Skeletal deformities associated with nutritional congenital rickets in newborn lambs

Abstract

CASE HISTORY: A group of 545 pregnant rising 2-year-old Coopdale ewes on a Southland sheep farm were grazed over winter on a fodder beet (Beta vulgaris) crop. Subsequently, 45 out of approximately 750 lambs were born with a variety of skeletal deformities, including shortened limbs, varus and valgus angular limb deformities, palmar grade stance and cranial bowing of the carpus. Analysis of the crop showed the fodder beet contained a low percentage of phosphorus. In addition, 60 out of 460 rising 2-year-old ewes that had been grazed on the fodder beet crop as 1-year-olds had incisor abnormalities and malocclusion.

PATHOLOGICAL FINDINGS: Two affected lambs (1-day-old and 3-days-old) with representative clinical signs examined postmortem were found to have markedly enlarged costochondral junctions, and noticeably enlarged long bone metaphyses. In addition, one lamb had a dense band of metaphyseal sclerosis beneath the physes of all long bones examined. Histopathological findings included small islands and columns of chondrocytes and eosinophilic cartilage matrix present in the metaphysis. Metaphyseal trabeculae were disorganised and often lined by accumulations of pale pink osteoid; similar pale pink osteoid was also present in the cortices. Unerupted molar teeth in the affected lambs lacked a layer of enamel, and the dentine was irregular with globular basophilia.

DIAGNOSIS: The gross and histopathological lesions were consistent with a diagnosis of rickets.

CLINICAL RELEVANCE: Nutritional congenital rickets has not been previously diagnosed in sheep, but is a recognised disease of human infants with vitamin D deficient mothers. The rickets in affected lambs was most likely associated with phosphorus deficiency as a result of the pregnant ewes grazing fodder beet during gestation. While vitamin D deficiency was not definitively ruled out in these cases, practitioners are alerted to the possible effects of feeding phosphorus-deficient fodder beet to ewes for long periods during gestation and to 1-year-old sheep during important growth periods.     

Dystocia in beef heifers: A review of genetic and nutritional influences

Breeding beef heifers for the first time at 15 months of age has potential to increase the efficiency of the beef breeding-cow herd. An increased incidence of dystocia in heifers calving at 2 years of age, compared to mature cows, is a major reason many farmers in New Zealand have not adopted the practice. The predominant type of dystocia affecting 2-year-old heifers is feto-maternal disproportion, a condition in which the fetus is too large relative to the size of the heifer's pelvis. Reducing birthweight of the calf is a means of reducing the incidence of dystocia. Birthweight and length of gestation are determined by genotype of the calf, maternal genetic effects and environmental effects.

Bulls with low estimated breeding values for birthweight have been selected for mating heifers; however, the positive genetic correlation between birthweight and mature weight meant that the progeny of these bulls tended to be lighter at finishing, making them less desirable in the beef industry. The genotype of the dam also plays a role in determining the risk of dystocia; the maternal ability of the dam to nurture the fetus influences birth- weight, and the dam's genetic potential for growth influences the size of her pelvic area. Heavy heifers tend to produce high- birthweight calves, counteracting the reduction in the incidence of dystocia resulting from the larger pelvis in larger heifers.

Manipulating feeding level during pregnancy offers an alternative method for manipulating the birthweight of calves. Little is known about the effects of nutrition in early gestation on placental development or birthweight of calves. No differences in the birthweight of calves have been observed in response to variation in feeding in mid-pregnancy, and variable responses in birthweight and the incidence of dystocia to feeding in the third trimester of pregnancy have been reported. Differences in birthweight have not always resulted in differences in the incidence of dystocia, primarily due to differences in liveweight of the heifer also induced by feeding regimens. Variability in the incidence of dystocia in response to feeding level in the third trimester of pregnancy makes it difficult to make recommendations for the feeding of heifers at this stage of gestation. More research is needed into the effects of nutrition in early gestation on fetal and placental development in cattle.     

Age-related changes to the molecular and cellular components of equine flexor tendons.

