Detection of twelve mycotoxins in mixed animal feedstuffs, using a novel membrane cleanup procedure.

A multimycotoxin thin layer chromatographic screening method is described which is applicable to most animal feedstuffs. Interference from nonspecific lipid, pigment, and other components of simple and mixed feeds is reduced to a minimum by using a membrane cleanup step. Aflatoxins B1, B2, G1, and G2, citrinin, diacetoxyscirpenol, ochratoxin A, patulin, penitrem A, sterigmatocystin, T-2 toxin, and zearalenone may be reliably detected. The sensitivity of the method is generally low for mixed feeds but even so aflatoxin B1 can be detected at a level of 3 ppb and ochratoxin A at 80 ppb. While the basic method is less sensitive for sterigmatocystin (330 ppb), patulin (600 ppb), zearalenone (1000 ppb), and the trichothecenes (1000-4000 ppb), it may be adapted so as to reduce the above detection limits when the presence of these toxins is suspected. Lower levels may be detected in extracts of simple feeds.     

THE EFFECT OF DEFOLIATION ON THE SEED-PRODUCING CAPACITY OF BRED VARIETIES OF GRASSES

Leafy grass varieties S24 perennial ryegrass, S26 cocksfoot, S215 meadow fescue and S51 timothy were cut in October and at various growth stages in spring; S53 meadow fescue was grazed at similar periods. Sub-plots were given different applications of N. The control plots had similar manurial treatments but were not defoliated. The seed yield of S24 following October cutting was significantly lower than the control in the first harvest year and significantly higher in the second; the mean yields over 2 years, as a result of cutting at this stage and before ear formation in March, were very similar to those of the control treatment. The mean yields from 3 harvest years for S26, S215 and S51 were generally improved by cutting in October and before ear formation, but cutting after ear formation reduced the number of heads and the seed yields. Extra N applied in conjunction with the defoliation had no significant effect on the number of seed heads or on seed yield. Double grazing of S53 in Sept. and Dec. reduced significantly its seed production in both harvest years. Application of N in spring gave a greater response than a similar application in autumn.     

Evaluation of non-chemical seed treatment methods for the control of Alternaria dauci and A. radicina on carrot seeds

The current study was initiated to evaluate the efficacy of physical methods (hot water, aerated steam, electron treatment) and agents of natural origin (resistance inducers, plant derived products, micro-organisms) as seed treatments of carrots for control of Alternaria dauci and A. radicina. Control of both Alternaria species by seed treatment with the resistance inducers was generally poor. Results were also not satisfactory with most of the formulated commercial micro-organism preparations. Based on the average of five field trials, one of these, BA 2552 (Pseudomonas chlororaphis), provided a low but significant increase in plant stand. Among the experimental micro-organisms, the best results were obtained with Pseudomonas sp. strain MF 416 and Clonostachys rosea strain IK726. A similar level of efficacy was provided by seed treatment with an emulsion (1%) of thyme oil in water. Good and consistent control was generally achieved with the physical methods aerated steam, hot water and electron treatment. Aerated steam treatment was, apart from the thiram-containing chemical standard, the best single treatment, and its performance may at least partially be due to extensive pre-testing, resulting in dosages optimally adapted to the respective seed lot. In some of the experiments the effect of the hot water treatment, which was tested at a fixed, not specifically adapted dosage, was significantly improved when combined with a Pseudomonas sp. MF 416 or C. rosea IK726 treatment. The results are discussed in relation to the outcome of experiments in which the same seed treatment methods and agents were tested in other seed-borne vegetable pathosystems.     

