Ammonium Nitrogen Deposition as a Dominant Source of Nitrogen in a Forested Watershed Experiencing Acid Rain in Central Japan

To clarify nitrogen (N) sources, the overall N budget in a forested watershed in Kanagawa Prefecture, Central Japan was estimated by measuring dissolved inorganic N (DIN; NH₄ ⁺ + NO₃ ^– + NO₂ ^–) from Nov 2004 through Oct 2005. The estimated N budget (–1.43 kg N ha^–1 year^–1) showed that the N output rate (stream water N) was higher than the N input rate (bulk deposition N) in the watershed. The annual NO₂ ^– and NO₃ ^– input rates were 0.02 and 1.99 kg N ha^–1 year^–1, respectively. NH₄ ⁺ was the predominant source in this forested watershed, accounting for 71% (4.99 kg N ha^–1 year^–1) of DIN input rate. In addition, this study estimated rainfall pH, air temperature, and wind direction, which were considered as controlling factors related to the atmospheric deposition rate of NH₄ ⁺. This study showed that the rainfall NH₄ ⁺ was inversely proportional to the initial pH of the rainfall, which was calculated by adding the amount of H⁺ consumed by the dissociation process of NH_3(aq) to the measured rainfall pH. This result implies that acid rain can elevate the solubility of NH_3(g) and the dissociation capacity of NH₄ ⁺ throughout the process of precipitation. Also, this study provides strong evidence that the high NH₄ ⁺ deposition rate is mainly derived from NH_3(g) emitted from livestock wastes under the NH₃ transport condition of warm summer and favorable wind direction.     

Polymerase chain reaction analysis of eae gene subtypes present in attaching and effacing Escherichia coli isolated from pigs with diarrhea.

In this study the subtype of eae gene was determined by polymerase chain reaction for a total of 59 attaching and effacing Escherichia coli isolated from preweaned (38 isolates) and postweaned (21 isolates) pigs. The eae(beta) gene detected in 19 E. coli from preweaned pigs and 10 E. coli from postweaned pigs was found to be the most common subtype, followed by eae(gamma), eae(epsilon), and eae(zeta) genes. Subtypes were not determined for 7 E. coli isolates. No other subtype of the eae gene was detected in eae+ E. coli evaluated in this study.     

Genotypic Prevalence of the Adhesin Involved in Diffuse Adherence in Escherichia coli Isolates in Pre‐weaned Pigs with Diarrhoea in Korea

A total of 1002 Escherichia coli strains isolated from pre‐weaned pigs with diarrhoea on 1114 swine farms were screened for the presence of the adhesin involved in diffuse adherence (AIDA) gene by polymerase chain reaction (PCR). Escherichia coli isolates that carried AIDA genes were also tested by PCR for the detection of five fimbriae (F4, F5, F6, F18 and F41), heat‐stable (STa, STb) and heat‐labile (LT) enterotoxin, enteroaggregative E. coli heat‐stable enterotoxin 1 (EAST1), and Shiga toxin 2 oedema disease (Stx2e) genes. Twenty‐three (2.3%) of the 1002 E. coli isolates carried the gene for AIDA. Among 23 isolates shown to carry genes for AIDA, three carried the AIDA gene as the only shown virulence factor. Other isolates carried other virulence factor genes in addition to AIDA. Four isolates carried genes for at least one of the fimbrial adhesins and enterotoxins. Sixteen isolates carried genes for enterotoxins only. The AIDA may represent an additional virulence determinant in pre‐weaned pigs with diarrhoea.     

4种混配除草剂防除大蒜田杂草效果研究

本文对4种混配除草剂防除大蒜田杂草的试验情况进行了总结,并介绍了试验田杂草发生的基本情况,以期对大蒜田化学除草剂的推广和应用有所帮助。     

Effects of dietary conjugated linoleic acid on fatty acid composition, lipid oxidation, color, and water-holding capacity of pork loin

The effects of dietary conjugated linoleic acid (CLA) on fatty acid composition, lipid oxidation, and pork quality were investigated. Pigs (n = 20) were fed a diet containing 0, 1, 2.5, or 5% CLA for 4 wk and slaughtered at 105 kg. The longissimus thoracis et lumborum muscle was collected at 24 h postmortem. Pork loin chops (3 cm thick) were packaged aerobically and stored at 4 degrees C for 7 d. Samples were analyzed for ultimate pH, intramuscular fat content, fatty acid composition, thiobarbituric acid-reactive substances, color (L*, a*, b*), and water-holding capacity. Dietary CLA reduced the concentration of linoleic acid and increased CLA concentration in intramuscular fat of pork loin (P < 0.05). The concentration of CLA in muscle was increased with dietary CLA level and did not change during storage. Thiobarbituric acid-reactive substance value of control was higher than that of the CLA-fed groups (P < 0.05). Intramuscular fat content was increased by dietary CLA, and less purge loss was observed with samples from CLA-fed pigs (P < 0.05). Dietary CLA improved the color stability of pork loin during cold storage. After 7 d, lightness (L*) and yellowness (b*) of the 5% CLA-fed group were significantly lower than those of control (P < 0.05). The results indicated that the water-holding capacity of pork loin was increased with increased intramuscular fat content apparently caused by dietary CLA. Also, the data indicated that color stability of pork was improved with inhibition of lipid oxidation and changing of fatty acid composition by dietary CLA.     

Influence of slaughter weight and sex on yield and quality grades of Hanwoo (Korean native cattle) carcasses

To assess the effects of slaughter weight and sex on APGS (Animal Products Grading Service) quality and APGS yield grade of Korean Hanwoo (n = 20,881) cattle, data were collected from cow, bull, and steer carcasses during a 1-yr period. Factors used to determine quality grade (marbling, meat color, fat color, texture, and overall maturity score) and yield grade (cold carcass weight, adjusted fat thickness, and longissimus muscle area) by the Korean grading system were recorded. Both yield and quality grades were improved (P < 0.01) with heavier slaughter weight, but there was no difference in yield grade for Hanwoo cattle classes heavier than 551 kg (P > 0.01). Longissimus muscle area, adjusted fat thickness, and marbling score increased (P < 0.01) with carcass weight. Bull carcasses showed higher yield but lower quality than those of cows or steers (P < 0.01). The quality grade of steer carcasses was higher (P < 0.01) than that of cow carcasses due to higher marbling scores, lower maturity scores, and heavier carcass weights. Hanwoo carcasses with larger longissimus muscle areas in relation to their carcass weight had lower APGS quality grades. The APGS quality grades were different between yield grade A and B carcasses (P < 0.01), but quality grade was not improved by increased fat thickness beyond the point of yield grade B. Adjusted fat thickness and marbling score showed significant (P < 0.01) differences among all yield grade classes, and this resulted in increased quality grade as yield grade decreased. Adjusted fat thickness showed the strongest correlation (r = -0.63) with yield grade, whereas marbling score had the strongest correlation (r = 0.81) with quality grade. Results showed a negative effect of castration on yield but a positive effect on quality. Also, data showed that Hanwoo carcasses with heavier weights had higher quality grades than those of lighter weight.     

秋大棚黄瓜新品种‘津优11号''

‘津优11号’黄瓜以优良自交系81和114为亲本杂交而成。该一代杂种生长势强，瓜的商品性好，畸形瓜率低，雌花分化对温度不敏感。果肉淡绿色，质脆味甜，抗霜霉病、白粉病、枯萎病，适合秋大棚栽培。