Specific tendons show a high incidence of partial central core rupture which is preceded by degeneration. In the performance horse, the superficial digital flexor tendon (SDFT) is most often affected. We have described previously the molecular changes that are associated with degeneration in the central core region of the equine SDFT. The pathophysiological mechanism leading to change in synthetic activity of central zone cells in degenerated tendons is not known. In this study, we test the hypothesis that ageing results in matrix composition changes within the central zone of the SDFT. Extracellular matrix composition and cellularity were analysed in equine SDFTs collected from Thoroughbred horses and compared with a flexor tendon which rarely shows degenerative change and subsequent injury (deep digital flexor tendon, DDFT). Data were examined for age-related changes to central and peripheral zone tissue of the SDFT and DDFT. Ageing in both tendons (SDFT and DDFT) resulted in a significant increase in collagen-linked fluorescence and a decrease in cellularity in the DDFT but not the SDFT. The central zone tissue from the SDFT had a significantly higher proportion of type III collagen than the peripheral zone of the tendon. The highest level of type III collagen was found in the central zone tissue of the SDFT from the older group of horses and this may represent the early stages of a degenerative change. Collagen content did not differ between the 2 flexor tendons; however, there were differences in collagen type and organisation. The SDFT had a higher type III collagen content, higher levels of the mature trifunctional collagen crosslink hydroxylysylpyridinoline, lower total chondroitin sulphate equivalent glycosaminoglycan content, smaller diameter collagen fibrils and a higher cellularity than the DDFT. In conclusion, differences in macromolecular composition exist between the flexor tendons and ageing contributes to a tendon specific change in composition.     

Nutrient changes in potting mix and Eucalyptus nitens leaf tissue under macadamia biochar amendments

The effect of macadamia nut shell biochar on nitrogen,potassium,phosphorus,magnesium,calcium and sodium concentrations in potting mix used to grow Eucalyptus nitens seedlings was investigated in a glasshouse experiment.The treatments combined two fertiliser rates(50 and 100% rate of the commercial mix commonly used in forestry nurseries) with eight biochar rates(0,2,5,10,20,50,80 and 100 t ha~(-1)) arranged in a randomised complete block with three replicates of four sample plants.Nutrients were quantified in the potting mix and seedling leaves at four destructive harvests 135,177,219 and269 days after planting.Biochar significantly increased nitrate-N,Colwell P,Colwell K and exchangeable Na andreduced ammonium-N,Mg and Ca concentrations in the potting mix.Seedling leaf concentrations of P,K and Na were increased by biochar application,while N remained dependent on fertiliser rate only.Mg and Ca leaf concentrations decreased in response to increasing biochar rates.Elevated nitrate-N and decreased ammonium-N concentrations suggest that biochar might have increased nitrification in the potting mix.We presumed that biochar mediated processes that reduced uptake of P and K when high doses of biochar were combined with full fertilisation.Changes in potting mix K,Na,Mg and Ca were consistent with selective adsorption of ions to biochar surfaces.     

Investigation of threatened arable weeds and their conservation status in Turkey

Agronomic operations carried out in arable lands may cause changes in weed populations and also decrease the number of animal species that depend on these weed species. An emerging paradigm is the conservation and sustainability of weed species. In this study, risk status of arable weeds in Turkey was evaluated and it was determined that 112 of them (76 endemic and 36 non-endemic species) were at risk according to the IUCN Red List. Turkey is extremely diverse, with over 3000 endemic plant species out of nearly 12 000 recorded. Considering endemic weeds, they are classified in the following risk categories: critically endangered (four weed species), endangered (EN) (six), vulnerable (VU) (14), near threatened (seven), least concern (41) and data deficient (DD) (four species). Among the non-endemic weeds, three species are EN, 31 VU and two are DD. The families with the highest threatened weed species are Scrophulariaceae, Fabaceae, Asteraceae, Brassicaceae and Lamiaceae. The identification of weed species in arable habitats and their risk status is a useful tool for assessing and monitoring how the sustainability of weed populations is affected by farming practices. The results show the necessity of adopting new environment-friendly agricultural methods to conserve the high number of endemic weed species under threat in Turkey.     

Impact of vitronectin concentration and surface properties on the stable propagation of human embryonic stem cells

The standard method for culturing human embryonic stem cells (hESC) uses supporting feeder layers of cells or an undefined substrate, Matrigel(?), which is a basement membrane extracted from murine sarcoma. For stem cell therapeutic applications, a superior alternative would be a defined, artificial surface that is based on immobilized human plasma vitronectin (VN), which is an adhesion-mediating protein. Therefore, VN adsorbed to diverse polymer surfaces was explored for the continuous propagation of hESC. Cells propagated on VN-coated tissue culture polystyrene (TCPS) are karyotypically normal after >10 passages of continuous culture, and are able to differentiate into embryoid bodies containing all three germ layers. Expansion rates and pluripotent marker expression verified that a minimal VN surface density threshold is required on TCPS. Further exploration of adsorbed VN was conducted on polymer substrates with different properties, ranging from hydrophilic to hydrophobic and including cationic and anionic polyelectrolyte coatings. Despite differing surface properties, these substrates adsorbed VN above the required surface density threshold and were capable of supporting hESC expansion for >10 passages. Correlating wettability of the VN-coated surfaces with the response of cultured hESC, higher cell expansion rates and OCT-4 expression levels were found for VN-coated TCPS, which exhibits a water contact angle close to 65°. Importantly, this simple, defined surface matches the performance of the benchmark Matrigel, which is a hydrogel with highly complex composition.