Calves Of Different Ages Research Articles

Effect of Age on the Pharmacokinetics of Marbofloxacin Following Intravenous Administration in Calves.

The aim of this study was to compare the pharmacokinetics of marbofloxacin after intravenous (IV) administration of a single dose of 10 mg/kg to calves of different ages. The study was carried on 1- (n = 6), 2- (n = 6), and 4-month-old (n = 6) Montofon calves. Plasma concentrations of marbofloxacin were measured using HPLC, and pharmacokinetic data were calculated by non-compartmental analysis. The elimination half-life (t1/2ʎz), volume of distribution at steady state (Vdss), total clearance (ClT), and area under the concentration-versus time curve (AUC0-∞) values of marbofloxacin in 1-month-old calves were 10.62 h, 1.03 L/kg, 0.08 L/h/kg, and 127.90 h*μg/mL, respectively. While the t1/2ʎz (from 10.62 to 3.36 h) and AUC0-∞ (from 127.90 to 47.35 h*μg/mL) decreased in parallel with the age of the calves, ClT (from 0.08 to 0.21 L/h/kg) increased. The Vdss of marbofloxacin was higher in 1- and 2-month-old calves compared to 4-month-old calves. After IV administration of marbofloxacin at a dose of 10 mg/kg, an ƒAUC0-24/MIC90 ratio of ≥ 125 was obtained for bacteria with MIC90 values of ≤ 0.60, ≤ 0.39 and ≤ 0.27 μg/mL in 1-, 2-, and 4-month-old calves, respectively. These results show that the antibacterial effect of marbofloxacin, which has concentration-dependent activity, decreases due to age-related pharmacokinetic changes and that the 10 mg/kg dose should be reviewed according to the MIC90 value of the bacteria.

Prevalence of extended-spectrum and AmpC β-lactamase-producing Escherichia coli in young calves on Dutch dairy farms

In young calves on dairy farms the animal prevalence of extended-spectrum and AmpC β-lactamase-producing Escherichia coli (ESBL/AmpC-EC) is significantly higher compared with the animal prevalence in young stock and dairy cows. Hitherto it was unknown at what age antimicrobial resistant bacteria appear for the first time in the gut of calves on dairy farms, and how long these infections persist. The aim of this study was to examine the prevalence of ESBL/AmpC-EC, the number of excreted ESBL/AmpC-EC (in cfu/g of feces), as well as the ESBL/AmpC genotypes in young dairy calves (0-21 d of age) and the variation of these parameters between calves of different ages. Next to this, the course of shedding ESBL/AmpC-EC during the first year in dairy calves was studied. In a cross-sectional study, fecal samples from 748 calves, from 0 to 88 d of age, on 188 Dutch dairy farms were collected. The prevalence of calves testing positive for ESBL/AmpC-EC in a phenotypic assay was determined for different age categories (per 2 d of age). Positive samples were subjected to a semiquantitative test to determine the numbers of ESBL/AmpC-EC per gram of feces and for a selection of ESBL/AmpC-EC isolates the ESBL/AmpC genotype was determined. Ten of the 188 farms were selected for a longitudinal study based on the presence of at least 1 female calf with ESBL/Amp-EC in the cross-sectional study. These farms were additionally visited 3 times with a 4-mo interval. All calves that were sampled in the cross-sectional study were, if still present, resampled during the follow-up visits. Results show that from the day of birth ESBL/AmpC-EC can be present in the gut of calves. The phenotypic prevalence of ESBL/AmpC-EC was 33.3% in 0- to 21-d-old calves and 28.4% in 22- to 88-d-old calves. The prevalence of ESBL/AmpC-EC positive calves varied per age category among calves up to 21 d of age: significant increases and decreases at an early age were shown. Results of the longitudinal study show that after 4, 8, and 12 mo the prevalence of ESBL/AmpC-EC positive calves dropped to 3.8% (2/53), 5.8% (3/52), and 2.0% (1/49), respectively. This indicates that early gut colonization in young calves with ESBL/AmpC-EC is transient and does not lead to long-term shedding of these bacteria.

