Prevalence of megabacteria in budgerigar colonies

Objective To measure the prevalence of megabacteria in budgerigar-breeding colonies and to evaluate possible methods to reduce the prevalence.
Design A monitoring study over several years.
Sample population Two budgerigar ( Melopsittacus undulatus ) colonies with over 300 birds each.
Procedure The prevalence of megabacteria in the faeces in two budgerigar breeding colonies, colony 1 and 2, was determined by faecal examination of each bird. Following an initial survey (1990), most of the birds that were scored 2+ or more were culled and a management practice was implemented to discriminate against positive birds. Consecutive yearly surveys (1991, 1992) were conducted on the young birds bred in these colonies. The prevalence of megabacteria in colony 2 was also evaluated in 1994 and 1996 after all the birds were treated with amphotericin B administered in drinking water.
Results The prevalence of megabacteria in the two colonies was significantly (P < 0.001) different. Overall the prevalence of megabacteria adjusted for colony differences was significantly higher (P < 0.025) in males compared to females. Age was not an influencing factor. After the initial survey, the prevalence in the offspring did not significantly (P > 0.05) decrease in the following two annual breeding seasons but by inference it did significantly decrease after amphotericin B treatment.
Conclusion The practice of culling most birds with more megabacteria in faeces and discriminating against positive birds when selecting birds for breeding or culling birds on show quality does not decrease megabacteria prevalence in the offspring. However, a reduction in prevalence does occur with administration of amphotericin B. Birds may have amphotericin B-resistant organisms and these birds need to be identified and culled.     

Micro-scaled high-throughput digestion of plant tissue samples for multi-elemental analysis

Background  

Quantitative multi-elemental analysis by inductively coupled plasma (ICP) spectrometry depends on a complete digestion of solid samples. However, fast and thorough sample digestion is a challenging analytical task which constitutes a bottleneck in modern multi-elemental analysis. Additional obstacles may be that sample quantities are limited and elemental concentrations low. In such cases, digestion in small volumes with minimum dilution and contamination is required in order to obtain high accuracy data.     

Suppression of C-hordein synthesis in barley by antisense constructs results in a more balanced amino acid composition

Barley has for feeding purposes a shortage of essential amino acids, especially lysine, threonine, and methionine, and an excess of proline and glutamine. In the present study, we have introduced into barley an antisense construct against C-hordeins, the storage protein with the lowest nutritional quality. SDS-PAGE and reverse phase HPLC revealed a relative reduction in the amounts of C-hordeins and relative increases in the content of the other storage proteins. The five different lines analyzed had lower amounts of proline, glutamic acid/glutamine, and phenylalanine (up to 12%, 6%, and 9% reductions), while the lysine, threonine, and methionine content was increased with up to 16%, 13% and 11%. It is concluded that antisense mediated suppression of C-hordein synthesis may be a promising approach for improving the nutritional value of barley as a feed crop while at the same time reducing the environmental nitrogen load.     

Changes in productivity and profitability of wool-growing farms that follow recommendations from agricultural and veterinary studies

Objective To estimate the changes in productivity and profitability in a group of wool-growing farms as they adopted major recommendations from agricultural and veterinary studies.
Farms Four wool-growing farms in south western Victoria were selected from the clients of the Mackinnon Project, a farm consultancy service run from the University of Melbourne. Each farm had closely followed recommended procedures, kept comprehensive financial and physical records and had been clients for at least 5 years. The comparison group was the South Western Victoria Monitor Farm Project (SWVMFP), about 45 farms in the same region as the study farms that were monitored annually by Agriculture Victoria.
Procedure For a 7-year period, the financial and physical performance of both groups of farms was estimated. Stocking rate, wool production, gross farm income, farm operating costs, net farm income and return on assets were compared.
Results Mean gross farm income of the four study farms steadily rose from 86% of the average SWVMFP farm before the adoption of recommendations to an average of 155%. During the same period, net farm income rose from 70% to 207% of the average of the SWVMFP. Return on asset of the four farms rose irregularly from 26% to 145% of the average of the SWVMFP. Farm operating costs on the four farms were higher than for the SWVMFP group, but the ratio of costs remained relatively constant.
Conclusion The adoption of proven research results was associated with large increases in net farm income. An increase in gross income, rather than a reduction in costs was the main reason for this. Research results offer a way to increase the financial viability of wool-growing farmers, many of whom are currently unable to maintain their lifestyle, resources and infrastructure.     

Residual nitrogen effect of clover-ryegrass swards on yield and N uptake of a subsequent winter wheat crop as studied by use of N methodology and mathematical modelling

The residual effect of 2-year-old swards of clover-ryegrass mixture and ryegrass in monoculture on yield and N uptake in a subsequent winter wheat crop was investigated by use of the ¹⁵N dilution method and by mathematical modelling. The amount of N in the wheat crop, derived from clover-ryegrass residues was 25–43% greater than that derived from residues of ryegrass which had been growing in monoculture. Expressed in absolute values, the N uptake in the subsequent winter wheat crop was 23–28 kg N ha ⁻¹ greater after clover-ryegrass mixture than after ryegrass in monoculture. Up to about 54 kg N ha⁻¹ of the N mineralised from the clover-ryegrass crop was calculated to be leached, whereas only 11 kg N ha⁻¹ was leached following ryegrass in monoculture.     

A simple passive sampler for measuring ammonia emission in the field

A new type of passive sampler for the determination of NH₃ emission from land surfaces and manure storages was tested in a micrometereological mass balance method. The sampler consists of 2 glass tubes, each with a length of 10 cm and an internal diameter of 0.7 cm. The two glass tubes are connected in series, with one end fitted with a thin stainless steel disc having a 1 mm hole in the center. The inner surface of each glass tube is coated with oxalic acid. The results show that the passive flux sampler can be used to give accurate determinations of NH₃ emission. The passive flux sampler makes gas washing bottles, pumps, flow meters, anemometers, and electricity unnecessary and ammonia loss can be determined easily and cheaply without the requirement of a large labor force.