Dietary protein for young grazing sheep: Interactions with gastrointestinal parasitism

Effects of protein supplementation and of nematode control on production responses in young grazing sheep and on nematode population dynamics were assessed. Young Merino wether sheep (n = 270) were allocated to one of three supplementation (Su) treatments and one of three regimes of nematode control (drench, Dr) in a factorial design. Each of the nine treatments was replicated three times in a randomised complete block. Animals received no supplement (SuO) or were given supplements at a level equivalent to 200 g day⁻¹, fed three times a week. The supplements contained 25% lucerne meal with either 75% sunflower meal (Su1) or 75% formaldehyde-treated sunflower meal (Su2). Nematode control regimes were: not drenched unless survival of individual animals was threatened (DrO); drenched according to a strategic drenching programme (Dr1); treatment with a controlled-release albendazole capsule (Dr2). Infections with Haemonchus contortus were suppressed by use of closantel. Due to drought conditions and lack of pasture growth, lucerne hay was fed to all sheep from Week 14 onwards (350 g per head per day, fed twice a week). Supplementation reduced the need for ‘survival drenching’ in Dr0 sheep considerably. Live-weight gain was increased significantly by supplementation with Su1 or Su2 during the 36-week experiment. Undrenched animals given Su1 or Su2 tended to grow faster than unsupplemented animals in the Dr1 and Dr2 groups. Greasy wool production and fibre diameter were increased by supplementation and anthelmintic treatment. Faecal worm egg counts (FEC) in undrenched sheep were significantly lower for Su1 and Su2 sheep than for Su0 sheep. There were no effects of supplementation on FEC in Dr1 or Dr2 sheep. Worm burden was generally unaffected by supplementation, while the drenching treatments Dr1 and Dr2 reduced worm burden at Week 16 and to a lesser extent at Week 27. Trichostrongylus colubriformis was the predominant nematode species, with smaller numbers of Nematodirus spp., Trichostrongylus vitrinus, Trichostrongylus axei and Ostertagia circumcincta also present. It was concluded that supplementary feeding with protein meal substantially reduced production losses attributable to nematode infections in young grazing sheep. This appears to be due to an enhanced resilience of the host, rather than any major changes in development of protective immunity.     

Modelling Plant Disease Epidemics

An epidemic is the progress of disease in time and space. Each epidemic has a structure whose temporal dynamics and spatial patterns are jointly determined by the pathosystem characteristics and environmental conditions. One of the important objectives in epidemiology is to understand such spatio-temporal dynamics via mathematical and statistical modelling. In this paper, we outline common methodologies that are used to quantify and model spatio-temporal dynamics of plant diseases, with emphasis on developing temporal forecast models and on quantifying spatial patterns. Several examples of epidemiological models in cereal crops are described, including one for Fusarium head blight.     

Laboratory and on‐farm evaluation of low‐cost salt mixtures for use during salinity acclimation and the nursery phase of Pacific white shrimp (Litopenaeus vannamei)

The current study evaluates the efficacy of a low‐cost salt mixture (LCSM) to replace expensive reconstituted sea salt (RSS) in the salinity acclimation and nursery phase of Pacific white shrimp under laboratory and farm conditions. LCSM was formulated to yield sodium, potassium, calcium and magnesium concentrations closely comparable to that of diluted seawater. Laboratory‐based nursery trials were conducted at 2, 6 and 15 g/L salinities, incrementally replacing RSS with LCSM (25%, 50%, 75% and 100%) at four replicates per treatment. Thirty postlarvae were reared for 7 days in 24‐L aquaria during the 2 and 6 g/L trials, while the nursery trial for 15 g/L salinity was conducted for 21 days with 400 postlarvae stocked in 150‐L tanks. On‐farm evaluation of LCSM was carried out in two tank‐based systems installed on levees adjacent to shrimp production ponds. RSS was incrementally replaced with LCSM (0%, 50%, 75% and 100%) and 100 postlarvae stocked into each 800‐L tank. Salinity acclimation was done from 30 g/L to 6 or 1.5 g/L within 2–3 days by pumping water from adjacent shrimp production ponds. Following salinity acclimation, the S4 system maintained flow‐through at 1.5 g/L, while N10 system was maintained static at 6 g/L salinity. At the conclusion, no significant differences were observed for either survival or growth of shrimp postlarvae between RSS and LCSM treatments at all salinities examined. Results reflect the potential use of LCSM to replace RSS, which could be an excellent solution to bring down the cost of production in inland shrimp aquaculture.     

