Chronic ergot exposure in adult bulls suppresses prolactin but minimally impacts results of typical breeding soundness exams.

Canadian standards allow ≤3000 µg ergot alkaloids/kg cattle feed. A concentration-response relationship was hypothesized between ergot in feed and reductions in plasma prolactin, sperm motility, sperm function, and increase in sperm abnormalities. The study consisted of pre-treatment (12 weeks), treatment (9 weeks), and post-treatment periods (10 weeks). Adult bulls were fed 1113 (n = 8; low ergot group) or 2227 (n = 6; high) µg/kg of dry matter intake. Endpoints were measured every two weeks. Ejaculates were analyzed for sperm concentration, total and progressive motility, plasma membrane and acrosome integrity, mitochondrial membrane potential and sperm abnormalities. Data were analyzed by repeated measures MIXED PROC in SAS. Average outside ambient temperature during the pre-treatment, treatment, and post-treatment periods was -13 (-31 to 1), 0.5 (-18 to 19), and 21 (13-28) °C. Plasma prolactin decreased markedly during treatment (-52.4%; Experimental period p < 0.01). Rectal temperature increased during the treatment and post-treatment periods (EP p < 0.01) but was within the normal physiological range. Bull weight increased during the study (EP p < 0.01). Scrotal circumference in low ergot group increased during treatment (+0.8 cm; Tx∗EP p = 0.05). Progressive motility in high ergot group decreased during treatment (-7%; Tx∗EP p = 0.05), however, semen volume and sperm concentrations were unaffected (p ≥ 0.11). Live sperm with high and medium MMP decreased during treatment (-1.4 and -3.7%; EP p < 0.01). Results suggest that feeding ≤2227 µg ergot alkaloids/kg has only minor effects on adult bull semen quality.

Sustained low-dose ergot alkaloids minimally affect post-thaw sperm characteristics in mature and yearling Angus bulls.

Our objectives were to determine if feeding mature and yearling Angus bulls ergot alkaloids (from Claviceps purpurea) within the Canadian permissible limit (∼3 mg/kg) affect post-thaw sperm quality. In Experiment 1, mature Angus bulls were group-fed ergot alkaloids (∼1 and ∼2 mg/kg of daily dry matter intake, DMI; n = 8 and n = 6 bulls, respectively) for 61 d; semen was collected and cryopreserved bi-weekly, from 12 wk pre-exposure to 10 wk post-exposure. In Experiment 2, yearling Angus bulls (12-13 mo) were individually fed placebo or ergot alkaloids (3.4 mg/kg of DMI; n = 7 bulls/group) daily for 9 wk, with semen collected and cryopreserved once weekly, from 5 wk before to 9 wk after exposure. All frozen semen was assessed 0 and 2 h post-thaw. In Experiment 1, post-thaw total and progressive sperm motilities decreased (P ≤ 0.05) from pre-exposure to exposure period, then returned to pre-exposure level. Likewise, during exposure, VAP and VSL decreased (P ≤ 0.01) at 0 h compared to pre-exposure and subsequently returned. Live sperm with intact acrosomes at 2 h post-thaw was affected by ergot (P = 0.01). Medium mitochondrial membrane potential increased (P ≤ 0.01) during exposure compared to pre-exposure and subsequently decreased. In Experiment 2, total and progressive sperm motilities at 0 and 2 h increased (P ≤ 0.01) throughout the study. During post-exposure, VCL, VAP and VSL at 0 h increased (P ≤ 0.01) whereas VSL at 2 h increased (P ≤ 0.01) from pre-exposure to exposure to post-exposure. Live sperm with intact acrosomes increased (P ≤ 0.01) at both 0 and 2 h during post-exposure. Medium mitochondrial membrane potential increased (P ≤ 0.01) from pre-exposure to exposure, followed by a slight decrease post-exposure. Mature Angus bulls partially supported our hypothesis, with only transient effects of ergot on sperm motilities and velocities. Post-thaw sperm characteristics in yearling bulls underwent expected age-related improvements, with any effects of ergot alkaloids potentially masked by sexual maturation. Overall, results partially supported our hypotheses that ergot has no detectable adverse effect on post-thaw sperm characteristics in mature and yearling bulls.

Feeding yearling Angus bulls low-level ergot daily for 9 weeks decreased serum prolactin concentrations and had subtle effects on sperm end points.

