Assessment of Proliferative Activity by AgNOR and PCNA in Prostatic Tissues of Ram Lambs Implanted with Zeranol

The aim of this study was to assess cellular proliferation using silver-stained nucleolar organizer regions (AgNOR) and the proliferating cell nuclear antigen (PCNA) in various tissues in the prostate of ram lambs implanted with increasing zeranol doses and to compare the sensitivity of different tissues of lamb prostate to zeranol. Twenty-four Akkaraman lambs were implanted with increasing zeranol doses, including 12 mg (n = 8), 24 mg (n = 8) and 96 mg (n = 8), with eight lambs serving as controls. After 33 days, the prostate tissues of the lambs were stained using AgNOR and PCNA techniques. The prostate tissues were divided into two compartments--the epithelial tissues, including glandular acinus, collecting duct and penile urethra, and the non-epithelial tissues, including interstitial tissue and striated muscle. AgNOR dots and PCNA index on each prostatic tissue were counted under a light microscope and were evaluated statistically. AgNOR staining in the treatment groups showed a higher score in the non-epithelial tissues than the epithelial components, whereas the PCNA index was significant in the epithelial tissues and non-epithelial tissues had very low PCNA immunostaining. According to the PCNA index, collecting duct epithelium showed more sensitivity to increasing zeranol doses and according to AgNOR counts, there was no difference of sensitivity to zeranol among tissues of the same origin. Both AgNOR counts and PCNA indexes seem to be valuable proliferating markers for the epithelial components of ram prostate, but PCNA index had no significance in relation to the non-epithelial components in contrast to AgNOR counts. Therefore, the controversial results arising from the combined use of both techniques as proliferating markers for the ram prostate should be considered in further studies.     

Effects of zeranol on in vitro growth hormone release by lamb and rat pituitary cells

A series of experiments was conducted to evaluate the effect of zeranol on release and synthesis of growth hormone (GH) by anterior pituitary cells established in either static or continuous flow cultures. Young adult male rats, slaughter-age lambs and juvenile lambs were used as sources of pituitary cells. In static primary cell cultures, no consistent effect of zeranol at 10(-7), 10(-9) or 10(-11) M was demonstrated by either rat or ovine cells. Rat pituitaries established in perifusion culture chambers showed no repeatable response to zeranol. Dissociated cells from lambs established in perifusion culture, however, had significant increases in release of GH in response to 37% of zeranol pulse exposures. When dissociated cells from juvenile lamb pituitaries were used, up to 10-fold increases in GH release consistently were measured within minutes of exposure to zeranol.     

Growth and carcass characteristics and serum growth hormone, prolactin and insulin profiles in Debouillet lambs treated with ovine growth hormone and(or) zeranol

Sixteen Debouillet wether lambs (approximately 3 mo old) were placed indoors in 1.5- x 3-m pens (14 h light:10 h dark) 28 d after weaning. Lambs received no implant or a 12-mg zeranol implant on d-2 (eight lambs/group). Two days later (d 0), animals received either 0 or 2.5 mg ovine growth hormone (oGH, eight lambs/group) s.c. on alternate days for 42 d. Animals had ad libitum access to water, salt, mineral and a pelleted alfalfa diet (16% CP). After 42 d, lambs were slaughtered to evaluate carcass traits, organ weights and femur characteristics. Zeranol by oGH interactions were not detected (P greater than .20). Zeranol increased (P less than .05) BW, improved (P less than .05) feed:gain during the first 20 d and increased (P less than .10) feed intake during the last 22 d of the 42-d trial compared with controls. Carcass characteristics were not altered (P greater than .10) by 12 mg zeranol. Serum insulin and prolactin were elevated (P less than .05), but serum GH was not influenced by zeranol compared with controls. Exogenous oGH decreased feed intake (P less than .10) and improved feed:gain (P less than .05) during the initial 20 d compared with controls, but did not influence (P greater than .20) these variables during the last 22 d of the study. Carcass traits were not influenced (P greater than .10) by oGH. Exogenous ovine GH dramatically elevated (P less than .05) serum GH, but did not affect serum insulin or prolactin (P greater than .10).(ABSTRACT TRUNCATED AT 250 WORDS)     

