Plasma S-nitrosothiol status in neonatal calves: ontogenetic associations with tissue-specific S-nitrosylation and nitric oxide synthase

Neonatal cattle and in part neonates of other species have manyfold higher plasma concentrations of nitrite plus nitrate than mature cows and subjects of other species, suggesting an enhanced and needed activation of the nitric oxide (NO) axis at birth. While the biological half-life of NO is short (<1 sec), its functionality can be prolonged, and in many regards more discretely modulated, when it reacts with low-molecular-weight and protein-bound thiols to form S-nitrosothiols (RSNO), from which NO subsequently can be rereleased. We used the calf as a model to test the hypothesis that plasma concentrations of RSNO are elevated at birth in mammals, correlate with ascorbate and urate levels, are selectively generated in critical tissue beds, and are generated in a manner temporally coincident with changes in tissue levels of active NO synthases (NOS). Plasma concentrations of RSNO, ascorbate, and urate were highest immediately after birth (Day 0), dropped >50% on Day 1, and gradually decreased over time, reaching a nadir in mature cattle. Albumin and immunoglobulin G were identified as major plasma RSNO. The presence of S-nitrosocysteine (SNC, a validated marker for S-nitrosylated proteins), inducible NOS (iNOS), and activated endothelial NOS (eNOS phosphorylated at Ser1177) in different tissues was analyzed by immunohistochemistry in another group of similar-aged calves. SNC, iNOS, and phosphorylated eNOS were detected in liver and ileum at the earliest timepoint of sampling (4 hrs after birth), increased between 4 and 24 hrs, and then declined to near-nondetectable levels by 2 weeks of life. Our data show that the neonatal period in the bovine species is characterized by highly elevated and coordinated NO-generating and nitrosylation events, with the ontogenetic changes occurring in iNOS and eNOS contents in key tissues as well as RSNO products and associated antioxidant markers.

Effects of dexamethasone on mRNA abundance of nuclear receptors and hepatic nuclear receptor target genes in neonatal calves

Hepatic nuclear receptors (NR), particularly constitutive androstane receptor (CAR) and pregnane X receptor (PXR), are involved in the coordinated transcriptional control of genes that encode proteins involved in the metabolism and detoxification of xeno- and endobiotics. A broad spectrum of metabolic processes are mediated by NR acting in concert with ligands such as glucocorticoids. This study examined the role of dexamethasone on hepatic mRNA expression of CAR, PXR and several NR target genes. Twenty-eight male calves were allotted to one of four treatment groups in a 2 x 2 arrangement of treatments: feed source (colostrum or milk-based formula) and glucocorticoid administration (twice daily intramuscular dexamethasone). Liver biopsies were obtained at 5 days of age. Real-time reverse transcription polymerase chain reaction was used to quantify mRNA abundances. No effects of feed source on mRNA abundances were observed. For the NR examined, mRNA abundance of both CAR and PXR in dexamethasone-treated calves was lower (p < 0.05) by 39% and 40%, respectively, than in control calves. Abundance of NR target genes exhibited a mixed response. SULT1A1 mRNA abundance was 39% higher (p < 0.05) in dexamethasone-treated calves compared with control calves. mRNA abundance of CYP2C8 tended also to be higher (+44%; p = 0.053) after dexamethasone treatment. No significant treatment effects (p > 0.10) were observed for mRNA abundances of CYP3A4, CYP2E1, SULT2A1, UGT1A1 or cytochrome P450 reductase (CPR). In conclusion, an enhanced glucocorticoid status, induced by pharmacological amounts of dexamethasone, had differential and in part unexpected effects on NR and NR target systems in 5-day-old calves. Part of the unexpected responses may be due the immaturity of NR and NR receptor target systems.

Intra-articular administration of doxycycline in calves

Objective-To evaluate local tissue compatibility of doxycycline hyclate (DOX) in antebrachiocarpal joints of calves. Animals-10 healthy calves between 80 and 110 kg. Procedures-Calves were assigned to 2 treatment groups. Calves in groups DOX(low) and DOX(high) were administered 5 and 10 mg of DOX, respectively, locally in 1 antebrachiocarpal joint. The contralateral joint served as a control joint and was injected with 0.9% NaCl solution. General and local clinical findings were scored. Several variables were assessed in blood and synovial fluid for 9 days. Calves were euthanatized and pathologic changes and drug residues evaluated. Results-Throughout the study, none of the calves had clinical changes or abnormal hematologic values. Significant differences between treatment and control joints were evident only for matrix metalloproteinases at 0.5 hours after injection, with less activity for the DOX-treated joints in both treatment groups. Values for all synovial fluid variables, except nitric oxide, increased significantly during the first 12 to 72 hours after arthrocentesis in control and DOX-treated joints. Histologic examination revealed minimal infiltration of inflammatory cells independent of the treatment. No drug residues were detected 9 days after arthrocentesis in any tissues obtained from the liver, kidneys, fat, and skeletal muscles. Conclusions and Clinical Relevance-DOX had excellent intra-articular compatibility in healthy calves. Arthrocentesis induced a mild transient increase of inflammatory mediators in the synovial fluid. Significant decreases in matrix metalloproteinase activity in DOX-treated joints may indicate a potential chondroprotective effect of DOX.

