Changes In Calves Research Articles

Meal patterns and meal-induced metabolic changes in calves fed milk ad lib

The feeding behavior of 11 calves fed milk ad lib was characterized and analyzed at the age of 5 weeks, and the short-term changes in the plasma concentrations of various metabolites (glucose, lactate, free fatty acids, triglycerides, β-hydroxybutyrate) and insulin in relation to a representative spontaneous milk meal were measured during the following week. In a 6-day period, the calves consumed 287 (=86%) of a total of 335 milk meals during the light phase from 0500–2200 [on average, 4.4 ± 0.5 (mean ± SEM) meals]. The meal size and duration during light were 2.0 ± 0.3 kg and 5.3 ± 0.3 min, respectively. However, only 0.7 ± 0.1 milk meals of similar size and duration were consumed during the dark phase. The plasma concentrations of insulin and glucose increased in response to the spontaneous milk meal and remained elevated for at least 2 h after meal end. The plasma concentrations of triglycerides, free fatty acids, and β-hydroxybutyrate also increased after meal termination, and remained elevated until 40 min (triglycerides, free fatty acids) and 60 min (β-hydroxybutyrate) after meal end, respectively. The observed spontaneous milk intake patterns were similar to the natural suckling behavior described for calves, suggesting that the conditions of the present experiment did not disrupt the animals' natural feeding behavior. Some of the profound metabolic changes in relation to a spontaneous milk meal might contribute to the control of milk intake in calves, but further experiments are necessary to test this idea.

Optimizing Replacement Decisions for Finnish Dairy Herds

The purposes of the study were to determine how "an optimal herd" would be structured with respect to its calving pattern, average herdlife and calving interval, and to evaluate how sensitive the optimal solution was to changes in input prices, which reflected the situation in Finland in 1998. The study used Finnish input values in an optimization model developed for dairy cow insemination and replacement decisions. The objective of the optimization model was to maximize the expected net present value from present and replacement cows over a given decision horizon. In the optimal solution, the average net revenues per cow were highest in December and lowest in July, due to seasonal milk pricing. Based on the expected net present value of a replacement heifer over the decision horizon, calving in September was optimal. In the optimal solution, an average calving interval was 363 days and average herdlife after first calving was 48.2 months (i.e., approximately 4 complete lactations). However, there was a marked seasonal variation in the length of a calving interval (it being longest in spring and early summer) that can be explained by the goal of having more cows calving in the fall. This, in turn, was due to seasonal milk pricing and higher production in the fall. In the optimal solution, total replacement percentage was 26, with the highest frequency of voluntary culling occurring at the end of the year. Seasonal patterns in calving and replacement frequencies by calendar month and variation in calving interval length or herdlife did not change meaningfully (< 1%-2% change in the output variables) with changes in calf, carcass or feed prices. When the price of a replacement heifer decreased, average herdlife was shorter and replacement percentage increased. When the price increased, the effect was the opposite.

人工膝関節置換術後におけるＶｅｎｏｕｓ Ｆｏｏｔ Ｐｕｍｐの使用経験

Deep venous thrombosis (DVT) is an important complication following total knee arthroplasty (TKA). Various methods have been used to prevent DVT including venous foot pump (VFP).However, only a few authors have reported the usefulness of the VFP. In this study, we evaluated the effectiveness of the VFP by examining coagulation and fibrinlytic factors and changes in calf and foot cicumference measurments.

