Acid-base balance of the domestic turkey during thermal panting.

The objectives of this research were to evaluate the effects of thermal panting in domestic turkeys on arterial blood values for the acid-base variables, pH(a), bicarbonate concentration ([HCO(-) (3)](a)), partial pressure of carbon dioxide (P(a)CO(2)), and hemoglobin concentration [Hb]. In addition, body temperature and partial pressure of oxygen (P(a)O(2)) were measured to determine the effectiveness of panting in their control. Nine adult (23 wk) broad-breasted white turkey toms, all from the same hatch and reared contemporaneously in the same facility, were acclimated to room conditions of 19 degrees C and 65% RH. After a 1-wk control period, a 3-wk heat-stress period (32 degrees C, 65% RH) was induced, for a heat-stress group of 9 turkeys. Thermal panting began at this time and continued to its end. A 1-wk recovery period followed (19 degrees C, 65% RH) during which panting ceased. An age-matched group of 8 turkeys was similarly acclimated (19 degrees C, 65% RH) but was continued at this level to the end of the experiment. During the heat-stress period, the bicarbonate concentration increased, whereas pH(a) and P(a)CO(2) did not change significantly. Body temperature changes were not significant. Parabronchial ventilation was not compromised by panting, as noted by a significant increase in P(a)O(2). Hemoglobin concentration decreases were significant. The only significant change that occurred for the age-matched group was an increase in [Hb]. Domestic turkeys, reared in confinement, have the ability to resist changes in blood pH and prevent the development of respiratory alkalosis while panting in response to thermal stress. Normal body temperature and oxygenation of the blood are also maintained.

Effects of storage time and temperature after blood sampling from turkeys on plasma concentrations of potassium, sodium, and chloride.

The objectives of this research were to study the effect of several time intervals of turkey blood storage from sampling to centrifugation on plasma K, Na, and Cl concentrations and to study the effect of ambient temperature of turkey blood storage on these same variables. In the first study, 6 consecutive blood samples were obtained from each turkey. The first sample was centrifuged immediately (control), and each of the others was respectively stored for 20, 40, 60, 120, or 360 min at 22 degrees C before centrifugation and plasma harvest. In the second study, 4 consecutive blood samples were obtained from each turkey. The first sample was centrifuged immediately (control), and each of the others was respectively stored at ambient temperatures of 9, 22, and 30 degrees C for 120 min before centrifugation and plasma harvest. Plasma K concentration declines and is significant (P < 0.01) for each of the 20, 40, 60, 120, and 360 min values. Plasma Na concentration increases and Cl decreases were not significant (P < 0.01) until 360 and 120 min, respectively. Significant (P < 0.01) reductions occurred for plasma K concentration for each of the ambient temperature values but were the least at 9 degrees C and greatest when stored at 30 degrees C. Plasma Na concentration decreased (P < 0.01) when stored at 9 degrees C. Though increased (P < 0.01) when stored at 22 and 30 degrees C, the difference was not significant (P < 0.01) between samples stored at either 22 or 30 degrees C. Plasma Cl concentration was decreased (P < 0.01) from control values, but there was no significant difference (P < 0.01) among samples stored at 9, 22, and 30 degrees C. Clot formation and its retraction from serum are unduly delayed after blood is withdrawn from turkeys because birds lack the intrinsic mechanism for blood coagulation. Accordingly, serum is not appropriate for the determination of K concentration in turkeys, and plasma harvested immediately after blood sampling is the fluid of choice for K analysis.

Effects of dietary potassium supplementation for growing turkeys on leg weakness, plasma potassium concentration, and selected blood variables.

The objectives of this research were to observe the effects of increased K in the diets of growing tom turkeys from 6 to 18 wk of age on body weight, feed-to-gain ratio, and leg weakness; to study the effects of time and temperature of blood storage after sampling and before centrifugation on plasma K concentration; and to evaluate plasma creatine kinase activity as an indicator of leg weakness. Male Nicholas White turkeys were fed corn-soybean meal based starter and grower diets from 1 d to 6 wk of age. At this time, each of three dietary treatments was assigned randomly to three pens of toms, 30 toms per pen. The dietary treatments consisted of 1) corn-soybean meal control (control) diets, 2) corn-soybean meal diets supplemented with 25% more K than the control diets contained (Mod K), and 3) corn-soybean meal diets supplemented with 50% more K than the control diets (High K). Potassium carbonate was used as the source of supplemental K for the Mod K and High K diets. Calculated K concentrations of the control diets fed from 6 to 9, 9 to 12, 12 to 15, and 15 to 18 wk were 0.84, 0.74, 0.57, and 0.54%, respectively. Results of laboratory analysis of the diets agreed closely with the calculated values. By 12 wk, toms fed the High K diets weighed less (P = 0.018) than toms fed the control diets, and this difference was still evident at 18 wk (P = 0.013), even though the High K groups were changed to the control diets at 12 wk. Toms fed the Mod K diets also tended to weigh less at 16 and 18 wk than those fed the control diets, however, the diet effect at the latter time was not significant (P > 0.05). There were no consistent effects of dietary K on feed efficiency. Total incidence of leg weakness at 12 wk was greater (P = 0.015) among toms fed Mod K and High K diets than for those toms fed the control diets. These results show that dietary K concentrations greater than those usually present in corn-soybean meal based diets for growing turkeys should be avoided. Increases in dietary K concentrations were associated with increases in plasma K concentration. Storage of blood after sampling and before centrifugation decreases the plasma concentration of K. The decrease is minimized when ambient temperature of storage is decreased. Accordingly, blood should be centrifuged immediately after sampling for accurate measurement of plasma K concentration. Plasma creatine kinase activity is not a good indicator of associated leg weakness unless physical activity and stress can be controlled before blood sampling.

