Spondylosis deformans in the boxer: Estimates of heritability

This study presents the estimates of heritability for spondylosis deformans in the boxer based on 353 offspring from 24 randomly selected sires, each with at least three radiographically investigated offspring. The estimated heritability (h²) for maximum degree of osteophyte development was high, both when estimated by paternal half-sib correlation (0·42) and by the regression of offspring based on the parents (0·62). The heritability for the number of affected discs estimated by paternal half-sib correlation was also high (0·47). The estimate of heritability for the number of affected discs based on regression of offspring on the parents was lower at 0·13. All heritabilities had large standard errors. A positive phenotypic correlation between spondylosis deformans and hip dysplasia was observed. Assuming a significant portion of the correlation is genetic, this fact may permit selection against spondylosis deformans without negatively influencing the incidence of hip dysplasia. Since the incidence of spondylosis deformans is high even in young dogs, it should be possible to detect a large proportion of genetically predisposed animals by radiographic examination of the spine at one year of age; at the same time that dogs are presented for a routine test for hip dysplasia.     

Infection of Cherax quadricarinatus (Decapoda: Parastacidae) by the microsporidium Thelohania sp. (Microsporida: Nosematidae)

Abstract The microsporidian parasite Thelohania sp. was present in a population of Cherax quadriearinatus in the Mitchell River, north Queensland. An infection rate of 7--8% was recorded for the population sampled. Cohabitation, passage of spores through fish, ingestion of spores and injection of blood from an infected individual failed to elicit infection in laboratory held animals. Injection of spores elicited a host responseconsisting of encapsulation and melanization of spores. Further studies are necessary to clarify the taxonomic position and mode of transmission of this parasite.     

Spring Barley Responses to Row Spacing and Fungicide Triadimefon in Regions with a Short Crop-growing Season

Aspects of intensive management practices such as high-yielding cultivars, narrow-row spacings and fungicide treatments could potentially increase cereal yields in regions with a short crop-growing season and occasionally dry and hot weather. A field experiment was carried out at McGill University, Canada for three years (1987 to 1989) to test the effects of triadimefon (1-[4-chlorophenoxy]-3,3-dimethyl-1-[1H-1,2,4-triazol-1-yl]-2-butanone, or Bayleton, a trade name) fungicide (0 vs. 140 g a.i. ha⁻¹) and row spacing (10 vs. 20 cm) on the yield components, yield and other agronomic traits (spike emergence, days to maturity, leaf disease and plant height) of spring barley ( Hordeum vulgare L.) cv. Cadette, Laurier and Leger. A cultivar by row spacing interaction resulted in a 11 to 13.5 % increase in grain yield due to narrow rows for Laurier in two out of the three years and up to 16 % for Leger in one year. Over the three years grain yields were on average increased 6 to 12 % due to use of the narrower row spacing. Fungicide application to barley at the early heading stage effectively controlled leaf diseases without influence on yield components or grain yield. Our results indicate that some components of intensive management such as narrow row spacing can be applicable in regions with a short crop-growing season.     

Toxic peripheral neuropathy with demyelination in Sprague-Dawley rats given CGS 21595--a 5-lipoxygenase inhibitor.

Male and female Sprague-Dawley rats were given CGS 21595, a pro-drug that is almost immediately metabolized to CGS 19213, a naphthoquinone that acts as a 5-lipoxygenase inhibitor. The compound was administered by gavage to five groups of Sprague-Dawley rats (group Nos. 1, 5, n = 30; group Nos. 2-4, n = 20) at daily doses of 0, 50, 150, 500, or 1,000 mg/kg for 13 weeks. Rats in the higher dose groups had a reduced weight gain, but significant neurologic signs were not observed. A peripheral neuropathy consisting predominantly of myelin destruction in the spinal nerve roots and sciatic nerves in male rats treated with greater than or equal to 150 mg/kg CGS 21595 and in female rats treated with greater than or equal to 50 mg/kg CGS 21595 for 13 weeks. This lesion was not fully reversible after a recovery period of 4 weeks. Lesions consisted of ballooning of myelin sheaths, infiltration by macrophages, demyelination, and occasional areas of remyelination. Axons were generally preserved, and the brain and spinal cord were not affected. Male and female rats in all treatment groups had cytoplasmic hyaline droplets in the proximal renal tubules. This change was reversible after 4 weeks and was not associated with any other adverse effects on the kidney.     

