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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 objectives of the study were to estimate the prevalence of anti-Toxoplasma gondii antibodies in free-range chickens in Aguascalientes, Mexico, its association with certain risk factors, and the frequency of parasite DNA in the heart. Eighty-one small rural family farms were included, and blood and heart samples were taken from 150 clinically healthy, adult, free-range chickens. Serum samples were processed by indirect immunofluorescence antibody test considering a dilution of 1:16 as a positive reaction, while the DNA detection was done by PCR. The correlation between the presence of antibodies and the potential risk factors was estimated with logistic regression. The overall seroprevalence in the examined populations was 67%, with a range from 33% to 100% among municipalities, and 78% of the farms having at least one seropositive bird. The PCR test identified the presence of parasite DNA for one case only. Among the variables, the presence of cats and the presence of other animal species on the farm were the ones that had the highest values, while the presence of feral cats and the presence of noxious fauna were also identified as potential risk factors. The results indicate high soil contamination by T. gondii oocysts, which implies the active role of cats living on the farms. [ABSTRACT FROM AUTHOR]

Aspergillus species can produce aflatoxins (AFs), which can severely affect human and animal health. The objective was to evaluate the efficacy of reducing AF contamination of a non-aflatoxigenic isolate of A. flavus experimentally coinoculated with different aflatoxigenic strains in whole plant (WP), corn silage (CS), immature grains (IG) and in culture media (CM). An L-morphotype of A. flavus (CS1) was obtained from CS in a dairy farm located in the Mexican Highland Plateau; The CS1 failed to amplify the AFs biosynthetic pathway regulatory gene (aflR). Monosporic CS1 isolates were coinoculated in WP, CS, IG and CM, together with A. flavus strains with known aflatoxigenic capacity (originating from Cuautitlán and Tamaulipas, Mexico), and native isolates from concentrate feed (CF1, CF2 and CF3) and CS (CS2, CS3). AF production was evaluated by HPLC and fungal growth rate was measured on culture media. The positive control strains and those isolated from CF produced a large average amount of AFs (15,622 ± 3952 and 12,189 ± 3311 µg/kg), whereas A. flavus strains obtained from CS produced a lower AF concentration (126 ± 25.9 µg/kg). CS1 was efficient (p < 0.01) in decreasing AF concentrations when coinoculated together with CF, CS and aflatoxigenic positive control strains (71.6–88.7, 51.0–51.1 and 63.1–71.5%) on WP, CS, IG and CM substrates (73.9–78.2, 65.1–73.7, 63.8–68.4 and 57.4–67.6%). The results suggest that the non-aflatoxigenic isolate can be an effective tool to reduce AF contamination in feed and to minimize the presence of its metabolites in raw milk and dairy products intended for human nutrition. [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]

This study, carried out in 13 sheep flocks of central-western Mexico, aimed to identify the prevalence of anti-N. caninum antibodies, to develop a risk analysis of the infection and to estimate the prevalence of parasite DNA in blood. A total of 368 serum and blood samples were subjected to ELISA and PCR tests, respectively, and the association between the prevalence of antibodies and some management factors was estimated. The overall prevalence of anti-N. caninum antibodies was 13.5% [50/368; 95% confidence interval (CI) 10–17], ranging from 2.7 to 90% per flock, and 92% of the farms had seropositive animals. In ewes the prevalence was 14% (48/348, 95% CI 10–17) and in rams 10% (2/20; 95% CI 1– 33). The mean prevalence of Neospora DNA in blood was 27% (99/368, 95% CI 22–31), implying a range between 16 and 82%. In rams, the prevalence was 5% (1/20 95% CI 2–26), while in ewes it was 28% (98/348, 95% CI 23–33). The agreement between the tests was k = 0.19. The presence of other domestic animal species in the farms [odds ratio (OR) 4.4] and the consumption of placental debris, fetuses and stillborn lambs by dogs living in the farms (OR 5.8) were demonstrated to be risk factors. [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]

