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Crops contamination with aflatoxins (AFs) and zearalenone (ZEA) threaten human and animal health; these mycotoxins are produced by several species of Aspergillus and Fusarium. The objective was to evaluate under field conditions the influence of the wet season on the dissemination of AF- and ZEA-producing fungi via houseflies collected from dairy farms. Ten dairy farms distributed in the semi-arid Central Mexican Plateau were selected. Flies were collected in wet and dry seasons at seven points on each farm using entomological traps. Fungi were isolated from fly carcasses via direct seeding with serial dilutions and wet chamber methods. The production of AFs and ZEA from pure isolates was quantified using indirect competitive ELISA. A total of 693 Aspergillus spp. and 1274 Fusarium spp. isolates were obtained, of which 58.6% produced AFs and 50.0% produced ZEA (491 ± 122; 2521 ± 1295 µg/kg). Houseflies and both fungal genera were invariably present, but compared to the dry season, there was a higher abundance of flies as well as AF- and ZEA-producing fungi in the wet season (p < 0.001; 45.3/231 flies/trap; 8.6/29.6% contaminated flies). These results suggest that rainy-weather conditions on dairy farms increase the spread of AF- and ZEA-producing Aspergillus spp. and Fusarium spp. through houseflies and the incorporation of their mycotoxins into the food chain. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the potential methane gas production from corn silages (CS) intended for Holstein cattle in dairy farms in the state of Aguascalientes (Ags), Mexico. Design/Methodology/Approach: Methane (CH4) is one of the greenhouse gases, and worldwide plans and actions are being developed to monitor, control, and reduce their environmental impact. In Mexico, methane emissions from livestock are equivalent to 10.1% of CO2 equivalent are recorded. CS samples were collected from six municipalities in Ags, representing a total of 18 dairy farms. The in vitro gas production technique was used to determine methane gas production, employing a nested mixed model to compare variables between municipalities using residual maximum likelihood method. Results: The average methane production in CS was 29.3 mL/gDM. The Ags municipality showed significantly higher methane production (35.9 mL/gDM, p<0.05), while San Francisco de los Romo (SFR) displayed the lowest production (21.5 mL/gDM, p<0.05). In the state of Aguascalientes, CS-derived CH4 production was projected at approximately 2,884 metric tons (MT) annually. Study Limitations/Implications: There were no identified limitations in the study. Findings/Conclusions: The potential CH4 gas production derived from CS projected in the study represented 0.103% of what was reported by INEGyCEI in 2019. [ABSTRACT FROM AUTHOR]

This work presents a pH control approach, robust to model uncertainties including the scaling-up process. The algorithm is based on a master-slave synchronization, where the real process is taken as the slave, and the master is generated by the real-time simulation of the closed-loop mathematical model of the process. In that sense, the objective is to control the pH value, under minimal process information and subject to perturbations and time-varying references ranging between the basic and acid regions, at laboratory and industrial scales. [ABSTRACT FROM AUTHOR]