Comparison of five diagnostic methods for detecting bovine viral diarrhea virus infection in calves

Five diagnostic techniques performed on skin biopsies (shoulder region) and/or serum were compared for detection of bovine viral diarrhea virus infection in 224 calves 0-3 months of age, 23 calves older than 3 months but younger than 7 months, and 11 cattle older than 7 months. The diagnostic methods used were immunohistochemistry (IHC), 2 commercial antigen ELISAs, 1 commercial antibody ELISA, and real-time RT-PCR. Results of 249 out of 258 skin and serum samples were identical and correlated within the 3 antigen detection methods and the real-time RT-PCR used. Twenty-six of these 249 samples were BVDV-positive with all antigen detection methods and the real-time RT-PCR. Nine out of 258 samples yielding discordant results were additionally examined by RT-PCR, RT-PCR Reamplification (ReA), and antigen ELISA I on serum and by immunohistochemistry on formalin fixed and paraffin-embedded skin biopsies. Virus isolation and genotyping was performed as well on these discordant samples. In 3 cases, transiently infected animals were identified. Two samples positive by real-time RT-PCR were interpreted as false positive and were ascribed to cross-contamination. The antigen ELISA II failed to detect 2 BVDV-positive calves due to the presence of maternal antibodies; the cause of 2 false-positive cases in this ELISA remained undetermined. Only persistently infected animals were identified in skin samples by IHC or antigen ELISA I. The 3 antigen detection methods and the real-time RT-PCR used in parallel had a high correlation rate (96.5%) and similar sensitivity and specificity values.

Histological assessment of testicular residues in lambs and calves after Burdizzo castration

To assess the reliability of the Burdizzo procedure for castrating calves and lambs, testicular tissue from 63 bull calves (15 intact and 48 castrated) and 69 male lambs (35 intact and 34 castrated) was collected at slaughter and assessed histologically. The bull calves were castrated at either one, four to five or 12 to 16 weeks of age and the lambs at either one or 10 weeks. There was clear evidence of spermatogenesis in testicular tissue from all the intact animals. In the samples from the calves that had been castrated at 12 to 16 weeks functional testicular tissue was completely lacking. However, there was evidence of spermatogenesis and steroidogenesis in the calves that had been castrated at one week or four to five weeks, respectively. Failure to achieve complete involution of the testicular parenchyma was observed in the majority of lambs, irrespective of the age at which they had been castrated.

Prophylactic and therapeutic efficacy of nitazoxanide against Cryptosporidium parvum in experimentally challenged neonatal calves

Diarrhoea caused by Cryptosporidium parvum is a major problem in calves younger than 4 weeks of age. To date only a few compounds have been approved for prophylactic and none for therapeutic use. Nitazoxanide (NTZ) has proven its efficacy in vitro against C. parvum and is approved by FDA for the treatment of human cryptosporidiosis. In a first experimental study, 3 uninfected calves were treated with NTZ and pharmacokinetics was followed through blood samples. Serum samples of uninfected treated calves contained both NTZ metabolites (tizoxanide and tizoxanide glucuronide) and oral administration at 12 h intervals was considered as optimal. Three groups of three calves (1-3 days old) were then each inoculated with 1x10(7) oocysts of C. parvum (cattle genotype): the prophylactic group received 15 mg/kg body weight NTZ twice daily orally in milk from 1 day before to 8 days postinoculation (dpi). The therapeutic group received the same dosage of NTZ for 10 days from the appearance of diarrhoea (between 1 and 5 dpi). The control group was left untreated. All calves were monitored daily from day -1 to 28 dpi and faecal samples were collected for evaluation of consistency and for determination of oocyst numbers per gram (OPG) of faeces. Diarrhoea was observed in all calves within the first week. Neither prophylactic nor therapeutic use of NTZ improved the clinical appearance and calves of the therapeutic showed a longer diarrheic episode (p<0.05) with strong altered faecal consistency compared to the untreated control group. The number of days with oocyst excretion did not differ significantly between the groups. In 5 out of 6 infected and treated calves oocyst excretion stopped only after discontinuation of treatment. In the prophylactic and in the control group mean values of the sum of the daily OPG per calf (8.5x10(6) and 8.0x10(6), respectively) and of the mean daily number of OPG (0.3x10(6) and 0.3x10(6), respectively) were similar, while the therapeutic group showed significantly lower values (1.9x10(6) and 0.06x10(6), respectively, p<0.05). However oocyst determinations in this group may have been altered by the severe diarrhoea, diluting oocyst densities in the analysed faecal samples. In conclusion, these preliminary results about the first prophylactic and therapeutic use of NTZ in calves did not show the expected positive effect on the course of the Cryptosporidium-infection, neither on reducing the clinical severity, nor on oocyst excretion.

