When less is more: heterogeneity in grass patch height supports herbivores in counter-intuitive ways

Herbivores are an integral part of the African landscape and have evolved with the vegetation to create the savanna landscape. Managers of these landscapes can benefit from a better understanding of how indigenous herbivores use the landscape to which they are adapted. In this study we observed which patches were frequently utilised, by doing regular monthly road counts, grass height observations and dung counts on selected short grass patches in the Kruger National Park. Smaller-framed impala and blue wildebeest (meso-herbivores) were most regularly seen on these nutritious patches, while from dung deposits it was clear that the even larger-framed buffalo (mega-herbivores) spent time there. This preference can be explained by considering the nutritional needs and food intake of the herbivores. Smaller-framed herbivores seem to be able to satisfy their dietary requirements on the high-quality forage patches, while larger-framed herbivores seem to supplement the quality forage by also spending foraging time on areas of higher grass biomass. From this insight we propose that range management should take herbivore preferences into account and allow herbivores to select and concentrate their foraging on the most nutritious forage. This approach is likely to decrease inputs while allowing animals to maintain or increase production.     

Assessment of clinical reasoning skills in veterinary students prior to and after the clinical year of training

OBJECTIVE: To examine the effect of various clinical tracks within the veterinary medical clinical curriculum at Texas A&M University on clinical diagnostic proficiency as determined by pre- and post-training assessment. We expected that the clinical track chosen by the student would impact their measured outcome with bias toward higher scores in their chosen field. DESIGN: Prospective cohort study. STUDY POPULATION: 32 students from the College of Veterinary Medicine and Biomedical Sciences at Texas A&M University. PROCEDURES: By use of standardized, written case scenarios, clinical reasoning was assessed twice: once prior to the clinical (fourth) year of the curriculum and again at completion of the clinical year. Students demonstrated their abilities to collect and organize appropriate clinical data (history, physical examination, and laboratory findings), determine clinical diagnoses, and formulate and implement acceptable treatment modalities. Data from clinical assessments were compared for a given cohort and correlated with other measures (eg, grades, standardized test scores, and species-specific curricular track). RESULTS: Differences were detected in clinical diagnostic proficiency among students in different clinical tracks and for different species groups in the case scenarios. Tracking by species group in the clinical veterinary curriculum appeared to affect development of clinical reasoning and resulted in differential proficiency among cases for differing species groups. CONCLUSIONS AND CLINICAL RELEVANCE: Differences in clinical experiences between small animal tracks and all other track opportunities (large animal, mixed animal, and alternative) influenced the development of clinical proficiency in fourth-year veterinary students during their clinical training period.     

Russet Norkotah: A new russet-skinned potato cultivar with wide adaptation

Russet Norkotah is a long, smooth, shallow-eyed, russet-skinned potato cultivar with wide adaptation. It has a smooth golden russet-skin and produces a high percent of medium sized U.S. No. 1 tubers that are good count-carton size.     

Effect of dry period length on the effect of an intramammary teat sealant on the risk of mastitis in cattle treated with antibiotics at drying off

AIM: The aim of this study was to evaluate, under farm conditions, the use of a teat sealant in addition to whole herd dry cow antibiotic therapy on the risk of clinical mastitis in dairy cattle at pasture, and to evaluate the impact of dry period length on that risk and the impact of the teat sealant on that risk.

METHODS: Dairy cows in three herds which used routine whole herd antibiotic therapy were randomly assigned to receive either treatment with an internal teat sealant (n=322) or no additional treatment (n=313) at drying-off between March and May 2010. All clinical mastitis cases during the dry period and to the end of the subsequent lactation were recorded by farm staff; factors affecting risk of clinical mastitis were then analysed using a Cox proportional hazards model.

RESULTS: Median duration of the dry period was 112 days with >25% of cows having a dry period >130 days. The incidence risk of mastitis during lactation for cows treated with teat sealant was 9.9 (95% CI=6.9–13.7) cases per 100 cows compared with 17.9 (95% CI=13.8–22.6) cases per 100 cows for cows treated with antibiotic alone. The addition of a teat sealant to dry cow antibiotic therapy decreased the risk of clinical mastitis only in the first 33 days after calving (Hazard risk 0.24 (95% CI=0.12–0.48)). Length of dry period did not significantly affect the risk of clinical mastitis, or the effect of adding teat sealant to dry cow antibiotic therapy on the risk of clinical mastitis.

