Anderson Saravia

This study evaluated the effects of dietary magnesium sulfate (MgSO₄) addition in twin-bearing ewes during late gestation on the duration of lambing, neonatal behavior, and blood biochemical variables. Fifty-one hogget and 54 adult Finnish × Polwarth ewes were allocated to four groups based on age category (hogget or adult) and dietary addition (MgSO₄ addition or control). Ewes in dietary MgSO₄ treatments received 7 g of MgSO₄/ewe/day. Duration of the expulsion phase (DII), interval between lamb births (IL), and total lambing time (TL) were recorded. Meconium score (0–3), birth weight, time to stand (TS), time to first successful suck (SS), and rectal temperature at birth (T0) and at 3 h of life (T3) were measured. Blood samples were collected from lambs and analyzed for blood biochemical and acid–base variables. MgSO₄ addition did not affect individual or litter birth weight (p > 0.05), but the DII was lower in the lambs from MgSO₄ ewes (p < 0.05). A greater proportion of lambs born to dietary MgSO₄ ewes had higher meconium scores. The treatment did not affect the acid–base variables (p > 0.05); however, the age category had an effect on BEecf, HCO₃⁻, tCO₂, lactate and glucose, and behavior variables (p < 0.05). Acidosis (pH < 7.20) occurred in lambs from control ewes. No differences were observed in T0, but lambs from control hoggets had lower T3 values (p < 0.05). In conclusion, in our conditions, dietary MgSO₄ addition in twin-bearing ewes during late gestation reduced the duration of the expulsion phase without affecting neonatal behavior or the main indicators of neonatal acid–base status. Further studies are needed to elucidate the mechanisms by which MgSO₄ influences the lambing process.

The New World screwworm fly, Cochliomyia hominivorax, represents a major threat to livestock production in several regions of the Americas. The objective of this study was to evaluate the effectiveness of three trap types for C. hominivorax surveillance. The study was conducted in Uruguay (32° S), in area with a known natural presence of C. hominivorax. NZI, NZI-M (a modified version designed to optimize capture efficiency), and vertical sticky traps (VST) were used, all baited with baited with Swormlure-4 (SL-4). A Latin square design was applied, testing each trap at four sampling sites (forest edge, near watercourses, pastureland, and near livestock corrals), rotating twice through each site over three consecutive days. This design was repeated across the four seasons of the year. Sampling points were separated by more than 1,200 m to ensure independence of captures. A total of 96 blowflies (Calliphoridae) were collected, of which 15 were identified as C. hominivorax (15.6%). Seven, five, and three screwworm flies were captured using NZI, NZI-M, and VST traps, respectively. C. hominivorax was captured during autumn (11/15) and summer (4/15), with no differences among sampling sites. The NZI and NZI-M traps baited with SL-4 showed potential as effective tools for C. hominivorax surveillance in comparison of VST trap, allowing the recovery of well-preserved specimens suitable for taxonomic and molecular identification.

The Tabanidae fauna of Uruguay has historically received limited attention, with most records dating from the 19th and early 20th centuries and concentrated near Montevideo. Here, we provide an updated synthesis of the Uruguayan Tabanidae fauna based on a comprehensive review of the literature, examination of historical material, recent field surveys, and validated records from citizen science. We recognized 52 valid species in 15 genera and six tribes, representing approximately 1% of the world diversity of the family. Four species are currently considered to be endemic to Uruguay. Since the last national revision, species richness has increased by 12%, largely through overlooked bibliographic records, the re-examination of museum specimens, and new distributional data. The fauna is dominated by the subfamily Tabaninae, particularly the tribes Diachlorini and Tabanini, whereas Pangoniinae is poorly represented. Males are described for 62% of the species, but immature stages are known for fewer than 20%, highlighting significant gaps in knowledge. Distributional data reveal a strong spatial bias: nearly half of the species are known from a single department, and four departments still lack records. A comparison with the Brazilian Pampa suggests that only slightly more than half of the species are shared, indicating that the regional fauna remains incompletely documented. Primary-type specimens are predominantly housed in European institutions, reflecting the historical development of Neotropical dipterology and the absence of resident specialists. Overall, our results suggest that the apparent modest diversity of Uruguayan Tabanidae likely reflects historical sampling bias, rather than true faunal impoverishment. Expanded field surveys and integrative taxonomic approaches are essential to clarify species limits, document immature stages, and better understand the biogeography of horse flies in the Pampa biome.