The aim of this study was to determine the efficacy of the entomopathogenic fungus, Metarhizium anisopliae strain 134 (Ma134), for dairy cattle naturally infested with Haematobia irritans (L.) An aqueous formulation of 1 x 108 conidia/ml was applied by aspersion on a group of eight cows every seven days for a total of four applications, while a control group was sprayed with the same solution without conidial content. The degree of horn fly infestation was estimated daily in both groups by the direct count of adult flies found resting or feeding on the animals, and Abbott's formula was used to calculate the effectiveness of the formulation. The Ma134 formulation resulted in a 68.6 % reduction of the fly infestation during the study period, and a significant reduction was observed from the first week post-application (p < 0.05). The results show that the Ma134 formulation is effective in reducing infestations of horn fly, H. irritans, on dairy cattle under natural conditions. Thus, the fungus, Ma134, can be considered a candidate for biological control for the integrated management of H. irritans. [ABSTRACT FROM AUTHOR]

Objective. To determine the seroprevalence of N. caninum antibodies and prevalence of parasite DNA in blood, and estimate the association between seroprevalence and the potential risk of some factors in beef cattle under grazing conditions in north-central Mexico. Materials and methods. Blood samples from 139 cows and only 10 bulls belonging to 13 farms were collected and evaluated by ELISA test to detect antibodies against N. caninum. Furthermore, to determine the presence of parasite DNA, nested PCR probe was performed on blood samples. Association between potential risk factors and seroprevalence was estimated. Results. Overall seroprevalence was 23% (35/149 samples), while the prevalence of parasite DNA in blood was 28% (42/149 samples). Of the 149 animals examined 28 (19%) were positive to both tests (25 cows and 3 bulls). Concordance between tests was k = 0.63. All herds had seropositive animals with positive parasite DNA detection in blood. The only risk factor identified was the presence of dogs (OR= 2.65). Conclusions. This study showed that bovine neospososis should be considered as an important infectious disease in north-central Mexico herds. Therefore, an epidemiological control should be taken into consideration to avoid the negative effect of this disease on mexican beef industry. [ABSTRACT FROM AUTHOR]

The aim of the study was to detect the DNA presence of N. caninum in naturally infected animals, at two moments of their first gestation and at parturition, as well as to record the presentation of abortions. Twenty females between 12 to 14 months of age, seropositive to ELISA test, were selected from a dairy farm with presence of this parasitosis. The females were artificially inseminated and blood samples were taken in the first and second third of gestation and during parturition; DNA was isolated and it was analyzed by a single tube nested PCR with specific primers. In the sampling corresponding to the first third of gestation, 7/20 positive cases were observed (35%), in the second 15/20(75%) and during parturition 10/20 positive cases (50%). From the total of the animals included in this study, three stayed negative to the test in the three samplings (15%), four were always positive (20%), eight were positive in the second sampling but negative in first (40%) and five were positive in the second and negative in first and the third sampling (25%). All animals remained seropositive during the study; four aborted in the last third of gestation. All the live born calves were seropositive to N. caninum. [ABSTRACT FROM AUTHOR]

The objective of the work was to study H. irritans population fluctuation in a cattle herd in Tecoman, Colima, Mexico. The cattle herd was visited weekly from March 2003 to May 2004; on each occasion, ten animals were randomly selected to estimate infestation by direct visualization method. Temperature and relative humidity (RH) were recorded daily. Population fluctuation was described and periods and population peaks were identified. Pearson's correlation analysis was calculated (P < 0.05) between temperature and RH, with fly average number per animal for each population period. H. irritans infestation had fluctuations, but with presence of flies all the year; the highest infestation was observed in summer, where two population peaks were present, with 236 and 120 flies per animal, respectively; the activity in autumn and winter also showed fluctuations and the population had an increment in spring, where a population peak could be observed, as well as at the beginning of the study (156 flies/animal) and at the end (323 flies/animal). In the first population period, a significant correlation coefficient (0.93) was found with temperature, similar situation was observed in the fourth period (-0.57); no significant coefficients were found in other population periods for the climatic factors in study. [ABSTRACT FROM AUTHOR]