Can the emotional state of calves be noticed by their facial expression and heart rate?

The aim of this study was to identify whether or not dairy calves change their facial expression and heart rate according to their emotional state when subjected to a stroking or umbrella stimulus. Thirty-two mixed-breed Holstein calves of different ages were submitted to stroking and umbrella stimulus. For the stroking stimulation, a researcher performed stroking for 1 min in the neck region with continuous and frequent movements (about 40–60 movements per minute) to simulate the speed with which an animal would receive allogrooming. As for umbrella stimulus, a researcher positioned himself one meter in front of the calf, with an umbrella in his hand, without making eye contact. Then, the umbrella was suddenly opened and remained open for one minute. The eyebrow position, mouth, eye white area, nostril area and heart rate were investigated. For the continuous variables, eye white area, nostril area and heart rate we used the linear mixed effects. For the binary variables, mouth (open or closed) and eyebrow (raised or normal). We used the generalized linear mixed model with logit link function. The variables eye white area, nostril area, mouth and eyebrow did not present significant effects (P > 0.05) as a result of the stimulus. However, the heart rate showed a significant difference (F(1150) = 15.264, P < 0.001) according to the stimulus the animals received. Dairy calves do not express facial changes in their emotional state when subjected to stroking or umbrella stimuli, but there is a reduction in heart rate relates to the valence of a stimulus.

First Molecular Genotyping of Cryptosporidium felis in Cattle, Iraq.

To the best of our knowledge, this is the first Iraqi study to detect C. felis in cattle by the polymerase chain reaction (PCR) assay and to confirm the local isolates in the National Center for Biotechnology Information (NCBI). Overall, 130 diarrheic calves of different ages and sexes were selected randomly from rural and sub-urban areas in Wasit province (Iraq) from February to April (2021) and subjected to direct collection of fresh fecal samples for DNA extraction and PCR examination. Targeting the heat shock protein 70 (HSP70) gene of C. felis showed that 17.69% of the animals were positive. Findings from clinical examination revealed no significant differences in values of temperature, pulse, or respiratory rates between the positive and negative calves. The association between the positive results and demographic risk factors showed no significant differences in the prevalence rate of infection and risk of exposure to C. felis between the rural and sub-urban areas; however, higher significant values were reported in calves aged 6 months than in calves aged 12 months, as well as in females than in males. Five of the local C. felis isolates were documented under the accession numbers MZ964600.1, MZ964601.1, MZ964602.1, MZ964603.1, and MZ964604.1. Finally, the data presented here provide epidemiological and molecular evidence that the range of C. felis in cattle is wider than expected globally, with a high probability of infection transmission from cattle to humans.

Effect of some current enzymes on milk coagulation indicators

Soft cheese technology involves using a significant number of enzymes involved in the circulation of milk. The market is filled with drugs of microbial origin; although they are cheaper than their counterparts made from ruminants, the demand for cheeses made with pure enzymes is relatively high. Brine cheeses are famous in Ukraine, and their production occupies an important place in cheesemaking and belongs to the dynamically developing food industries. Cheese is a source of complete protein, calcium, magnesium, and vitamins. Cheeses contain all the essential nutrients of milk except carbohydrates. The task of our work was to establish the effectiveness of the action on the circulation of milk and rennet enzymes obtained from rennet calves of different ages (from 2 to 20 weeks). The research was conducted in the conditions of the Research Institute of Food Technologies and Technologies of Processing of Livestock Products of Bila Tserkva National Agrarian University. It was found that enzymes derived from the abomasum of calves slaughtered at an earlier age coagulate milk faster, and enzymes obtained at an older age convert milk more slowly, but the quality of milk clots in organoleptic characteristics is almost the same. The effect of enzymes obtained from the abomasum of calves of different ages on serum acidity has not been established.

Unmitigated Surgical Castration in Calves of Different Ages: Cortisol Concentrations, Heart Rate Variability, and Infrared Thermography Findings.

