Experimental oral administration of pollen beetle (Astylus atromaculatus) to cattle results in an acute lethal gastrointestinal disease.

In the summer of 2023, ingestion of Astylus atromaculatus (pollen beetle) was linked to spontaneous fatal disease in grazing cattle and sheep in Argentina and Uruguay. While the disease was experimentally reproduced in sheep and guinea pigs in the 1970's, no experimental reproductions have been attempted in cattle, and controversy exists as to whether this insect is indeed noxious to cattle and at which dose. Here, we demonstrate that A. atromaculatus causes acute fatal disease in Hereford calves at single oral dosages of 2.5, 4.5, 10.0, and 15.0 g of insect/kg body weight. Death or severe disease necessitating euthanasia occurred at 38 to 48 hours postinoculation regardless of the dose, suggesting that the single fatal dosage is likely <2.5 g/kg body weight (this dose representing approximately 850 mL of intact beetles in a 100 kg calf). Clinically, the disease was characterized by acute anorexia, prolonged recumbency, reluctance to move, listlessness/apathy, depression, ruminal hypomotility and tympany, hypothermia, bruxism with frothing at the mouth, and mucoid diarrhea progressing to death. Hematologic and biochemical alterations included hemoconcentration, stress/acute inflammatory leukogram, negative energy balance, and ketosis. The pathological hallmark of this experimental disease is acute necrotizing omaso-reticulo-rumenitis, fibrinohemorrhagic enteritis, and exfoliative colitis with intralesional chitinous insect fragments. While A. atromaculatus might contain a gastrointestinal toxin or pathogen, extensive toxicological testing failed to identify a causative toxin. Other pathomechanisms such as direct physical damage caused by insect fragments on the alimentary tract seem plausible, although further studies are needed to elucidate the pathogenesis of A. atromaculatus-associated disease.

Characterization of Raid Hipico Uruguayo Competencies by Ride Type: Causes of Death and Risk Factors.

RHU is the oldest endurance sport in Uruguay. However, despite 80 years of racing, there are no studies to characterize this type of competition, explore rates and causes of death, and identify the associated risk factors. The aim was to characterize the Raid Hipico Uruguayo (RHU) competencies according to the distance (short (SR, 60 km) vs. long (LR, 80-115 km)), the causes of deaths, and the associated risk factors. The study population comprised horses (n = 16,856) that participated in RHU rides from 2007 to 2018. LR were more frequent than SR (p < 0.001). The average speed of winners was higher in SR (32.12 km/h) than in LR (28.14 km/h) (p < 0.001). There were 99 fatalities (5.9 per 1000 starts). SR had greater frequency of high comfort index (CI = Temp [°F] + Humidity [%]) than LR, and LR had greater frequency of low CI than SR (p < 0.001). The percentage of inexperienced horses and those who completed the ride was greater in SR than in LR (p < 0.001). In both types of rides, more horses died during than after the ride, and inexperienced horses were more likely to suffer fatalities than horses with prior experience in the sport (p < 0.05). SR were associated with increased risk of sudden death, while LR were associated with increased risk of death due to metabolic alterations. The high fatality index shown in this work warrants urgent investigation in this sport to minimize mortality associated with RHU-specific diseases.

Clinical disease incidence during early lactation, risk factors and association with fertility and culling in grazing dairy cows in Uruguay.

This paper aims to describe clinical disease incidence in early lactation and explore its association with fertility and culling in 13 commercial grazing dairy herds in Uruguay. Seven farms with less than 250 dairy cows considered small herds (SH) with a herd size average ± (SD) of 144 ± (56) cows and six farms with more than 500 cows considered large herds (LH) with a herd size average ± (SD) of 830 ± (239) cows were selected. Herd managers recorded health events during the first 90 days in milk in 5375 Holstein dairy cows [24.5% (n=1316) of them were primiparous cows, (PP)] during one year. Overall, 36.5% (n=1959) of the cows had at least one clinical health event between 1-90 days in milk. The cumulative incidences were 2.2% for twin birth and 4.9% for stillbirth. Cumulative incidence was 4.4% for retained placenta-metritis (RP-metritis), 27.6% for clinical mastitis and 5.0% for lameness. Our data showed that parity and herd size were risk factors for postpartum disease in grazing dairy herds. In PP cows, stillbirth incidence was higher than in multiparous (MP) cows (PP=6.9 ± 3.4, SD vs. MP=4.3 ± 2.6, SD), while in MP cows twin births (MP=2.7 ± 1.7, SD vs. PP=0.7 ± 2.7, SD), RP-metritis (MP=4.6 ± 3.9, SD vs. PP=3.8 ± 3.7, SD) and mastitis incidence (MP=30.9 ± 11.4, SD vs. PP=17.2 ± 13.9, SD) was higher. Clinical mastitis (LH=29.4 ± 9.6, SD vs. SH=19.1 ± 11.3, SD) and lameness incidence (LH=5.6 ± 1.9, SD vs. SH=2.3 ± 2.1, SD) was higher in large herds than in small herds. RP-metritis was increased by stillbirth (OR=4.4, 95 % CI=2.9-6.5) and twin birth (OR=2.8, 95 % CI=1.5-5.1). Diseases had a negative impact on time to first service and pregnancy rate and increased culling hazard rate. Disease incidence in early lactation was high and showed a wide variation among herds (10.4%-48.7%), which highlights the relevance of a herd health program prioritizing the early lactation disease control.

