The immunology and genetics of resistance of sheep to Teladorsagia circumcincta

Teladorsagia circumcincta is one of the most economically important gastrointestinal nematode parasites of sheep in cool temperate regions, to which sheep show genetically-varying resistance to infection. This is a very common parasite and viable sheep production requires the extensive use of anthelmintic drugs. However, the emergence of drug-resistant parasites has stimulated the search for alternative control strategies to curb production losses. Lambs become infected soon after weaning and begin to control parasite burden within 8–10 weeks of continual infection. This control is an acquired characteristic mediated by the development of parasite-specific antibodies. This paper describes the immunology associated with resistance and susceptibility, focussing on differential T cell activation that regulates the production of specific effector mechanisms. It continues by summarizing the methods used to identify genes that could be exploited as molecular markers of selection for resistance. In particular it focusses on the link between understanding the molecular immunology of infection and the identification of candidate genes for selection.     

Aortic rupture and aorto‐pulmonary fistulation in the Friesian horse: Characterisation of the clinical and gross post mortem findings in 24 cases

Reasons for performing study: In horses, aortic sinus of Valsalva aneurysms or tears in the aortic root are well‐recognised conditions in breeding stallions, often leading to sudden death. A more uncommon form of aortic rupture, located proximal to the ligamentum arteriosum has been reported in 3 Friesian horses. Objectives: The purpose of this study was to phenotypically characterise aortic rupture and aorto‐pulmonary fistulation in Friesian horses in terms of clinical and post mortem data based on 24 cases. Methods: Friesian horses that were diagnosed with aortic rupture and aorto‐pulmonary fistulation over a period of 13 years (1997–2010) at the Department of Equine Sciences of Utrecht University (n = 15) and Wolvega Equine Hospital (n = 9), were included in this study. Case history, results of clinical examination and gross post mortem findings were screened and analysed. Results: Some cases were found dead without prior symptoms, but in several cases signs such as recurrent colic, peripheral oedema and sustained tachycardia were present for several weeks prior to cardiac failure. Clinical examination during hospitalisation revealed increased rectal temperature, peripheral oedema and increased jugular pulse with a bounding arterial pulse. In the majority of horses an aortic rupture of the aortic arch near the ligamentum arteriosum, concurrent with a circumferential cuff of perivascular haemorrhage and aorto‐pulmonary fistulation, was found at post mortem examination. Conclusions: Aorto‐pulmonary fistulation in conjunction with aortic rupture is more common in Friesians than previously estimated. In some cases findings demonstrate a progressive pathology rather than acute cardiac failure and sudden death. An appropriate approach is necessary during post mortem examination of the heart in order not to overlook the diagnosis. Potential relevance: Equine practitioners should realise that in Friesian horses presented with a history of recurrent false colic, coughing, sustained tachycardia and/or peripheral oedema, aortic rupture and aorto‐pulmonary fistulation should be included in the differential diagnosis.     

Two‐dimensional speckle tracking for quantification of left ventricular circumferential and radial wall motion in horses

Reasons for performing study: The use of two‐dimensional speckle tracking (2DST) for quantification of left ventricular (LV) function has recently been described in horses using long‐axis images and short‐axis images at chordal but not at papillary muscle level. Objectives: To compare the feasibility and reliability of 2DST for quantification of circumferential and radial LV function in short‐axis images at papillary muscle and chordal level. Methods: Repeated echocardiographic examinations were performed on 10 healthy trotter horses by 2 observers from a right parasternal short‐axis view at papillary muscle and chordal level. Segmental and averaged peak values and timing of circumferential and radial strain and strain rate, radial displacement and rotation were measured in 6 LV wall segments in each imaging plane. Global peak values were calculated for circumferential strain and strain rate. The inter‐ and intraobserver within‐ and between‐day variability was assessed by calculating coefficients of variation for repeated measurements. Results: 2DST analysis was feasible in each cardiac cycle, although tracking was often inadequate during early diastole. Measurements of averaged systolic circumferential and radial strain and strain rate and radial displacement as well as global circumferential strain and strain rate could be determined with low variability. Early and late diastolic strain rate and systolic rotation showed a moderate variability. Radial segmental measurements were more reliable than circumferential measurements. The interventricular septum showed a higher circumferential and lower radial strain compared with the LV free wall. Peak timing was earlier at papillary muscle compared with chordal level. Conclusions: 2DST measurements of global and regional circumferential and radial LV wall motion are feasible both at papillary muscle and chordal level. Potential relevance: Several measurements had good reliability and should be used for evaluation of the technique in a clinical setting.     

