Gossypol toxicity in preruminant calves

SUMMARY Twenty-four of 57 calves fed a diet containing 33% cotton seed meal (CSM) died between 7 and 15 weeks of age. Initial deaths were not accompanied by premonitory signs, but after CSM withdrawal most calves developed rough coats, anorexia, weakness, ascites and subcutaneous oedema. Those that died had large volumes of serous fluid in the body cavities, hard livers of ‘nutmeg’ appearance, and pulmonary congestion. Histopathologically the livers showed periacinar necrosis in acute cases and periacinar fibrosis in chronic cases. Lungs from several calves had oedema, haemosiderosis and fibrosis in some pulmonary vessels. Atrophy of myocardial fibres was present in most cases. The concentration of free gossypol in the diet was 100 to 220 mg/kg. Ante-mortem and post-mortem findings supported a diagnosis of gossypol poisoning. The deaths continued for 4 weeks after withdrawal of CSM from the diet.     

SSR-based genetic linkage analysis of resistance to crown rust (Puccinia coronata f. sp. lolii) in perennial ryegrass (Lolium perenne)

Crown rust (caused by Puccinia coronata f. sp. lolii) is a serious foliar disease of the pasture and turfgrass perennial ryegrass (Lolium perenne). Previous genetic studies have detected both qualitative and quantitative resistance mechanisms, and interpretation of the genetic system is complicated by variation within the sexually reproducing pathogen. Resistant and susceptible parental genotypes of ryegrass were identified using a composite urediniospore population collected from three geographically distinct locations. A two-way pseudo-testcross mapping population was obtained as the F₁ progeny of the pair-cross between ryegrass parental genotypes Vedette₆ and Victorian₉. Both parents showed intermediate resistance against a pathogen population collected in a single geographical zone (Hamilton, Victoria), but in the F₁ population, significant variation for a range of resistance-associated characters was detected. Statistical analysis of phenotypic data suggested a major gene effect, hence bulked segregant analysis with map-assigned simple sequence repeat (SSR) markers was used to scan the genome. A marker showing strong association with resistance was assigned to linkage group (LG) 2 of perennial ryegrass. Analysis of 11 LG2 SSR markers defined an interval between loci xlpssrh03f03 and xlpssrk02e02 as containing the gene or genes (LpPc1) conferring crown rust resistance. Resistance gene determinants were inherited from both parents, with up to 80% of the total phenotypic variation explained by markers segregating from Vedette₆ and up to 26% of the variation explained by markers segregating from Victorian₉. The two contributions together resulted in an additive increase in effect, with fully resistant individuals requiring determinants from both parents. A conserved syntenic relationship was observed with linkage group B of Avena strigosa, which is the location of a cluster of resistance genes to the oat form of crown rust. The implications of this study for marker-assisted selection of disease resistance in perennial ryegrass are discussed.     

The use of ultrasonography in the reproductive evaluation of boars

The objective was to study the use of ultrasound as a complementary test in the breeding soundness evaluation in male pigs and study the pattern of echogenicity of the testicular parenchyma in boars of different racial groups. Twenty‐six adult boars from four different racial groups were used, 10 from the Piau breed (group 1), four from the commercial and finishing group (group 2), six Pietrain breed (group 3) and six from the Duroc breed (group 4). All animals were evaluated for breeding soundness evaluation and the ultrasound examination of the testicles. The groups of animals that were evaluated showed no difference in the main semen parameters that were evaluated, except for the sperm volume, concentration of the ejaculated sperm and the supravital staining; the lowest figures were for the animals from the Piau breed (group 1). In relation to the testicular biometrics, Duroc animals (group 4) had a greater scrotal width compared to the other groups. But when we assessed the intensity of pixels of the testicles, there was a difference between groups. The groups 2 (finishing animals), 3 (Pietrain) and 4 had no difference between themselves. Group 3 had greater pixel intensity in relation to group 1. Of the 26 animals studied, five showed an abnormality during ultrasound evaluation, like hydrocele, hyperechoic mass in the testicular parenchyma, cyst in the head of the epididymis and the presence of fluid in the head and tail of the epididymis. The various animal groups studied did not differ in the principal reproductive parameters evaluated, showing that despite the great variability of reproductive traits between breeds and within the same breed, the breeding soundness evaluation, the more complete it is, is essential for the selection of breeders and the ultrasonography of the reproductive system becomes an important addition in this examination.     

