Variations in isolates of Mycogone perniciosa and in disease symptoms in Agaricus bisporus

Eight isolates of Mycogone perniciosa , five from Agaricus bisporus and three from Agaricus arvensis , were studied. One isolate of Mycogone rosae was also included. Aleuriospore and phialospore morphology varied among the isolates as did other characteristics, but M. rosae was the only isolate to produce a red colouration of the medium. Growth was also variable, with three isolates of M. pemiciosa growing at about half the rate of the fastest. The slow-growing isolates contained virus-like particles, 36 nm diameter, and produced sclerodermoid mushrooms. The fast-growing isolates did not contain virus-like particles and caused cap spotting, a symptom not previously described for M. perniciosa. M. rosae produced characteristic cap spots and no scierodermoid mushrooms. A comparison of two isolates of St. perniciosa. one from A. bisporus and one from A arvensis , showed a much greater yield reduction as a result of symptoms caused by the isolate from A. bisporus. The isolate of M. rosae had no significant effect on yield.
Restriction fragment banding patterns of ribosomal DNA showed no differences among the seven isolates of M. perniciosa from England, but the isolate from China was slightly different. The single isolate of M. rosae was distinct from M. perniciosa.     

Surgical Reduction of Ileal Impactions in the Horse: 28 Cases

Objective —To evaluate the seasonal influence, signalment, type of hay consumed, clinical examination findings, and outcome after surgery for horses with ileal impaction. Study Design —A retrospective study. Results —Between 1988 and 1993, 28 horses had surgical correction of ileal impaction. There was a significantly higher rate of ileal impaction during the Fall (September-November, P= .0041). Mean duration of clinical signs of abdominal pain before referral was 15 hours. Transrectal palpation was used to localize the impaction in 11 horses. The ileal impaction was reduced by extraluminal massage aided by admixing of intestinal fluid oral to the impaction or injection of fluids intraluminally and then movement of the ingesta into the cecum alone in 24 horses. A total of 26 horses recovered from surgery; 24 horses were discharged from the hospital and eventually returned to previous use. Two horses had fatal postoperative complications: jejunocec-ostomy dehiscence and development of extensive small intestine adhesions after manual reduction of the impaction. One horse initially treated by manual reduction required jejunocecostomy twice for management of recurrent ileal impaction. Follow-up information was obtained for 21 horses, of which 20 were alive 1 year or longer after surgery. A total of 27 of 28 horses were fed Coastal Bermudagrass hay as the primary type of hay consumed. A total of 9 horses continued to be fed Coastal Bermudagrass hay as the only roughage source, whereas 6 horses were fed Coastal Bermudagrass with at least 50% other hay, and in 6 horses, Coastal Bermudagrass hay was entirely eliminated from the diet. Conclusion and Clinical Relevance—Ileal impactions can be successfully reduced by celiotomy and extraluminal massage and injection techniques to soften the ingesta for passage into the cecum without enterotomy or bypass techniques in most horses. Changes in weather and feeding practices in the Fall may account for an increased risk of ileal impaction in horses in the southeastern United States at that time of year.     

The effect of grazed sward height and stocking rate on animal performance and output from beef cow systems

During three consecutive summers, forty spring-calving beef cows and their calves grazed perennial ryegrass-dominant swards receiving 250 kg N ha^?1 at one of two annual stocking rates [2.0 (SR 2.0) or 2.5 (SR 2.5) cows ha^?1] and one of two sward heights [4–5 (LS) or 7–8 (HS) cm] in a 2 × 2-factorial experiment, replicated twice. Sward heights were maintained from turn-out in spring by weekly adjustment of the area grazed and herbage was cut for silage in June and again in August from the areas not grazed. After the second cut of silage there was no control of sward height. Calves were weaned in early October and cows removed from pasture and housed when sward heights fell to 4 cm in autumn. Cows were fed in groups a variable but measured quantity of silage during winter to achieve a body condition score of 2.0–2.25 at turn-out the following spring. During the period of sward height control the cows on the HS treatment gained more live weight than those on the LS treatment (0.841 vs. 0.496 kg day^?1; P<0.01) as did the calves (1.167 vs. 1.105; P<0.05). but the stocking rate treatment had no effect. From the time of second-cut silage to the time of weaning and housing respectively, calves and cows gained more live weight on the SR 2.0 treatment because sward heights were higher. Reproductive performance of cows was not affected by treatment. The quantity of silage produced and consumed per cow was not affected by sward height treatment, but the SR 2.0 treatment produced significantly (P<0.001) more silage (1559 kg dry matter per cow) than the SR 2.5 treatment (833 kg dry matter per cow) and had higher winter silage requirements (1249 vs. 1153 kg dry matter per cow: P<0.05). The overall mean stocking rate at which winter fodder production and requirements would be in balance was calculated as 2.25 cows ha^?1 but values were 1.86, 2.60 and 2.28 in each of the three years of the experiment. The results showed that it was possible to control sward height in temperate beef cow systems by adjusting the area available for grazing. Body condition score can be used as a means of determining the feeding levels required to manipulate body condition of cows over winter to achieve prescribed levels of body condition. The experimental approach allows the identification of the stocking rate at which self-sufficiency in winter fodder can be achieved and the year-to-year variation associated with that stocking rate. This approach could be generalized if information on herbage growth rate were available, either from direct measurement or from predictive models.     

Hair growth in the greyhound

Monthly regrowth of clipped hair was measured in greyhounds over a two-year period; plasma progesterone and testosterone were measured at the time of clipping. Entire males and females showed virtually no growth in late winter and late summer while maximal growth occurred in mid-summer. Oestrus, and its associated hormones, appeared to suppress hair growth in entire females while spayed females showed good growth throughout most of the year. Low environmental temperature was considered to depress growth in late winter.     

XANTHINE DEHYDROGENASE IN DROSOPHILA; DETECTION OF ISOZYMES

Two or possibly three isozymes of the enzyme, xanthine dehydrogenase, have been detected in wildtype Drosophila melanogaster. by starchgel electrophoresis. Two genes, rosy and maroon-like, may control these isozymes by producing two different polypeptides that assemble in groups of three or four.     

Effects of rearing density on sexual maturation and growth in sea-cage reared Atlantic salmon, Salmo salar L.

Abstract. Paired subgroups of fish were derived in January from each of two parent sea-cages of Atlantic salmon, Salmo salar L. The proportion of fish which later became sexually mature in each parent group, after one winter (as grilse) and under commercial rearing density, was determined. Maturity rates in the subgroups, reared in sea-cages at lower density, were significantly greater than in the parent groups. Rearing at reduced density was associated with increased growth in some, hut not all, comparisons. Periodic anaesthesia, handling and sampling of blood for steroid hormone determinations did not consistently affect maturation rate or growth among fish in one of each pair of subgroups. Sexual development was assessed by determining levels of the steroid hormones 11-oxotestosterone or 17β-oestradiol in samples of blood serum taken monthly from individually marked fish in one of each pair of subgroups. Between February and April specific growth rates in maturing male grilse were significantly higher than in fish subsequently shown to have remained immature. Growth rates in maturing female grilse differed similarly between March and April. Between July and August, however, growth rates of non-maturing salmon exceeded those of grilse.