Endocrine and reproductive parameters in sick and healthy primiparous and multiparous dairy cows.

To investigate the association of health status and parity with hormone profiles during the transition period and reproductive parameters in Holstein dairy cows, a prospective observational cohort study was carried out including only healthy primiparous (PP, n = 116) and multiparous (MP, n = 172) cows at the beginning of the study. A subset of 120 healthy and sick cows was randomly selected for insulin, IGF-I, leptin and adiponectin determination. Primiparous cows had greater IGF-I and adiponectin concentrations (P < 0.05) and tended (P=0.07) to have greater insulin concentrations than MP cows. While healthy and sick MP and sick PP cows presented a sharp decrease in IGF-I concentrations after calving, healthy PP cows maintained them. Postpartum adiponectin concentrations were lower in sick than in healthy MP cows. A greater percentage of healthy cows ovulated during the first 7 weeks after calving when compared to sick cows (67.9% vs 50%, P=0.002) and a similar trend was found for MP vs PP cows (64% vs 53%, P=0.01). More healthy cows were inseminated in comparison to sick cows (94% vs 76.5%, P < 0.01) and more PP than MP cows (90.4% vs 82.7%, P < 0.05). Similarly, healthy cows presented a greater proportion of pregnancy than sick cows (75% vs 54%, P < 0.01) and the proportion of pregnancy was higher in PP than in MP cows (74% vs 56%, P=0.04). Health status interacting with parity yielded different endocrine profiles, which may partially explain the differences in reproductive performance.

Metabolic predictors of peri-partum diseases and their association with parity in dairy cows.

The predictive values of plasma non-esterified fatty acid (NEFA), beta-hydroxybutyrate (BHB), cholesterol, albumin and calcium to predict risk of peripartum diseases in primiparous (PP) and multiparous (MP) Holstein cows was investigated. Besides it was assessed if the health status interacted with parity on body condition score and metabolic profiles during the transition period. Dairy cows (126 PP and 182 MP) from a commercial dairy free stall herd (loose-housing system) were weekly body condition scored and tail bled for metabolites determination from -3 to +4 weeks relative to calving. Peripartum diseases were diagnosed by a single trained veterinarian, while subclinical diseases (ketosis and hypocalcemia) were diagnosed at the laboratory. Cows were classified as healthy cows, cows with one event, or cows with two clinical events following a prospective observational cohort study, with only healthy cows enrolled at the beginning of the study. The largest incidence was for metritis (26.6%) followed by retained placenta (17.2%) and mastitis (15.2%) with no effect of parity, while subclinical hypocalcemia incidence was greater in MP than PP cows (43% vs 9.5%) respectively. In MP cows albumin concentrations were predictive for metritis at week -2 and for retained placenta at weeks -2 and -1, while cholesterol was predictive for mastitis at week -2, -1 and at calving. The interaction between health status and parity affected all metabolites during the transition period. This study showed a different evolution of metabolic profiles in healthy and sick cows during the transition according to parity, pointing out albumin and cholesterol as diseases predictors before calving.

Metabolic and endocrine profiles and reproductive parameters in dairy cows under grazing conditions: effect of polymorphisms in somatotropic axis genes.

BACKGROUND: The present study hypothesized that GH-AluI and IGF-I-SnabI polymorphisms do change the metabolic/endocrine profiles in Holstein cows during the transition period, which in turn are associated with productive and reproductive parameters. METHODS: Holstein cows (Farm 1, primiparous cows, n = 110, and Farm 2, multiparous cows, n = 76) under grazing conditions were selected and GH and IGF-I genotypes were determined. Blood samples for metabolic/endocrine determinations were taken during the transition period and early lactation in both farms. Data was analyzed by farm using a repeated measures analyses including GH and IGF-I genotypes, days and interactions as fixed effects, sire and cow as random effects and calving date as covariate. RESULTS AND DISCUSSION: Frequencies of GH and IGF-I alleles were L:0.84, V:0.16 and A:0.60, B:0.40, respectively. The GH genotype was not associated with productive or reproductive variables, but interaction with days affected FCM yield in multiparous (farm 2) cows (LL yielded more than LV cows) in early lactation. The GH genotype affected NEFA and IGF-I concentrations in farm 1 (LV had higher NEFA and lower IGF-I than LL cows) suggesting a better energy status of LL cows.There was no effect of IGF-I genotype on productive variables, but a trend was found for FCM in farm 2 (AB cows yielded more than AA cows). IGF-I genotype affected calving first service interval in farm 1, and the interaction with days tended to affect FCM yield (AB cows had a shorter interval and yielded more FCM than BB cows). IGF-I genotype affected BHB, NEFA, and insulin concentrations in farm 1: primiparous BB cows had lower NEFA and BHB and higher insulin concentrations. In farm 2, there was no effect of IGF-I genotype, but there was an interaction with days on IGF-I concentration, suggesting a greater uncoupling somatropic axis in AB and BB than AA cows, being in accordance with greater FCM yield in AB cows. CONCLUSION: The GH and IGF-I genotypes had no substantial effect on productive parameters, although IGF-I genotype affected calving-first service interval in primiparous cows. Besides, these genotypes may modify the endocrine/metabolic profiles of the transition dairy cow under grazing conditions.