Simple SummaryIn the United States, castration is a common husbandry procedure utilized in the cattle industry. Despite castration being painful, it is commonly performed without the use of analgesia, one reason being the lack of available approved analgesics in the United States for use in alleviating pain associated with castration in cattle. Additionally, if pain mitigation is used, it is more often provided to older animals as there is a notion that younger animals experience pain to a lesser degree than older ones. The aim of this study was to characterize physiological responses to unmitigated surgical castration in calves of varying ages in terms of cortisol concentration, heart rate variability, and changes in eye temperature. Overall, our results indicate that the measured physiological responses to castration differed between age groups and changed over time post-castration. Younger calves showed a different response pattern than older calves for many of the variables measured suggesting that the response to castration-induced pain may be age-specific. For example, the youngest calves had lower cortisol and average eye temperature as compared to the oldest calves. Additionally, many variables showed a differential response to castration-induced pain, as compared with simulated castration, thus suggesting physiological indicators that could be targeted in future development and validation of analgesics for alleviation of pain associated with castration in cattle.The objective was to characterize physiological responses to unmitigated surgical castration in calves of varying ages. Thirty male Holstein calves of three ages [<6 w (6W); 3 m (3M); 6 m (6M); n = 10] underwent a simulated castration treatment (SHAM) followed 24 h later by castration (CAST). For both treatments, heart rate variability, eye temperature, and cortisol were measured over time from treatment to specified end points to capture the acute response period. Interactions between treatment and age (p = 0.035) and time and age (p < 0.001) were noted for cortisol. The 6W calves had lower cortisol compared to 6M calves at SHAM and CAST. Cortisol of 6W calves decreased from peak to pre-treatment levels faster than 6M calves. An interaction between time and age was reported in squared differences of inter-beat-intervals (RMSSD; p = 0.02) and high-frequency power (HFP; p = 0.05), whereby both responses decreased in 6W calves during the sampling period which was not seen in 3M and 6M calves. Average eye temperature (AET) differed by age (p = 0.0018) whereby 6W calves had lower AET than 6M calves (p = 0.0013) regardless of treatment and time. The findings suggest that responses to unmitigated surgical castration seem to be mediated by the autonomic nervous system in an age-related manner.

Unmitigated Surgical Castration in Calves of Different Ages: Electroencephalographic and Neurohormonal Findings.

Simple SummaryCastration is a painful procedure that is commonly performed on cattle without analgesia. Although castration is considered to be more painful in older calves, studies examining the effect of age on electrophysiological and neurohormonal responses to pain under the same experimental conditions are limited. There are several limitations to providing pain mitigation for castration, one being the lack of available approved analgesics for use in alleviating the pain associated with castration in the United States. It is necessary to validate methods of pain assessment in cattle to support the development of pain relief drugs. The aim of this study was to investigate the effect of unmitigated surgical castration on the electroencephalography (EEG) responses and plasma substance P (SP) concentrations in calves, without pain relief across different age groups. Age, time, and procedure (castration or a simulated castration) impacted outcomes. The findings suggest that surgical castration without pain relief causes variations in EEG responses and in SP concentrations and that these responses are age related.Castration is a common management procedure employed in North American cattle production and is known to cause a pain response. The present study was designed to investigate the effect of unmitigated surgical castration on the electroencephalography (EEG) responses and plasma substance P (SP) concentrations in calves of different ages under the same experimental conditions. Thirty male Holstein calves in three age categories [<6 weeks (6W); 3 months (3M); 6 months (6M); 10 calves per age group] were used in the study. Calves were subjected to a simulated castration session (SHAM) followed 24 h later by surgical castration (CAST) without analgesia. An EEG analysis was performed before the procedure (i.e., baseline), at treatment, and 0–5, 5–10, and 10–20 min post-treatment for both SHAM and CAST, respectively. Blood samples were collected immediately prior to both treatments (time 0) and again at 1, 2, 4, 8, and 12 h after both treatments. The EEG results showed a three-way interaction between treatment, age, and time for delta and beta absolute power, beta relative power, total power, and median frequency (p = 0.004, p = 0.04, p = 0.04, p = 0.03, and p = 0.008, respectively). Following CAST, EEG total power decreased, and median frequency increased relative to SHAM in 6W and 3M calves only following treatment. For 6W and 3M calves, delta and beta absolute power increased at CAST and at later time points relative to SHAM. Marginal evidence for two-way interactions was noted between time and treatment and between age and treatment on the concentration of SP (p = 0.068 and p = 0.066, respectively). Substance P concentrations decreased in CAST treatment compared to SHAM at the later times (8 h: p = 0.007; 12 h: p = 0.048); 6W calves showed lower SP concentration at CAST relative to SHAM (p = 0.017). These findings indicate variation in EEG responses and in SP concentrations following unmitigated surgical castration in calves and that these responses may be age specific. These EEG findings have implications for supporting the perception of the pain associated with surgical castration in young calves and emphasize the urgency of pain mitigation strategies during routine husbandry practices such as castration, as typically implemented in North American cattle management.

