A test for linkage of the loci for dominant white and barring with loci controlling growth rate in the fowl 1

Females from a coloured inbred line of Leghorns (ii) were mated to three groups of males heterozygous for the dominant white gene (Ii). The parents transmitting the I gene to the three groups of males were respectively larger, smaller and of the same size as the parents transmitting the i gene. No differences were observed between the three types of crosses in the effect of colour genotype on body weight, providing no evidence for linkage between the dominant white locus and loci affecting body weight.

When comparisons were made between the colour genotype classes, pooled within full sib groups, the coloured genotype was larger in ten of the twelve test cross‐sex‐hatch combinations. Two of these differences, were statistically significant, but when the data were pooled over hatch, sex and test cross, no significant difference was found. The data thus offer meagre support for weight differences in favour of the coloured genotype, but the negative evidence of the pooled analysis raises considerable doubt that real differences in weights between the colour classes exist in these populations.

A similar comparison was made between the barred and non‐barred genotypes among the coloured female progeny in one test cross. The barred progeny were heavier in each hatch, in spite of the fact that the barring gene and sex chromosome were derived from the smaller grandparent. The differences were not statistically significant in either hatch or when the mean squares were pooled over hatches. It is concluded, therefore, that this experiment provides no evidence for any association between the barring locus and the genes for growth rate in this population.     

Comparison of two thiopental infusion rates for the induction of anaesthesia in dogs

OBJECTIVE: To compare the induction dose requirements of thiopental using two different infusion rates for induction of anaesthesia in dogs. STUDY DESIGN: Prospective, randomized study. ANIMALS: Fifty, healthy (ASA I or II) client-owned dogs with a mean age of 4.1 years and a mean mass of 20.4 kg undergoing elective surgery. MATERIALS AND METHODS: Animals were randomly assigned to receive an infusion of 2.5% thiopental at a rate of either 0.1 ml kg(-1) minute(-1) or 0.4 ml kg(-1)minute(-1), 30-40 minutes after pre-anaesthetic medication with intramuscular acepromazine (0.025 mg kg(-1)) and pethidine (3.5 mg kg(-1)). Thiopental administration was controlled by a precision syringe driver. Statistical analyses of the results, using the outcome 'mg kg(-1) required for induction' (log-transformed) included unpaired t-tests for all categorical data (thiopental infusion rate, breed, sex, obesity, sedation quality) and univariable linear regression for continuous variables (mass, age). All variables were then considered in a multivariable linear regression model. The quality of induction with the two different infusion rates was also assessed. RESULTS: After controlling for quality of sedation, the thiopental induction dose requirement was significantly less (p < 0.001) with the slower infusion rate (median = 7.5 mg kg(-1); range 4.9-13.7) compared with the faster infusion rate (median =11.0 mg kg(-1); range 6.6-18.0). The quality of sedation also affected the dose required (p = 0.03). The slower infusion rate was associated with a significantly poorer induction quality (p = 0.03) [corrected] CONCLUSIONS: Slow thiopental infusion (0.1 ml kg(-1) minute(-1)) for anaesthesia induction after acepromazine/pethidine pre-anaesthetic medication reduced the induction dose requirement, although the quality of induction was inferior. CLINICAL RELEVANCE: The induction dose of thiopental was reduced with a slower administration rate and so slow administration is recommended in thiopental-sensitive animals.     

Does occasional movement make pecking devices more attractive to domestic chicks?

1. Previous studies have shown that a bunch of string is a particularly attractive pecking stimulus for chicks and adult laying hens. Because movement is thought to be an important attribute of enrichment objects, this study determined whether occasional movement would affect the attractiveness of this device. 2. In experiment 1 the responses of pair-housed chicks to string were compared when devices in adjacent cages were either linked (so that pecking or pulling at the string in one cage moved the adjoining one) or not (separate). In experiment 2 the devices in half the cages were jigged remotely by the experimenter whereas the others remained static. In both cases, the string devices were introduced into the cages for 10 min on each of 5 consecutive days. 3. No treatment effects were apparent in experiment 1 when pooled data was analysed but comparison of responses on days 1 and 5 revealed that only the chicks presented with non-linked devices showed increased interest with repeated exposure. 4. Chicks given static devices in experiment 2 pecked sooner, more often and longer at them than did those exposed to similar ones that were jigged regularly by the experimenter. Jigged devices attracted slightly more pecking with repeated exposure, which may have reflected familiarity-induced fear-reduction, but chick responses showed no apparent changes from day 2 onwards. Conversely, rather than showing habituation, the chicks pecked progressively more at the static devices with repeated presentation. 5. The present results show that chicks pecked readily at bunches of white string, thus confirming its attractive properties but that static devices were more attractive than those incorporating occasional movement. These and previous findings are discussed in terms of their implications for the development of effective environmental enrichment.     

