Naturally occurring and experimental Stachys arvensis (staggerweed) toxicity in lambs in New Zealand

Stachys arvensis (staggerweed) is a common, widely distributed weed of cultivated and waste land with the potential to intoxicate sheep. Two naturally occurring outbreaks of suspected staggerweed toxicity in the lower North Island were investigated. Affected lambs had been recently moved onto staggerweed-contaminated Brassica spp. crops. In total, 150/1,200 (13%) lambs developed hindlimb paresis, a fine generalised muscular tremor, and hunched posture. When forced to move, many became recumbent. Most lambs recovered within 48 h of removal from staggerweed, although a few developed clinical signs again when transported 2–3 weeks later. Grossly, affected lambs had large amounts of staggerweed plant material and seeds within the rumen. Histopathology showed mild, multifocal degeneration of the white matter tracts of the central nervous system (CNS), most commonly in the ventral funiculi of the spinal cord, and acute, mild to moderate, multifocal degeneration of skeletal muscles. Creatine kinase (CK) activity in serum was mildly to markedly elevated in affected lambs. In a feeding trial, ten 10-month-old Romney lambs were randomly assigned to equal treatment and control groups. Treated lambs were drenched with a liquid extract of staggerweed once daily for 7 days. Three of five treated lambs developed mild exercise intolerance, and 1/5 displayed mild paresis of the hindlimbs, slightly crouched hindlimb stance, and shortened gait, on days 6 and 7. Histologically, 4/5 treated lambs had degeneration in white matter tracts of the CNS, indistinguishable from those seen in the lambs in the outbreak, and in 1/5 lambs there was scattered regeneration of skeletal muscle. CK activity in serum in treated lambs was not significantly higher than that in control lambs. None of the control lambs developed significant clinical signs, histological changes or increases in CK activity in serum. The clinical signs and lesions observed in both the outbreaks and feeding trial were similar to those previously described in studies in Australia, with the exception that myodegeneration was more prominent in the outbreaks in New Zealand. Further characterisation of the pathogenesis of staggerweed toxicity and its potential role as a food safety hazard will be facilitated through identification of the toxic principle(s).     

Colostrum yield and litter performance in multiparous sows subjected to farrowing induction

The consumption of colostrum at a low level can compromise the survival and growth of piglets. Therefore, this study aimed to evaluate the effect of farrowing induction on colostrum yield, IgG concentration and the survival and performance of piglets until the weaning. Sows of parity 3 to 7 were assigned into two groups: Control (n = 48), sows with spontaneous farrowing; and induction (n = 48), sows induced to farrow on day 114 of gestation with a PGF₂ analogue. Colostrum and blood samples were collected from the sows, at farrowing and 24 hr later. Blood samples from the piglets were collected at 24 hr after birth. The performance of the piglets was evaluated in a subsample of 28 litters from each group. All piglets were weighed at 7, 14 and 20 days of age. The farrowing length, the number of piglets born alive, stillborn piglets, weight at birth, litter weight at birth and colostrum yield were not significantly affected (p > .05) by farrowing induction. There was no difference between the groups (p > .05) in the percentage of sows with obstetric interventions. Serum IgG concentration, in both sows and piglets, and colostrum IgG concentration were similar between the groups (p > .05). Furthermore, survival rate, piglet weight and litter weight at 7, 14 and 20 days of age were also similar between the groups (p > .05). Therefore, it can be concluded that the farrowing induction performed on day 114 of gestation does not affect the colostrum yield, the IgG concentration in colostrum and serum of piglets, and the litter performance until the weaning.     

Endometrial gene expression in primiparous dairy cows at the end of the voluntary waiting period is affected by nutrition: Total mixed ration vs increasing levels of herbage allowance