Mesoscale eddies and survival of late stage Pacific sardine (Sardinops sagax) larvae

We examined the distribution of sardine larvae relative to environmental conditions with the purpose of identifying and characterizing habitat that encourages high larval growth and survival, based on the 1983–1998 surveys of the California Cooperative Oceanic Fisheries Investigations (CalCOFI). Long-term averages show that sardine 'survivors' (spatially aggregated larvae ≥ 18 days old) were most abundant offshore, whereas sardine egg density, chlorophyll biomass and zooplankton volume were greatest inshore. In contrast, mesoscale eddies, observed in remotely sensed sea surface temperature imagery, were found only in offshore regions. To further examine the link between eddies – which often result in locally elevated chlorophyll and zooplankton – and sardine survival, we compared the distribution of larvae and eddies survey by survey. Sardine survivors were most abundant offshore in only one-quarter of the research surveys, and when they were most abundant offshore they were associated with eddies. This indicates that the offshore eddy habitat produced exceptionally large numbers of survivors, as evidenced by the disproportionate effect on the long-term average.     

The effects of exogenous xylanase supplementation on the in vivo generation of xylooligosaccharides and monosaccharides in broilers fed a wheat-based diet

ABSTRACT

1. This study quantified xylanase-induced changes in soluble monosaccharides, xylooligosaccharides (XOS) and volatile fatty acid (VFA) contents of the different sections of the gastrointestinal tract (GIT) and whether these were related to altered bird performance.

2. An in vitro digestion of the wheat-based diet was carried out with the xylanase (Econase XT at 16,000BXU/kg diet) to compare the in vitro and in vivo generation of these XOS and monosaccharides. For the in vivo study, 80 male Ross 508 b roiler chicks were split into two groups fed a wheat-based diet with or without Econase XT (16,000BXU/kg diet) for 21 days.

3. There were no effects of Econase XT inclusion on growth performance characteristics, likely a result of the high-quality wheat diet, the corresponding high performance of the control group (FCR average of 1.45 in controls) and the relatively young age of the birds (from four to 26 days of age).

4. Econase XT supplementation increased the xylotetraose (X₄) content in the colon (P = 0.046, enzyme x GIT section interaction) and the xylose contents in the colon and caeca (P < 0.001, enzyme x GIT section interaction).

5. The trend for increased acetate production in the caeca of Econase XT treated birds (P = 0.062) suggested that the XOS generated were subsequently fermented in the caeca, potentially impacting upon the types of microbiota present.

6. The present study suggested that wheat arabinoxylan degradation was enhanced by xylanase supplementation, which may have increased the production of beneficial volatile fatty acids (VFA) in the caeca, and thereby potentially modulated the caecal microbiome, but without affecting bird performance at this early age.     

Ocular metastasis of a vaccine-associated fibrosarcoma in a cat

A 6‐year‐old, neutered male domestic shorthair cat was evaluated for a recurrent vaccine‐associated fibrosarcoma. The cat had three excisions of the tumour prior to presentation and was referred for radiation therapy. Ten months following treatment with radiation therapy, the cat was presented again for a cloudy appearance to the eye. An exenteration was performed, and biopsy revealed fibrosarcoma. At the same time, two discrete pulmonary nodules were identified on thoracic radiographs. Two doses of doxorubicin (20 mg/m²) and cyclophosphamide (100 mg/m²) were administered intravenously 3 weeks apart. Despite treatment, the pulmonary nodule doubled in size. This case represents the first antemortem report of ocular metastasis of a vaccine‐associated sarcoma and supports the highly aggressive nature of these tumours.     

The use of intrathecal analgesia and contrast radiography as preoperative diagnostic methods for digital flexor tendon sheath pathology

Reasons for performing study: The sensitivity of ultrasonography for the diagnosis of manica flexoria (MF) tears within the digital flexor tendon sheath (DFTS) is lower than for diagnosis of marginal tears of the deep digital flexor tendon (DDFT). Additional diagnostic tools would assist in appropriate decision making for either conservative or surgical management. Objectives: To evaluate the improvement in lameness of horses with MF or DDFT tears following intrathecal analgesia and to assess the sensitivity and specificity of contrast radiography for the diagnosis of these tears. Methods: The case records of horses presented to a referral clinic over a 7‐year period that underwent intrathecal diagnostic analgesia, or intrathecal analgesia and contrast radiography, of the DFTS with subsequent tenoscopy were examined. Results: Fifty‐three limbs had intrathecal diagnostic analgesia performed and 23 contrast tenograms were assessed in horses undergoing DFTS tenoscopy. Horses with DDFT tears were significantly more likely to respond positively to intrathecal diagnostic analgesia than those with MF tears (P = 0.02). Using contrast radiography, tears of the MF were predicted with an overall sensitivity of 96% and specificity of 80%; marginal tears of the DDFT were predicted with an overall sensitivity of 57% and specificity of 84%. Conclusions: The results of intrathecal analgesia of the DFTS in combination with contrast radiography have a high sensitivity for predicting MF tears. The sensitivity of contrast radiography for predicting tears of the DDFT is lower but the specificity remains high. Potential relevance: Contrast radiography performed at the same time as intrathecal analgesia provides useful information regarding the presence of MF tears and DDFT tears, which can assist in the decision of whether to manage the lameness conservatively or with tenoscopic evaluation.     