Pulmonary hypertension and arterial changes in calves with a systemic-to-left pulmonary artery connection

The pathogenic mechanisms by which increased pressure and flow lead to pulmonary vascular disease are poorly understood, especially in newborns. To study the pathophysiological correlations and timing of the development of structural changes in response to high flow in nonhypoxic neonates, a model of high pulmonary flow was developed in newborn calves by anastomosis of the isolated left pulmonary artery (LPA) to the aorta. LPA pressure and flow increased acutely. LPA pressure reached near-systemic levels by 10 wk, whereas LPA flow was maximally increased at 1 mo before decreasing in several calves. Right pulmonary arterial pressure remained normal, and ventricular hypertrophy did not develop. Morphometric evaluation of the left lung demonstrated decreased arteriolar diameter, increased medial thickness, muscularization of arterioles at the bronchoalveolar junction, luminal obliteration of small arteries, and dilation lesions. The LPA pressure and vascular changes were greater and developed over a shorter time period than did prior models of nonhypoxic flow-induced pulmonary vascular changes. Lesser degrees of decreased arteriolar diameter and muscularization of small vessels were seen in the right lung, indicating a difference in the vascular response to moderately increased flow vs. increased pressure and flow. Thus, calves with an isolated LPA-to-aortic anastomosis simulate the hemodynamic and pulmonary vascular changes seen in newborns with congenital heart defects. Such calves may serve as models to assess effects of mechanical stresses on a newborn's vasculature.

The response of various hematologic parameters in the young bovine subjected to multiple phlebotomies.

Specific guidelines for the optimal collection of blood from calves maintained as donors do not exist. This investigation was conducted to document erythrocytic changes in calves subjected to controlled blood loss. Two groups of Holstein calves ranging in age from 2 to 5 months were compared. Six animals were designated controls and six were subjected to a series of three blood collections over an 8 day period. Each collection was roughly 50% of the total circulating blood volume (30 ml/kg of body weight). Hematologic values were compared for 18 days. All calves survived the study. There was no significant difference in circulating cortisol levels or growth rate between groups. Packed cell volumes (PCVs) for the phlebotomized group did not return to original levels during the monitoring period (initial 36%, final 26%), but were within normal limits at 30 days. All phlebotomized calves had a high reticulocyte count (0% control, 11% phlebotomized). Reticulocytes were not observed until the PCV fell below 20. HbF to HbA ratios were a sensitive and acute indicator of accelerated erythropoiesis. Variant ratios stabilized within 18 days. Other parameters compared were red cell indices, total erythrocyte count, total leukocyte count, total plasma protein, total hemoglobin values, and neutrophil to lymphocyte ratios.

Initial Results of a Statewide Extension Program in Calf and Heifer Management in Pennsylvania

This study was designed to evaluate changes in calf and heifer management in a sample of Pennsylvania dairy farms in conjunction with a statewide extension program on dairy replacements. The extension program reached dairy farmers in addition to individuals in agribusiness, veterinarians, and others who have frequent contact with dairy farmers through a multiplicity of information channels. An extensive survey was conducted during the 1st yr of the project on 329 commercial dairy farms throughout Pennsylvania. The same farms were contacted 2.5 to 3 yr later for comparison. Most (84.7%) of the farmers in the original random sample learned new information about calf and heifer management during this time, and 77.3% reported that they received all or part of this new information from extension. Sources of information most often used by the farmers in this study were dairy magazines, extension newsletters, and meetings organized either through extension or agribusiness. Adoption by farmers of many of the targeted practices specific to calving management, preweaned calves, and health management increased over this period.

Blood Coagulability and Hematological Changes in Calves with Chronic Centrifugal Biventricular Bypass Pumps