The study postulated that differential nutritional management during the early lactation period would be reflected in endometrial expression of genes related to embryo growth at the end of the voluntary waiting period. Thus, the effect of the combined use of total mixed ration (TMR) and grazing under different herbage allowances during the first 75 days post‐partum (DPP) on endometrial gene expression was evaluated in primiparous dairy cows. Cows were blocked by body weight, age and body condition score and randomly assigned to three grazing treatments: high (HA, 30 kg DM per cow per day), medium (MA, 15 kg DM per cow per day) and low (LA, 7.5 kg DM per cow per day) herbage allowance (mixed pasture, 2,600 kg DM per ha) plus 8 kg DM of supplement or TMR (55% forage, 45% concentrate) fed ad libitum (TMR) from calving to 75 DPP. At 57 DPP, cows were synchronized for oestrus (day 0, 68 DPP) and at day 7, endometrial biopsies were obtained. The nutritional treatment did not affect insulin, IGF‐1 and leptin concentrations on days 0, 4 or 7. Expression of IGF1, IGFBP3, IGFBP4, ADIPOR1 and ADIPOR2 mRNA was significantly affected by the nutritional treatment. Endometrial IGF1 and IGFBP4 mRNA were twofold greater in TMR and HA than MA and LA cows. Expression of IGFBP3 and ADIPOR1 mRNAs was greater in TMR and HA than MA cows, but did not differ from LA cows. All groups had greater expression of ADIPOR2 mRNA than MA cows. This study provided solid evidence of the importance of nutritional management during early lactation on uterine environment at the end of the voluntary waiting period. The greater expression of genes related to embryo growth and uterine function (IGF system, progesterone and adiponectin receptors) in cows fed diets maximizing energy intake suggests a favourable environment for embryonic growth, which may explain the improved reproductive performance of cows in good energy balance.     

Sensitivity of boreal forest carbon balance to soil thaw

We used eddy covariance; gas-exchange chambers; radiocarbon analysis; wood, moss, and soil inventories; and laboratory incubations to measure the carbon balance of a 120-year-old black spruce forest in Manitoba, Canada. The site lost 0.3 +/- 0.5 metric ton of carbon per hectare per year (ton C ha-1 year-1) from 1994 to 1997, with a gain of 0.6 +/- 0.2 ton C ha-1 year-1 in moss and wood offset by a loss of 0.8 +/- 0.5 ton C ha-1 year-1 from the soil. The soil remained frozen most of the year, and the decomposition of organic matter in the soil increased 10-fold upon thawing. The stability of the soil carbon pool ( approximately 150 tons C ha-1) appears sensitive to the depth and duration of thaw, and climatic changes that promote thaw are likely to cause a net efflux of carbon dioxide from the site.     

Gas-phase ionic reactions: dynamics and mechanism of nucleophilic displacements

Nucleophilic displacement reactions (the SN2 reaction) of ions in the gas phase are a prototypical reaction system that allows a study of dynamics, mechanisms, and structure-energy relations. This article reviews aspects of the kinetics (especially the applicability of statistical reaction rate theory), the relation of structure and reactivity, and the effects of small numbers of solvent molecules on the reaction and compares the behavior of the ionic reaction in the gas phase with that in solution.     

戊型肝炎病毒研究新进展

戊型肝炎病毒(hepatitis Evirus,HEV)是非甲非乙型急性肝炎的病原体,主要经粪-口途径传播,也有报道可以通过血液传播。戊型肝炎在亚洲、非洲及美洲的墨西哥等发展中国家常呈爆发流行,我国1986-1988年在新疆曾经发生戊型肝炎暴发流行[1],而在包括发达国家在内的世界各地呈散在传     

Cutaneous neoplasia in 340 cats.

A total of 340 cases of cutaneous neoplasia were diagnosed in 340 of 3,564 cats that were examined by biopsy or necropsy during a 41-month period from January 1, 1986 through May 31, 1989. Eighteen types of tumor occurred, but four types comprised 77% of the cases. These were basal cell tumor, 89 cases (26%, mean age 10.3); mast cell tumor, 72 cases (21%, mean age 8.6); squamous cell carcinoma, 52 cases (15%, mean age 11.6); and fibrosarcoma, 50 cases (15%, mean age 10.2). For each of these four types of tumors, peak number of cases occurred in cats older than 10 years. Mast cell tumor was the only tumor diagnosed in cats younger than 1 year. The head was the most common site for basal cell tumors, mast cell tumors, and squamous cell carcinomas. The legs were the most common location of fibrosarcomas. Siamese cats had approximately three times as many mast cell tumors as statistically expected, but only one-fourth as many squamous cell carcinomas. Breed predilection for other skin tumors was not apparent. Sex predilection was not detected for any skin tumor.