Additive effects of L-carnitine and chromium picolinate on sow reproductive performance

Caustic paste is frequently used for disbudding young female dairy calves. Nerve blocking may not be completely effective after such chemical tissue damage. Regional anaesthesia, together with a non-steroidal-anti-inflammatory drug (NSAID), was shown to reduce plasma cortisol in calves disbudded using caustic paste. To find out whether pre-emptive NSAID alone could control pain or whether NSAID reduces cortisol response by a mechanism other than by pain control, we compared cortisol levels and behaviour of 10 chemically disbudded calves treated with IV flunixin-meglumine, five of which were injected at 5 min (F0) and five injected at 60 min before dehorning (F1), with 5 sham-dehorned (ND) and 5 non-treated chemically disbudded animals (CD). There was a higher (p < 0.001) cortisol level in both NSAID-treated groups compared with ND at 1 h after disbudding, but no differences from control animals (CD). Non-treated disbudded animals showed higher cortisol at + 3 h compared with ND. A higher incidence of pain-related behaviours was shown in disbudded animals up to 3 h post-disbudding.We conclude that pre-emptive analgesia treatment by itself is not effective in controlling pain and does not prevent blood cortisol increase after disbudding of calves with caustic paste.     

乳果糖对围产期犊牛免疫功能的影响

为研究乳果糖的替抗生素作用,选用同一牛场同一批从澳大利亚进口的青年荷斯坦奶牛所产公犊牛25头,按时间顺序分为5组,以随机单位组设计方法确定每组犊牛围产期内(初生至15日龄)乳料中不同的添加物:对照组(A);金霉素组(B),1万IU/头·d(3￣15日龄);金霉素 乳果糖组(C),金霉素添加同B组、乳果糖添加同D组;乳果糖组(D),10g/头·d;乳果糖组(E),15g/头·d。实验结果显示,乳果糖对犊牛免疫器官指数,血液中T、B淋巴细胞百分含量无显著影响。淋巴细胞转化率从24h开始,D、E组均与A组和B组组间差异极显著(p<0.01),乳果糖与金霉素在促进淋巴细胞转化率方面存在协同效应。乳果糖能提高犊牛血液中C反应蛋白(CRP)含量及IgG含量,金霉素与乳果糖之间存在协同效应,但金霉素的增加效果不如添加乳果糖增加的效果。     

An extended outbreak of congenital chondrodysplasia in calves in South East Australia

OBJECTIVE: To report an outbreak of congenital chondrodystrophy in calves in South East Australia. METHODS: District veterinarians investigated reported cases of calf deformities. Owners of affected herds were interviewed using a standard questionnaire to identify potential risk factors. Dams of several affected calves were serologically tested for Akabane virus, Aino virus, pestivirus and bluetongue, and affected calves were tested for pestivirus antigen and serum immunoglobulin concentrations. Gross and histopathological examinations of numerous calves were performed, concentrating on the musculoskeletal system. RESULTS: A case definition of distinctive skeletal deformities was established, and 89 property owners reported calves with chondrodystrophy in Spring 2003, 2004 or 2005. Some 14 property owners reported affected calves in more than one year. Prevalence and severity of deformity varied greatly between and within properties. None of breed, sex, age of dam, lineage, pasture type, supplementary feeding, fertiliser use or toxic plants was consistently associated with the disease. All dams experienced hot, dry conditions during the first trimester of pregnancy and were exposed to adverse conditions thereafter. Consistently dams were reported to have been grazing undulating to hilly terrain during early pregnancy. All serological tests were negative for Akabane virus, Aino virus, pestivirus and bluetongue. Histopathology of affected skeletal samples showed chondrodysplasia. CONCLUSION: The outbreak had similarities with previous outbreaks reported in the region. No specific aetiology could be determined. There is some evidence that the cause of the deformities could be a manganese deficiency during foetal development. Ongoing work to test this hypothesis is therefore warranted.     

Mixed-breed twin production by contralateral direct-transfer of male embryos to beef cow recipients bred to GnRH-based, fixed-time AI

Two experiments were conducted to develop protocols for the use of fixed-time artificial insemination and embryo transfer (TAI and TET, respectively) to increase beef cattle productivity. Suckled beef cows were given GnRH (100 µg im) on Day − 10, and PGF (25 mg im) on Day − 3, with TAI on Day 0 (66 h later), and assigned to either embryo recipient (ER) or no embryo (NR) treatments on Days 6 or 7. Semen from Gelbvieh (GB) beef sires was used for TAI; sexed-male in vivo developed Holstein embryos (HO) were placed nonsurgically (TET) into the uterine horn contralateral to the corpus luteum. In Experiment 1, ovarian status of cows (n = 111; 69 ± 11 d postpartum; mean ± SD on Day 0) in Groups I and II was presynchronized with a single PGF treatment on Day − 24; Groups II and III received GnRH concurrent with TAI, and ER (n = 78) were selected from all groups on Days 6 or 7. Neither presynchronization nor GnRH affected rates of recipient selection, Day 45 pregnancy (43.2, 43.2, and 54.0% for Groups I, II and III, respectively), or calving (40.5, 37.8, and 43.2%). However, treatment with GnRH increased HO-birth rate (8.0, 14.0 and 24.0%; P < 0.05). In Experiment 2, cows (n = 99, 113 ± 10 d postpartum) were assigned on Day 7 to NR and ER, with and without hCG (2500 IU im), following a TAI protocol (as per Group III in Experiment 1). Treatment with hCG increased reproductive rate (1.16 vs 1.44 calves/calving; P < 0.05), but had no significant effect on rates of Day 45 pregnancy (45.3 vs 41.3%), calving (31.2 vs 37.0%) or HO-births (20.0 vs 26.0%). In summary, GnRH-based synchronization rates were 71.2% (based on circulating progesterone concentrations that were < 1.0 ng/mL on Day 0 and ≥ 1.0 ng/mL on Day 7); TET did not affect GB-birth rate, but more calves were produced by ER than NR cows (1.43 vs 1.02 calves/calving; P < 0.01); and weaned calf production was 53% greater for twin- than singleton-suckled cows (392 ± 25 vs 256 ± 11 kg/dam; mean ± SEM, P < 0.05). Therefore, GnRH-based TAI and TET protocols for mixed-breed twin production increased beef cow productivity.     