Blood studies and performance among calves reared by different methods.

Three methods of feeding calves were compared as follows: 1) milk replacer only with restricted movement, 2) milk replacer only with freedom of movement, and 3) hay, grain, and water with freedom of movement. No significant differences were noted for variables of acid-base balance (sampled while resting). An Fe deficiency, microcytic, hypochromic anemia, developed in the calves receiving milk replacer only. Average daily gain, carcass grade, and sale price were superior for calves receiving only milk replacer with freedom of movement as compared with those with restricted movement. A fourth method (calves nursing cows), represented by calves having a different origin, was compared as a supplemental group. Absolute numbers for lymphocyte and neutrophils were significantly higher for calves nursing cows than for calves reared by the other methods.

Erythrocyte changes, serum iron concentration and performance following iron injection in neonatal beef calves.

The injection of iron-dextran into beef calves at an early age immediately increased values for erythrocyte (RBC) numbers, hemoglobin (Hb) concentration, packed cell volume (PCV), mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV), even though the calves were not anemic. There were no significant differences in average daily gain (ADG) from birth through 15 wk between those that were injected and those that were not injected. Hereford calves had lower values for PCV, Hb, MCH and MCV than Angus and crossbred calves, and both Hereford and Angus calves had lesser body weight and slower ADG than crossbred calves. Serum iron (Fe) concentrations were higher in calves born in the spring and pastured in the summer than in calves born in late summer and fall and pastured in the fall. The serum Fe concentration of calves at first sampling (during first week of life) was positively correlated with their weight at that and subsequent times to 15 wk. Mean corpuscular volume and MCH in cows before calving were positively correlated with the MCV and MCH in their calves at first sampling. Serum Fe concentration in cows before calving was negatively correlated with the ADG of their calves through 15 wk.

Injection of iron in newborn beef calves: erythrocyte variables and weight gains with newborn-dam correlations.

Iron injection in beef calves during the 1st week after birth increased their PCV, hemoglobin (Hb) concentrations, mean corpuscular volumes (MCV), and mean corpuscular Hb (MCH). These increases persisted between weeks 2 and 12. The RBC count during the 1st week after birth had a positive correlation with the PCV and Hb concentrations and a negative correlation with the MCV and MCH. There was a positive correlation between the serum iron concentration of the dams and their MCV and mean corpuscular Hb concentration. There was also a positive correlation between the MCV and MCH of the dam and their calf's MCH. Seemingly, iron injection did not affect weight gain during the first 18 weeks of life.

Acid-base balance and selected hematologic, electrolytic, and blood chemical variables in calves nursing cows: one week through fifteen weeks.

Definition was given to acid-base balance, erythrocyte variables, serum iron, and several plasma variables in nursing calves, beginning at 1 week of age to 15 weeks of age. Of all the variables measured (once a week), arterial blood pH was the only one for which there was a significant difference due to sex of the calves (female calves had blood slightly more acidic than did male calves). Significant differences due to time were noted for the erythrocyte variables and for plasma potassium and chloride ion and serum iron concentrations. There were no significant changes from week to week for the acid-base balance variables. A significant sex X time interaction was noted for serum iron concentration-after week 6, the concentration of iron in female calves was higher than it was in male calves.

Response of anemic calves to exertion.

Twenty-one calves, 16 weeks of age, comprised 3 treatment groups. All calves in 2 of these groups were anemic. Several variables were measured before and immediately after an imposed exertion period. The anemic calves had significantly faster heart rates than did nonanemic calves, but there was no significant difference either in respiratory rates or acid-base variables. However, anemic calves became more acidic when made to work and also showed greater increase in respiratory rate than did nonanemic calves. The partial pressure of oxygen in venous blood was significantly lower in the anemic calves than in nonanemic calves both before and after exertion, but still represented adequate saturation of hemoglobin with oxygen.

Acid-base balance and selected hematologic, electrolyte, and blood chemical variables in calves: milk-fed vs conventionally fed.

Several hematologic, acid-base, and electrolyte variables were chacterized for newborn milk-fed calves and conventionally fed calves at weekly intervals for 15 weeks. Definition was given to the iron deficiency, microcytic, hypochromic anemia which developed in milk-fed calves. Acid-base variables in milk-fed calves differed from variables in conventionally fed calves only in having a greater value for base excess. Acid-base variables responded with decreasing magnitude by weeks for both feeding treatments, and responses associated with ambient temperature were suggested. Responses of the other variables and their comparisons between the feeding treatments also were analyzed.

Intestinal infusion of endotoxin in adrenalectomized calves.

Four adrenalectomized calves, 3 to 4 months old, were allowed to develop adrenocorticosteroid insufficiency and then were given 50 mg of Escherichia coli endotoxin by infusion via cannula into the duodenum. Several physiologic variables were studied to detect changes indicative of endotoxemia. It is concluded that adrenocorticosteroid insufficiency in calves is not an independent factor allowing an intestinal source of endotoxin to cause the development of clinical signs and physiologic changes characteristic of endotoxemia.