Co-Infection of Bovine Papular Stomatitis Virus, Rotavirus and Cryptosporidium Spp. in a Calf

Abstract Concurrent occurence of bovine papular stomatitis, rotavirus infection and cryptosporidiosis was diagnosed postmortem in a 7-days-old calf from a farm containing 65 calves of different ages. Multifocal papular stomatitis and rumenitis were present on necropsy. While polymerase chain reaction analysis revealed rotavirus and papular stomatitis virus infections; bovine viral diarrhea, foot and mouth disease, bovine papilloma virus and coronavirus could not be detected. Overall; concurrent co-infection with bovine papular stomatitis virus, rotavirus and cryptosporidium spp. was reported for the first time.

Longitudinal surveillance of rotavirus A genotypes circulating in a high milk yield dairy cattle herd after the introduction of a rotavirus vaccine

Worldwide, neonatal diarrhea is one of the most important health issues affecting dairy calves, and rotavirus A (RVA) is one of its primary causes. Among the measures to mitigate the risk of diarrhea outbreaks, cow vaccination stands out as one of the most important. However, the immune pressure resulting from routine vaccination may be able to select specific G and P genotypes in RVA field strains. This study aimed to determine the frequency and intensity of neonatal diarrhea and the incidence of RVA and attempted to monitor the G and P genotypes present in the RVA strains circulating in a high milk yield cattle herd vaccinated with RVA G6P[5] strain. Fecal samples (n = 1220) from 122 Holstein heifer calves between 0–30 days old that were born from RVA-vaccinated cows were collected at 10 different time points, regardless of the presence or absence of diarrhea. The presence of RVA in fecal samples was determined by the polyacrylamide gel electrophoresis (PAGE) technique and confirmed by reverse transcription polymerase chain reaction (RT-PCR). G and P amplicons from 10 RVA-positive fecal samples from calves of different ages and collections were subjected to nucleotide sequencing. The proportion of the calves and fecal samples that were positive for RVA were 62.3% (76/122) and 8.1% (99/1220), respectively. Using sequence analysis, all 10 RVA field strains presented genotype G10P[11]. The protection of G6P[5] vaccination is clear, as this genotype was not detected in this study, and it is known that vaccination against RVA reduces the incidence of diarrhea independent of genotype involved. This result demonstrates the importance of epidemiological monitoring of RVA genotypes circulating in vaccinated dairy cattle herds to the early detection of new potential pathogenic RVA strains.

Relationship between hepcidin and oxidant/antioxidant status in calves with suspected neonatal septicemia.

