氧化应激与疾病

2．4胎衣不下（RIM） 该症是导致抗氧化状况衰竭的第一步。奶牛RFM可引起子宫内膜炎、连续的卵巢周期延误、妊娠推迟等系列损失。     

Evaluation of an enzyme-linked immunosorbent assay for diagnosis of trichinellosis in swine.

Experimental and field trials were conducted to evaluate an ELISA for its ability to detect Trichinella-infected domestic swine and to compare ELISA results with muscle-digestion test results. The ELISA used was a commercial double-antibody kit, containing an excretory-secretory antigen, and was evaluated principally for epidemiologic use. Experimentally induced infection in swine (4 groups of 3 pigs each; inoculated with 0, 50, 500 or 5,000 larvae) was detected as early as postinoculation week 4, with seroconversion of all inoculated swine by postinoculation week 8. The rate of seroconversion appeared to be affected by initial larval dose, time after inoculation, and immunocompetence of the individual host. Determination of antibody kinetics generally revealed rapidly increasing antibody titer, followed by its steady decrease in most pigs. Once seropositive, however, all pigs remained seropositive for the duration of the 10-week study. Presence of muscle larvae was confirmed in all infected pigs at termination of the study. We recognize that the experimental conditions may not be truly representative of those under which natural infection develops in pigs; however, the ELISA detected an infected pig with muscle larval density of 0.87 larvae/g of tissue. Results of a field trial (n = 310) indicated no muscle digestion test-positive pigs (35 g of diaphragm muscle digested/pig), but 3 samples tested positive by ELISA for specificity of 99.0%.     

Bilateral ureterocystostomy in a 450-kg horse with ectopic ureters.

A 450-kg yearling Clydesdale filly was determined to have bilateral ectopic ureters. The resulting incontinence caused severe malodorous perineal dermatitis. Bladder capacity was measured at 800 ml. The urethral sphincter lacked tone, and the horse was seen to urinate in a normal manner only 2 or 3 times a week. A midline celiotomy was performed, and the ureters were identified by cannulation from the ectopic openings. The ureters were ligated, and the cut ends were anastomosed to the dorsal bladder surface by an extravesicular end-to-side technique. A partial thickness seromuscular layer of the bladder was sutured over the ureters in a cranial direction from the anastomosis site for 15 mm. This fixed the ureters to the dorsal surface of the bladder and protected the anastomosis site from tension. After surgery, the horse urinated n a normal manner many times a day. Urinary incontinence continued, but gradually improved. Bladder capacity increased over 13 months to 4.3 L. Surgical (urethral extension) and medical (phenylpropanolamine and estrogen) treatments were instigated to increase urethral sphincter tone. Urinary incontinence continued to improve and, at 11 months after surgery, incontinence was negligible, and the perineal dermatitis had healed.     

Selenium levels of beef cattle in southeastern british columbia relative to supplementation and type of pasture

Moderate to extremely low levels of selenium in hay were related to marginally deficient levels of selenium in sera from cattle in the Windermere Valley of southeastern British Columbia. Deficiency was most pronounced in cattle fed local hay during the winter or grazed on fertilized/irrigated pastures. Cattle on range had adequate levels of serum selenium. When sodium selenite was fed at 1.0 and 3.5 mg per head per day, serum selenium levels increased commensurate with the dose. Clinical observations indicated that a variety of clinical problems disappeared after injection or supplementation with selenium/vitamin E.     

The effect of level of nutrition on the development of resistance to Haemonchus contortus in sheep

Merino wether weaners, 5-months old at the start of the experiment and fed lucerne-based pellets at 600 g per head per day, developed resistance to Haemonchus contortus given as a continuous or "trickle" infection at the rate of 500 larvae 3 times per week over a period of 17 weeks. By contrast, the development of resistance was impaired in weaners fed pellets at 400 g per head per day. Low food intake and protein-energy deprivation, therefore, have a major effect in impairing the development and expression of host-protective immunity against haemonchosis. The point at which low food intake causes outbreaks of haemonchosis in sheep at pasture is critical in determining procedures for prevention and control of the disease.     

The effect of dietary bacitracin on the incidence of streptococcus faecalis subspecies liquefaciens and related streptococci in the intestines of young chicks

1. A study has been made of changes occurring in the numbers and types of faecal streptococci in the intestines of chicks from hatching to 23 d of age, when fed on a diet containing 50 mg bacitracin/kg.

2. It was found that Streptococcus faecalis sub‐species liquefaciens predominated in chicks prior to feeding and in control birds the organism remained as a significant part of the flora throughout the experiment.

