Testicular damage from anabolic treatments with the beta(2)-adrenergic agonist clenbuterol in pigs: a light and electron microscope study

The morphological consequences of anabolic clenbuterol treatment on the testicular parenchyma were investigated in 30 pigs at morphological and ultrastructural levels. Clenbuterol was given with food (1 ppm). In the first group (n=10), treatment was maintained until slaughter (experimental period 3 months). In the second group (n=10), clenbuterol was withdrawn 2 weeks before slaughter (experimental period 2.5 months). A third group (n=10) of pigs not fed with clenbuterol served as controls. Animals were slaughtered at 9 months of age and samples of testicular parenchyma were collected for light and electron microscope studies. In the clenbuterol-treated groups, the interstitial cells showed a considerable increase in the organelles involved in testosterone production, with an increased development of the mitochondria, smooth endoplasmic reticulum, Golgi apparatus and lipid droplets compared to the control group. The seminal epithelium displayed many lipid vacuoles and evident signs of tubular involution, such as degenerating and multinucleate germ cells. Sertoli cells gave evidence of metabolic alterations such as large lipid deposits and cytolysosomes.     

Quantitative modification of the testicular structure in pigs fed with anabolic doses of clenbuterol

Morphological and structural data of the testes of thirty male pigs were recorded in order to evaluate the effects of an anabolic clenbuterol treatment. Pigs aged 6 months were randomly allocated to one of three experimental groups. In two treated groups, the animals were fed with anabolic doses of clenbuterol (1 ppm); in the CLB group (n = 10) clenbuterol was given until they were slaughtered (treatment period = 3 months) whereas in the CLBW group (n = 10) the clenbuterol was withdrawn two weeks before slaughter (treatment period = 2.5 months); clenbuterol was not given to the pigs of the control group (n = 10). Stereological estimations of the tissular volume fraction and tubular volume density were applied to quantify the structural constituents of the testes. The results showed an increased volume fraction of the testicular interstitium especially in the Leydig cell population, as a result of the clenbuterol treatment. The increase in the nuclear volume fraction of the Leydig cells was the more persistent change in the variations recorded in both treated groups with respect to the control. A regression of the seminal epithelium was also recorded in the treated animals. The rest of the structural parameters were closer to the normal figures in the CLBW group, suggesting a recovery of the testicular structure when clenbuterol was withdrawn.     

Morphological and quantitative study of the Leydig cells of pigs fed with anabolic doses of clenbuterol

The effects of clenbuterol administered at anabolic doses on the testicular interstitium were studied in 30 pigs allocated to three experimental groups. The diet of two groups was supplemented with clenbuterol (Clb) (1 ppm), but whereas in the Clb+ group the treatment was given until slaughter (treatment period: 3 months), in the Clb- group the clenbuterol was withdrawn 2 weeks before slaughter (treatment period: 2-5 months); in the control group, the pigs were fed without clenbuterol. For histological procedures, a fractional sampling scheme was applied and routine techniques for light and transmission electron microscopy were used. The results of subjective morphology and morphometrics showed slight differences between the treated and the control groups. Conversely, the stereological results identified a prominent hyperplasia of the Leydig cells and ultrastructural analysis of these cells revealed a conspicuous increase in the organelles related to testosterone production, suggesting a functional activation of the interstitial cells in response to the clenbuterol treatment.     

Immunohistochemical study of Ki‐67 protein,androgen receptor,and estrogen receptor beta in testicular tissues of male pigs immunocastrated with different times of GnRH vaccination

