Chlamydia psittaci: a suspected cause of reproductive loss in three Victorian horses

Chlamydia psittaci was detected by PCR in the lung and equine foetal membranes of two aborted equine foetuses and one weak foal from two different studs in Victoria, Australia. The abortions occurred in September 2019 in two mares sharing a paddock northeast of Melbourne. The weak foal was born in October 2019 in a similar geographical region and died soon after birth despite receiving veterinary care. The detection of C. psittaci DNA in the lung and equine foetal membranes of the aborted or weak foals and the absence of any other factors that are commonly associated with abortion or neonatal death suggest that this pathogen may be the cause of the reproductive loss. The detection of C. psittaci in these cases is consistent with the recent detection of C. psittaci in association with equine abortion in New South Wales. These cases in Victoria show that C. psittaci, and the zoonotic risk it poses, should be considered in association with equine reproductive loss in other areas of Australia.     

Foliar Application of Urea and Triazone Nitrogen to Cotton

Upland cotton (Gossypium hirsutum) requires adequate nitrogen (N) for optimum yields. Foliar applications of urea to supplement soil applied N have been tried for many years across the Cotton Belt, but responses have been highly variable. No published information is available regarding response by irrigated cotton to foliar applied N in subtropical South Texas. This study investigated the response of cotton to foliar applied urea and triazone N over a three-year period near Weslaco, Texas. In all years, foliar applied urea tended to increase seed cotton yield when soil applied N was limiting. In the absence of soil applied N, the increase due to foliar urea was significant in two of the three years (28.7 and 15.7% increases). Foliar applied triazone N was ineffective at increasing seed cotton yields.     

Indicators of Cotton Nitrogen Status

ABSTRACT

Nitrogen (N) deficiency limits cotton yields, while too much N causes excessive vegetative growth hurting yields, wastes expensive inputs, and causes environmental pollution. Diagnostic indicators are needed to assess cotton N status so that yields can be optimized as efficiently as possible. This study evaluated selected tools for predicting cotton responses to N fertilizer application. Petiole nitrate (NO₃)-N (PNN) concentration was found to correlate with cotton N status and a good indicator of potential for response to N application. Critical PNN concentrations for irrigated cotton in subtropical South Texas at first bloom, and 10, 20 and 30 d later were determined to be 15.0, 9.0, 4.5, and 2.0 g kg^{? 1}, respectively. These critical PNN levels are higher than in more humid areas of the traditional southern US Cotton Belt, probably due to the effects of the subtropical climate. Cotton plants in this area tend to be less vegetative, possibly due to shorter growing season day lengths, and therefore need to be “pushed” slightly harder with greater N fertilization. Leaf total N concentrations were found to be less responsive to changes in applied N than were PNN levels. Although leaf N tended to be more stable over time, there was no consistent pattern between years. Leaf N values of 35 g kg^{? 1} or less appear to represent a deficiency at any time, and optimum levels may be slightly higher. Nodes above white flower showed very small responses to N fertilization and the differences occurred late in the bloom period. Chlorophyll meter readings showed a good relationship with N fertilizer application within a given sampling date, but much greater variability occurred between dates and due to other factors. The most effective indicator of cotton N status was found to be PNN, and to a lesser extent leaf N, but none of other parameters could be recommended for purposes of making inferences as to N status of cotton.     

In situ and potential CO2 evolution from a Fluventic Ustochrept in southcentral Texas as affected by tillage and cropping intensity

Quality of agricultural soils is largely a function of soil organic matter. Tillage and crop management impact soil organic matter dynamics by modification of the soil environment and quantity and quality of C input. We investigated changes in pools and fluxes of soil organic C (SOC) during the ninth and tenth year of cropping with various intensities under conventional disk-and-bed tillage (CT) and no tillage (NT). Soil organic C to a depth of 0.2 m increased with cropping intensity as a result of greater C input and was 10% to 30% greater under NT than under CT. Sequestration of crop-derived C input into SOC was 22±2% under NT and 9±4% under CT (mean of cropping intensities ± standard deviation of cropping systems). Greater sequestration of SOC under NT was due to a lower rate of in situ soil CO₂ evolution than under CT (0.22±0.03 vs. 0.27±0.06 g CO₂–C g⁻¹ SOC yr⁻¹). Despite a similar labile pool of SOC under NT than under CT (1.1±0.1 vs. 1.0±0.1 g mineralizable C kg⁻¹ SOC d⁻¹), the ratio of in situ to potential CO₂ evolution was less under NT (0.56±0.03) than under CT (0.73±0.08), suggesting strong environmental controls on SOC turnover, such as temperature, moisture, and residue placement. Both increased C sequestration and a greater labile SOC pool were achieved in this low-SOC soil using NT and high-intensity cropping.     

Oocyte holding in the Iberian red deer (Cervus elaphus hispanicus): Effect of initial oocyte quality and epidermal growth factor addition on in vitro maturation

Current in vitro embryo production protocols in the Iberian red deer (Cervus elaphus hispanicus) need to be optimized; oocyte harvesting in situ followed by overnight holding could reduce the human effort and shipping costs. In our work, post‐mortem ovaries were retrieved, and the oocytes were harvested and allocated to G1 group (good quality) or G2 + G3 group (low quality). The oocytes were separately subjected to immediate in vitro maturation (IVM) or held overnight in a holding medium composed of 40% of TCM 199 with Earle's salts, 40% TCM 199 with Hanks' salts and 20% fetal bovine serum (FBS), at room temperature (16 hr). In vitro maturation was carried out in a basal medium supplemented or not with 50 ng/ml of epidermal growth factor (EGF). Our data showed that addition of EGF to the maturation medium increases the percentage of G1 oocytes reaching metaphase II (3.9% vs. 50%, basal vs. EGF; p < .001) and decreased their degeneration rate (69.9% vs. 22.2%, basal vs. EGF; p < .01) when oocytes were immediately matured. Overnight holding increased the meiotic competence of G1 oocytes (37.5% matured in basal medium) and EGF increased prophase arrest in G2 + G3 oocytes (16.1% vs. 38.8% in germinal vesicle [GV] stage in basal medium vs. EGF added medium; p < .05). Our data demonstrate that oocyte holding can be used in Iberian red deer oocytes. Interestingly, EGF addition increases the oocytes' meiotic competence in immediately matured oocytes but not after oocyte holding depending upon initial oocyte quality.