3. Strep. faecalis s.s. liquefaciens was not found after the first week in birds given dietary bacitracin.

4. Although outnumbered initially in the caeca by Strep, faecalis s.s. liquefaciens, other streptococci were present at 10⁶ to 10⁷/g contents from 14 d onwards in both control and bacitracin‐treated birds; these included Strep. faecium biotypes and two other unidentified but related groups.

5. Tests made in vitro showed that Strep. faecalis s.s. liquefaciens was more sensitive to bacitracin than Strep. faecium.

6. The possible effects of Strep. faecalis s.s. liquefaciens on the developing bird are discussed.     

Towards an integrated understanding of green space in the European built environment

In recent years social, economic and environmental considerations have led to a reevaluation of the factors that contribute to sustainable urban environments. Increasingly, urban green space is seen as an integral part of cities providing a range of services to both the people and the wildlife living in urban areas. With this recognition and resulting from the simultaneous provision of different services, there is a real need to identify a research framework in which to develop multidisciplinary and interdisciplinary research on urban green space. In order to address these needs, an iterative process based on the delphi technique was developed, which comprised email-mediated discussions and a two-day symposium involving experts from various disciplines. The two outputs of this iterative process were (i) an integrated framework for multidisciplinary and interdisciplinary research and (ii) a catalogue of key research questions in urban green space research. The integrated framework presented here includes relevant research areas (i.e. ecosystem services, drivers of change, pressures on urban green space, human processes and goals of provision of urban green space) and emergent research themes in urban green space studies (i.e. physicality, experience, valuation, management and governance). Collectively these two outputs have the potential to establish an international research agenda for urban green space, which can contribute to the better understanding of people's relationship with cities.     

Application of sperm cryopreservation in selective breeding of the Pacific oyster,Crassostrea gigas (Thunberg)

The robustness of Pacific oyster, Crassostrea gigas (Thunberg), sperm cryopreservation in the context of selective breeding based on family lines was investigated. Irrespective of egg density, high fertilization success was achieved with cryopreserved sperm when sperm:egg ratios of 1000:1 to 10 000:1 were used. Variation among replicate runs on the same oyster batches was minimal, indicating that cryopreservation and larval rearing procedures were repeatable. Twenty independent single male–female crosses were made to assess the utility of cryopreserved sperm in selective breeding. The fertility of unfrozen sperm was generally a poor predictor of cryopreserved sperm fertility. Based on D‐larval yields, 17 of the 20 crosses were likely to yield adequate spat for selective breeding (>10⁵ D‐larvae from 1 million eggs), two were marginal (5 × 10⁴ D‐larvae) and one was inadequate (4 × 10³ D‐larvae). An alternative fertilization strategy to improve D‐yield from a given number of sperm was then tested. Fertilizing 10 million eggs at a sperm:egg ratio of 200:1 increased the total D‐yield when compared with fertilizing 1 million eggs at a sperm:egg ratio of 2000:1 for the same male–female pair. We conclude that, despite wide variation in fertility, cryopreserved sperm is useful for family production.     

Foraging specialisms, prey size and life-history patterns: a test of predictions using sympatric polymorphic Arctic charr (Salvelinus alpinus)

Abstract –  We use arguments based on optimal foraging theory to predict body size constraints and the consequences of these on a range of life-history traits in three trophic specialist morphs of Arctic charr, Salvelinus alpinus , living in sympatry in Loch Rannoch, Scotland. As predicted, foraging specialists feeding on small prey items with a narrow size range showed evidence of deterministic growth; the ultimate body size of macrobenthos feeders being larger ( L _∞ = 238 mm) than that of planktivores ( L _∞ = 216 mm). In contrast, the piscivorous morph showed no evidence of reaching a maximal body size.
The two size-constrained morphs (benthivores and planktivores) matured earlier and died younger (living for up to 11 and 7 years, respectively, in this study) than did the piscivorous charr which showed continuous growth up to at least 17 years.
The pattern of annual reproductive investment in maturing individuals was complex. Planktivores invested in larger eggs than the other two forms, but benthivores produced a greater number of eggs than planktivores, which in turn produced more than piscivores. Planktivorous males had a greater investment in mean testis weight than the other two forms.
Lifetime reproductive output was the greatest in the benthivorous charr, intermediate in planktivorous and the lowest in the piscivorous charr when measured either as fecundity or as gonadal weight. We conclude that constraints imposed upon foraging specialists by foraging efficiency is a significant driver of body size and ultimately reproductive investment in gape-limited foraging salmonids.