Survey of equine castration techniques,preferences and outcomes among Australian veterinarians

Objectives

(1) To collect the perceptions of veterinarians performing equine castrations in Australia on techniques, preferences and outcomes, (2) to investigate veterinarian use and experience with the Henderson castrating instrument and (3) to investigate potential associations between demographics, castration methods and techniques, and complications.

Design

Online survey of members of the Australian Veterinary Association’s Special Interest Group, Equine Veterinarians Australia (EVA).

Methods

A link to the survey was included in the EVA e‐newsletter and practices on the EVA website were contacted by telephone and follow‐up email. Fisher’s exact test was used to determine associations between ligation and complications. A generalised linear model with a negative binomial family was used to determine associations between count response variables and categorical independent variables.

Results

Responses were obtained from 138 veterinarians (response rate, 13.1%) who performed 5330 castrations over 12 months. Castrations were most commonly performed in the field, on anaesthetised horses, using emasculators, via an open approach and without ligation of the spermatic cord. Estimated complications after use of emasculators were swelling (25%), haemorrhage (5%) and infection (5%). The Henderson instrument was used by approximately 10% of respondents and its use for castration was associated with fewer reports of postoperative swelling compared with emasculators (P = 0.002). Rates of evisceration with the Henderson and emasculator methods were comparable (0.43% and 0.9%, respectively).

Conclusion

Castration preferences varied widely among survey participants. Reported complication types and rates were comparable to those reported previously in other countries. Perceptions that the Henderson instrument was associated with less swelling should be investigated further via a prospective controlled investigation.     

The effect of low protein feeding and realimentation on skeletal growth and proportions in two strains of male turkey

Two experiments were conducted to study the effect of feeding a low protein diet in early life and subsequent realimentation on skeletal growth and proportions in turkeys. In the first experiment male poults of a “small” strain were fed isocaloric diets containing either 27.0% followed by 25.0% or 19.8% followed by 16.6% crude protein from o to 6 and 6 to 11 weeks of age respectively. At 11 weeks of age regressions of length of lower‐leg and mid‐wing on body weight for the two treatments indicated that normal skeletal proportions were not disturbed by the 11‐week period of moderate undernutrition. Percentage depressions in length of lower‐leg and mid‐wing, due to undernutrition, were 5.3 and 2.5% respectively. These were of a similar order of magnitude as the corresponding depression in the one‐third power of body weight, 3.4%, rather than that of simple body weight, 9.9%. Nutrition did not materially affect individual variation in body weight at n weeks of age, but coefficients of variation for lengths of lower‐leg and mid‐wing tended to be greater for undernourished than for fully‐fed turkeys.

In the second experiment male poults of the same small strain and of a faster‐growing larger strain were fed isocaloric diets containing 26.2 or 16.8% crude protein from 0 to 5 weeks of age. Thereafter all groups were fed the same adequate diets until 21 weeks of age. At 5 weeks of age growth depressions in live‐weight and linear measurements, due to undernutrition, were relatively greater in the faster‐growing strain. In the slower‐growing strain, mid‐wing length of retarded turkeys was appropriate to their body weight at the time; length of lower‐leg was only slightly shorter compared with fully‐fed poults when they were at the same live‐weight. However, skeletal proportions were apparently reduced by undernutrition in the faster‐growing strain. In this experiment low‐protein feeding had no adverse effect on individual variation of body weight or linear measurements in the smaller strain. But the 5‐week period of undernutrition tended to increase variability of live‐weight and bone length in the faster‐growing strain. Neither strain exhibited compensatory gains in live‐weight during the recovery period. This was probably due to an outbreak of sinusitis at about 12 weeks of age. However, this did not prevent recovery of normal bone length, which was completed by about 10 weeks of age in the smaller strain but not until each bone was approaching its mature length in the faster‐growing strain.     

Protein requirements for early finishing of male and female Turkeys

Five diets each calculated to contain about 3.0 kcal ME/g, with determined crude protein levels of 17.5, 19.8, 21.7, 23.2 and 24.4% were fed to male and female turkeys from 8 to 12 weeks of age. The 23.2 and 24.4% protein diets were estimated to contain about 115 and 125% respectively of the lysine and methionine allowances recommended for maximum growth at this stage. But for both sexes growth increments increased progressively as dietary protein increased up to the highest level fed, indicating that protein requirements for maximum growth were in this case considerably in excess of currently recommended levels.

There was no consistent effect of sex or diet on visual assessment of carcass finish or conformation at 12 weeks of age. “Skin‐pinch” thickness was significantly greater for females than for males. In the case of females there was a tendency for skin‐pinch thickness to decrease with increasing dietary protein level and body weight.     

Low-voltage organic transistors on plastic comprising high-dielectric constant gate insulators

The gate bias dependence of the field-effect mobility in pentacene-based insulated gate field-effect transistors (IGFETs) was interpreted on the basis of the interaction of charge carriers with localized trap levels in the band gap. This understanding was used to design and fabricate IGFETs with mobility of more than 0.3 square centimeter per volt per second and current modulation of 10(5), with the use of amorphous metal oxide gate insulators. These values were obtained at operating voltage ranges as low as 5 volts, which are much smaller than previously reported results. An all-room-temperature fabrication process sequence was used, which enabled the demonstration of high-performance organic IGFETs on transparent plastic substrates, at low operating voltages for organic devices.     