This study aimed to investigate the immunoexpression of Ki‐67 protein, androgen receptor (AR), and estrogen receptor beta (ERβ) in testicular tissues of male pigs immunocastrated using GnRH vaccine (Improvac?, Zoetis Co., Ltd., Thailand) with different times. Totally, 30 male pigs were classified by castration protocol into three groups: T1 (n = 10) consisted of pigs immunocastrated at 14 and 18 weeks of age, T2 (n = 10) included pigs immunocastrated at 9 and 19 weeks of age, and C (n = 10) contained intact pigs. The results revealed that testicular length of pigs in C was longer than that of both T1 (8.1 ± 0.76 vs 6.5 ± 0.5 cm, p < 0.001) and T2 (8.1 ± 0.76 vs 6.9 ± 1.0, p = 0.007). Spearman correlation coefficients showed negative correlation between testicular length and H‐score of AR (r = ?0.38, p = 0.037), as well as positive correlation between testicular length and Ki‐67 index (r = 0.602, p < 0.001). Generally, mean Ki‐67 index and mean H‐scores of AR and ERβ of pigs in T1 were not different from those in T2 (p > 0.05). However, mean Ki‐67 index and mean AR H‐scores of T1 and T2 were significantly different from C group (p < 0.05). In summary, the immunocastration significantly affected testicular length, including expressions of Ki‐67, AR, and ERβ in pig testes. Moreover, the duration between two shots of GnRH vaccine could be extended from 4 to 10 weeks without difference in Ki‐67 protein, AR, and ERβ immunoexpressions.     

Efficiency of the Spermatogenesis in Zebu Bulls (bos taurus indicus)

The objective of the research was to evaluate the efficiency of the spermatogenesis through the morphology of the testicular parenchyma in bulls of different zebu breeds. We used testicular fragments from bull of the breeds Nelore (n = 10), Polled Nelore (n = 6), Gyr (n = 5), Guzerat (n = 5) and Tabapuã (n = 5). The tissue was perfused with Karnovsky solution, included in glycol methacrylate and stained with toluidine blue–sodium borate 1%. Animals of the Nelore breed presented higher population of primary spermatocyte in pre‐leptotene/leptotene (38.30) and in pachytene (38.14) and round spermatids (113.30), higher yield of spermatogonia mitosis (21.2) and higher daily spermatic production per gram of testicular parenchyma (32.8 × 10⁶) than those from breeds Gyr, Guzerat and Tabapuã and higher general yield of spermatogenesis (62.4) than breeds Gyr and Tabapuã. There was no significant difference in any of the evaluated parameters between breeds Nelore and Polled Nelore. The rate of Sertoli cells did not vary between the studied breeds. Apparently, the genetic selection applied to the breeds has been improving the yield in the spermatogenic process by decreasing cellular loss, although it did not increase the support capacity of the Sertoli cells.     

Influence of On‐farm pig Salmonella status on Salmonella Shedding at Slaughter

The risk of Salmonella shedding among pigs at slaughter with regard to their previous on‐farm Salmonella status was assessed in a group of pigs from a farm from NE of Spain. A total of 202 pigs that had been serologically monitored monthly during the fattening period and from which mesenteric lymph nodes (MLN) and faecal (SFEC) samples were collected at slaughter for Salmonella isolation were included. A repeated‐measures anova was used to assess the relationship between mean OD% values during the fattening period and sampling time and bacteriology on MLN and SFEC. Pigs were also grouped into four groups, that is pigs seronegative during the fattening period and Salmonella negative in MLN (group A; n = 69); pigs seronegative during the fattening period but Salmonella positive in MLN (B; n = 36); pigs seropositive at least once and Salmonella positive in MLN (C; n = 50); and pigs seropositive at least once but Salmonella negative in (D; n = 47). Pigs shedding at slaughter seroconverted much earlier and showed much higher mean OD% values than non‐shedders pigs. The proportion of Salmonella shedders in groups A and D was high and similar (26.1% and 29.8%, respectively), but significantly lower than that for groups B and C. The odds of shedding Salmonella for groups B and C were 4.8 (95% CI = 1.5–15.5) and 20.9 (3.7–118) times higher, respectively, when compared to A. It was concluded that a large proportion of Salmonella seronegative pigs may shed Salmonella at slaughter, which would be likely associated to previous exposure with contaminated environments (i.e. transport and lairage). For pigs already infected at farm, the likelihood of shedding Salmonella was much higher and may depend on whether the bacterium has colonized the MLN or not. The odds of shedding Salmonella spp. were always much higher for pigs in which Salmonella was isolated from MLN.     