Aim:This study has been conducted for the purpose of determining serum hepcidin, total antioxidant status (TAS), total oxidant status (TOS), and Fe levels in calves with suspected neonatal septicemia before and after treatment and the clinical significance of hepcidin in calves with suspected neonatal septicemia.Materials and Methods:The study material consisted of 15 calves of different ages and sexes brought to the Training, Research and Application Center at the Kafkas University Faculty of Veterinary Medicine with suspected neonatal septicemia. 8.5 mL of blood was drawn from the jugular vein of each animal into coagulant tubes before and after treatment for one-off biochemical analyses and centrifuged. After this, the serum was separated. Hepcidin, TAS, TOS, and Fe levels in the serum were measured.Results:While pre-treatment hepcidin levels were 58.42±3.46 ng/mL, post-treatment levels were 46.87±2.98 ng/mL (p<0.05). Pre-treatment Fe levels were 60.13±7.27 µg/dl, while post-treatment levels were 83.1±8.09 µg/dl (p<0.05). The changes in the TAS and TOS levels were also found to be statistically significant.Conclusion:In light of the fact that hepcidin plays a role function in the regulation of Fe as well as the fact that Fe is a significant nutritional source for many microorganisms, it was concluded that hepcidin may play a significant role in nutritional immunity and the pathogenesis of diseases.

The influence of sodium propionate on blood glucose, insulin and cortisol concentrations in calves of different ages

The process of gluconeogenesis in ruminants is under the direct influence of insulin and glucocorticoid hormones. The goal of this study was to determine the effects of added Na-propionate on the neuroendocrine regulation of blood glucose in calves at three specific physiological periods: on exclusive milk nutrition; on mixed milk and forage nutrition; and with established ruminant digestion. The influence of Na-propionate on blood glucose, insulin and cortisol concentrations was examined in the same 20 female Holstein calves at different stages of forestomach development (15 days, 2 months, and 4 months of age of calves). Group 1 of calves (n = 10) received Na-propionate intravenously; group 2 (n = 10) received Na-propionate mixed in milk. Blood sampling was performed 1 and 3 h after Na-propionate administration. After i.v. administration of Na-propionate, a significant increase (P &lt; 0.05) in blood glucose concentration was observed 1 h after administration only in calves aged 2 and 4 months; blood insulin concentration was significantly higher (P &lt; 0.01) 1 and 3 h after i.v. administration in 2-month-old calves; and cortisol concentration increased (P &lt; 0.01) 1 h after administration in each selected calf in all testing periods. Orally administered Na-propionate led to a significant increase (P &lt; 0.01) of insulin concentration 1 and 3 h after administration in 15-day-old calves, and 3 h after administration in 2-month-old calves. Based on these results it could be assumed that i.v. and p.o. administration of Na-propionate affects the neuroendocrine regulation of glycaemia in calves of different age.

Effects of sex and age on behavior and weight gain in beef calves after abrupt weaning.

The effects of weaning on beef calves of different ages were investigated. Forty male and 40 female calves were either weaned at 6 (W6, n = 40) or 8 (W8, n = 40) months of age. The vocalization activity and behaviors (feeding, lying and standing/walking) were observed during the first 3 days following weaning. Body weight was recorded at 6 and 8 months and 2 weeks following weaning. W6 animals vocalized more often than W8 calves and females more than males on day 1 (P < 0.05). The vocalization activity decreased at a higher rate in W8 than in W6 from days 1 to 3. On day 2, W6 calves spent less time lying and more standing/walking than W8 calves (P < 0.05). The behaviors did not differ between males and females. The average daily gain after weaning did not differ between weaning ages (P > 0.05), but W8 calves gained more from 6 to 8 months of age. In conclusion, weaning distress was more pronounced in W6 than in W8 calves. W8 calves also had a superior growth performance during 6 to 8 months of age. The effect of the calves' sex was less pronounced. Therefore, it is recommended to wean beef calves later than 6 months of age.