Fecal pH and Microbial Populations in Thoroughbred Horses During Transition from Pasture to Concentrate Feeding

Abrupt dietary transitions and feeding of rapidly fermentable diets are common practices in the horse industry and have been associated with digestive and metabolic disorders that can impair the performance of horses. The present study investigated the effect of dietary transition from pasture grazing to confinement with concentrate feeding, and back, on fecal pH and bacterial populations of Streptococcus spp and Lactobacillus spp. Six Thoroughbred fillies, previously grazing perennial ryegrass and white clover-based pasture, were housed in individual stalls and fed an increasing ratio of concentrate to conserved forages for 13 days (days 1-13), followed by an abrupt transition back to only pasture-grazing for 3 days (days 14-16). The concentrate was initially offered at 0.83 kg dry matter (DM)/d and increased to 5 kg DM/d, whereas ensiled alfalfa was initially offered at 0.61 kg DM/d, increasing to 1.22 kg DM/d. Meadow hay was initially offered at 6.73 kg DM/d, decreasing to 1.6 kg DM/d. Fecal specimens were collected daily for determination of pH, and every 2 days for quantitative analysis of Streptococcus spp and Lactobacillus spp. Mean fecal pH increased significantly from pasture baseline values (pH 6.18) during the initial confinement and supplementation on day 1 (6.37), day 2 (6.52), day 3 (6.58), and day 4 (6.43) (standard error of mean [SEM]: 0.056; P < .001). By day 5, mean fecal pH values had decreased to, and remained at, baseline values until the horses returned to pasture, when another increase occurred at day 15 (6.45). Fecal colony forming units (cfu) of Streptococcus spp and Lactobacillus spp increased linearly (r = 0.94; P < .001) from 6.0 and 6.1 log₁₀ cfu/g on day -4, to 7.8 log₁₀ cfu/g on day 14 (SEM: 0.2 P < .001), respectively. Fecal cfu decreased on return to a pasture-only diet (P < .001). In this study, the increment of bacterial populations was associated with a relatively stable fecal pH and highlights the difficulty in identifying the effects of dietary transition on the equine hindgut health, without microbial culture.     

Selection of Eucalypt Plus Trees with Regard to Splitting in the Sawn Timber / SELEKSIE VAN EUCALYPTUS-PLUSBOME MET BETREKKING TOT SPLITSING IN DIE GESAAGDE HOUT

A practical method in use in South Africa for quantifying the extent of splitting in the timber of the genus Eucalyptus in order to determine minimum standards for selection purposes, is explained. The standards are used to assist in the choice of phenotypes, the progeny of which it is hoped will produce timber which splits less.     

Treatment of Softwoods with CCA at High Moisture Levels

A literature study on the feasibility of treating wood with aqueous solutions at high moisture levels revealed a positive indication. The objective of the present study was to determine treatability of Pinus radiata and P. pinaster lumber at high moisture levels with commercial CCA in controlled experiments. The wood samples were treated at levels of moisture content ranging from 20 to 100%.

A statistical analysis of the data showed that specific gravity and moisture content influence solution-absorption, the effect being different for different species. Chemical analyses showed a screening out of copper- and arsenic compounds. The effect of higher moisture contents on screening out was negligible. The results indicated that certain wood species can be treated satisfactorily with CCA at moisture levels higher than 25%.     

Calculation of E-Moduli of Beams under Third- or Centre-Point Loading: Program for HP-25 Calculator

A method for precision sowing Eucalyptus seeds was needed at the Florida Division of Forestry's nursery. A way to do this is to coat cleaned seeds to form uniform pellets, which are easy to handle with mechanical equipment. The small volume of the seed lots to be pelleted in Florida restricted choice of commercial companies that could do the pelleting. Small volumes (50 to 125 ml) of Eucalyptus robusta Sm. seeds were successfully pelleted in-house with a coating of fine silica sand filler and two polyvinyl alcohol (P.V.A.) binders, and by two commercial companies—Germain's, Inc. and Hilleshog Seed Co., Ltd. Nursery performance of sand-P.V.A. and Hilleshog pellets was similar to that of uncoated seeds, although germination speed was slowed. The binder Gelvatol®,¹ a coldwater soluble P.V.A., had advantages over Elvanol®, a cold-water insoluble binder. Plant yield of Germain's Filcoat® pellets was appreciably less than that of uncoated seeds, but the toughness of the Filcoat® pellets might be an advantage in some sowing situations. The Florida Division of Forestry routinely pellets seeds of several Eucalyptus species in a reciprocating-rotating pan using fine sand and Gelvatol®.