Simple Summary: The brown dog tick is cosmopolitan with medical and veterinary importance. Control with acaricides is the commonly used alternative; however, its indiscriminate use can generate resistance. A discriminant dose (d.d) can be used to rapidly and inexpensively identify resistant populations in samples collected in the field; however, to date, there is limited information on the subject. This study aimed to determine the d.d of amitraz to identify resistance in larvae natives from Mexico and to evaluate its application in field-collected ticks. Because there was no reference strain, the search for samples susceptible to amitraz was carried out in naturally infested rural dogs using a larval immersion test (LIT); the d.d. was determined as a consensus value by multiplying the LC99 × 2, and then, we proceeded to evaluate it in in-field samples by using the LIT technique. The d.d. calculated was 4 ppm. The in-field evaluation found 64% of the samples resistant to amitraz, with mortality percentages between 98.3% and 0.35%; these samples were widely distributed in all the areas of study. With this, bases are established so that scrutiny can be initiated in order to document amitraz resistance in field populations. The brown dog tick, Rhipicephalus sanguineus s.l., is considered the most widely distributed three-host tick in the world and has medical and veterinary importance; the control of infestation is carried out with acaricides, towards which it can develop resistance. This study aimed to determine the discriminant dose (d.d) of amitraz to identify resistance in R. sanguineus s.l. larvae natives from Mexico and to evaluate its application in field-collected ticks. Engorged ticks were collected from naturally infested dogs residing in rural communities and were incubated for 25 days, and their progeny was used in a larval immersion test (LIT) to be exposed to the d.d. determined in Rhipicephalus microplus, and those that were susceptible were analyzed using the LIT in six concentrations. Mortality was analyzed through probit methodology to calculate the lethal concentration (LC) 50 and 99. The d.d. was determined as a consensus value by multiplying the LC99 × 2, and then, we proceeded to evaluate it in in-field samples by using the LIT technique. The d.d. calculated was 4 ppm. The in-field evaluation found 64% of the resistant samples to amitraz with mortality percentages between 98.3% and 0.35%. This dose can be used to rapidly and inexpensively identify resistant populations in samples collected in the field. [ABSTRACT FROM AUTHOR]

Objective: The aim of the present study was to evaluate the effect of the temperature-humidity index (THI), the content of neutral detergent fiber (NDF), and rumination rate (RR) on milk production in Holstein cows in a dairy farm located in Bajío de San José, Jalisco, Mexico. Design/methodology/approach: The THI is an indicator of the effect of the environmental climate can have on milk production, and likewise the nutritional content of forage is affected by weather conditions, such as the NDF is related with rumination activity of cows; increasing THI has shown a direct effect on milk production in cows. The HealthyCow 24® CSR remote equipment was used (SCR Engineers Ltd., Netanya, Israel), to monitor rumination, from a total registry of 284 cows with 2, 3, and 4 lactations distributed between August and December 2020 period, analyzing the NDF content from total mixed portion and monitoring the THI. Results: The results showed there was no effect of THI on milk production (p>0.05), despite having reached a THI score of 76, while NDF (p<0.05) and RR (p<0.001) affected milk production; an effect of THI on RR (p>0.05) was not found, and the NDF only had a trend (p<0.1). Limitations on study/implications: There were no limitations for the study. Findings/conclusions: According to the results obtained, the THI threshold should be reconsidered according to the resistance of the productively active cattle on dairy farms. [ABSTRACT FROM AUTHOR]

The horn fly Haematobia irritans is a cosmopolitan hematophagous ectoparasite of great importance in livestock. In Mexico, H. irritans is distributed across the country, and is found during the whole year. The fluctuation of H. irritans population is related with climate conditions. Despite its wide distribution, the effects on animal health, and its negative impact on meat and milk production, little data exists on its infestation and epidemiology is limited. This paper is a review on the current situation of H. irritans in cattle in Mexico, its economic impact, control methods, perspectives, and research opportunities. [ABSTRACT FROM AUTHOR]

The annual infestation pattern of R. sanguineus sensu lato (Latreille) was studied for dogs in a tropical sub-humid region of Mexico. Infestation was monitored for a year at five veterinary clinics in different parts of the urban area of Colima City, Mexico. Dogs were considered positive for infestation when at least one specimen of any stage of the parasite was identified by physical search. R. sanguineus occurred throughout the year, with 21.4% average (446/2083; 95% C.I. 19-23) and infestation ranging from 17% in January to 29% in May. Seasonal distribution was homogeneous: spring 22.2% (96/432), summer 21.5% (103/477), autumn 21.4% (132/616), and winter 20.6% (115/558). No correlation was found between seasonal prevalence and weather during a season (p > 0.01). Tick specimens and all parasitic stages were found throughout the year. There were more larvae in March to June, September, and November; nymphs in March to May and December; and more adults in January, February, July, and October. Activity of each stage of ticks where dogs are always available indicated that R. sanguineus develop at least three generations per year. [ABSTRACT FROM AUTHOR]