Our objective was to determine whether feeding yearling bulls with the higher recommended Canadian limit of ergot alkaloids (∼3 mg/kg dry matter intake, DMI) would affect sperm characteristics and plasma prolactin concentrations. Aberdeen Angus bulls (12-13 mo old, n = 7/group) allocated by blocking for sperm concentration and body weight, were fed placebo or ergot alkaloids in gelatin capsules (60 µg/kg body weight daily, 3.4 mg/kg of DMI) for 9 wk. Semen samples were collected weekly by electroejaculation and examined with a computer assisted semen analyzer (CASA) and flow cytometry, for the intervals 5 wk before (Pre-exposure period), 9 wk during (Exposure period) and 9 wk after (Post-exposure period) treatment. Weekly plasma samples were analyzed for prolactin by radioimmunoassay. Plasma prolactin concentrations decreased markedly (mean ± SEM, 16.74 ± 3.70 in Exposure and 33.42 ± 3.08 ng/mL in Post-Exposure periods; P < 0.01) compared to Control (67.54 ± 21.47 and 42.59 ± 15.06 ng/mL). Treatment did not affect (P ≥ 0.17) body weight gain, sperm concentration, sperm count/ejaculate, motility or percent live sperm. Averaged over the exposure and post-exposure durations, the scrotal circumference was smaller (P = 0.02) by 2.7% in the Ergot group. Progressive motility remained unchanged from 59.92 ± 2.31% in Exposure to 59.61 ± 2.59% in Post-Exposure periods, compared to marked increase in Control (61.42 ± 1.60% to 67.52 ± 1.47%; P = 0.02). Straight-line sperm velocity decreased (-3.15 ± 1.53 µm/s) from exposure to post-exposure periods in Ergot group (P = 0.04) versus an increase (2.96 ± 2.17 µm/s) in Control. Midpiece defects decreased from Exposure to Post-exposure periods in Control group but remained unchanged in Ergot group (trt∗age, P < 0.01). Ergot feeding resulted in a smaller proportion of sperm with medium mitochondrial potential (Ergot: 22.65 ± 0.98%, Control: 24.35 ± 1.05%, P = 0.04). In conclusion, feeding ergot at Canadian permissible limit for 9-wk resulted in a 4-fold decrease in plasma prolactin concentrations. Semen end points were not significantly affected, although there were subtle effects on progressive motility, midpiece defects and mitochondrial membrane potential. Clinical relevance of observed changes requires further evaluation. Results supported our hypothesis that prolonged low-level ergot will adversely affect plasma prolactin. However, semen parameters were partially affected, supporting similar work on fescue toxicosis.

A retrospective study of canine strychnine poisonings from 1998 to 2013 in Western Canada.

This study describes observations related to 93 cases of strychnine poisoning in dogs over a 16-year period in Saskatchewan, Alberta, and Manitoba. Epidemiological information describing age, gender, breed, and size of the dogs, geographical distribution of poisonings, and strychnine concentrations in tissue matrices were tabulated. The mortality in dogs poisoned with strychnine was 60.2%. Strychnine poisoning cases varied by year (P = 0.0012) and by season (P = 0.0005). The highest number of confirmed cases occurred in years 2000 and 2001. Poisonings occurred most frequently during the spring. There were no statistical differences related to age or gender, but older, male dogs appeared to be more commonly affected. Large dog breeds were most commonly affected. Strychnine was detected in multiple tissue matrices, including stomach contents, liver, urine, vomitus, and gastric washings. The study indicates that strychnine poisoning in the dog remains a common toxicosis in western Canada.

Étude rétrospective des empoisonnements canins à la strychnine de 1998 à 2013 dans l'Ouest canadien. Cette étude décrit les observations se rapportant à 93 cas d'empoisonnement à la strychnine chez des chiens pendant une période de 16 ans en Saskatchewan, en Alberta et au Manitoba. Des renseignements épidémiologiques décrivant l'âge, le sexe, la race et la taille des chiens, la répartition géographique des empoisonnements et les concentrations de strychnine dans les matrices des tissus ont été compilés. La mortalité des chiens empoisonnés à la strychnine était de 60,2 %. Les cas d'empoisonnement à la strychnine variaient selon l'année (P = 0,0012) et selon la saison (P = 0,0005). Le nombre le plus élevé de cas confirmés s'est produit en 2000 et en 2001. Les empoisonnements se produisaient le plus fréquemment au printemps. Il n'y avait pas de différences statistiques reliées à l'âge ou au sexe, mais les chiens mâles âgés semblaient être le plus fréquemment touchés. Les chiens de grande race étaient le plus souvent affectés. La strychnine a été détectée dans des plusieurs matrices de tissus, notamment le contenu de l'estomac, le foie, l'urine, les vomissures et les lavages gastriques. L'étude indique que l'empoisonnement à la strychnine chez le chien demeure une toxicose commune dans l'Ouest canadien.(Traduit par Isabelle Vallières).