A Hemadyne centrifugal pump was used to determine the effects of long-term circulatory assist on platelet number and aggregability. Five calves were supported on biventricular bypass with a pair of Hemadyne centrifugal pumps. On the 7th postoperative day (POD), the heart was fibrillated after pump flow rates were increased to compensate for the total cardiac output. The animals were anticoagulated with heparin throughout the study and adjustments were made to maintain the activated clotting time at between 180 and 220 sec. To maintain the activated clotting time level in the therapeutic range, it was necessary to gradually increase the heparin dose with time due to the developing heparin tolerance. Fibrinogen levels increased significantly on the 3rd postoperative day when compared to the preoperative control value. Platelet aggregation was measured using a whole blood impedance method with adenosine diphosphate and collagen as agonists. Platelet function was found to be significantly depressed following the biventricular bypass procedure ( P < 0.05 on the 7th, 14th, and 21st POD). Platelet numbers were significantly decreased compared to the preoperative control values, being the lowest on the 1st and 3rd POD, recovering to 76% of the control values by the 7th POD, and then gradually decreasing to the 55% level by the 28th POD. These results show that, when tested for up to 4 weeks following surgery, both platelet number and function in calves supported with centrifugal pumps remain depressed. Despite the progressive heparin tolerance and suppressed platelet number and function, none of the animals showed abnormal bleeding tendencies on biventricular bypass.

Relationship of maternal milk expected progeny differences to actual milk yield and calf weaning weight

Calf weaning weights and estimates of 205-d milk yield (n = 317) were obtained from 90 Polled Hereford (PH) and 80 Simmental (SM) cows to evaluate the relationship of these measures with maternal milk and total maternal EPD from national cattle evaluations. An inverse parabolic exponential function predicted 205-d milk yields for each cow from five estimates of daily milk yield taken once per month via calf weigh-suckle-weigh. Changes in calves' 205-d adjusted weights were greater than predicted (P < .02) by maternal milk EPD of PH and SM dams and PH maternal grandsires (MGS) but were similar to changes predicted by SM MGS (P > .50). These changes were also greater than those predicted by total maternal EPD of PH dams and MGS (P < .02) but were similar to those predicted in SM dams and MGS (P > .38). Interactions of maternal milk and total maternal EPD with sex of calf and year did not influence calves' 205-d adjusted weights (P > .10). A positive relationship was found in both breeds between 205-d milk yield EPD (calculated from 205-d milk yield estimates) and maternal milk EPD from national cattle evaluations. Objectively assessing the magnitude of this relationship was hindered by problems in estimating heritability and interpreting correlations between EPD. These data indicate that maternal milk and total maternal EPD from national cattle evaluations are reasonably good predictors of genetic differences in milk yield and weaning weight.

Serum liver enzyme and histopathologic changes in calves with chronic and chronic-delayed Senecio jacobaea toxicosis

SUMMARY Progressive changes in serum enzyme activity and liver histologic features were monitored in calves fed tansy ragwort (Senecio jacobaea)-contaminated pellets. The experiments were designed to simulate natural intoxicant ingestion conditions in relationship to the dose and duration of exposure to the toxic plant to correlate early laboratory diagnostic changes with the natural progression of the disease, thereby facilitating early diagnosis and intervention by veterinary clinicians. Eight calves were fed tansy ragwort and 4 additional calves served as controls. In group 1, 4 calves were continuously fed dried tansy ragwort mixed in a pelleted feed at a 5% concentration by dry weight until terminal liver disease developed. Serum liver enzyme (alkaline phosphatase, glutamate dehydrogenase, and γ-glutamyltransferase) activities were monitored at weekly intervals in these calves and in the 2 controls. In group 2, 4 calves were fed the same contaminated feed for only 60 days, with return to normal feed for the duration of the trial. Two additional calves served as controls. Their liver enzyme activities were monitored every other week in conjunction with percutaneous liver biopsies. All 8 calves fed tansy ragwort-contaminated pellets developed terminal hepatopathy in either a chronic pattern (n = 6) or a chronic-delayed pattern (n = 2), with the onset of a moribund state or sudden death at 11 to 17 weeks and 27 to 51 weeks, respectively. The calves were euthanatized when classic terminal signs of hepatic encephalopathy first became evident. The clinicopathologic patterns of chronic and chronic-delayed toxicoses were typical of over 5,000 cases of field tansy toxicosis diagnosed at the diagnostic laboratory. Serum glutamate dehydrogenase was the first enzyme to increase in most animals, with a short-term increase to peak values followed by a rapid return to normal. This enzyme change was followed by increases in alkaline phosphatase and γ-glutamyltransferase. Serum enzyme changes preceded development of recognizable histologic lesions. Vacuolar changes in hepatocyte nuclei, biliary hyperplasia, and fibrosis sequentially developed in liver biopsy specimens from each animal, whereas megalocytosis was not a predominant feature until necropsy. On the basis of our findings, we suggest that the optimal tests for diagnosis of pyrrolizidine alkaloid intoxication should consist of liver biopsy and determination of concurrent serum liver-enzyme activities.