Influence of piglet birth weight on postnatal growth performance, tissue lipogenic capacity and muscle histological traits at market weight

High fecundity of sows induces a large within-litter variation in piglet birth weight. This study aimed to determine whether piglet birth weight influenced growth performance, tissue lipogenic capacity and muscle characteristics at slaughter. A total of 19 piglets were assigned to either light birth weight group (LBW: 0.80-1.10 kg, n=9) or heavy birth weight group (HBW: 1.75-2.05 kg, n=10). Light birth weight was associated significantly with reduced average daily gain during suckling and post-weaning periods only. At slaughter (102±0.6 kg), LBW pigs were 12 days older than HBW littermates (P<0.01). Plasma IGF-I concentration was reduced by 24% (P<0.05) in LBW pigs compared to HBW pigs. Subcutaneous fat depth, tissue lipid content and lipogenic capacity did not differ between groups. Fiber mean cross-sectional area was increased by 14% in semitendinosus, and by 20% in longissimus and rhomboideus muscles, respectively (P<0.05), in LBW pigs compared with HBW pigs. Total fiber number was reduced in both semitendinosus (−13%) and rhomboideus muscles (−20%, P<0.10) of LBW pigs compared with HBW pigs. Whether such histological modifications influence the sensory quality of pork remains to be established.     

Prevalence of extra-intestinal porcine helminth infections and assessment of sanitary conditions of pig slaughter slabs in Dar es Salaam city,Tanzania

A study was carried out to establish the prevalence of extra-intestinal porcine helminth infections and to assess the pig slaughter slab sanitary conditions in Dar es Salaam city, Tanzania. A total of 24 privately owned pig slaughter slabs were assessed. All slaughter slabs were sub-standard; wrongly located, poorly designed and constructed and lacked most basic requirements for a slaughter house. Because of inadequate slaughtering, disposal and cleaning facilities, the slaughter slabs were under unhygienic condition with questionable safety, soundness and wholesomeness of the pork produced. Routine meat inspection procedures were used to detect extra-intestinal porcine helminth infections. Of the 731 examined pigs; 8.1%, 5.9% and 0.4% were infected with ascariosis, porcine cysticercosis and hydatidosis, respectively. It was noted that almost all slaughter pigs in Dar es Salaam originated from different regions. Based on the region of origin, the status of porcine cysticercosis was 8.2% for Dodoma (n = 98), 8.2% for Manyara (n = 260) and 6.9% for Mbeya (n = 116). This study disclosed the unhygienic sanitary condition prevailing in Dar es Salaam pig slaughter slabs and recommends that strategies should be devised to improve the situation. Porcine ascariosis and cysticercosis were widely prevalent and caused economic losses due to condemnations. Because of their zoonotic nature, the observed extra-intestinal porcine helminth infections in pig pose a public health risk among consumers. Thus, there is a need to introduce appropriate control measures of parasitic infections in pigs.     

Evaluation on the pathogenicity of Erysipelothrix tonsillarum for pigs by immunosuppression with cyclophosphamide or dexamethasone

The pathogenicity of Erysipelothrix tonsillarum was evaluated in pigs immunosuppressed with cyclophosphamide (CY) or dexamethasone (DM). Animals were treated with 15 mg/kg CY (n = 8, five injections), 1 mg/kg DM (n = 8, nine injections) or left untreated (n = 8). On the fifth day after the beginning of drug treatments, swine were inoculated with one of two E. tonsillarum serovar 7 strains (approximately 10⁶ CFU per pig). In the CY-treated group, both circulating neutrophil and lymphocyte counts decreased, whereas in the DM-treated group, lymphocyte counts decreased but neutrophil counts increased. During the observation period, none of the CY- or DM-treated pigs developed clinical signs or gross lesions, as well as non-treated pigs. Growth agglutination antibody titres in all pigs remained unchanged. Our findings indicate that E. tonsillarum strains are avirulent for swine, regardless of immune status.     

Reduced lung lesions in pigs challenged 25 weeks after the administration of a single dose of Mycoplasma hyopneumoniae vaccine at approximately 1 week of age