Effects of predator-induced visual and olfactory cues on 0+ perch (Perca fluviatilis L.) foraging behaviour

Abstract –  Foraging juvenile fish with relatively high food demands are usually vulnerable to various aquatic and avian predators. To compromise between foraging and antipredator activity, they need exact and reliable information about current predation risk. Among direct predator-induced cues, visual and olfactory signals are considered to be most important. Food intake rates and prey-size selectivity of laboratory-reared, naive young-of-the-year (YOY) perch, Perca fluviatilis , were studied in experiments with Daphnia magna of two size classes: 2.8 and 1.3 mm as prey and northern pike, Esox lucius , as predator. Neither total intake rate nor prey-size selectivity was modified by predator kairomones alone (water from an aquarium with a pike was pumped into the test aquaria) under daylight conditions. Visual presentation of pike reduced total food intake by perch. This effect was significantly more pronounced (synergistic) when visual and olfactory cues were presented simultaneously to foraging perch. Moreover, the combination of cues caused a significant shift in prey-size selection, expressed as a reduced proportion of large prey in the diet. Our observations demonstrate that predator-induced olfactory cues alone are less important modifiers of the feeding behaviour of naive YOY perch than visual cues under daylight conditions. However, pike odour acts as a modulatory stimulus enhancing the effects of visual cues, which trigger an innate response in perch.     

CIDR PMSG FSH联合处理不同品种绵羊效果的研究

CIDR、PMSG、FSH联合使用对初产供体羊Borderdale(波德代)3♂15♀、Poll Dorset(无角陶赛特)5♂18♀和Ger-man Mutton Merino(德国肉毛兼用美利奴—德美)3♂15♀进行同期发情和超数排卵。同期化发情波德代、无角陶赛特和德美分别为100.00%、88.89%和93.33%,羊只同期化发情时间经历和各时间点分布3个品种各有特点。超数排卵效果品种间存在差异,波德代、无角陶赛特、德美分别为6.60±2.97(枚)、3.63±2.25(枚)、5.50±3.32(枚),波德代极显著地高于无角陶赛特(P<0.01)。超排有效率波德代、无角陶赛特、德美分别为100.00%、87.50%、92.86%。未受精卵波德代极显著地高于德美羊和无角陶赛特羊(P<0.01)。胚胎总数德美羊极显著地高于波德代(P<0.01)。有效胚胎波德代羊、无角陶赛特羊、德美羊分别为2.40±2.31、2.75±2.05、4.07±3.79,德美极显著地高于波德代(P<0.01)。同一方法进行同期化发情,羊只经历时间和各时间点均衡分布能否有效控制是同期发情的焦点问题,是有效胚胎数目差异的主导因素之一。     

禁用抗生素促生长剂(AGPs)对畜禽的影响

自20世纪40年代后期发现抗生素对畜禽有促生长作用以来,饲喂低于治疗剂量的抗生素已经成为家畜营养中必不可少的部分。但今天很多国家在对动物饲料中使用抗生素进行了重新评估。自Sw ann(1969)的报告发表以来,细菌对特定抗生素产生抗药性的潜在风险引起了很大关注,这些抗药性可     

Effects of Added Substrate on Production of Red Swamp Crawfish, Procambarus clarkii, in Earthen Ponds without Planted Forage

The effects of addition of substrate consisting of plastic mesh fencing to experimental earthen ponds were evaluated for the culture of the red swamp crawfish, Procambarus clarkii, without planted forage. Mean daily yield (kg/ha/d), number of crawfish harvested (number/ha/d), and mean individual harvest weight were compared for ponds with and without substrate during a 2‐yr period. The surface area of added substrate was equivalent to 50% of the bottom surface area of the pond. Mean daily yield in the ponds containing substrate, based on a comparison with that of the previous year, increased by 80.2% and was principally attributed to a 66.7% increase in the number of crawfish harvested. Comparative values for the ponds without substrate were ?13.1 and ?11.7%. For the second year, the treatment‐dependent response was consistent. Mean daily yield for the substrate ponds increased by 48.8% compared to 15.0% for the ponds lacking substrate. The primary benefit of the substrate appears to be provision of refuge and three‐dimensional distribution of crawfish in the pond, thereby reducing the incidence of cannibalism and increasing the total number of crawfish harvested per hectare per day. The benefit of the substrate in a commercial production setting must be weighed against its cost and longevity as well as the conditions of the particular management scenario into which it may be incorporated.