Comparisons of energy balance and evapotranspiration between flooded and aerobic rice fields in the Philippines

The seasonal and annual variability of sensible heat flux (H), latent heat flux (LE), evapotranspiration (ET), crop coefficient (K_c) and crop water productivity (WP_ET) were investigated under two different rice environments, flooded and aerobic soil conditions, using the eddy covariance (EC) technique during 2008-2009 cropping periods. Since we had only one EC system for monitoring two rice environments, we had to move the system from one location to the other every week. In total, we had to gap-fill an average of 50-60% of the missing weekly data as well as those values rejected by the quality control tests in each rice field in all four cropping seasons. Although the EC method provides a direct measurement of LE, which is the energy used for ET, we needed to correct the values of H and LE to close the energy balance using the Bowen ratio closure method before we used LE to estimate ET. On average, the energy balance closure before correction was 0.72 ± 0.06 and it increased to 0.99 ± 0.01 after correction. The G in both flooded and aerobic fields was very low. Likewise, the energy involved in miscellaneous processes such as photosynthesis, respiration and heat storage in the rice canopy was not taken into consideration.Average for four cropping seasons, flooded rice fields had 19% more LE than aerobic fields whereas aerobic rice fields had 45% more H than flooded fields. This resulted in a lower Bowen ratio in flooded fields (0.14 ± 0.03) than in aerobic fields (0.24 ± 0.01). For our study sites, evapotranspiration was primarily controlled by net radiation. The aerobic rice fields had lower growing season ET rates (3.81 ± 0.21 mm d⁻¹) than the flooded rice fields (4.29 ± 0.23 mm d⁻¹), most probably due to the absence of ponded water and lower leaf area index of aerobic rice. Likewise, the crop coefficient, K_c, of aerobic rice was significantly lower than that of flooded rice. For aerobic rice, K_c values were 0.95 ± 0.01 for the vegetative stage, 1.00 ± 0.01 for the reproductive stage, 0.97 ± 0.04 for the ripening stage and 0.88 ± 0.03 for the fallow period, whereas, for flooded rice, K_c values were 1.04 ± 0.04 for the vegetative stage, 1.11 ± 0.05 for the reproductive stage, 1.04 ± 0.05 for the ripening stage and 0.93 ± 0.06 for the fallow period. The average annual ET was 1301 mm for aerobic rice and 1440 mm for flooded rice. This corresponds to about 11% lower total evapotranspiration in aerobic fields than in flooded fields. However, the crop water productivity (WP_ET) of aerobic rice (0.42 ± 0.03 g grain kg⁻¹ water) was significantly lower than that of flooded rice (1.26 ± 0.26 g grain kg⁻¹ water) because the grain yields of aerobic rice were very low since they were subjected to water stress.The results of this investigation showed significant differences in energy balance and evapotranspiration between flooded and aerobic rice ecosystems. Aerobic rice is one of the promising water-saving technologies being developed to lower the water requirements of the rice crop to address the issues of water scarcity. This information should be taken into consideration in evaluating alternative water-saving technologies for environmentally sustainable rice production systems.     

Early harvest and ensilage of forage sorghum infected with ergot (Claviceps africana) reduces the risk of livestock poisoning

Sorghum ergot produces dihydroergosine (DHES) and related alkaloids, which cause hyperthermia in cattle. Proportions of infected panicles (grain heads), leaves and stems were determined in two forage sorghum crops extensively infected 2 to 4 weeks prior to sampling and the panicles were assayed for DHES. Composite samples from each crop, plus a third grain variety crop, were coarsely chopped and half of each sealed in plastic buckets for 6 weeks to simulate ensilation. The worst-infected panicles contained up to 55 mg DHES/kg, but dilution reduced average concentrations of DHES in crops to approximately 1 mg/kg, a relatively safe level for cattle. Ensilation significantly (P = 0.043) reduced mean DHES concentrations from 0.85 to 0.46 mg/kg.     

Report on Salmonella isolates submitted to the German National Veterinary Salmonella Reference Laboratory in the year 1999

The National Salmonella Reference Laboratory (NRL-Salm) of the Federal Institute for Health Protection of Consumers and Veterinary Medicine receives putative Salmonella isolates originating from animals, food, feed and the environment for typing. This report summarises the results of the sero- and phagetyping studies. In livestock S. Typhimurium DT 104 with 24% and S. Enteritidis PT 4 with 9% of all isolations predominate like in the human isolates. These sero- and phagetypes are frequently isolated from food as well and consequently can reach the consumer via the food chain.     

Variation in clinical and parasitological traits in Pietrain and Meishan pigs infected with Sarcocystis miescheriana

Future prophylaxis needs new concepts, including natural disease resistance of hosts against infectious agents. Genomic approaches to detect and improve disease resistance in farm animals and the molecular mechanisms involved in host-parasite interactions depend to a high degree on the trait differences between founder breeds, i.e. on the animal model. The present study evaluates differences in susceptibility/resistance against Sarcocystis miescheriana in the European Pietrain (PI) and the Chinese Meishan (ME) pig breeds, based on 25 individuals, infected orally with 5x10(4) sporocysts of S. miescheriana. Significant differences appeared in clinical, serological, haematological and parasitological findings. The major discriminating period post infection (p.i.) was between days 42 and 45. Severity of signs was negatively correlated with specific immunoglobulin titres during the first 3 weeks p.i. and positively with the load of bradyzoites in muscle tissues of the pigs. Loads of bradyzoites in muscle tissues were 20 times higher in PI than in ME. Sarcocystis-specific differences between the two breeds were in the range of 1-2 standard deviations. The study lays the foundation for further experiments to analyse chromosomal regions, candidate genes, and thus the molecular basis of Sarcocystis susceptibility/resistance as a model for host-parasite interaction in protozoan infectious disease.     

人员在岗培训在实施兽药GMP现场管理中的作用

论述了对兽药生产企业进行人员在岗培训的必要性,对实施在岗培训的基本程序和应注意的事项进行了总结,旨在为兽药企业进行GMP现场管理提供参考。