Conjunctival habronemiasis in a square‐lipped rhinoceros (Ceratotherium simum)

A captive female square‐lipped rhinoceros born in 1993 had been showing intermittent signs of bilateral conjunctivitis and conjunctival proliferation since 1998. Periodic improvement was noted, especially in winter, but overall the condition had deteriorated over the years. Treatment with various topical, intralesional, and systemic antibiotics and glucocorticosteroids was largely ineffective, as were repeated dewormings. No primary cause for these lesions was found in biopsies taken in 2000 and 2006, although a severe infiltrate of numerous eosinophils was observed in the latter. As the condition worsened, secondary corneal changes were noted, and eventually vision was lost due to proliferative conjunctival tissue. Aggressive resection of the proliferating tissue in 2013 restored vision and submitted biopsies yielded a diagnosis of severe allergic conjunctivitis, eosinophilic granuloma, and habronematid (Habronema or Draschia) larval infection. As no other rhinoceros in the herd was affected, including two calves born to the patient who were in close contact with their mother, it was concluded the presentation was most likely due to a hypersensitivity reaction to the dead or dying larvae. Fly repellent is now regularly applied around the eye of this rhinoceros, and a protective face mask has been fitted. Ongoing periodic relapses are treated with oral ivermectin, topical antibiotics, and steroids.     

The detection of CD2+, CD4+, CD8+, and WC1+ T lymphocytes, B cells and macrophages in fixed and paraffin embedded bovine tissue using a range of antigen recovery and signal amplification techniques

In order to develop procedures to label the main bovine leucocyte populations in paraffin embedded sections, the immunoreactivity of 25 monoclonal antibodies (mAbs) to different leucocyte antigens was assessed with formal dichromate (FD5) and 10% formalin fixation, a battery of antigen retrieval (AR) methods, and the biotin-tyramide amplification system. All the leucocyte populations investigated (CD2+, CD4+, CD8+, WC1+ T lymphocytes, B cells and macrophages) were strongly and specifically detectable under an appropriate combination of mAb, AR method and signal amplification system. CD4 and CD8 required the most stringent conditions and could only be demonstrated in FD5 fixed sections. For detection of CD2, WC1+ T lymphocytes, B cells and macrophages, all the mAbs produced immunoreactivity in FD5 or formalin fixed tissues. The need to check a range of different AR methods is stressed, as the method of choice varied for each individual mAb. The incorporation of the signal amplification system was necessary to observe a strong signal and the complete distribution of CD4, CD8 and B cells. Fixation by FD5 proved to be better than formalin for the preservation of surface antigens but it was inferior for the detection of markers which were found to show cytoplasmic immunoreactivity, such as the macrophage marker MAC387 or the B cell markers BAQ155 or IL-A59.     

Assessment of the Intensity of Behavioural Traits and Ovulation between Synchronized and Non-synchronized Cows

Thirty cyclic, non-suckled Brahman cows were divided into three groups, all of which were synchronized sequentially with CIDR-B and observed continuously for 100 h to determine different behavioural oestrus signs. Twenty-four hours after implant withdrawal, all synchronized cows in the group, together with all other cows displaying oestrus, were subjected to intensive ultrasonographic observations (every 6 h for 120 h) to pinpoint the moment of ovulation. In the first group, oestrus and ovulation response was 60% (6/10), in the second 44% (4/9) showed oestrus and six ovulated, and in the third group oestrus and ovulation were 80% (8/10). Significant differences were observed between the second and third groups (p < 0.05). No differences were observed in the duration of oestrus, time when oestrus was displayed after implant withdrawal, time of ovulation and onset of oestrus, end of oestrus to ovulation, and intensity of oestrus on a point scale. The relationship between duration of oestrus and time of ovulation was r(2) = 0.16. Ovulation, on average, was 32.1 +/- 14.5 h after the onset of oestrus, 22.3 +/- 16.5 h after the end of oestrus, and 91.8 +/- 16.7 after implant withdrawal, although no significant differences were observed. One non-synchronized animal showed oestrous activity in the second group but failed to ovulate. In the third group, 8 animals showed oestrus, 4 with high concentrations of progesterone. Of the other four one ovulated. In conclusion, oestrous behaviour is not necessarily the best marker to predict the time when ovulation takes place due to variation in the length of the oestrous period and the possible integration of non-ovulatory animals into sexually active groups.