Neotropical Bats from Costa Rica harbour Diverse Coronaviruses

Bats are hosts of diverse coronaviruses (CoVs) known to potentially cross the host–species barrier. For analysing coronavirus diversity in a bat species‐rich country, a total of 421 anal swabs/faecal samples from Costa Rican bats were screened for CoV RNA‐dependent RNA polymerase (RdRp) gene sequences by a pancoronavirus PCR. Six families, 24 genera and 41 species of bats were analysed. The detection rate for CoV was 1%. Individuals (n = 4) from four different species of frugivorous (Artibeus jamaicensis, Carollia perspicillata and Carollia castanea) and nectivorous (Glossophaga soricina) bats were positive for coronavirus‐derived nucleic acids. Analysis of 440 nt. RdRp sequences allocated all Costa Rican bat CoVs to the α‐CoV group. Several CoVs sequences clustered near previously described CoVs from the same species of bat, but were phylogenetically distant from the human CoV sequences identified to date, suggesting no recent spillover events. The Glossophaga soricina CoV sequence is sufficiently dissimilar (26% homology to the closest known bat CoVs) to represent a unique coronavirus not clustering near other CoVs found in the same bat species so far, implying an even higher CoV diversity than previously suspected.     

套作玉米产量与栽培密度及氮磷钾肥施用量的关系

采用二次回归通用旋转组合设计方法试验,以马铃薯套作玉米产量为目标,以套作的玉米密度、氮、磷、钾肥施用量为探讨对象,建立了套作玉米产量与密度、氮、磷、钾肥施用量间关系的数学模型(y=7396.05-536.7x1 129.0x2 135.6x3 104.7x4-19.65x1x2-5.4x1x3 147.75x1x4 165.15x2x3-86.55x2x4 113.7x3x4-478.8x12-407.7x22-446.25x32-450.3x42),通过模拟寻优,提出了玉米产量≥6750.00kg/hm2的综合农艺栽培方案(玉米密度44856-51135株/hm2,平均48000株/hm2;N279.30-350.70kg/hm2,平均315.00kg/hm2;P2O5189.00-231.00kg/hm2,平均210.00kg/hm2;K2O167.70-222.30kg/hm2,平均195.00kg/hm2。N:P:K=1:0.667:0.619)。     

Efficacy of parenteral antibiotics for disease prophylaxis in feedlot calves

Trimethoprim-sulfadoxine (TMPSDX) and two formulations of oxytetracycline (OTC) were examined for their prophylactic efficacy in feedlot calves when given by intramuscular injection on arrival at a large commercial feedlot. The study included 2,112 high-risk feeder calves that developed disease early in the feeding period. Both formulations of OTC reduced bovine respiratory disease morbidity during the first two weeks on feed and for the entire feeding period by 15-19% (p<0.05), and they also reduced all fatal fibrinous pneumonia by 67% and 84% (p<0.05). All three drugs significantly reduced all fatal disease in animals first treated during the second week on feed, but not for the overall feeding period. Oxytetracycline with 2-pyrrolidone reduced the incidence of all fatal disease by 44% (p<0.05) during the entire feeding period. The case fatality risk for calves first treated during the second week on feed was lower (p<0.05) in the TMPSDX group and in the OTC with polyvinyl-pyrrolidone group.     

A comparison of the adrenal cortical response to ACTH stimulation in Angora and non-Angora goats

The adrenal cortex is believed to be implicated in the high incidence of abortion in the Angora goat. Stimulation testing with adrenocorticotrophic hormone (ACTH) was used to assess the adrenal cortical function in 5 Angora does from herds with a history of abortion and 5 non-Angora does. An acute test involving a single intramuscular (i.m.) injection of 0.25 mg of synthetic ACTH was given during anoestrus, at mid-oestrus, on day 90 and on day 120 of gestation. Blood samples were collected from the jugular vein at 30 min intervals for 1 h before and 5 h after injection. Cortisol concentrations rose within 30 min and returned to baseline values within 3.5 h. Cortisol production was lower (p<0.01) in the pregnant state compared to the non-pregnant state in both groups. Production of cortisol was consistently lower (p<0.05) in the Angora does compared to the non-Angora does during anoestrus and pregnancy and marginally so at mid-oestrus. A chronic stimulation test involving once daily injections of 0.5 mg of a depot form of ACTH i.m. for 7 days commencing on day 90 of pregnancy was also conducted. Cortisol concentrations rose to reach a peak on the third day of treatment in both groups. The values then declined in the Angora does despite continued ACTH treatment, while those for the non-Angora does exhibited a second peak. During and following this treatment, two non-Angora does delivered live kids (day 95, day 120). Out of 7 Angora pregnancies, one Angora doe aborted two dead fetuses at day 116. No significant difference in the cortisol response in the acute test was detected between the animals that aborted and their respective cohorts, but the two non-Angora does that aborted had significantly lower cortisol concentrations during depot ACTH administration. Progesterone and oestradiol levels did not differ between Angora and non-Angora animals during pregnancy or on the test days. The results suggest that the steroidogenic response of the adrenal cortex to ACTH stimulation is significantly less in Angora does with a history of abortion than it is in non-Angora does and support the view that the Angora goat would make a more limited adrenal cortical response to a stressful occurrence during pregnancy.     