Genetic variability of two Italian indigenous chicken breeds inferred from microsatellite marker analysis

1. The objective of this study was to determine the genetic structure and variability of Bionda Piemontese and Bianca di Saluzzo (Piedmont, Northwest Italy) using an international set of microsatellite loci (AVIANDIV-FAO). Differences compared with commercial lines and other Italian breeds were verified to justify the implementation of conservation programmes.

2. Flock contribution to genetic variability was assessed following the approach implemented in the MolKin software. Comparison was performed using the fixation index and the Reynolds genetic distance. The most likely number of different populations was estimated using the clustering procedure implemented in STRUCTURE.

3. The molecular information suggests that management practices could have prevented random mating and produced inbreeding and heterogeneity across flocks. In this respect, Bionda and Bianca show substructuring and are more similar to British breeds than other continental European breeds.

4. Bionda and Bianca fit into the European breeds provided with the highest number of alleles and expected heterozygosity. There is a clear distinction between the Piedmont breeds and the other populations. The Piedmont poultry differ from both commercial lines and other Italian breeds and retain a high level of genetic variability.

5. As for other indigenous breeds, Bionda and Bianca could make an original contribution to the industry in the future. A collective planned approach to restoration is essential, because the flocks are managed with poor regulation. Enhancing connection between breeders with an efficient replacement interchange and mating plan is the right way of controlling inbreeding, preventing substructuring and increasing variability within the flocks.

     

Epidemiological survey of Phthorimaea operculella granulosis virus in Tunisia

In Tunisia, Phthorimaea operculella is an important pest in traditional, unrefrigerated potato stores. An integrated control approach including the use of biological control agents and specifically insect viruses is being developed. From this perspective, we carried out a screening and an evaluation of local Phthorimaea operculella granulosis virus naturally present in Tunisian pest populations. On the basis of symptomatology, P. operculella larvae were collected from different regions (North, Cap Bon, Sahel). Indirect ELISA using a serum raised against the purified Tunisian isolate of the virus was used to establish the geographical distribution of the virus. Comparison of the two approaches showed that symptomatology is not so virus-specific, as morphologically healthy insects were sometimes ELISA-positive. The serological technique therefore gives better detection of the virus.     

Effect of inoculum type and timing of application of Coniothyrium minitans on Sclerotinia sclerotiorum: influence on apothecial production

The effects of different inocula of the mycoparasite Coniothyrium minitans on carpogenic germination of sclerotia of Sclerotinia sclerotiorum at different times of year were assessed. A series of three glasshouse box bioassays was used to compare the effect of five spore-suspension inocula of C. minitans , including three different isolates (Conio, IVT1 and Contans), with a standard maizemeal–perlite inoculum. Apothecial production, as well as viability and C. minitans infection of S. sclerotiorum sclerotia buried in treated soil, were assessed. Maizemeal–perlite inoculum at 10⁷ CFU per cm³ soil reduced sclerotial germination and apothecial production in all three box bioassays, decreasing sclerotial recovery and viability in the second bioassay and increasing C. minitans infection of sclerotia in the first bioassay. Spore-suspension inocula applied at a lower concentration (10⁴ CFU per cm³ soil) were inconsistent in their effects on sclerotial germination in the three box bioassays. Temperature was an important factor influencing apothecial production. Sclerotial germination was delayed or inhibited when bioassays were made in the summer. High temperatures also inhibited infection of sclerotia by C. minitans . Coniothyrium minitans survived these high temperatures, however, and infected the sclerotia once the temperature decreased to a lower level. Inoculum level of C. minitans was an important factor in reducing apothecial production by sclerotia. The effects of temperature on both carpogenic germination of sclerotia and parasitism of sclerotia by C. minitans are discussed.