Radioimmunoassay of the anabolic agent zeranol. V. Residues of zeranol in the edible tissues, urine, faeces and bile of steers treated with Ralgro

Two trials were conducted on steers implanted with zeranol (Ralgro) to determine the edible tissue residues and the secretion pattern in faeces, urine and bile of zeranol residues throughout and beyond the recommended withdrawal period (70 days) for this drug. In the first trial there was considerable variation in the zeranol residue concentration in all edible tissues, the highest concentrations found in the liver being significantly above the control values (P less than 0.05). In the other tissues, only fat sampled 14 days after implanting was significantly above the control value (P less than 0.05). The zeranol concentration in bile samples obtained at slaughter [70 days (18), 90 days (5) and 120 days (2)] were all higher than the apparent concentration in the bile of untreated steers. The mean concentration of zeranol in the faeces and urine varied from day to day and between animals sampled on the same day following implantation. The highest mean concentrations were observed during the first 40 days following implanting, declining steadily to approach the control values 70 days after implantation. The second trial using steers prepared with bile duct re-entrant cannulae resulted in a similar pattern of zeranol excretion in bile, faeces and urine. The highest concentrations of zeranol were observed in bile and ranged from 24 to 34 micrograms/l; there was considerable variation between animals and within animals sampled on successive days. Although the concentration declined steadily, zeranol was still readily detectable 120 days after implanting.(ABSTRACT TRUNCATED AT 250 WORDS)     

Radioimmunoassay of the anabolic agent zeranol. II. Zeranol concentrations in urine of sheep and cattle implanted with zeranol (Ralgro)

A radioimmunoassay for zeranol has been validated and used to measure the concentration of zeranol in the urine of sheep and cattle treated with zeranol (Ralgro). The assay uses an antibody raised against zeranol-16-carboxy-propyl ether conjugated to human serum albumin. In sheep and cattle urine the limits of detection were approximately 2 ng/ml and 2.5 ng/ml, respectively. In two trials 13 sheep were implanted with 12 mg zeranol at the base of the ear. The mean maximum concentrations of zeranol observed in urine were 45 ng/ml (Trial I) on day 35 and 90 ng/ml (Trial II) on day 56, and had declined to 26 ng/ml 42 days after implantation (Trial I) and 11.7 ng/ml 70 days after implantation (Trial II). In four cattle implanted with 36 mg zeranol the concentrations of zeranol in urine reached a mean maximum concentration of 13.5 ng/ml 22 days after implantation and had declined to 2.9 ng/ml 69 days after implantation.     

Effect of zeranol implantation on body weight changes in zebu crossbred cattle grazing tropical pasture

Nine experiments on the effect upon bodyweight change of subcutaneous ear implantation of 36 mg zeranol in 605 Bos indicus crossbred cattle were conducted. Bullocks aged 3 to 4 years, steers aged 18 months and entire heifers aged 18 to 30 months were used over the period January to August, 1980. They were grazed on 6 commercial farms in tropical northern Australia. Seven of the experiments examined the results of single implantation after the initial 60 to 97 days. Growth rates of untreated cattle in the January to May period ranged from 0.43 kg/day over 97 days in heifers to 1.07 kg/day in bullocks. Bodyweight gains attributed to zeranol ranged from 1.8 kg (4.3% increase) over 97 days in heifers (NS) to 22.3 kg (28.9% increase) over 90 days in 18 month-old steers (P < 0.01). The significant bodyweight responses to zeranol treatment in all 5 experiments involving older 3-to 4-year-old bullocks have not been previously reported. Hot dressed weights of the zeranol-treated bullocks were significantly heavier than the untreated controls and dressing percentages were similar. Increases in bodyweight attributable to implantation with zeranol yielded 50 to 54% saleable carcase weight. Single-, repeat-, and non-implanted treatments were compared over 186 days from January to August. Both zeranol treatments significantly out-performed the controls (P < 0.05), and the repeat-implanted bullocks gained 9.2 kg more than the single-implanted bullocks (P<0.10) in spite of bodyweight tosses recorded in the 3 treatments over the final 105 days. In 2 experiments bullocks implanted once in January/February were weighed in August to monitor compensatory bodyweight changes after April/May. The cattle retained 72.4% and 92.6% of the original bodyweight advantage attributed to zeranol treatment, depending upon whether they lost or gained in bodyweight respectively during the April/May to August period. The commercial relevance of these results is discussed and suggestions are made for further work.     