Regulation of tissue beta-adrenergic, glucocorticoid and androgen receptors induced by repeated exposure to growth promoters in male veal calves

Biochemical modifications induced by a combination of anabolic compounds in target organs of male veal calves have been evaluated. Six male Friesian crossbred calves were treated with of 17beta-estradiol, dexamethasone sodium phosphate and clenbuterol or served as controls. beta-Adrenoceptors (beta-ARs) were measured in myocardium, lung, spleen, cerebral cortex, hippocampus, thalamus, hypothalamus, and hypophysis, glucocorticoid receptors (GRs) in the spleen and androgen receptors (AnRs) in the testis, by binding assay. A significant decrease in beta-ARs was observed in all tissue samples from treated animals. In the spleen the two GR subtypes found, low (LA) and high (HA) affinity GRs, were down-regulated by the treatment. A significant (P<0.05) decrease of testis weight and a significant (P<0.05) up-regulation of AnRs was also observed. Our data demonstrate that long-term treatment with anabolic compounds markedly affects receptor concentrations in target organs of male veal calves. Thus, studies investigating biological assays as screening methods to detect such compounds should be encouraged.     

犊牛全混合日粮(TMR)膨化技术及其营养特性

采用优化植物蛋白质、糊熟化淀粉,调整粗精料比例,控制瘤胃发酵类型等营养调控措施,改善饲料的加工状态,利用饲料膨化工艺,生产适合犊牛消化生理特点的营养全面的全混合日粮膨化饲料。经多次试验确定的膨化技术参数合理可行,既杀灭了犊牛TMR中的抗营养因子和有毒有害物质,又保证了犊牛TMR的营养成分不被破坏,后喷涂技术应用可以达到预期的目的。     

An experimental infection model for reproduction of calf pneumonia with bovine respiratory syncytial virus (BRSV) based on one combined exposure of calves

Bovine respiratory syncytial virus (BRSV) has been recognised as an important pathogen in calf pneumonia for 30 years, but surprisingly few effective infection models for studies of the immune response and the pathogenesis in the natural host have been established. We present a reproducible experimental infection model for BRSV in 2-5-month-old, conventionally reared Jersey calves. Thirty-four colostrum-fed calves were inoculated once by aerosol and intratracheal injection with BRSV. Respiratory disease was recorded in 91% of the BRSV-inoculated calves, 72% had an accompanying rise in rectal temperature and 83% exhibited >5% consolidation of the lung tissue. The disease closely resembled natural outbreaks of BRSV-related pneumonia, and detection of BRSV in nasal secretions and lung tissues confirmed the primary role of BRSV. Nine mock-inoculated control calves failed to develop respiratory disease. This model is a valuable tool for the study of the pathogenesis of BRSV and for vaccine efficacy studies.     

Evaluation of safety and efficacy of DNA vaccines against bovine herpesvirus-1 (BoHV-1) in calves

Four DNA vaccines against BoHV-1 were evaluated for their efficacy in calves. Twelve animals were divided into four groups which were injected with four different DNA vaccines: pVAX-tgD (Vaccine A); pVAX-tgD co-immunised with pVAX-48CpG (Vaccine B); pVAX-UbiLacI-tgD-L (Vaccine C); pVAX-UbiLacI-tgD-L co-immunised with pVAX-48CpG (Vaccine D). Three additional calves were given the plasmid vector and served as controls. Ninety days after the first vaccination all calves were challenge infected with BoHV-1.All animals developed a severe form of infections bovine rhinotracheitis. Only the calves given the pVAX-tgD co-immunised with pVAX-48CpG (Vaccine B) developed humoral antibodies against BoHV-1 between 56 and 90 days after the first vaccination, whereas in calves of other groups and in the controls, antibodies appeared only after the infection. In the calves vaccinated with either pVAX-tgD (Vaccine A) or pVAX-tgD combined with pVAX-48CpG (Vaccine B), BoHV-1-specific IFN-γ secreting cells were detected in PBMCs 90 days after the first vaccination and their number increased after challenge exposure. In the other groups the IFN-γ secreting cells were detected after virus infection and at low values.