Dietary protein concentration correlates in a complex way with glucose metabolism and growth performance in pregnant rats

We studied the influence of dietary protein concentration (PC) on the adaptation mechanism of maternal glucose metabolism to gestation, and on maternal body weight (BW) gain using pregnant rats fed 4% (low protein, LP), 10% (medium protein, MP) or 20% (high protein, HP) dietary protein concentration. Feed (FI), energy (EI) and protein (PI) intakes were recorded. Plasma glucose, insulin and GH were determined, and insulin:glucose (insulin resistance) and insulin:GH ratios computed. Correlation and regression analyses were used to determine the physiological relationships between metabolic and ponderal variables. MP dams with greater FI and EI (12%), and lower PI (44%) than HP dams showed similar maternal and fetal growth performance because of the maintained energy efficiency (EE). LP dams, with similar FI and EI, and lower PI (81%) than HP dams, failed to catch up due to the low EE. PC exerted a non-linear influence on BW gain, insulin and GH, through EI and EE modifications. The EI linearly influenced hormone concentrations with the maximum and minimum hormone response in MP and LP dams, respectively. Insulin resistance increased as PC decreased, whereas the GH lipolytic effect appeared to predominate over insulin action. Circulating hormones and metabolites affected nutrient partitioning between dam and fetus, with the result that the competing demands for materno-fetal growth of HP and MP dams, but not the LP dams, were satisfied. A deeper knowledge of the nature of the materno-fetal energy relationships will enhance the manipulation of the growth performance of the fetus in several animal species.     

The effect of bovine viral diarrhea virus infections on health and performance of feedlot cattle

The aim of this study was to investigate the effect of bovine viral diarrhea virus (BVDV) infections (unapparent acute infections and persistent infections) on the overall health and performance of feedlot cattle. Calves from 25 pens (7132 calves) were enrolled in the study. Overall and infectious disease mortality rates were significantly higher (P < 0.05) in pens categorized at arrival as positive for type I BVDV and lower in pens that were positive for type II BVDV than in negative pens. Mortality attributed to BVDV infection or enteritis was significantly more common (P < 0.05) in the pens containing persistently infected (PI) calves than in pens not containing PI calves (non-PI pens). There were no statistically detectable (P > or = 0.05) differences in morbidity, overall mortality, average daily gain, or the dry matter intake to gain ratio between PI and non-PI pens. Although type-I BVDV infections in feedlots appear to contribute to higher mortality rates, the presence of PI calves alone does not appear to have a strong impact on pen-level animal health and feedlot performance.     

Effects of quebracho tannin extract on intake,digestibility, rumen fermentation,and methane production in crossbred heifers fed low-quality tropical grass

The aim of this work was to evaluate the effect of quebracho tannins extract (QTE) on feed intake, dry matter (DM) digestibility, and methane (CH₄) emissions in cattle fed low-quality Pennisetum purpureum grass. Five heifers (Bos taurus × Bos indicus) with an average live weight (LW) of 295 ± 19 kg were allotted to five treatments (0, 1, 2, 3, and 4% QTE/kg DM) in a 5 × 5 Latin square design. Intake, digestibility, and total methane emissions (L/day) were recorded for periods of 23 h when cattle were housed in open-circuit respiration chambers. Dry matter intake (DMI), organic matter intake (OMI), dry matter digestibility (DMD), and organic matter digestibility (OMD) were different between treatments with 0 and 4% of QTE/kg DM (P < 0.05). Total volatile fatty acid and the molar proportion of acetate in the rumen was not affected (P < 0.05); however, the molar proportion of propionate increased linearly (P < 0.01) for treatments with 3 and 4% QTE. Total CH₄ production decreased linearly (P < 0.01) as QTE increased in the diet, particularly with 3 and 4% concentration. When expressed as DMI and OMI by CH₄, production (L/kg) was different between treatments with 0 vs 3 and 4% QTE (P < 0.05). It is concluded that the addition of QTE at 2 or 3% of dry matter ration can decrease methane production up to 29 and 41%, respectively, without significantly compromising feed intake and nutrients digestibility.     

A report of 7 cases of feline vulval adenocarcinoma

Seven cases of feline vulval adenocarcinoma are reported. Follow-up information was available for 5 cats, and all but 1 of these was euthanized within 2-18 mo of diagnosis (median 9.2 mo) for reoccurrence of local disease (3 cases) and/or clinical signs consistent with metastases (3 cases). There was no relationship between histological features of the tumor and outcome.