Slow volume changes in calf and thigh during cycle ergometer exercise

To study the transcapillary fluid movements in the human lower limb in the upright body position and during muscle exercise, the slow changes in thigh and calf volumes were measured by mercury-in-rubber-strain gauge plethysmography. Measurements were carried out on 20 healthy volunteers while sitting, standing and doing cycle ergometer exercise at intensities of 50 and 100-W. A plethysmographic recording of slow extravascular volume changes during muscle exercise was possible because movement artefacts were eliminated by low-pass filtering. While standing and sitting the volumes of both thigh and calf increased due to enhanced transcapillary filtration. While standing the mean rate of increase was 0.13%.min-1 in the calf and 0.09%.min-1 in the thigh. During cycle ergometer exercise at 50 and 100 W, the calf volume decreased with a mean rate of -0.09.min-1. In contrast, the thigh volume did not change significantly during exercise at 50 W and increased at 100 W. Most of the increase occurred during the first half of the experimental period i.e. between min 2 and 12, amounting to +0.6%. Thus, simultaneous measurements revealed opposite changes in the thigh and calf. This demonstrates that the conflicting findings reported in the literature may have occurred because opposite changes can occur in different muscle groups of the working limb at the same time. Lowered venous pressure, increased lymph flow and increased tissue pressure in the contracting muscle are considered to have caused the reduction in calf volume during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid Compositional Changes in Calves Fed Excess Iodine

Calves were fed milk replacer containing .57, 10, or 200ppm iodine (from ethylenediaminedihydriodide) to determine the effects of excess dietary iodine on composition of lipids in blood plasma, liver, and heart. High iodine intakes had no effect on plasma total lipids or lipid classes, but caused lipid class concentration changes in liver and heart. Both 10 and 200ppm iodine increased concentration of liver phosphatidylethanolamine and heart phosphatidylcholine, cholesterol, and total lipids, and the 200ppm intake also increased concentration of liver phosphatidylcholine, total lipids, and heart phosphatidylethanolamine. Both iodine treatments tended to increase all the other minor lipid classes in liver and heart as well. Both 10 and 200ppm iodine treatments increased some of the n—3 polyunsaturated fatty acids in the major phospholipids of plasma, liver, and heart. For the preruminant calf, liver and heart may be more useful than blood plasma for indicating excess iodine effects on lipid metabolism.

Muscle acidosis during static exercise is associated with calf vasoconstriction.

In this study we measured (n = 6) the phosphocreatine-to-inorganic phosphate ratio (PCr/Pi), Pi, and pH with 31P-nuclear magnetic resonance (31P-NMR) in the human forearm during static work at 30% of maximal voluntary contraction (MVC) for 2 min followed immediately by 3 min of circulatory arrest (forearm arterial occlusion). Static exercise, with its central volitional and skeletal muscle metabolic and mechanical afferent components, caused a rise in heart rate (HR, 32%), blood pressure (BP, 29%), and calf vascular resistance (calf R, 30%). During forearm occlusion after static exercise, HR returned to base line, the increase in BP was attenuated by 30%, and calf R remained elevated and unchanged. The percent change in calf R was correlated with forearm cellular pH (R = 0.56, P less than 0.001) but only weakly associated with PCr/Pi (R = 0.33, P less than 0.042). 30% MVC for 1 min followed by arterial occlusion (3 min) reduced PCr/Pi by 65% and pH by 0.16 U (P less than 0.05). Calf R was unchanged. Circulatory arrest alone (20 min) caused no change in either pH or calf R but large changes in PCr/Pi (50% reduction). We conclude that 1) there is an association between forearm cellular acidosis and calf vasconstriction during static forearm exercise and 2) large changes in PCr/Pi without concomitant changes in pH are not associated with changes in calf R.