Effects of different types of solid feeds on health status and performance of Swiss veal calves. II. Basic feeding with whole milk

The objective of this study was to identify a suitable alternative to the current practice of complementing the feeding of whole milk with straw. The influence of 3 different solid supplements on the health and performance of Swiss veal calves was investigated during 3 production cycles of 90 veal calves each with a mean initial age of 42 days and a mean initial weight of 68.7 kg. The calves were housed in groups of 30 in stalls strewn with wheat straw without outside pen. Liquid feeding consisted of whole milk combined with an additional skim milk powder ad libitum. Groups were assigned to one of the three following experimental solid feeds provided ad libitum: Pellet mix (composition: oat hulls, corn [whole plant], barley, sunflower seeds, squeezed grains of corn, molasses and a pellet binder), whole plant corn pellets, and wheat straw as control. Calves of the straw group showed significantly more abomasal lesions in the fundic part as compared to the pellet mix and corn pellets groups (P < 0.001), the prevalence of insufficient papillae was highest (P < 0.05), and ruminating behavior was unsatisfactory. In contrast to the pellet mix and straw groups, performance of calves in the corn pellets group was good. Additionally, prevalence of abomasal fundic lesions was lowest (P < 0.001), and rumen development was best in calves of the corn pellets group (P < 0.01). As in part I, the results reveal that whole-plant corn pellets are most consistent with an optimal result combining the calves' health and fattening performance. Therefore, it can be recommended as a solid supplement for veal calves basically fed whole milk under Swiss conditions.

Effects of different types of solid feeds on health status and performance of Swiss veal calves. I. Basic feeding with milk by-products

The objective of this study was to identify a suitable alternative to the current practice of complementing the feeding of milk by-products with straw. The influence of 5 different types of solid feeds on health and performance of Swiss veal calves was investigated in 2 production cycles of 200 veal calves each with a mean initial age of 40 days (d). The calves were housed in groups of 40 in stalls with outside pen. Liquid feeding consisted of a milk by-product combined with an additional skim milk powder ad libitum. Groups were assigned to 1 of the 5 following experimental solid feeds provided ad libitum: mix (composition: soy flakes, corn, barley, wheat, oat, barley middling, plant oil, molasses), whole plant corn pellets, corn silage, hay, and wheat straw as control. Daily dry matter intake per calf averaged 2.25 kg of the liquid food, 0.16 kg of straw, 0.33 kg of mix, 0.47 kg of corn silage, 0.38 kg of corn pellets, and 0.39 kg of hay. No significant differences (P > 0.05) among groups were found in calf losses that amounted to 4.8 % (68 % because of gastrointestinal disorders). Four percent of the calves were slaughtered prematurely. Daily doses of antibiotics were higher in the mix (36.9 d, P < 0.01) and in the corn silage groups (35 d, P < 0.01) compared to control. Compared to the 4 other groups, calves of the straw group showed the highest prevalence of abnormal ruminal content (73 %, P < 0.05), of abnormal ruminal papillae (42 %, P < 0.05), of abomasal fundic lesions (13.5 %, P < 0.1), and the lowest number of chewing movements per bolus (45, P < 0.05). The hemoglobin concentration averaged 85 g/l at the beginning and 99 g/l at the end of the fattening period with no significant differences among groups (P > 0.1). The duration of the fattening period averaged 114 d, slaughter age 157 d, and carcass weight 122 kg. The average daily weight gain (ADG) was highest in the control group straw (1.35 kg), and lowest in the hay group (1.22 kg, P < 0.01). The number of carcasses classified as C, H, and T (very high to medium quality) was lower in the hay group compared to straw (P < 0.01). No significant differences between groups were found in meat color (P > 0.1): 73 % of the carcasses were assessed as pale (267/364), 18 % as pink (66/364), and 9 % (31/364) as red. The results reveal that whole-plant corn pellets are most consistent with an optimal result combining the calves' health and fattening performance. Therefore, it can be recommended as an additional solid feed for veal calves under Swiss conditions.