Two independent studies assessed the duration of immunity of an inactivated adjuvanted Mycoplasma hyopneumoniae vaccine against mycoplasmal pneumonia in seronegative (study A, n = 52) and seropositive (study B, n = 52) pigs. The pigs were allocated randomly to treatment and were then injected with a single dose of either the vaccine or a placebo at approximately 1 week of age. Twenty-five weeks after treatment administration, the pigs were challenged with a virulent strain (LI 36, Strain 232) of M. hyopneumoniae and the extent of lung lesions consistent with mycoplasmal pneumonia was assessed 4 weeks later.In study A, the geometric mean lung lesion score (expressed as least squares mean percentages of lung lesions) was significantly (P = 0.0001) lower in vaccinated (0.3%, n = 20) than in control pigs (5.9%, n = 24) seronegative to M. hyopneumoniae at enrolment; similarly, in study B, the extent of lung lesions was significantly reduced (P = 0.0385) in seropositive vaccinated pigs (2.0%, n = 22) compared to controls (4.5%, n = 26). At the end of the investigation period, 4 weeks after challenge, mean antibody sample-to-positive (S/P) ratios were significantly higher both in seronegative (P = 0.0012) and seropositive (P = 0.0001) vaccinated pigs (mean values = 0.77 and 0.81, respectively) than in controls (mean values = 0.51 and 0.38, respectively).     

Acute and Subacute Metabolic and Endocrine Effects of Clenbuterol in Female Pigs

The aim of the study was to assess the relationship between acute and subacute metabolic and endocrine effects after intravenous administration of the ₂-adrenergic agonist clenbuterol in a growth-promoting dose to female pigs. Acute metabolic and endocrine effects were assessed by measuring the blood glucose, serum insulin and nonesterified fatty acid (NEFA) concentrations during 300 min after a single administration of clenbuterol. Significantly higher serum insulin and NEFA concentrations (19.90±2.50 U/ml, p<0.01, and 0.69±0.04 mmol/L, p<0.001, respectively) were measured 30 min after the preprandial administration of clenbuterol in female pigs. Over the same period, the levels of blood glucose (4.42±0.30 mmol/L) showed no difference from those of control pigs. The postprandial serum NEFA concentration decreased moderately during 210 min after feeding. Postprandial blood glucose and insulin concentrations increased and reached maximal levels 120 min after clenbuterol administration (10.91±0.60 mmol/L and 85.22±7.24 U/ml, respectively), and returned to basal levels at 300 min (4.20±0.21 mmol/L and 7.75±1.60 U/ml, respectively) after the administration of clenbuterol. Subacute metabolic and endocrine effects were assessed by measuring the blood glucose, serum insulin and NEFA concentrations for 21 days after the repeated doses of clenbuterol. In addition, the influence of clenbuterol administration on the endocrine regulation of the onset of the next expected oestrus in female pigs was assessed by measuring their serum 17-oestradiol and progesterone concentrations. Blood glucose, serum insulin and NEFA concentrations after the last administration of clenbuterol did not differ significantly from those in control animals. The onset of the next expected oestrus occurred regularly without any significant difference in serum 17-oestradiol or progesterone concentrations between the treated (9.83±2.60 pg/ml and 0.15±0.03 ng/ml) and control pigs (8.52±2.70 pg/ml and 0.25±0.06 ng/ml). The study results suggest the duration of intravenous administration of clenbuterol in a growth-promoting dose necessary to influence the metabolic and endocrine activities in female pigs.     

Echinococcosis in pigs and intestinal infection with Echinococcus spp. in dogs in southwestern Lithuania

Cystic echinococcosis is a major emerging zoonosis in many Eastern European and Asian countries. Post slaughter examinations of 684 pig livers in Lithuania revealed significantly higher numbers of Echinococcus granulosus infections in animals from family farms (13.2%; 95% CI 10.7–16.2) as compared with those from industrial farms (4.1%; 95% CI 0.8–11.5). The prevalence was also significantly higher in pigs older than 1 year than in younger ones. In addition, in 0.5% of the pigs from the family farms, infertile and calcified E. multilocularis lesions were identified by PCR. Faecal samples from rural dogs (n = 240) originating from 177 family farms in 12 villages were investigated for taeniid eggs with two methods. Significantly more dogs excreting taeniid eggs were diagnosed with the flotation/sieving method (n = 34) as compared to the modified McMaster method (n = 12). Multiplex PCR performed with DNA from taeniid eggs isolated from faeces of 34 dogs revealed 26 infections with Taenia spp., 9 with E. granulosus and 2 with E. multilocularis (4 cases with concurrent Taenia spp. and E. granulosus or E. multilocularis infections). Genotyping of E. granulosus cyst tissues from 7 pigs, 1 head of cattle and from E. granulosus eggs from 8 dog faeces revealed the genotype G6/7 (‘pig/camel strain’) in all cases. The high infection pressure with Echinococcus spp. in family farms necessitates initiating control programs.     