Radioimmunoassay of the anabolic agent zeranol. IV. The determination of zeranol concentrations in the edible tissues of cattle implanted with zeranol (Ralgro)

Rapid solvent extraction combined with a radioimmunoassay using a monoclonal antibody raised against a derivative of zeranol has been used to measure the residues of the anabolic agent zeranol in the edible tissues (muscle, liver, kidney and fat) of cattle treated with Ralgro. Calibration curves, both with and without, tissue extracts exhibit good parallelism. Regression analysis for the extraction of zeranol from tissues dosed with standard amounts of zeranol have correlation coefficients of 0.979, 0.991, 0.986 and 0.985 for muscle, liver, kidney and fat, respectively. The limits of decision defined as the mean value + 3 SD for the concentrations apparently observed (noise) in tissues from animals not treated with Ralgro were 278, 121, 373 and 110 ng/kg for muscle, fat, liver and kidney, respectively. In the tissues of 4 cows implanted with Ralgro (36 mg), and sampled 70 days after implanting, the highest concentration of zeranol in each tissue was 232 ng/kg (muscle), 391 ng/kg (liver), 287 ng/kg (kidney) and 293 ng/kg (fat), and residues were detected in all samples of fat (4), 3 kidney samples and 1 liver sample.     

Fenbendazole and its effect on the immune system of the sheep

Ten parasite-free 6-month-old lambs were drenched on days 0 and 28 with fenbendazole and 1 day after each drench were injected with human erythrocytes and ovalbumin. Ten other lambs injected with the antigens were not drenched with anthelmintic and served as controls. Lymphocytes from the fenbendazole-drenched lambs collected 3 days after the first antigen injections and cultured in vitro in RPM1 1640 plus 5% foetal calf serum, and lymphocytes collected at 3 and 7 days and cultured in RPM1 plus 50% autologous serum, had decreased blastogenic activity compared with lymphocytes from control lambs. Similarly, decreased blastogenesis was observed with lymphocytes collected 7 days after the second antigen injections from drenched lambs and cultured in 50% autologous serum containing concanavalin A. In contrast, increased blastogenesis was seen with lymphocytes collected 14 days after the second antigen injections from the drenched lambs and cultured in 50% autologous serum containing phytohaemagglutinin. Similar antibody responses were seen for the drenched and control lambs in response to the injections of both antigens except that, after the second injection, there was a significant reduction in antibody response to human erythrocytes in the fenbendazole-treated lambs. Decreased serum complement levels were seen particularly 3 and 7 days after the second antigen injections in drenched lambs. These serum samples had increased conglutinin activity. At the end of the experiment, the fenbendazole-drenched lambs were significantly heavier than the control lambs. However, this did not appear to be related to any effects of fenbendazole on levels of growth promoting hormones.     

Effect of long or short acting anabolic agents, given singly or repeated, on growth rate and carcase weight of steers

A trial was carried out using 490, 12- to 15-month-old steers which were at pasture from April to November and then housed and fed grass silage and concentrates until sold live or slaughtered. Animals were allocated at random to one of the following treatments: (i) Control; (ii) implanted with 45 mg oestradiol -17 beta in silastic rubber in April; (iii) implanted with oestradiol in April and with 300 mg trenbolone acetate in April, August and November; (iv) implanted with 36 mg zeranol in April, August and November and (v) implanted with zeranol and trenbolone acetate in April, August and November. Daily liveweight gains were 0.69, 0.75, 0.78, 0.83 and 0.86 (+/- 0.02) kg, and carcase weights were 300, 306, 311, 316 and 321 (+/- 3.4) kg, for treatments (i) to (v), respectively. All implanted animals had significantly higher daily gains than control animals and an additive response was obtained where trenbolone acetate was used with oestradiol or zeranol. Pooled results for animals treated with oestradiol plus zeranol, with or without trenbolone acetate, show that the overall response for zeranol treated animals was higher than from the animals treated with oestradiol. Daily gains after the first, second and third implant period show a reduced response from the oestradiol implant for the final 63 days of the trial. This may have been caused by loss of some oestradiol implants from animals early in the trial.     