Clinical signs and biochemical changes in calves caused by injection of ivermectin.

Eight-month-old Jersey bull calves given ivermectin intravenously or subcutaneously showed signs of depression, ataxia, difficulty in breathing, tachycardia, salivation, diarrhoea, miosis, and an increase in pseudocholinesterase activity. The clinical signs were severe in calves given the drug intravenously. The findings suggest that the cholinergic nervous system may be involved in some of the adverse effects of ivermectin observed in calves.

Epinephrine and norepinephrine related to cardiorespiratory and metabolic changes in calves during physical exercise.

Experiments were designed to study changes of blood levels of norepinephrine (NE) and epinephrine (E) and their possible role in metabolic adaptation to short-lasting physical exercise in calves. After a resting period for 5 min (I), animals walked on a treadmill for 10 min at a speed of 60 m/min, first horizontally for 5 min (II), then at a slope of 6 degrees for another 5 min (III), followed by a recovery period for 5 min (IV). Levels of NE and E increased within minutes during walking and then decreased. Changes were closely related to respiration rate, ventilation volume, O2-uptake, heart rate and blood lactate levels. Blood triiodothyronine and protein slightly increased only during period III, whereas glucose, non-esterified fatty acids and the respiration quotient increased throughout the experiment. Blood insulin levels were decreased during walking and rapidly increased afterwards. Blood glucagon did not change significantly. Work load affected all parameters except glucagon and triiodothyronine. There were individually significant differences for all parameters, except for NE and the respiration quotient. The data demonstrate rapid reactions of the cardiorespiratory system and of blood insulin and lactate levels on submaximal work load, normally in close association with plasma E and NE.

Non‐neoplastic pulmonary multinucleate giant cells

Pulmonary multinucleate giant cells (MGCs) in porcine dermatosis vegetans (DV) were compared with virus-induced and inflammatory-associated MGCs, with particular attention to mechanisms involved in the formation of such cells. Ultrastructurally, pigs with DV showed numerous pulmonary MGCs with transversely-sectioned interdigitating microvillous structures. Microvilli were observed closely apposed to type-II pneumocytes and with morphological characteristics of membrane bridge formation. Rabbits infected with Mycobacterium bovis exhibited multiple pulmonary granulomas with prominent MGC formation 14 days after infection. Close apposition between MGCs and small macrophages and membrane bridge formation were demonstrated ultrastructurally. Pulmonary changes in calves infected with bovine respiratory syncytial virus (BRSV) included lobular consolidation and intense infiltration of inflammatory cells into the bronchial, bronchiolar and alveolar walls. Proliferation of bronchiolo-alveolar epithelial cells was prominent, but syncytiae were only occasionally demonstrated. This study of the morphological characteristics of MGCs is related to the present knowledge of mechanisms involved in membrane fusion and allows for an interpretation of an active fusion process involved in the formation of MGCs in porcine DV.

Early metabolic and endocrine effects of perorally administered ß-adrenoceptor agonists in calves