Effect of castration method on neurohormonal and electroencephalographic stress indicators in Holstein calves of different ages

As public concern for food animal welfare increases, a need to validate objective pain assessment tools exists in order to formulate animal welfare policies and facilitate regulatory approval of compounds to alleviate pain in livestock in the United States. The aims of this study were (1) to compare the physiological response to pain induced by surgical and nonsurgical (band) castration in calves and (2) to elucidate age-related differences in pain response of calves subjected to different castration methods. Seventy-six Holstein bull calves were blocked by age (≤8-wk and ≥6-mo-old) and randomly assigned to 1 of 4 treatment groups: control (n=20), castration by banding (n=18), cut-and-clamp surgical castration (n=20), and cut-and-pull surgical castration (n=18). Measurements included electroencephalogram, heart rate variability, infrared thermography, electrodermal activity, and concentrations of serum cortisol and plasma substance P before, during, and within 20min following castration. Electroencephalogram recordings showed desynchronization for all treatments, consistent with increased arousal; yet the magnitude of desynchronization was greatest for 6-mo-old calves castrated by cut-and-clamp. Additionally, older calves in the cut-and-pull group showed greater desynchronization than younger calves in the same group. Based on the heart rate variability analysis, 6-mo-old calves in the control or cut-and-pull castration groups showed greater sympathetic tone than younger calves in the same treatment groups. Overall, younger calves showed lower electrodermal activity than older calves. Regardless of treatment, concentrations of cortisol and plasma substance P were greater in 6-mo-old calves relative to their younger counterparts, indicating a more robust response to all treatments in older calves. In summary, neurohormonal and electroencephalographic stress responses of calves to castration were age-specific. Castration by cut-and-clamp showed the most pronounced stress response in 6-mo-old calves. These findings provide evidence that support welfare policies recommending castration at an early age and the use of analgesic compounds at the time of surgical castration especially in older calves. However, the potential long-term negative consequences of early untreated pain must be considered and warrant further investigation.

Studies of the structure of the Solovetsky reproductive gathering of beluga whales (Delphinapterus leucas) in the White Sea using the photo identification method

The structure of the reproductive gathering of beluga whales (RG) was studied near Cape Beluzhii in the Solovetsky Islands in the White Sea by the photo identification of individuals in 2007–2008; in addition, the peculiarities of the seasonal and interseasonal dynamics of the RG incomings were analyzed. The gathering is formed by predominantly females and calves of different ages, which visit the RG area as stable “family” groups. About 15% of the observed females come to Beluzhii Cape every year and stay there during the whole summer season; thus, forming the regular part of the RG. The other animals come there for a certain time period, which is probably preconditioned by their physiological readiness for coupling and procreation for some of the females. When comparing our data with the catalogue of the visually registered beluga whales’ markers (1996–2008), we found that most of the identified animals of the Solovetsky RG appear here during one summer season or even with an off period of several years despite the significantly regular findings of most of them for this area. We conclude this may be linked with the natural changes of the individual markers due both to the shedding and the sexual cycle in the mature animals. Our data allow concluding that the total population of the Solovetsky PG is higher than was reported before using the visual supervision methods.

Effects of Burdizzo castration on CO 2 laser induced thermal nociception of Holstein–Friesian calves of different ages

The objective was to investigate the effects of Burdizzo castration on the thermal nociception (stress-induced hypoalgesia) of Holstein–Friesian bull calves of different ages. Calves castrated at 5.5 mo of age were compared with either intact calves of the same age, or calves castrated at 1.5, 2.5, 3.5, and 4.5 mo of age ( n = 10 calves/treatment). Treatments were conducted on the same day for all calves. The baseline surface skin temperatures on the caudal part of metatarsi, and the latency of the calves to perform hind leg withdrawal (i.e., thermal nociception threshold) in response to a CO 2 laser beam applied on the same area were measured 72 h before, and 12, 24 and 48 h after treatment. The thermal nociception threshold varied inversely with the baseline skin temperature (pooled correlations, r = −0.45, −0.31 and −0.48 at 12, 24 and 48 h, respectively; P < 0.01). There were no differences ( P > 0.05) in the skin temperatures between castrated and intact calves at 5.5 mo of age. Calves castrated at 1.5 mo-old had consistently lower skin temperatures than all other castrated calves throughout the study. These calves had markedly increased skin temperatures following castration, while the opposite trend was observed in older castrated calves, and no change was observed in intact calves. At −72 h, the 1.5 mo-old calves had higher thermal nociception thresholds than older calves. In all calves, the thermal nociception threshold increased after treatment. Calves castrated at 5.5 mo of age tended to display higher thermal nociception threshold than intact calves. However, variations in the initial skin temperature accounted for these differences between treatments or interactions between time and treatment. In conclusion, the laser-based thermal nociception assay can be influenced by the surface skin temperature of the hind legs and the age of animals, particularly in calves less than 2 mo of age which have lower skin temperatures and longer latency to respond to the laser. Burdizzo castration increased the skin temperature of 1.5 mo-old calves, but had the opposite effects on older calves. Within the temporal limits of this study, no conclusive evidence was found to support the presence of acute stress-induced hypoalgesia following castration.