Live weights at slaughter significantly affect the meat quality and flavor components of pork meat

One‐hundred‐twenty crossbred pigs finished at 175–185 days of age were used to investigate the effects of live weights at slaughter on the meat quality, volatile flavor compounds, and sensory attributes of pork meat. Based on the live weights at slaughter, three weight groups (n = 36 per group) were classified as follows: light weight (LW: 100 kg), medium weight (MW: 110 kg), and heavy weight (HW: 120 kg). After slaughter, longissimus dorsi muscle samples were taken and used for the analyses of aforementioned parameters. The HW group had higher fat content and water holding capacity compared to the LW or MW group (p < 0.05). The HW group also showed higher levels for majority of unsaturated fatty acids and total polyunsaturated fatty acids than the LW group (p < 0.05). The slaughter weight significantly affected the amounts of 11 among the 47 flavor compounds identified. Significantly higher amounts of fatty acids oxidation‐derived flavor compounds (aldehydes) were found in the HW group than in the other groups. Noticeably, increasing slaughter weight was associated with higher sensorial scores for flavor, juiciness, and acceptance scores (p < 0.05). Based on the obtained results, 120 kg body weight is recommended as the market weight for this commercial breed without compromising the meat quality.     

Effects of GnRH in combination with PGF2α on the dynamics of follicular and luteal cells in post-pubertal Holstein heifers

Holstein heifers were randomly allotted by weight, age and body condition score to one of three treatments to test the hypothesis that GnRH administration concurrent with PGF_2α injection would advance follicle or corpus luteum (CL) development parallel to an induced luteolysis of the pre-existing CL. Heifers in the control group (n = 14) received two treatments of PGF_2α(25 mg, im) given 10 days apart. Groups 2 (n = 14) and 3 (n = 14) received an additional treatment of GnRH (100 μg, im) after the first and second PGF_2α respectively. Estrus detection began immediately after PGF_2α and continued for 80 h. Blood sampling was initiated 7 days prior to the first PGF_2α (day − 7) and continued on days 0, 7, 10 (prior to the second PGF_2α), 17 and 24. Heifers were artificially inseminated after the second PGF_2α and pregnancy diagnosed at 60 days. There was a trend (P < .10) toward a lower estrus response in group 3 when compared to the other groups. Pregnant heifers in group 2 had lower progesterone (0.44 ± 0.09 vs. 1.72 ± 0.56 ng/ml) a week after the second PGF_2α than the non-pregnant animals in that group (P < .05). Similar results were observed in the control group but only within the responding heifers (0.61 ± 0.08 vs. 0.93 ± 0.03 ng/ml; P < .05). Progesterone in heifers in group 2 remained high on day 0, 7, and 10 (1.48 ± 0.37, 1.23 ± 0.39, 1.96 ± 0.36 ng/ml) in spite of the treatment with PGF_2α. This data suggest that administration of GnRH following PGF_2α alters bovine luteal and/or follicular cell function.     

Cortisol and catecholamine levels in lambs: Effects of slaughter weight and type of stunning

The objectives of this study were (1) to determine the levels of cortisol (C) and catecholamines (adrenaline, A, and noradrenaline, NA) in lambs (n = 45) at different age/slaughter weight [suckling vs light], in farm (T0), after transport (T1), in the slaughterhouse after lairage (T2) and (2) to study the effect of the type of stunning, electrically vsgas, on C, A and NA values, in both groups of slaughter weight. Levels of C and A at T0 and T1 were similar in both groups (suckling and light), but NA was higher in suckling lambs as in T0 (P < 0.05) as in T1 (P < 0.01). Levels of all hormones were higher in suckling lambs at T2 (P < 0.05, P < 0.001 and P < 0.01, for C, A and NA, respectively). In general, the younger group showed higher values of C, A and NA than the light group after stunning, with significant differences on A and C in the electrically stunned lambs (P < 0.001, P < 0.05 respectively) and on A in the gas stunned group (P < 0.01). Only in the light group, levels of A were higher (P < 0.01) in the electrically than in the gas stunned group. In conclusion CO₂ could be a good method to stun lambs because stress indexes were similar to levels found in electronarcosis method.     