CONCLUSIONS: In these herds where, based on the mastitis history, whole herd antibiotic therapy had been recommended, the use of a teat sealant significantly reduced the risk of clinical mastitis. This effect was limited to the first 33 days after calving; subsequently there was no significant effect of treatment. There was no effect of dry period length on risk of clinical mastitis, nor any significant interaction with treatment.

CLINICAL RELEVANCE: Combination therapy with teat sealant and antibiotic was effective under New Zealand conditions in herds using whole herd antibiotic treatment at drying off. Teat sealant reduced risk of clinical mastitis in cattle with dry periods substantially longer than 100 days, and there was no evidence that this effect changed as dry period length increased.     

Impact of Ultra‐Rapid Freezing on the Motility,Morphology, Viability and Acrosome Integrity of Epididymal Cat Sperm Diluted in Sucrose‐Based Extenders

The objective of the present study was to investigate the influence of different sucrose‐based extenders on the motility, morphology, viability and acrosomal integrity of epididymal cat spermatozoa cryopreserved by ultra‐rapid freezing method. Nine cats were castrated, and collected semen was diluted 1 : 1 with Dulbecco`s phosphate‐buffered saline‐BSA1%‐based extender supplemented with different sucrose concentrations (0, 0.25, 0.4 and 0.6 m ). After ultra‐rapid freezing, samples were thawed and sperm motility, morphology, viability and acrosome status were assessed. At thawing, the number of progressively motile (p < 0.01) and morphologically normal (p < 0.01) sperm was higher in the sucrose‐supplemented groups than in the sucrose‐free group. Viability of spermatozoa cryopreserved without sucrose was significantly reduced. In extender supplemented with 0.4 m sucrose, spermatozoa viability showed higher values (57.0 ± 4.7; p < 0.01). No significant differences were detected among groups for sperm acrosome integrity. Results support that cat sperm survive after ultra‐rapid freezing using sucrose as a cryoprotectant, and the best results were achieved when 0.4 m of sucrose was used. This is the first report on sperm ultra‐rapid freezing of cat sperm and further studies on extenders, sperm management or cryovials should be carried out to improve sperm cryosurvival.     

Comparison of tramadol and morphine for pre-medication of dogs undergoing general anesthesia for orthopedic surgery

Tramadol is a centrally acting analgesic with opioid and monoaminergic actions. Its clinical effects have been well characterized in humans, where it has been in use for many years, but little is known for veterinary species. This study evaluated the sedative, emetic, thiopental‐sparing and intraoperative respiratory and hemodynamic effects of tramadol in comparison to morphine for pre‐medication of dogs undergoing orthopedic surgery under halothane anesthesia. Sixteen adult, healthy, mixed breed dogs (8.0 ± 2.6 kg) were studied. Eight dogs were pre‐medicated with tramadol (1.0 mg kg^‐1 IM) and the other eight with morphine (1.0 mg kg^–1 IM). After 20 minutes, anesthesia was induced with thiopental and subsequently maintained with halothane in oxygen using a Bain system, with spontaneous respiration. Degree of sedation and occurrence of emesis were evaluated after pre‐anesthetic medication. Dose of thiopental necessary for tracheal intubation was compared between the two groups. Arterial blood gas analyzes were done before pre‐medication and at 60 minutes of anesthesia. Heart rate and noninvasive arterial blood pressure were recorded before pre‐medication and every 10 minutes during anesthesia. Observer was blinded of the treatment given for each dog. Tramadol produced no visible sedation and no vomiting, while morphine induced a moderate degree of sedation in all dogs and vomiting in 62% of them. Dogs pre‐medicated with tramadol required significantly more thiopental (17 ± 3.8 mg kg^–1) for induction of anesthesia than those pre‐medicated with morphine (12 ± 1.8 mg kg^–1). Pre‐medication with morphine was associated with significantly higher PaCO₂ and lower pH at 60 minutes of anesthesia. The remaining respiratory parameters and the hemodynamic variables were similar between the two groups. In conclusion, dogs pre‐medicated with tramadol at 1 mg kg^–1 IM do not become visibly sedated and require a greater amount of thiopental for induction of anesthesia than pre‐medication with morphine. As intraoperative respiratory function is better preserved with tramadol, it may be useful for pre‐medication of respiratory compromised patients.     