Use of tilmicosin in a severe outbreak of respiratory disease in weaned beef calves

Severe respiratory disease, associated with seroconversion to bovine respiratory syncitial virus (BRSV), caused the death of two cattle and necessitated antibiotic treatment of 70 calves (rectal temperature of 39.6°C or greater) from a group of 96 (73%) during an 8-day period. Tilmicosin injection resulted in a reduction in median rectal temperature from 40.3°C to 39.2°C and 39.0°C for the first and second days after treatment. The rectal temperature was 39.5°C or lower in 72% (48 of 67) and 96% (64 of 67) of cattle 1 and 2 days after tilmicosin treatment, respectively. Ten cattle were re-treated with tilmicosin 6 to 16 days after the first treatment. Our study demonstrated that bovine respiratory syncytial virus infection could cause severe respiratory disease in a beef herd that had no previous history of BRSV-related disease. Secondary bacterial invasion after BRSV infection was controlled effectively by tilmicosin treatment but repeat antibiotic treatments were occasionally necessary due to bacterial re-infection of the respiratory tract.     

Severity and persistence of footrot in Merino sheep experimentally infected with a protease thermostable strain of Dichelobacter nodosus at five sites

Objective To test the hypothesis that ovine footrot associated with a thermostable protease strain of Dichelobacter nodosus undergoes self cure or is sustained as an annually recurring disease, depending on the environment.
Design and procedure Forty Merino sheep from a single blood line were infected with a protease thermostable strain of D nodosus a t each of five sites in Western Australia. Footrot lesions and microscopic evidence of D nodosus were recorded every fortnight for 2.5 years, supplemented by laboratory culture. Rainfall, soil and air temperature, pasture quantity and composition and soil types were also recorded. Flocks that apparently self cured were relocated to a more favourable site for footrot in the final spring season.
Results The maximum prevalence of feet with clinical footrot lesions was 80.6, 1.3, 14.4, 3.8 and 88.1% at the five sites. Severe footrot occurred for three consecutive spring seasons at one site that had clay loam soil and at least 3500 kg/ha total pasture dry matter annually. However, the infection was asymptomatic for up to 10 weeks between outbreaks. D nodosus was isolated from flocks for 2.5 years at only two sites, although there was microscopic evidence of the organism at other sites in the final year. A thermolabile variant (strain U6) of D nodosus was isolated from the two sites where footrot persisted.
Conclusion Depending on time and location, ovine footrot induced by a protease thermostable strain of D nodosus either self cured or persisted as annual outbreaks interspersed with periods of asymptomatic infection.     

The effect of photoperiod on performance of female turkeys from two to 16 weeks of age

1. Female turkeys were subjected, from 2 to 16 weeks of age, to four lighting treatments, 23 h/d, 14 h/d, 8 h/d and a “step‐down” pattern in which light was reduced from 22 h/d by 1 h per week to 14 h/d.

2. Within each lighting treatment half the groups were offered food ad libitum and half received the same restricted amounts of food on all lighting treatments.

3. There were no significant differences in final body weight or food conversion efficiency (FCE) between photoperiod treatments. FCE was superior in restricted groups (P<0.05).     

Diets for laying hens containing unusual ingredients and varying concentrations of cereals including no cereals

1. Light‐ and medium‐hybrid laying hens received one of six diets (A, B, C, D, E and F) containing decreasing amounts (758, 560, 374, 270, 185 and 0 g/kg) of cereals and increasing amounts of unusual ingredients, from 22 weeks of age.

2. The diet containing no cereal and 225 g dried poultry manure/kg (diet F) caused a severe reduction in performance and was discontinued at 27 weeks of age; the other treatments were continued until 48 weeks of age.

3. In the case of medium hybrids, rate of lay (number of eggs/100 hen d) was similar with diets A, B and C and about 2 percentage points lower with diets D and E; egg output (g per hen d) tended to decrease slightly as dietary cereal concentration decreased.

4. In the case of light hybrids, rate of lay was about 5 percentage points lower with diets B, C and D and about 13 percentage points lower with diet E than with diet A.

5. Mortality was similar on each diet.

6. The effect of diet on live‐weight gain was inconsistent and statistically not significant.     

The effect of photoperiod on performance of male Turkeys from 2 to 15 weeks of age

1. Two‐week‐old male turkeys were subjected, for 13 weeks, to four lighting treatments, 23 h/d, 14 h/d, 8 h/d, and a “step‐down” pattern in which light was reduced from 22 h/d by 1 h a week to 14 h/d.

2. Within each lighting treatment half the groups were offered food ad libitum and half received restricted amounts of food which were similar for all lighting treatments.

3. There were no statistically significant differences in final body weights or food conversion ratios between photoperiod treatments, although within groups fed ad libitum food conversion ratio was slightly superior for turkeys which had received 23 h light/d throughout.