Expression of receptor tyrosine kinases VEGFR-1 (FLT-1), VEGFR-2 (KDR), EGFR-1, PDGFRa and c-Met in canine primary brain tumours

Inhibition of tumour growth and angiogenesis by targeting key growth factor receptors is a promising therapeutic strategy for central nervous system tumours. Characterization of these growth factor receptors in canine primary brain tumours has not been done. Using quantitative real‐time TaqMan polymerase chain reaction (PCR), we evaluated the expression of messenger RNA (mRNA) for five tyrosine kinase growth factor receptors (vascular endothelial growth factor receptor [VEGFR]‐1, VEGFR‐2, endothelial growth factor receptor [EGFR]‐1, platelet‐derived growth factor receptor a [PDGFRa], and c‐Met) relative to normal cerebral cortex in 66 spontaneous canine primary brain tumours. Increased expression of VEGFR‐1 and VEGFR‐2 mRNA was greatest in grade IV astrocytomas (glioblastoma multiforme) and grade III (anaplastic) oligodendrogliomas. EGFR‐1 mRNA expression was more consistently increased than the other receptors in all tumour types, while increased PDGFRa mRNA expression was mostly restricted to oligodendrogliomas. The similarities in increased expression of these tyrosine kinase growth factor receptors in these canine tumours, as compared to data from their human counterparts, suggest that common molecular mechanisms may be present.     

Selection for breed-specific long-bodied phenotypes is associated with increased expression of canine hip dysplasia

Hip dysplasia (HD) is the most common skeletal disease in purebred dogs. Radiographic schemes developed to reduce prevalence through selective breeding have had limited success, but the role of selecting for morphological characteristics prized in the show-ring and dictated by breed standards has not been fully explored. This study correlated published scores of hip pathology with measurements of body length to height ratio from photographs of Best-of-Breed specimens from 30 breeds (n = 12/breed) to establish whether selection criteria could be compromising welfare by increasing susceptibility to HD.Relative body length correlated strongly with higher rates of HD by breed data from the Orthopedic Foundation for Animals (Spearman r = 0.727, P < 0.001), the British Veterinary Association (r = 0.701, P < 0.001), and the Australian Veterinary Association (r = 0.577, P < 0.01). By favouring body shapes that are longer than they are tall, judges may be inadvertently selecting for conformational attributes predisposing dogs to HD, suggesting that ambiguity in breed standards and extreme relative body length phenotypes can engender serious welfare consequences and need to be re-evaluated.     

Farmers' Attitudes to the Benefits and Barriers of Adopting Automation for Surface Irrigation on Dairy Farms in Australia

The study reports farmers' attitudes andperceptions towards the ``barriers' and ``benefits' of automaticirrigation systems. Factor analysis was used to identify perceived ``barriers' and ``benefits' andthe impact of these on farmers' priority to adopt automation wasexamined. Results suggest that farmers'attitudes, particularly with respect to ``cost' and``lifestyle' influenced the priority given to adopting automaticirrigation systems. The area under pasturecultivation was also an importantdeterminant in the farmers' priority foradopting automatic irrigation systems.     

Application of sperm cryopreservation in selective breeding of the Pacific oyster,Crassostrea gigas (Thunberg)

The robustness of Pacific oyster, Crassostrea gigas (Thunberg), sperm cryopreservation in the context of selective breeding based on family lines was investigated. Irrespective of egg density, high fertilization success was achieved with cryopreserved sperm when sperm:egg ratios of 1000:1 to 10 000:1 were used. Variation among replicate runs on the same oyster batches was minimal, indicating that cryopreservation and larval rearing procedures were repeatable. Twenty independent single male–female crosses were made to assess the utility of cryopreserved sperm in selective breeding. The fertility of unfrozen sperm was generally a poor predictor of cryopreserved sperm fertility. Based on D‐larval yields, 17 of the 20 crosses were likely to yield adequate spat for selective breeding (>10⁵ D‐larvae from 1 million eggs), two were marginal (5 × 10⁴ D‐larvae) and one was inadequate (4 × 10³ D‐larvae). An alternative fertilization strategy to improve D‐yield from a given number of sperm was then tested. Fertilizing 10 million eggs at a sperm:egg ratio of 200:1 increased the total D‐yield when compared with fertilizing 1 million eggs at a sperm:egg ratio of 2000:1 for the same male–female pair. We conclude that, despite wide variation in fertility, cryopreserved sperm is useful for family production.