Bone Morphogenetic Protein‐6 (BMP‐6) Stimulates the Antrum Formation by the Regulation of its Signalling Pathway in Caprine Pre‐antral Follicles Cultured In Vitro

BMP‐6 has been found to be important to ovarian cells and oocyte, as well as to uterus. Thus, this study investigated the effect of bone morphogenetic protein (BMP‐6) and recombinant follicle‐stimulating hormone (rFSH) alone or in combination on the in vitro culture (IVC) of isolated caprine secondary follicles (Experiment 1) and the mRNA levels for BMP receptors/Smad signalling pathway (BMPR1A, BMPR2, SMAD1, SMAD4, SMAD5, SMAD6, SMAD7 and SMAD8) in vivo and in vitro using BMP‐6 (Experiment 2). Secondary follicles were cultured in αMEM⁺ alone (control medium) or supplemented with BMP‐6 at 1 or 10 ng/ml and rFSH alone or the combination of both BMP‐6 concentrations and rFSH. The results from Experiment 1 showed that the antrum formation rate was higher in the BMP‐6 at 1 ng/ml (p < 0.05) than in MEM. In Experiment 2, the mRNA expression for BMPR2, SMAD1, SMAD5 and SMAD6 was detected in non‐cultured control and after in vitro culture (MEM and 1 ng/ml BMP‐6); while the expression of SMAD7 and SMAD8 mRNA was only detected after IVC, SMAD4 was only detected in the BMP‐6 at 1 ng/ml treatment. In conclusion, the low BMP‐6 concentration positively influenced antrum formation and ensured normal mRNA expression for BMP receptor and Smads after IVC of caprine secondary follicles.     

Subclinical mastitis of beef cows

Two beef cow herds were investigated to determine the prevalence of subclinical mastitis and to determine whether it contributed to decreased weaning weight of calves nursed by affected cows. Quarter samples obtained about 30 days after calving were evaluated by the California mastitis test and by direct microscopic cell count. In 1 herd, a 92-cow confinement operation, 17 quarters of 12 cows were infected with Staphylococcus aureus, Streptococcus sp other than agalactiae, or Klebsiella sp. Mean 205-day adjusted weights were 203.9 kg and 218.2 kg for calves nursed by infected vs noninfected cows. In the other herd, a 75-cow range-pasture operation, 8 quarters of 8 cows were infected, all with S aureus. Mean 205-day adjusted weights were 162.5 kg and 174.6 kg for calves nursed by infected vs noninfected cows.     

The Importance of Having Zinc During In Vitro Maturation of Cattle Cumulus–Oocyte Complex: Role of Cumulus Cells

The aim of this study was to investigate the influence of zinc (Zn) on the health of cumulus–oocyte complex (COC) during in vitro maturation (IVM). Experiments were designed to evaluate the effect of Zn added to IVM medium on: DNA integrity, apoptosis, cumulus expansion and superoxide dismutase (SOD) activity of cumulus cells (CC). Also, role of CC on Zn transport during IVM was evaluated on oocyte developmental capacity. DNA damage and early apoptosis were higher in CC matured with 0 μg/ml Zn compared with 0.7, 1.1 and 1.5 μg/ml Zn (p < 0.05). Cumulus expansion did not show differences in COC matured with or without Zn supplementation (p > 0.05). Superoxide dismutase activity was higher in COC matured with 1.5 μg/ml Zn than with 0 μg/ml Zn (p < 0.05). Cleavage and blastocyst rates were recorded after IVM in three maturation systems: intact COCs, denuded oocytes with cumulus cells monolayer (DO + CC) and denuded oocytes (DO). Cleavage rates were similar when COC, DO + CC or DO were matured with 1.5 μg/ml Zn compared with control group (p > 0.05). Blastocyst rates were significantly higher in COC than in DO + CC and DO with the addition of 1.5 μg/ml Zn during IVM (p < 0.01). Blastocyst quality was enhanced in COC and DO + CC compared with DO when Zn was added to IVM medium (p < 0.001). The results of this study indicate that Zn supplementation to IVM medium (i) decreased DNA damage and apoptosis in CC; (ii) increased SOD activity in CC; (iii) did not modify cumulus expansion and cleavage rates after in vitro fertilization; (iv) improved subsequent embryo development up to blastocyst stage; and (v) enhanced blastocyst quality when CC were present either in intact COC or in coculture during IVM.