Scielo RSS <![CDATA[Onderstepoort Journal of Veterinary Research]]> vol. 82 num. 1 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Relationship between haemoglobin concentration and packed cell volume in cattle blood samples</b>]]> A convention that has been adopted in medicine is to estimate haemoglobin (HB) concentration as a third of packed cell volume (PCV) or vice versa. The present research set out to determine whether a proportional relationship exists between PCV and Hb concentration in cattle blood samples, and to assess the validity of the convention of estimating Hb concentration as a third of PCV. A total of 440 cattle in Ghana from four breeds (Ndama, 110; West African Short Horn, 110; Zebu, 110 and Sanga, 110) were bled for haematological analysis, specifically packed cell volume, using the microhaematocrit technique and haemoglobin concentration using the cyanmethaemoglobin method. Means, standard deviations, standard errors of mean and 95% confidence intervals were calculated. Trendline analyses generated linear regression equations from scatterplots. For all the cattle, a significant and consistent relationship (r= 0.74) was found between Hb concentration and PCV (%). This was expressed as Hb concentration (g/dL) = 0.28 PCV + 3.11. When the Hb concentration was estimated by calculating it as a third of PCV, the relationship was expressed in linear regression as Hb concentration (g/dL) = 0.83 calculated Hb + 3.11. The difference in the means of determined (12.2 g/dL) and calculated (10.9 g/dL) Hb concentrations for all cattle was significant (p < 0.001), whereas the difference in the means of determined Hb and corrected calculated Hb was not significant. In conclusion, a simplified relationship of Hb (g/dL) = (0.3 PCV) + 3 may provide a better estimate of Hb concentration from the PCV of cattle. <![CDATA[<b>Functional anatomy of the lacrimal gland in African black ostrich <i>Struthio camelus domesticus </i>in the embryonic and postnatal period</b>]]> The aim of the present study was morphological and histochemical analysis of the lacrimal gland (LG) in African black ostrich Struthio camelus domesticus in the embryonic and postnatal period. Studies were conducted on 50 ostriches aged between the 28th day of incubation until 7 months old. Tissue sections were stained with haematoxylin and eosin, Azan trichrome, periodic acid-Schiff, Alcian blue pH 2.5, aldehyde fuchsin and Hale's dialysed iron. The LG in ostrich was classified as a tubulo-acinar type. The primordia of the lobes were determined in the LG structure on the 28th day of incubation, whilst the weakly visible lobes with acini and tubules were observed on the 40th day of incubation. Morphometric studies of the LG showed steady growth, characterised by an increase in both length and width. Histometric measurements of lobe size showed little difference between the first, second and third age groups, whilst in the fourth age group a marked increase in size of lobes was observed. The study showed that, apart from morphological changes, during the growth of the LG the character of acid mucopolysaccharides changed. Sulphated acid mucopolysaccharides were indicated, particularly with aldehyde fuchsin (AF) staining in the fourth age group. The Hale's dialysed iron (HDI) staining showed a low concentration of carboxylated acid mucopolysaccharides in the first and second age groups and a higher concentration in the third and fourth age groups. Periodic acid-Schiff staining (PAS)-positive cells were observed in each age group, but only a small number of cells with a weakly PAS-positive reaction were demonstrated in the first age group. <![CDATA[<b>Virulence gene profiles of avian pathogenic <i>Escherichia coli </i>isolated from chickens with colibacillosis in Bulawayo, Zimbabwe</b>]]> Colibacillosis, a disease caused by avian pathogenic Escherichia coli (APEC), is one of the main causes of economic losses in the poultry industry worldwide. This study was carried out in order to determine the APEC-associated virulence genes contained by E. coli isolates causing colibacillosis in chickens. A total of 45 E. coli isolates were obtained from the diagnostics and research branch of the Central Veterinary Laboratories, Bulawayo, Zimbabwe. These isolates were obtained from chickens with confirmed cases of colibacillosis after postmortem examination. The presence of the iutA, hlyF, ompT, frz, sitD, fimH, kpsM, sitA, sopB, uvrY, pstB and vat genes were investigated by multiplex polymerase chain reaction (PCR) assay. Of the 45 isolates, 93% were positive for the presence of at least one virulence gene. The three most prevalent virulence genes were iutA (80%), fimH (33.3%) and hlyF (24.4%). The kpsM, pstB and ompT genes had the lowest prevalence, having been detected in only 2.2% of the isolates. All 12 virulence genes studied were detected in the 45 APEC isolates. Virulence gene profiles were constructed for each APEC isolate from the multiplex data. The APEC isolates were profiled as 62.2% fitting profile A, 31.1% profile B and 6.7% profile C. None of the isolates had more than seven virulence genes. Virulence profiles of Zimbabwean APEC isolates are different from those previously reported. Zimbabwean APEC isolates appear to be less pathogenic and may rely on environmental factors and stress in hosts to establish infection.