Stomoxys calcitrans (Linnaeus, 1758), the stable fly, is a hematophagous pest that affects animal livestock worldwide by lowering productivity and mechanically transmitting pathogens. This study evaluated the effectiveness of the Nzi trap and a modified version (with and without bait) for capturing stable flies on two dairy farms in southwestern Uruguay, under conditions of natural infestation by these flies. The study used a 4 × 4 Latin square design with five replicates conducted independently at each dairy farm. Traps at each dairy were emptied daily to identify and count stable flies before being rotated and reset at the next planned location. Among all configurations, standard Nzi traps captured the highest number of S. calcitrans compared to the other trap evaluated, regardless of whether an attractant was used. This study represents the first evaluation in South America of Nzi traps for S. calcitrans used in combination with a commercial bait. Findings indicate that Nzi traps are a potentially effective tool for capturing S. calcitrans at dairy farms.

In April–June 2017, a cluster of 4 third-trimester abortions caused by Coxiella burnetii was diagnosed on a dairy farm with 356 Holstein cows in Uruguay. We investigated 1) the seroprevalence of C. burnetii in cows delivering normal calves in this herd, 2) whether non-aborting cows gave birth to seropositive and/or PCR-positive newborn calves in the year of the abortion cluster, and 3) whether seronegative newborn calves seroconverted after ingesting colostrum replacer. In March–September 2017, serum samples were collected from 133 calving cows and their calves immediately after birth and before colostrum ingestion. All 266 sera were analyzed for anti– C. burnetii IgG by ELISA. Additionally, 179 blood samples from some of these animals (82 cows, 97 calves) were PCR-tested for C. burnetii DNA. Thirty of the 133 (22.5%) cows delivering normal calves were seropositive at parturition; 4 of 82 (4.9%) were PCR-positive. All calves tested at birth by ELISA and PCR were negative. Our results suggest that congenital infection is not an important route of C. burnetii transmission to live-born calves in this herd. We observed that 76 of 80 (95%) seronegative newborn calves in 2021 became seropositive for anti– C. burnetii IgG at 24-h-old after drinking an imported commercial colostrum replacer, which could confound seroepidemiologic surveys in herds using colostrum replacers.

Surveillance and diagnostics are critical for the early detection, containment and eradication of exotic pests. For the screwworm fly, this is usually via targeted surveillance and exclusion testing of trap‐caught flies, as well as the identification of larvae associated with myiasis wounds. We present a specific and sensitive real‐time polymerase chain reaction (PCR) assay for the detection of the New World screwworm fly, Cochliomyia hominivorax Coquerel (Diptera: Calliphoridae). The assay targets the cytochrome oxidase subunit 1 ( cox1 ) gene from adult flies or larvae and retains high analytical sensitivity when multiplexed with an existing assay for the Old World screwworm fly, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae), achieving a limit of detection of less than 1 copy per microlitre of reaction. To assess its utility for surveillance and diagnostics, a novel non‐destructive DNA extraction method was performed on spiked trap catches of field‐caught flies, and on boiled and unboiled specimens of larval instars. The multiplexed assay detected 95% of spiked flies, and all screwworm flies from positive samples were retrieved and morphologically identified. Results from larval instars confirmed that the assay can be used for larvae, with higher sensitivity observed for unboiled larval instars. This molecular assay enables the simultaneous detection of Co. hominivorax and Ch. bezziana , offering a reliable alternative to existing single‐target and destructive methods of bulk fly testing. It also holds potential for broader application in the identification of larval stages.