The effect of varying the size of the seeding population of a cross-fertilized crop on the performance of the progeny

Summary Studies were made on the effect of the size of a seeding population on the performance of progeny of the winter cabbage variety Cambridge Drumhead. Clones were produced from 80 selected plants and separate seed lots were derived by seeding the genotypes in one group of 80, two groups of 40, four groups of 20, eight groups of 10 and sixteen groups of 5. When comparing records of head weight and quality of the various progenies, the effect of the size of the seeding group was separated from the effect of the different genotypes in the groups.Mean performance was best in the progeny of the 40-plant groups and variability was greatest in either those of the 80- or in the 40-plant groups, both factors declining with reduction in size of the seeding group. In spite of the phenotypic similarity of the original selected parents, there was clear evidence that superior (and inferior) genotypes or combinations of genotypes existed for weight and grade of head. As the size of the seeding group was progressively reduced, these genotypes could be traced by their influence on the performance of the particular group in which, by chance, they had been included.     

The effect of intensity of selection during successive generations of seed multiplication,on the field performance of Brussels sprouts

An experiment in which two different intensities of selection were applied, in each of three successive generations, to two varieties of Brussels sprout showed that the progeny resulting from lax selection were frequently inferior in agronomic characteristics to those from the more stringent selection. In one of the varieties used, this inferiority took the form of an increase in the proportion of off-types, and in the other there was a decrease in yield.These results imply that deterioration in the agronomic value of a variety is likely to occur whenever standards of selection are relaxed, for example, to accelerate the multiplication of seed. It is suggested that such deterioration is most likely to occur in those characteristics for which selection has improved the uniformity of a variety but has produced only partial homozygosity over the range of loci affecting those characteristics.     

The abundance of milk cathelicidin proteins during bovine mastitis

Current on-farm methods for detecting mastitis in dairy cows have limitations with their specificity and sensitivity, particularly at an early stage of infection. There is therefore a need to explore new approaches for detecting early and subclinical mastitis. This study examined the expression of a group of neutrophil-specific proteins, the cathelicidins, in milk samples from naturally occurring as well as experimentally induced mastitis infections. Immunoblot analysis indicated that cathelicidin proteins are only observed in infected quarters and demonstrate a high correlation with somatic cell count (SCC) during the onset of infection. In most of the infections examined, cathelicidin was detected prior to the observation of clinical symptoms and at SCC counts as low as 6.2 × 10(3)cells/mL. In naturally occurring mastitis the correlation between cathelicidin and infection status is not as strong, with 25% of pathogen-positive milk samples containing no detectable cathelicidin. This may reflect the varying levels of neutrophil concentration and activity at different stages or severities of infection. Our results indicate that milk cathelicidin levels increase following intramammary infection and cathelicidin-based biomarkers may assist in the detection of preclinical mastitis or determining the stage of infection.     

Tibiotarsal arthrodesis in a Moufflon sheep

Restraint of a mature Moufflon sheep resulted in severe fracture and luxation of a previously osteoarthritic tibiotarsal joint. Arthrodesis was accomplished by means of internal pin fixation and an external fiberglass cast. After 3 months of hospitalization, the ram was returned to the original flock. Competition for dominance within the flock resulted in physical trauma to the ram. Seven months after surgery, the ram sustained a fractured ulna and died from exposure.     

A retrospective study of the causes of morbidity and mortality in farmed elk (Cervus elaphus)

A survey of North American farmed elk (Cervus elaphus) producers was performed to determine the causes of sickness and mortality in farmed elk and to estimate mortality rates. Records over a 10-year period from 8 North American veterinary diagnostic pathology laboratories were also examined and summarized. The primary diagnosis for each record was used to classify diseases into categories such as parasitic, infectious, toxicological, and neoplastic. Nonspecific trauma was the most frequently reported known cause of mortality in both sexes and all age classes by elk producers. Ranked on perceived economic importance, producers cited trauma, chronic wasting disease, calf scours, dystocia, pneumonia, winter tick, tuberculosis, and grain overload. One-year mortality rates for adults and yearlings were 2.6% and 2.7%, respectively. Mortality rates for male and female adult animals were 2.4% and 2.7%, respectively. In general, the major findings of the survey matched reported causes for mortality provided by elk producers.     

Nitrate leaching from a small, underdrained, grassland, clay catchment

Abstract. Losses of nitrogen in the tile drainflow from a clay soil (Evesham series) under grazed grassland were monitored during the 1982/83 and 1983/84 drainflow seasons. In 1982/83, 40% of the discharge had a NO₃⁻ concentration > 11.3 mgNl⁻¹, while in 1983/84 concentrations were always > 20 mgNl⁻¹. Total N lost by leaching was 17.5 and 48.7 kg ha⁻¹ in 1982/83 and 1983/84 respectively, which was equivalent to 9 and 43% of the fertilizer applied. The marked difference in N losses for the two seasons was attributed to differences in the quantity and timing of N fertilizer applications, the dryness of the preceding summer and the duration and density of stocking.