Some observations on the liver copper status of pigs in the northern part of New Zealand

The copper content of the livers from 347 pigs was analysed. Two hundred and three of these samples were from animals varying in age from full term foetus to five years, which were submitted to the laboratory (laboratory cases) for a variety of diagnostic tests. The remaining 144 liver samples were obtained from pigs slaughtered at an abattoir (abattoir survey) at 75-85 kg liveweight (approximately 20-30 weeks old). Liver copper levels of 12 mg/kg D.M. (Dry Matter) or less, a level consistent with copper deficiency, were found in 6.9% of the laboratory cases and in 9.0% of the abattoir survey pigs. Liver levels less than 20 mg/kg suggesting insufficient dietary copper to produce a growth-promoting effect, were found in 21.6% of the former and 36.1% of the latter pigs. A significantly greater frequency of illthrift and anaemia was found in the laboratory cases in which liver copper levels were less than 20 mg/kg compared with animals with higher levels. Liver copper levels less than 20 mg/kg were also more common in pigs derived from dairy farms or fed garbage than in animals from pig farms or fed on meal. All of 26 samples of commercial pig meal analysed contained sufficient copper to satisfy the daily essential copper requirements of pigs (greater than 5-6 mg/kg) but 14 of these (53.8%) contained less than 125 mg/kg levels of copper and were unlikely to produce a growth-promoting effect.     

The efficacy of a leptospirosis vaccine in preventing leptospiruria in pigs

A commercially manufactured leptospirosis vaccine containing serovars pomona and hardjo and licensed for use in cattle and sheep was investigated to determine if it would prevent leptospiruria in pigs exposed to serovar pomona. Twenty piglets were each vaccinated twice at an interval of three weeks. Twenty other piglets were unvaccinated and served as controls. Three weeks after the second dose of vaccine all animals were exposed for 64 to 89 days to a natural infection with pomona. During the investigation blood samples were examined serologically and urine samples were examined by dark ground microscopy and cultured for the presence of leptospirae. Attempts were made to culture leptospirae from kidneys at slaughter. Kidneys were also examined histologically for evidence of leptospira infection. One vaccinated animal developed a respiratory disease. It was treated with antibiotics and removed from the trial. Leptosphuria was demonstrated in six of the remaining 19 vaccinated pigs and leptospirae were found in nine of 578 (1.5%) urine samples examined from these animals during the period of exposure. In contrast leptospiruria occurred in 19 of 20 unvaccinated pigs and leptospirae were found in 253 of 642 (39.4%) urine samples examined from these animals. Histopathological lesions consistent with leptospirosis were found in kidneys examined from two of 16 vaccinates and 17 of 18 non-vaccinates. Antibodies to serovar pomona were detected in 12 of 19 vaccinated pigs examined three weeks after the second dose of vaccine and before exposure to infection, and in all of 18 unvaccinated pigs examined after exposure to infection. It was concluded that use of this vaccine in pigs resulted in a significant degree of protection against leptospiruria.     

Investigation of the effect of Equivac® HeV Hendra virus vaccination on Thoroughbred racing performance

Objective

To evaluate the effect of Equivac® HeV Hendra virus vaccine on Thoroughbred racing performance.

Design

Retrospective pre‐post intervention study.

Methods

Thoroughbreds with at least one start at one of six major south‐eastern Queensland race tracks between 1 July 2012 and 31 December 2016 and with starts in the 3‐month periods before and after Hendra virus vaccinations were identified. Piecewise linear mixed models compared the trends in ‘Timeform rating’ and ‘margin to winner’ before and after initial Hendra virus vaccination. Generalised linear mixed models similarly compared the odds of ‘winning’, ‘placing’ (1st–3rd) and ‘winning any prize money’. Timeform rating trends were also compared before and after the second and subsequent vaccinations.

Results

Analysis of data from 4208 race starts by 755 horses revealed no significant difference in performance in the 3 months before versus 3 months after initial Hendra vaccination for Timeform rating (P = 0.32), ‘Margin to winner’ (P = 0.45), prize money won (P = 0.25), wins (P = 0.64) or placings (P = 0.77). Further analysis for Timeform rating for 7844 race starts by 928 horses failed to identify any significant change in Timeform rating trends before versus after the second and subsequent vaccinations (P = 0.16) or any evidence of a cumulative effect for the number of vaccines received (P = 0.22).

Conclusion

No evidence of an effect of Hendra virus vaccination on racing performance was found. The findings allow owners, trainers, industry regulators and animal health authorities to make informed decisions about vaccination.     

Mineral resources, environmental issues, and land use

Contrary to predictions from the 1950s through the mid-1980s, persistent shortages of nonfuel minerals have not occurred, despite prodigious consumption, and world reserves have increased. Global availability of raw materials is relevant to policy decisions regarding mineral development and land use. Justification for environmental protection may exceed that for mining a specific ore body. Demand for environmental accountability is rising worldwide, and new technologies are enabling internalization of costs. Mineral-rich developing nations plagued by inefficient state-owned mining enterprises, high population growth rates, and environmental degradation could realize substantial benefit by reforming government policies to encourage foreign investment in resources and by appropriate allocation of mineral rents.     

Evaluation of action thresholds for chronic rice insect pests in the Philippines. I. Less frequently occurring pests and overall assessment

Action thresholds as decision tools for insecticide application were developed and tested against the major insect pests of rice at four sites in the Philippines over a 13-year period. Action threshold treatments were compared to the farmers' practice, prophylactic insecticide usage, and an untreated check. Yield loss data using the insecticide check method partitioned yield losses over three crop growth stages in the same test fields. Chronic pests that exceeded action thresholds in 79% of fields were whorl maggot Hydrellia philippina Ferino (Diptera: Ephydridae), defoliators Naranga aenescens Moore and Rivula atimeta (Swinhoe) (Lepidoptera: Noctuidae), leaffolders Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae), and stemborers Scirpophaga incertulas (Walker) and S. innotata (Walker) (Lepidoptera: Pyralidae). Minor chronic pests reached threshold levels in only one site each: rice bug Leptocorisa oratorius (F.) (Koronadal), whitebacked planthopper Sogatella furcifera (Horvath) (Zaragoza) and green leafhopper Nephotettix virescens (Distant) (Guimba); brown planthopper Nilaparvata lugens (Stål) did not exceed a threshold in any field. Stemborers were the most important pest group in terms of yield loss. Despite the insecticide check method underestimating losses, a mean crop loss of 0.62 t/ha was measured which showed ample scope for corrective action. But loss was evenly distributed across crop growth stages (0.15?–?0.24 t/ha) reducing the impact of insecticides. Action threshold treatments overall outyielded the untreated check, more so in the two sites with highest pest density. The benefit of thresholds was to reduce insecticide usage, as a cost saving. However all the practices showed poor economic returns including the farmers' practice. Farmers' practice employed low insecticide dosages and timing was not consistent with pest damage, but yields were often similar to threshold treatments. Farmers appear to use insecticide more for risk aversion than for profit. The best threshold characters when evaluated against resulting pest density and yield loss criteria showed accuracies >?90% correct decisions. Future work is needed to improve the insecticide response rather than monitoring tools. Thresholds need to be incorporated into improved crop management, which was often found suboptimal by farmers, to take advantage of the high levels of tolerance in modern high tillering cultivars. Crop husbandry practices which improve yield potential such as selection of longer maturing varieties and nitrogen fertilizer may be a more effective pest management strategy than insecticides.