caused by infusion of the three drugs were minimal.