Fenbendazole and its effect on the immune system of the sheep

Ten parasite-free 6-month-old lambs were drenched on days 0 and 28 with fenbendazole and 1 day after each drench were injected with human erythrocytes and ovalbumin. Ten other lambs injected with the antigens were not drenched with anthelmintic and served as controls. Lymphocytes from the fenbendazole-drenched lambs collected 3 days after the first antigen injections and cultured in vitro in RPM11640 plus 5% foetal calf serum, and lymphocytes collected at 3 and 7 days and cultured in RPM1 plus 50% autologous serum, had decreased blastogenic activity compared with lymphocytes from control lambs. Similiarly, decreased blastogenesis was observed with lymphocytes collected 7 days after the second antigen injections from drenched lambs and cultured in 50% autologous serum containing concanavalin A. In contrast, increased blastogenesis was seen with lymphocytes collected 14 days after the second antigen injections from the drenched lambs and cultured in 50% autologous serum containing phytohaemagglutinin. Similar antibody responses were seen for the drenched and control lambs in response to the injections of both antigens except that, after the second injection, there was a significant reduction in antibody response to human erythrocytes in the fenbendazole-treated lambs. Decreased serum complement levels were seen particularly 3 and 7 days after the second antigen injections in drenched lambs. These serum samples had increased conglutinin activity. At the end of the experiment, the fenbendazole-drenched lambs were significantly heavier than the control lambs. However, this did not appear to be related to any effects of fenbendazole on levels of growth promoting hormones.     

The effect of zeranol on muscle structure and the development of the testes in bulls

The effect was investigated of the Ralgro preparation with the active substance zeranol on histological and histochemical properties of bull muscles. The anabolic effect was displayed by a trend toward greater thickness of muscle fibres in m. longissimus thoracis, m. semitendinosus and m. triceps brachii, whilst differences between the muscles of experimental and control animals were not statistically significant. The bulls administered zeranol had the higher proportions as well as the higher relative volumes of white (aW) muscle fibres, but neither were these differences statistically significant in comparison with the control. The growth and development of testicles are inhibited by zeranol. The inhibition is significant and persists during 30 days after the last administration. Later on, the rate of development and growth are increased with the testicles reaching the weight of the sexual glands of control animals in 90 days after the last administration; the coiled seminiferous tubules grow and spermiogenesis occurs.     

Effect of oxytetracycline therapy on experimentally induced pneumonic pasteurellosis in lambs

Two groups of 10, specific pathogen free lambs were injected with a long acting oxytetracycline preparation at a dose rate of 20 mg/kg either 24 hours before or 24 hours after exposure to an aerosol of Pasteurella haemolytica. When compared with the response of similarly infected but untreated lambs, the effect of pretreatment was to postpone the appearance of clinical signs of pneumonia for four days and the deaths of five lambs for five to six days post infection, by which time seven untreated lambs had died. Treatment 24 hours after infection caused a rapid clinical recovery which persisted until six days after infection but two treated lambs died seven days after infection. Lung lesions in the group treated after infection were significantly less extensive than those in the untreated lambs.     

Levamisole and its influence on the immune response of lambs

Ten parasite-free lambs were drenched with 8 mg/kg of levamisole on days 0 and 28 and were injected with human erythrocytes and ovalbumin one day after each drench. Ten other antigen-injected lambs were not drenched with anthelmintic as controls. Lymphocytes from the control and drenched lambs were culturedin vitro with RPMI 1640 plus 5% fetal calf serum (FCS), with 50% autologous serum only, with concanavalin A (Con A) or with phytohaemagglutinin (PHA). Decreased blastogenesis was observed in cells from the drenched lambs cultured in the presence or absence of mitogen and was most obvious when 50% autologous serum was used, particularly with PHA, and when lymphocytes were collected 3 and 7 days after the first and 3 days after the second antigen injection. There were no significant changes in antibody titres between the groups. Decreased serum complement activity was seen 3 days after the second antigen injection in the drenched lambs. Although there was a significant reduction in the serum insulin-like growth factor I levels 4 days after each levamisole drench, the drenched lambs gained significantly more weight than the non-drenched control lambs.Abbreviations Con A concanavalin - EIA enzyme immunoassay - FCS fetal calf serum - GH growth hormone - IGF-I insulin growth factor I - PHA phytohaemagglutinin     

