Comparison of a combination of oxfendazole and fenthion versus ivermectin in feedlot calves

A trial involving 6,169 feedlot calves was conducted under commercial feedlot conditions in western Canada to compare the relative efficacy of treatment with a combination of oxfendazole and fenthion (O/F) versus ivermectin (I) with respect to the outcome variables, final weight, gain, days on feed (DOF), dry matter intake (DMI), average daily gain (ADG), dry matter intake to gain ratio (DM:G), and morbidity, mortality, and carcass grade parameters.

There were no significant differences (p ≥ 0.05) between the treatment groups for final weight, gain, DOF, DMI, ADG and DM:G. In addition, there were no significant differences (p ≥ 0.05) in the carcass grading parameters between the treatment groups. The bovine respiratory disease (BRD) relapse rates, the overall mortality rates, and the cause specific mortality rates were not significantly different (p ≥ 0.05) between the treatment groups. The BRD treatment rate in the O/F group was significantly lower (p ≤ 0.05) than in the I group, but this difference was not economically important.

These data indicate that a combination of oxfendazole and fenthion is comparable to ivermectin with respect to performance, animal health, and carcass grade parameters.

     

Association of stomatal frequency and morphology in Lycopersicon species with resistance to Xanthomonas campestris pv. vesicatoria

Study of the stomata and leaf epidermis of eight Lycopersicon species has revealed a relationship between frequency of stomata, stomatal size and some morphological leaf characteristics, and resistance to bacterial leaf spot caused by Xanthomonas campestris pv. vesicatoria. Significant correlations were found between the stomatal frequency in both adaxial and abaxial leaf epidermis and the number of bacterial lesions per leaf area ( r = 0.70 and 0.68, respectively) and the frequency of stomata in both adaxial and abaxial epidermis and disease incidence (percentage of diseased plants) ( r =0.87 and 0.80, respectively) for all the Lycopersicon species and one hybrid tested. A correlation was also found between disease incidence and number of bacterial lesions per leaf area ( r = 0.85). The length and width of stomata were correlated with frequency of stomata in adaxial and abaxial epidermis ( r = 0.85, 0.75, 0.89 and 0.90, respectively). The stomatal width was correlated with the number of bacterial lesions per cm² ( r =0.82; P = 0.0065). Scanning electron microscopic studies of the leaf surface and stomata indicated that other morphological features such as the raised stomatal complex in L. hirsutum and persistent, hydrophobic waxy coating of the epidermis in L. peruvianum may also be relevant in disease response.     

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.     

An evaluation of the relative efficacy of tulathromycin for the treatment of undifferentiated fever in feedlot calves in Nebraska

A field trial was performed under commercial feedlot conditions in central Nebraska to assess the relative efficacy of tulathromycin (TULA) to florfenicol (FLOR) for the treatment of undifferentiated fever (UF) in feedlot calves that did not receive a metaphylactic antimicrobial or vaccines/bacterins containing Mannheimia haemolytica or Histophilus somni at feedlot arrival by comparing animal health, feedlot performance, and carcass characteristic variables. Two hundred recently weaned, auction market derived, crossbred beef calves that met the study-specific case definition of UF were randomly allocated in a 1:1 ratio to 1 of 2 experimental groups as follows: TULA, which received tulathromycin administered subcutaneously at the rate of 2.5 mg/kg body weight (BW) once at the time of allocation; or FLOR, which received florfenicol administered subcutaneously at the rate of 40 mg/kg BW once at the time of allocation. In terms of animal health, the first UF relapse (RR = 0.65), overall mortality (RR = 0.33), and BRD mortality (RR = 0.29) rates in the TULA group were significantly (P < 0.05) lower than in the FLOR group. There were no significant (P > or = 0.05) differences between the TULA and FLOR groups for the other animal health variables measured. There was no significant (P > or = 0.05) difference in average daily gain between the TULA and FLOR groups. There were no significant (P > or = 0.05) differences in the overall distributions of quality grade and yield grade between the experimental groups; however, a significantly (P < 0.05) higher proportion of carcasses in the TULA group graded yield grade USDA-4 as compared with the FLOR group. In the economic analysis, the benefits observed resulted in an economic advantage of $52.50 USD/animal in the TULA group due to lower first UF relapse and overall mortality rates, even though the occurrence of yield grade USDA-4 carcasses increased and the initial UF treatment cost was higher.