Developing Integrated Disease Management Strategies Against Non-persistently Aphid-borne Viruses: A Model Programme

There is a need to develop integrated disease management strategies that are comprehensive and can protect farmers from the economic hardship that arises when epidemics of non-persistently aphid-borne viruses damage their crops. The aim of this review is to provide a model for future programmes to use when developing such strategies for different combinations of non-persistently aphid-borne viruses and crops. The model programme described is a 15-year study to develop integrated management strategies against two non-persistently aphid-borne viruses causing damaging diseases of lupins and to get them adopted by farmers. The success of the programme depended on an interdisciplinary team approach, obtaining a detailed understanding of the factors favouring virus epidemics, field evaluation for virus resistance, and field experiments that determined the effectiveness of individual control measures. The strategies developed were designed to cause few additional labour demands, and minimal disruption to normal farming operations or extra expense.The programme devised integrated management strategies for the diseases caused by Cucumber mosaic virus (CMV) and Bean yellow mosaic virus (BYMV) in crops of narrow-leafed lupin (Lupinus angustifolius) under the conditions of low-input, dryland agriculture in the south-west Australian grainbelt, which has a Mediterranean-type climate. CMV is introduced into lupin crops by sowing virus-infected lupin seed while aphids spread BYMV into the growing crop from adjacent virus-infected, clover-based pastures. Grain yield losses are substantial when virus spread by aphids is sufficient to cause high incidences of infection within crops. The management strategies were gradually improved and expanded as understanding of the epidemiology of viruses in lupins improved and the results of field experiments involving potential control measures became available. The individual measures combined within the integrated management strategy for each virus were: sowing seed stocks with minimal virus contents, sowing cultivars with inherently low seed transmission rates and isolation from neighbouring lupin crops (CMV only); perimeter non-host barriers and avoiding fields with large perimeter : area ratios (BYMV only); nobreak promoting early canopy development, generating high plant densities, adjusting row spacing, direct drilling into retained stubble, sowing early maturing cultivars, maximising weed control and crop rotation (both viruses). Recommendations to apply insecticide were included solely for spraying high value seed crops (CMV only) or virus-infected pastures next to crops (BYMV only). The justification for selection of each individual control measure, its mode of action in either removing or minimising the virus infection source or suppressing virus spread by aphids and the extent to which it has been adopted by farmers is described. The approach used to transfer the strategies to farmers and the need to avoid complacency following the overall success of the work is emphasised. An integrated disease management strategy developed to clean up the lupin breeding programme from seed-borne virus infection and prevent release of infected seed stocks of new cultivars is also described. It can serve as an example of what is needed to tackle seed-borne virus contamination in other plant breeding or selection programmes.     

Suspected zinc-induced copper deficiency in growing kittens exposed to galvanised iron

AIM: To investigate the possible causes of fading coat colour and an acquired hind-limb ataxia affecting sixteen 4 to 5-month old kittens in a closed feline colony during 1993 and 1994. METHODS: Records of kittens and litters born in the colony between 1991 and 1997 were analysed. The kittens had been kept from birth until approximately 5 months of age in plastic cages with galvanised iron bar doors. Histopathological sections from 4 of the worst affected ataxic kittens necropsied in 1993 were re-examined. In addition, 6 of the original 16 affected kittens that survived were re-examined as 4 to 5-year old adults, which were moderately ataxic; these cats were then humanely killed for necropsy. RESULTS: In the kittens, clinical signs included lordosis, dysmetria, ataxia of the hind-limbs and fading coat colour; histopathological lesions included Wallerian-type degeneration in the spinal cord, pons and medulla, and neuronal degeneration in the vestibular nuclei and ventral horns of the spinal cord. Analysis of colony data ruled out an inherited disease, and there was no evidence of dietary inadequacy or excess. Similar, though milder, clinical and histopathological changes were noted in the affected adults. CONCLUSIONS: Circumstantial evidence is consistent with a diagnosis of zinc-induced copper deficiency caused by the ingestion of zinc oxide from the galvanised iron bar doors. CLINICAL RELEVANCE: Because of the possibility of zinc-induced copper deficiency, galvanised iron should be avoided when designing and constructing cages for cats in veterinary clinics, pet shops and boarding facilities.     

Gastrocutaneous fistula as a result of migration of a foreign body in a dog

A six-year-old, female Tibetan terrier was referred for investigation of a non-healing wound on the left caudal thorax. A subcutaneous swelling had initially developed on the chest wall, followed by a draining tract from which seropurulent fluid drained for two months. There had been no response to antibiotic treatment. Following radiographic and ultrasonographic examinations, a bone sequestrum from a fractured rib or a foreign body was suspected. Surgical exploration of the wound identified a sinus tract and a wooden foreign body (an ice-lolly stick) was located in subcutaneous tissues. Partial wound dehiscence of the surgical site occurred postoperatively, but healed after 10 days. One month later, fluid began to discharge from the area again. Further surgical exploration confirmed a gastrocutaneous fistula. Dissection of the fistula and surgical closure of the stomach, body wall and skin led to resolution of all signs.