Effects of leucocyte extract, levamisole and sulphadimidine on natural coccidial infections (Eimeria spp.) in young lambs

The efficacy of leucocyte extract (LE) and sulphadimidine in preventing coccidiosis in naturally infected lambs on pasture was evaluated in 3 separate experiments, whereas the prophylactic effect of levamisole was studied in 1 of the experiments. LE prepared from ewes immune to coccidia (Eimeria spp.) was administered either intravenously or intraperitoneally to young lambs 7, 5, or 2 days before they were turned out on pastures contaminated with coccidia. In all experiments, LE failed to transfer protective immunity to the lambs against the first coccidial infection on pasture. The LE preparations used apparently had an immunosuppressive effect, which resulted in more severe clinical signs of coccidiosis in the recipients. The lambs given LE showed a higher incidence of diarrhoea, a poorer weight gain, a higher mortality, and a higher oocyst output than the untreated control lambs. In lambs treated with sulphadimidine at 200 mg/kg on days 12, 13, and 14 after turnout there was a reduced severity of the coccidial infections in all experiments. The sulphadimidine-treated lambs had better weight gains and passed fewer oocysts than the controls during the third and fourth week after turnout, but some of them developed diarrhoea. Lambs treated with levamisole at 2 mg/kg 2 days before turnout, at turnout, and 2 days after turnout were more severely affected by the first coccidial infection on pasture than the controls.To study the lambs’ immunity against a heavy challenge infection with coccidia as compared with their immunity against the natural reinfection on pasture, some of the lambs from the original groups (untreated, sulphadimidine-treated, LE-treated) were each inoculated with 2 mill. Eimeria spp. oocysts about 6 weeks after turnout. The oocyst counts of the challenged lambs, except the LE-treated lambs, increased to a new peak 19–20 days after challenge. The challenge infection caused a softening of the faeces and a marked depression in weight gain in all challenged groups of lambs, mainly between days 10 and 17 after challenge. The lambs were thus only partially immune to coccidia after the first coccidial infection on pasture. The lambs treated with either LE or sulphadimidine in connection with the first coccidial infection on pasture were not appreciably more susceptible to the challenge infection than the untreated lambs.     

Efficacy of ivermectin against benzimidazole-resistant Nematodirus spathiger in sheep

Eighteen helminth-free lambs were randomly allocated to six groups of three. Each lamb was dosed with 3300 infective larvae pooled from two isolates of Nematodirus spathiger known to be benzimidazole resistant. One lamb from each group was treated with oral ivermectin, one with oral oxfendazole and one left untreated 21 days after infection. All lambs were humanely killed 14 days later and small intestine worm counts performed. No Nematodirus were found in the ivermectin-treated lambs. Nematodirus numbers were reduced by 13% in oxfendazole-treated lambs relative to the control lambs.     

The effectiveness of copper oxide wire particles as an anthelmintic in pregnant ewes and safety to offspring

The objective of the experiment was to determine the effectiveness of copper oxide wire particles (COWP) in pregnant ewes and safety to lambs. COWP have been used recently as an anthelmintic in small ruminants to overcome problems associated with nematode resistance to chemical dewormers. Doses of COWP (相似文献   

Interaction of bovine respiratory syncytial virus and Pasteurella haemolytica in the ovine lung