Early metabolic and endocrine changes in calves in response to two ß-adrenoceptor agonists in the absence and presence of the ß-adrenoceptor blocking agent propranolol have been studied in calves. The agonists were administered p.o. with milk in different amounts, whereas propranolol was infused i.v. for 10 h. Respiration volume, O 2 consumption, CO 2 production, respiratory quotient, blood glucose, lactate, non-esterified fatty acids and Insulin transiently increased within 2–4 h in a dose-dependent manner, whereas glucagon, adrenaline, noradrenaline, triioothyronine, urea, albumin and protein did not change significantly. Propranolol completely inhibited the effects on glucose, lactate, non-esterified fatty acids and insulin. Six hours after the administration of the ß-adrenoceptor agonists, the glucose clearance rates following i.v. infusion of glucose were markedly reduced and the glucose decrements in response to an i.v. injection of insulin were much smaller than in the absence of the ß-adrenoceptor agonists. The metabolic changes demonstrate an enhanced glycogenolysis and fat mobilisation, an increased metabolic rate and the development of insulin resistance within 6 h after the administration of the ß-adrenoceptor agonists.

Serum enzyme changes in calves experimentally infected with Schistosoma bovis

The activities of the enzymes SD, GD, AAT, 5′NT, GGT, LDH and CPK were determined weekly in sera of two calves each infected with 10 000 S. bovis cercariae and in two controls. In infected animals, LDH activity increased from the first week of exposure and remained high throughout the experiment (22 weeks). GGT activity increased nine weeks after exposure and remained high. CPK activity was elevated during weeks 8–15 of infection. No change was detected in the activity of the other enzymes, nor in any enzymes of the controls.

The efficacy of dexamethasone and flunixin meglumine in treating endotoxin-induced changes in calves.

Eicosanoids have been implicated in the pathophysiology of endotoxic shock. Drugs which alter eicosanoid production such as corticosteroids and non-steroidal anti-inflammatory drugs (NSAID) are beneficial in treating endotoxic shock. Experiments were conducted to investigate the efficacy of dexamethasone, a corticosteroid, and/or flunixin meglumine, a NSAID, in treating endotoxin-induced changes in calves. Fourteen male calves were assigned to one of four treatment groups: group 1, endotoxin-untreated; group 2, endotoxin-flunixin meglumine treated; group 3, endotoxin-dexamethasone-treated; group 4, endotoxin-flunixin meglumine and dexamethasone-treated. Each calf was given three intravenous and intraperitoneal injections of E. coli endotoxin. Hemodynamic, blood gas, blood chemical and eicosanoid level determinations were obtained. Thirty minutes after endotoxin injection, pulmonary artery pressure (PAP) increased and cardiac output (CO) decreased compared with baseline, corresponding to increased thromboxaneB2 levels in groups 1 and 3. These groups exhibited a decreased mean arterial pressure (MAP) at three and five hours corresponding to increased 6-keto-prostaglandinF1 alpha. The MAP, PAP and CO of group 4 remained near baseline for the entire six hours, except for a late drop in MAP. Lactic acid levels were significantly increased and arterial bicarbonate levels were reduced by six hours in all groups except for group 4. These results indicate that the combination treatment of flunixin meglumine and dexamethasone prevents many of the metabolic derangements observed during endotoxic shock in calves.

Serum biochemical changes in calves with Johne's disease.

Calves clinically affected with experimentally induced Johne's disease exhibited elevation of caeruloplasmin oxidase activity, and marked depression of alpha-mannosidase activity during the period when clinical signs of the disease were most prominent. Changes in serum copper levels and alkaline phosphatase activity were closely correlated with the elevation of caeruloplasmin oxidase activity, and depression of alpha-mannosidase activity. The pattern of these changes was similar to nutritional and metabolic changes described previously in acute infectious conditions in man and animals.

Neural changes in calves intranasally inoculated with two strains of infectious bovine rhinotracheitis virus

Two different strains (Teshio and Erimo) of infectious bovine rhinotracheitis (IBR) virus were intranasally inoculated into calves and produced a slight rhinitis. Changes were consistently observed in the trigeminal ganglion. The severity of the lesions was more extensive in the calves exposed to the Erimo strain and the lesions were accompanied by degeneration of the ganglion cells and neuronophagia. Trigeminal ganglionitis produced by the two strains of virus may be a useful feature for the histopathological diagnosis of IBR virus infection in calves.