Risk factors for death and unwanted early slaughter in Swiss veal calves kept at a specific animal welfare standard

Calf losses (CL, mortality and unwanted early slaughter) in veal production are of great economic importance and an indicator of welfare. The objective of the present study was to evaluate CL and the causes of death on farms with a specific animal welfare standard (SAW) which exceeds the Swiss statutory regulations. Risk factors for CL were identified based on information about management, housing, feeding, and medication. In total, 74 production cohorts (2783 calves) of 15 farms were investigated. CL was 3.6%, the main causes of death were digestive disorders (52%), followed by respiratory diseases (28%). Factors significantly associated with an increased risk for CL were a higher number of individual daily doses of antibiotics (DDA), insufficient wind deflection in winter, and male gender. For administration of antibiotics to all calves of the cohort, a DDA of 14-21 was associated with a decreased risk for CL compared to a DDA of 7-13 days.

Efficiency of risk-based vs . random sampling for the monitoring of tetracycline residues in slaughtered calves in Switzerland

In all European Union countries, chemical residues are required to be routinely monitored in meat. Good farming and veterinary practice can prevent the contamination of meat with pharmaceutical substances, resulting in a low detection of drug residues through random sampling. An alternative approach is to target-monitor farms suspected of treating their animals with antimicrobials. The objective of this project was to assess, using a stochastic model, the efficiency of these two sampling strategies. The model integrated data on Swiss livestock as well as expert opinion and results from studies conducted in Switzerland. Risk-based sampling showed an increase in detection efficiency of up to 100% depending on the prevalence of contaminated herds. Sensitivity analysis of this model showed the importance of the accuracy of prior assumptions for conducting risk-based sampling. The resources gained by changing from random to risk-based sampling should be transferred to improving the quality of prior information.

Blood vessel anomalities in the oral cavity of two calves

Two calves were presented with a congenital mass in the rostral mandibular gingiva. In both cases the masses relapsed after surgical removal. Histologically, the two masses were composed of irregularly arranged vascular cavities, embedded in loosely arranged stroma and alcian-blue PAS positive ground substance. Radiologically, a destruction of the alveolar cavity was recognized in both cases, which was in case 1 histologically compatible with bone resorption and remodeling associated with the infiltration of abundant granulation tissue. A literature survey revealed that no consistent criteria for a correct classification for vascular tumours exists, resulting in the fact that comparable lesions were named differently in the past. We therefore propose to classify such lesions as congential vascular malformation until distinct morphological, immunohistochemical and molecular genetic analysis criteria will exist.

Acute and chronic pain in calves after different methods of rubber-ring castration

The goal of the present study was to evaluate the effect of different methods of rubber-ring castration on acute and chronic pain in calves. Sixty-three 4-6 week-old calves were randomly and sequentially allocated to one of five groups: Group RR (traditional rubber ring castration); group BRR (combination of one rubber ring with Burdizzo); group Rcut (one rubber ring applied with the scrotal tissue and rubber ring removed on day 9); group 3RR (three rubber rings placed one above the other around the scrotal neck); and group CO (controls; sham-castrated). All calves received 0.2 mL/kg bodyweight lidocaine 2%, injected into the spermatic cords and around the scrotal neck 15 min before castration. The presence of acute and chronic pain was assessed using plasma cortisol concentrations, response to palpation of scrotal area, time from castration until complete wound healing, and behavioural signs. Calves of group 3RR showed severe swelling and inflammation, and licking of the scrotal area occurred significantly more often than in groups Rcut and CO. Technique 3RR was discontinued for welfare reasons before the end of the study. All castration groups had significantly more pain upon palpation than calves of group CO, but palpation elicited markedly less pain in group Rcut than in the other castration groups. The most rapid healing time and shortest duration of chronic pain after castration was achieved in group Rcut. For welfare reasons, the Rcut technique should be considered as a valuable alternative to traditional rubber ring castration of calves at 4-6 weeks of age.

Gammaglobulin and selenium status in healthy neonatal dairy calves in Switzerland

Serum samples from 142 calves and their dams were analyzed for gammaglobulins (gammaG, calves) and selenium concentrations (Se, calves and dams). A questionnaire provided information about birth and colostrum management. The calves and their dams were distributed into two groups according the calves' gammaG concentration (< 10 and >= 10 g/L), Se concentrations were compared between groups. The correlation between gammaG and Se concentrations in the calves and their dams was analyzed. Risk factors for failure of passive transfer and Se deficiency were assessed based on the questionnaire. The gammaG concentration of 42.9 % of the calves was < 10 g/L (median: 10.9). Calves showed significantly higher gammaG values after optimized colostrum administration than calves with suboptimal colostrum administration (p < 0.004). The median Se concentration was 26.8 and 36.5 microg/L for the calves and dams, respectively. A high correlation was observed between the Se concentration of the dam and her calf (r = 0.72, p < 0.001). The calves' Se and gammaG concentrations were not significantly correlated. These results demonstrate that further efforts toward better information of farmers regarding colostrum management and Se supply are warranted.