Effect of dihydrotestosterone on mouse embryonic stem cells exposed to H2O2-induced oxidative stress

Oxidative stresses induced by reactive oxygen species (ROS) have been shown to be involved in several physiological and pathophysiological processes, such as cell proliferation and differentiation. Steroid hormones can protect cells against apoptosis or induce cell proliferation by several mechanisms. Among androgenic hormones, dihydrotestosterone (DHT) is generated by a 5α-reduction of testosterone. Unlike testosterone, DHT cannot be aromatized to estradiol, therefore DHT is considered a pure androgenic steroid. This study was conducted to examine the effect of DHT (10^-7 M) on H₂O₂ (10^-3 M) -induced injuries in mouse embryonic stem (ES) cells. H₂O₂ induced ROS generation and increased lipid peroxide formation and DNA fragmentation. These effects of H₂O₂ were inhibited by pretreatment with DHT. H₂O₂ also increased the phosphorylation of p38 MAPK, SAPK/JNK and nuclear factor kappa B (NF-κB), but DHT blocked these effects. Moreover, H₂O₂ decreased DNA synthesis and the levels of cell cycle regulatory proteins [cyclin D1, cyclin E, cyclin-dependent kinase (CDK) 2, and CDK 4]. These effects of H₂O₂ were inhibited by pretreatment with DHT. In conclusion, DHT may partially prevent H₂O₂-induced cell injury through inhibition of ROS and ROS-induced activation of p38 MAPK, SAPK/JNK and NF-κB in mouse ES cells.     

The effect of feeding system at weaning on performance,health and feeding behaviour of pigs of different sizes

Abstract

Pigs weaned at 31 to 34 days of age (n=280) were mixed into groups of 10 and fed from either feeders (2 feeding places per pen) or troughs (10 feeding places per pen). Analyses on performance, diarrhoea scores and feeding behaviour were made separately on small-, medium- and large-sized pigs, defined as their relative size in the group. During the second week after weaning, feed conversion ratio (FCR) was lower for pigs fed from feeders. Trough feeding resulted in lower total diarrhoea scores for small (p=0.002) and large (p=0.04), and higher scores for medium pigs (p=0.03). Small pigs had lower scores on individual days around the peak on day 6. All three size categories of pigs spent a numerically higher amount of time feeding when fed from a trough. Feeding bouts were longer in pigs fed from a trough (p=0.0002 – 0.05).     

Aspects of the Macroscopic Testicular and Epididymal Morphology in the Greater Rhea,Rhea Americana (Linneaus – 1758) Birds

The purpose of this research was to study the macroscopic testicular and epididymal morphology of the greater rhea. The testicles of 54 greater rhea bred in captivity were utilized. The samples were collected November 2005 (n = 14), December 2006 (n = 20) and May 2007 (n = 20). During commercial slaughter, the testicles and epididymides were collected and their following morphometric parameters were immediately measured: length, width, thickness, circumference, volume, weight of the parenchyma and the tunica albuginea, also aspects such as shape, cavity implantation, relationship with other organs and vascularization. The testicles presented cylindrical shape, with a thin, dense and transparent tunica albuginea, and the vascularization was accomplished by the testicular artery that ramifies from the cranial rectal artery. In the samples from December 2006 and May 2007, the media from the macroscopic measures of the right testicles were volume 58.7 and 14.7 ml, length 9.87 and 3.5 cm, width 2.4 and 0.6 cm, thickness 2.4 and 0.5 cm, circumference 8.0 and 2.3 cm, parenchyma weight 27.6 and 6.1 g and tunica albuginea weight 1.0 and 0.3 g, P < 0.05, respectively. The epididymides, the media from macroscopic measures December 2006 and May 2007 were volume 7.7 and 3.0 ml, length 5.8 and 1.3 cm, width 0.7 and 0.3 cm, thickness 0.6 and 0.3 cm, circumference 2.5 and 1.2 cm, tissue weight 6.4 and 2.8 g and capsule weight 0.4 and 0.1 g, P < 0.05, respectively. Some measures from the right testicle and epididymis were superior to measures taken from the left ones (P < 0.05), but these were not characterizing asymmetry. The morphometric parameters observed during November 2005 remained on an intermediate situation (P < 0.05); however, they were quantitatively closer to the means of December 2006, which may characterize it as a potential transition period between repose and sexual activity. Morphologically, the testicles and epididymides of greater rhea have common points with other researched birds; however, differences were observed. The testicles and epididymides of the Rhea americana are influenced by the environment, presenting reproductive activity season (November–December) during late spring, early summer and sexual repose season (May) during autumn–winter. The morphometric testicular and epididymal measurements were introduced. The morphometric parameters of testicles and epididymides exhibited differences between winter and spring–summer that could be established like sexual activity season.     