The potential synergistic effect of bovine respiratory syncytial virus (RSV) and Pasteurella haemolytica in the production of pneumonia after aerosol/intranasal infection of conventionally reared lambs was evaluated. A mild clinical response was observed in lambs given virus and/or bacteria. Gross pulmonary lesions were seen in 3 of 6 lambs given RSV and then P haemolytica 3 or 6 days later, respectively (groups D and E), and in 1 lamb of 5 given virus and bacteria simultaneously (group G). Gross lesions were not seen in control sheep (group A), in lambs given virus or bacteria alone (groups B and C), or in lambs exposed to bacteria and then virus 3 days later (group F). Bovine RSV and P haemolytica were recovered from the lungs of 5 of 7 lambs with macroscopic lesions. Gross pulmonary lesions were cranioventral firm areas of red consolidation. Microscopically, the predominant lesion was a suppurative bronchopneumonia. Bovine RSV was recovered from the nasal cavity of 8 of 27 (30%) lambs given RSV during days 3 to 6 after viral inoculation, including 1 lamb in group B, 2 in groups D, E, and F, and 1 in group G. Pasteurella haemolytica was recovered from the nasal cavity of 9 of 28 (32%) inoculated lambs, including 2 lambs from groups C and E, 3 in group D, and 1 in groups F and G. Viral antigen, as determined by immunofluorescence, was concentrated mainly in individual cells in alveolar walls, some alveolar macrophages, and a few bronchiolar epithelial cells. In vitro alveolar macrophage assays indicated decreased numbers of Fc receptors on those macrophages collected from lambs given RSV 6 days before P haemolytica infection, as compared with that in the other groups. These cellular defects disappeared after 24 hours of culture. Seemingly, bovine RSV does facilitate P haemolytica pulmonary infection in conventional, immuno-competent lambs and provides evidence for decreased Fc receptors on alveolar macrophages.     

The effect of parainfluenza virus type 3 and Pasteurella haemolytica on oxygen-dependent and oxygen-independent bactericidal mechanisms of ovine pulmonary phagocytic cells

Groups of caesarean-derived, colostrum-deprived lambs were inoculated by the intratracheal route with Pasteurella haemolytica, either alone or 4 or 6 days after the inoculation of parainfluenza virus type 3 (PI3). Other groups were inoculated with PI3 followed by veal infusion broth, or with uninfected cell culture fluid followed by veal infusion broth (controls). All lambs were killed 24 h after the second inoculation. Pulmonary phagocytic cells were recovered by lavage and separated into alveolar macrophage (AM) and neutrophil fractions by density gradient centrifugation. Bacterial proliferation was detected in the lungs of all five lambs inoculated with P. haemolytica 6 days after PI3 but in only one of five inoculated with P. haemolytica 4 days after PI3 and one of five inoculated with P. haemolytica alone. The number of phagocytic cells recovered from the lungs was highest in animals inoculated with P. haemolytica 6 days after PI3 and, overall, a greater number of both AM and neutrophils was recovered from the lungs of animals where bacterial proliferation occurred (greater than 10(5.0) P. haemolytica 100 g-1 lung) than from those that controlled the bacterial infection. Oxygen-dependent bactericidal activity of AM and neutrophils was measured by chemiluminescence. Infection with PI3 and P. haemolytica increased the chemiluminescence responses. The highest responses were recorded from lambs inoculated with P. haemolytica 6 days after PI3, the group where pulmonary clearance was poorest. Overall, responses were higher in lambs in which bacterial proliferation occurred than in those that controlled the infection. On the other hand, oxygen-independent bactericidal activity, measured by the direct effects of neutrophil lysates on Escherichia coli, was lowest in lambs inoculated with P. haemolytica 6 days after PI3 and was lower in lambs where bacterial proliferation occurred.     

The influence of colostral antibodies on the immunization of lambs against adenoviruses

The effect of colostral antibodies on the immune response in lambs following adenovirus vaccination was studied. Young lambs of different ages, born from vaccinated ewes, were vaccinated with an inactivated and aluminium hydroxide-adsorbed sheep adenovirus vaccine. In a group of lambs vaccinated at 5–7 days of age, the titre of humoral antibodies declined in parallel to unvaccinated controls. In lambs vaccinated at 24–35 days of age, antibody titres to adenovirus stabilised and persisted after an initial fall. Cell mediated immunity, as measured by blastogenic responses of circulating lymphocytes, was stimulated in both groups, but higher numbers of IgG-producing cells became evident in the group of lambs vaccinated at 24–35 days of age.