Establishment of spermatogenesis in neonatal bovine testicular tissue following ectopic xenografting varies with donor age.

Ectopic testicular xenografting can be used to investigate spermatogenesis and as an alternative means for generating transgenic spermatozoa in many species. Improving the efficiency of spermatogenesis in xenografted testicular tissue will aid in the application of using this approach. The present study was conducted to evaluate age-related differences in the establishment of spermatogenesis in grafted testicular tissue from bulls between 2 and 16 wk of life. Testicular tissue was ectopically xenografted under the skin on the backs of castrated nude mice and subsequently evaluated for growth, testosterone production, and establishment of spermatogenesis 24 wk after grafting. The greatest weight increases occurred in donor tissue from calves of the ages 2, 4, and 8 wk compared with the ages of 12 and 16 wk. Recipient mouse serum testosterone concentration was at normal physiological levels 24 wk after grafting and no significant differences were detected between recipients grafted with testicular tissue from bull calves of different ages. The development of germ cells to elongated spermatids were observed in seminiferous tubules of grafts from donor calves of the ages 4, 8, 12, and 16 wk but not observed in grafts from 2-wk donors, which contained round spermatids as the most advanced germ cell stage. Grafts from 8-wk donors contained a significantly higher (10-fold) average percentage of seminiferous tubules with elongated spermatids than all other donor ages. These data demonstrate differences in the ability of testicular tissue from donor animals of different ages to establish spermatogenesis following ectopic testicular xenografting.

Pathophysiology of Severe Diarrhoea and Suggested Intravenous Fluid Therapy in Calves of Different Ages Under Field Conditions

Bouda 1., 1. Doubek. M. Medina-Cruz. L. Paasch M., E. Candanosa A., R. Dvorak, V. Soska: Pathophysiology of Severe Diarrhoea and Suggested Intravenous Fluid Therapy in Calves of Different Ages under Field Conditions. Acta vet. Bmo 1997, 66: 87-94. Selected clinical and biochemical variables were studied in 2 groups of severely dehydrated. diarrhoeic calves before and after fluid therapy. Group 1 (n = 10) included calves aged 2 to 7 d, Group 2 (n = 9) calves aged 8 to 14 d. Clinical examination and blood sampling for biochemical and haematological analyses were performed in each animal before and after fluid therapy. Samples of faeces for microbiological examination were taken before intravenous (IV) rehydration. Solutions used for IV rehydration contained salts of NaC!, NaHC03, KCI and glucose in different quantities for calves in Groups 1 and 2. These rehydration solutions were infused IV at a volume of 41 to each calf during 3 hours and then followed by oral rehydration. In Group 1, rotavirus in faeces was diagnosed in 50.0 % of all calves; combined infectious agents rotavirus and Cryptosporidillm spp. occurred in 10.0 %, none of the calves had in faeces coronavirus, enterotoxigenic E. coli K99 and Salmonella spp.; that means in 40% of calves of this group no infectious agents were isolated. In Group 2, coronavirus was found in 11.1 %, combined infectious agents rota virus and Cryptosporidiwn spp. were diagnosed in 55.5%. none of the calves had enterotoxigenic E. coli K99 or Salmonella spp in faeces. Before IV rehydration diarrhoeic calves in Group 2 presented mean blood values of pH 7.12, base excess (BE) -14.72 mmolll, standard bicarbonate (SB) 9.86 mmolll which were significantly lower (P<O.OS) than in calves in Group 1 before IV rehydration, where pH was 7.16. BE -11.68 mmolll and SB 12.S4 mmolli. In both groups of calves before IV rehydration these low values of blood pH. BE. SB and normal value of pCO,. corresponded to partially compensated metabolic acidosis. The differences in blood values of pH, BE. SB. PCV. urea and K in both groups before and after rehydration were significant (P < 0.(1). The metabolic acidosis together with hyperkalemia, prerenal uremia and haemoconcentration were restored after fluid therapy. Rehydration was successful in 79.0 % of all diarrhoeic calves. Calves aged 8 d or older suffering from severe diarrhoea needed more bicarbonate for IV rehydration than diarrhoeic calves younger than 8 d. The suggested composition and volume of solutions for IV rehydration used in this study simplify fluid therapy in severely diarrhoeic calves of different ages in lateral or sternal recumbency without suckling reflex and under field conditions. Neonatal diarrhoea, dehydration. metaholic acidosis, hyperkalemia, uremia, packed cell volullle, fluid therapy, calf