Objective. Assess the efficacy of Metarhizium anisopliae strain 135 (Ma135) applied by aspersion to reduce simultaneous infestation of Haematobia irritans and Stomoxys calcitrans in naturally infested cattle maintained in a production system which combine grazing and confinement in pens. Materials and methods. Was applied an aqueous formulation of Ma135 (1x108 conidia/ml) on a nine cows group in six occasions with seven days interval, while the control group received the same formulation without conidial content. The infestation index was estimated daily for each fly independently; the effectiveness of the formulation was calculated using the Abbott's formula. Results. The Ma135 formulation had a reduction in the fly population of 58% for H. irritans and 69% for S. calcitrans, taking into consideration the six study weeks, in addition to causing no negative effects on animal health. An Infestation index reduction was observed from the first week post-treatment (p<0.05) and maintained this trend throughout the study. Conclusions. The present study has demonstrated the potential of strain Ma135 to reduce the simultaneous infestation of both hematophagous flies in cattle under conditions of natural infestation. [ABSTRACT FROM AUTHOR]

Virulence of 10 isolates of entomopathogenic fungi native to Mexico and their effect on reproductive behavior were evaluated in nonfed larvae and engorged females of R. sanguineus sensu lato (Latreille). Virulence was evaluated by immersion in a concentration of 1 x 108 conidia per milliliter, while checks received the same aqueous formulation but without conidia. Reproductive potential was determined by calculating Reproductive Efficiency Index (eggs laid per engorged female weight) and Reproductive Aptitude Index (eggs hatched as larvae per engorged female weight). Results of bioassays on nonfed larvae showed that 40% of the isolates were able to kill ≥90% at 20 days post-treatment. Isolate Metarhizium anisopliae (Metchnikoff) Sorokin 135 with an LC50 of 1 x 106 killed 97%, while Beauveria bassiana (Bals.-Criv.) Vuill. Bb154 with an LC50 of 8 x 106 killed 90%. In engorged females, 70% of isolates killed ≥90% at 15 days post-treatment; isolate Bb154 reduced egg oviposition 83% and hatchability 96%. The isolates should be considered potential biological control agents for R. sanguineus. [ABSTRACT FROM AUTHOR]

Background: This work studied the natural infection of Neospora caninum during the first gestation of heifers in a dairy farm in animals consuming a ration contaminated naturally with Zearalenone (ZEA), and to find out effect of mycotoxin in the levels of estrogen (E) and progesterone (P4) and that's relation to the infection to N. caninum and in the abortions. Methods: The study was conducted in a dairy farm located in El Llano municipality, in Aguascalientes, Mexico, in 2013. Two groups were formed, the group "A" with 20 seronegative animals to N. caninum, and group "B" with 20 seropositive. Once a month was determined the levels of total IgG to N. caninum, the serum concentration of E and P4, and the level of ZEA in the ration; in cases of abortion, fetal brain samples were taken to identify the presence of N. caninum DNA. Results: In group "A", was observed two subgroups: seronegative (60%) and seroconverted (40%), and three abortions. In group "B", all animals maintain their serostatus, and three animals aborted. All abortions were positive for N. caninum DNA. The level of ZEA in the ration has an average of 426 μg/kg; during the gestation did not identify that animals suffer any alteration in the levels of E or P4. No statistical differences among the studied variables (levels of E and P) in time (nine months of gestation) were detected. It was not identified any interaction with the natural exposure to ZEA intake in any of the groups under study. Conclusion: The chronic ingestion of ZEA does not affect serum concentrations of E and P4 during gestation of heifers under study and cannot be related to the infection for N. caninum and the abortion. [ABSTRACT FROM AUTHOR]