Experimental Dual Infection of Specific Pathogen‐Free Pigs with Porcine Reproductive and Respiratory Syndrome Virus and Pseudorabies Virus

Twenty 6‐week‐old specific pathogen‐free pigs were divided into four groups. On day 0 of the experiment, PRRSV–PRV (n = 6) and PRRSV (n = 4) groups were intranasally inoculated with porcine reproductive and respiratory syndrome virus (PRRSV) (10^5.6 TCID₅₀). On day 7, the PRRSV–PRV and PRV (n = 6) groups were intranasally inoculated with pseudorabies virus (PRV) (10^3.6 TCID₅₀). Control pigs (n = 4) were kept as uninoculated negative controls. Half of the pigs in each group were euthanized and necropsied on day 14 or 21. Clinical signs such as depression and anorexia were observed in the PRRSV–PRV and PRV groups after inoculation with PRV. Although febrile response was observed after virus inoculations, the duration of that response was prolonged in the PRRSV–PRV group compared with the other groups. The lungs in the PRRSV–PRV group failed to collapse and were mottled or diffusely tan and red, whereas the lungs of the pigs in the other groups were grossly normal. Histopathologically, interstitial pneumonia was present in all PRRSV‐inoculated pigs, but the pneumonic lesions were more severe in the PRRSV–PRV group. Mean PRRSV titres of tonsil and lung in the PRRSV–PRV group were significantly (P < 0.05) higher than that in the PRRSV group on day 21. These results indicate that dual infection with PRRSV and PRV increased clinical signs and pneumonic lesions in pigs infected with both viruses, as compared to pigs infected with PRRSV or PRV only, at least in the present experimental conditions.     

An investigation of shedding and super‐shedding of Shiga toxigenic Escherichia coli O157 and E. coli O26 in cattle presented for slaughter in the Republic of Ireland

Shiga toxigenic Escherichia coli (STEC) are an important group of pathogens and can be transmitted to humans from direct or indirect contact with cattle faeces. This study investigated the shedding of E. coli O157 and O26 in cattle at the time of slaughter and factors associated with super‐shedding (SS) animals. Rectoanal mucosal swab (RAMS) samples were collected from cattle (n = 1,317) at three large Irish commercial beef abattoirs over an 18 month period, and metadata were collected at the time of sampling regarding farm of origin, animal age, breed and gender. RAMS swabs were examined for the presence and numbers of E. coli O157 and O26 using a previously developed quantitative real‐time PCR protocol. Samples positive by PCR were culturally examined and isolates analysed for the presence of stx subtypes, eae and phylogroup. Any samples with counts >10⁴ CFU/swab of STEC O157 or O26 were deemed to be super‐shedders. Overall, 4.18% (55/1,317) of RAMS samples were positive for STEC O157, and 2.13% (28/1,317) were classified as STEC O157 SS. For STEC O26, 0.76% (10/1,317) of cattle were positive for STEC O26, and 0.23% (3/1,317) were classified as super‐shedders. Fewer STEC shedders and SS were noted among older animals (>37 months). There was a seasonal trend observed for STEC O157, with the highest prevalence of shedding and SS events in the autumn (August to October). The majority of E. coli O157 (50/55) isolates had stx2 and were eae positive, with no significant difference between SS and low shedders (LS). Interestingly, all STEC O26 (n = 10) were eae negative and had varied stx profiles. This study demonstrates that, while the overall shedding rates are relatively low in cattle at slaughter, among positive animals there is a high level of SS, which may pose a higher risk of cross‐contamination during slaughter.