Comparative pharmacokinetics of aditoprim in milk-fed and conventionally fed calves of different ages

Aditoprim body disposition was described after intravenous and oral administration of 5 or 10 mg kg −1 bodyweight to milk-fed and conventionally fed calves with bodyweights of 80 kg, 160 kg and 210 kg. After intravenous administration to conventionally fed calves, aditoprim total body clearance increased and elimination half-life decreased with age. Oral administration of aditoprim with feed was associated with a longer absorption half-life and consequently longer elimination half-life in the older calves, because the drug was deposited in a functionally mature rumen. The weak base aditoprim is slowly absorbed from the rumen according to the pH partition hypothesis and probable binding to dietary fibres and other macromolecules. The favourable pharmacokinetics of aditoprim indicate a potential use for this antimicrobial in bovine practice, pending further studies on residue depletion profile, safety and therapeutic efficacy.

Epidemiological observations on helminth infections of calves in southern Ghana

This paper describes helminth infections in three groups of calves of different ages grazing naturally infested pastures from March 1987 to May 1988. Calves in which the faecal egg output was followed from birth showed Toxocara vitulorum eggs as early as two days after birth and maximum patency occurred after two months. The fall in Toxocara egg output coincided with a rise in that of the strongylates; Haemonchus spp., Trichostrongylus spp. and Oesophagostumum spp. The influence of rainfall in dictating strongylate nematode infection was clear with high egg output during high rainfall and low egg counts when the rainfall was lower. There was an indication that calves carry the infection from the end of the minor rainy season in November to the beginning of the next rains in March and then contribute to pasture contamination. However, calves born in December may remain uninfected until the onset of the rains.

Development of frozen-thawed demi-embryos and production of identical twin calves of different ages.

The percentages of morphologically transferable embryos obtained from frozen-thawed demi-embryos which were embedded with or without agar, and from those with or without zonae pellucidae were 26.3% (5/19), 36.4% (8/22), 39.5% (15/38) and 40.0% (22/55), respectively. No significant differences were observed between these groups. Development to calves of frozen-thawed demi-embryos with or without zonae pellucidae was 25.0% (3/12) and 26.7% (4/15), respectively. There was also no significant difference between them. On the trial for production of identical twin calves of different ages, the pregnancy rates of fresh and frozen demi-embryos after transfer were 69.2% (9/13) and 11.1% (1/9), respectively. Out of 13 fresh demi-embryos and 9 frozen demi-embryos transferred, only one pair of identical twin male calves of different ages were produced. This frozen-thawed demi-embryo was stored for 43 days in liquid nitrogen before thawing and transfer. These twin calves were confirmed to be identical by blood typing. Although these calves had different birth dates, their growth rates indicated similar developmental patterns. We suggest that it is possible to produce identical twin calves of different ages. This possibility would be useful for predicting the sex, milk producing ability and progeny test of a pair of demi-embryos before a decision to transfer the other half of a pair is made.