With the aim to determine possible association between some management factors and seroprevalence to N. caninum infection in dairy cattle of Aguascalientes, Mexico, serum samples were collected from 381 Holstein cows distributed in 29 dairies located in eight of the eleven Aguascalientes municipalities. Samples were analyzed by ELISA test and association between seroprevalence and abortion history in the cows, replacement origin, presence of dogs living in dairies and disposal procedure for placental and fetal material was estimated. Overall seroprevalence was 57.5%, with different values between municipalities in a range from 22% to 67%. Seroprevalence in cows with history of abortions was 69%, while in non-aborted cows it was 48%; the prevalence ratio was 1.4 (P < 0.001), suggesting an association between abortion and seropositivity. Seroprevalence, according to the replacement origin (raised or purchased), was 57% and 58%, respectively; in reference to presence or absence of dogs it was 61% and 54%, respectively. Finally, in dairies that had or did not have disposal procedure program for placental and fetal materials, seroprevalence was that of 61% and 55%, respectively. It was not possible to detect association of seroprevalence with any of the last three factors. [ABSTRACT FROM AUTHOR]

This study investigated the effect of controlling stable flies (Stomoxys calcitrans) on the number of dairy cows lying down and their pen distribution. The study randomly assigned 80 Holstein cows to 1 of 2 groups. The treated group (T) included cows individually sprayed with insecticide when found with an average of 10 stable flies per cow; in the control group (C), cows received no application of insecticide. The pen had 4 equal-size areas: (a) feeding, (b) drinking and sunny, (c) covered, and (d) manure. The study recorded the number of cows lying and the area of the pen where the nonhuman animal was located. The study found no difference (p > .05) between the proportion of T and C cows lying. However, cows preferred to lie down in pen area 3 when fewer than 10 stable flies per cow were found. Area 4 was the most avoided section of the pen, except when a high incidence of flies was present. The study concluded that high populations of S. calcitrans (> 10 flies per cow) did not affect the number of dairy cows lying down. However, it modified site preferences for lying. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the degree of susceptibility to permethrin in stable fly populations, Stomoxys calcitrans, on dairy cattle in Aguascalientes, Mexico. Samples of adult stable fly populations, from sixteen dairies were exposed to two discriminating doses of permethrin in glass vials that represented the LD50 and LD99 (0.0014 µg/cm² and 0.0026 µg/cm², respectively) of a permethrin susceptible strain. Stable fly populations from all dairies proved to be susceptible to permethrin when compared with the reference strain. This is the first report in Mexico on the susceptibility of stable flies to any insecticide. [ABSTRACT FROM AUTHOR]

The objective of the present study was to investigate the repellence effect of M. minutiflora plant extracts on B. microplus larvae, and to identify the chemical compounds present in the extracts. The effect was evaluated by a repellence bioassay in an olfactometer using extracts from stems, leaves and whole plants treated with different organic solvents such as methanol, chloroform, hexane and acetone. The identification of the chemical compounds was carried out by a gas chromatography-mass spectrometry procedure using whole plant extract in acetone. The study demonstrated that all extracts evaluated showed a repellence effect that ranged from 43 to 90%. The best repellence percentages were observed from extracts obtained using acetone as the extraction solvent. Twelve chemical compounds were identified, the highest relative abundance corresponded to eicosane (18.53%), followed by methyl ester linolenic acid (16.08%) and hexadecanoic acid (14.20%). However, it is possible that the repellence effect was influenced by the additive action of all the compounds identified. [ABSTRACT FROM AUTHOR]

A dairy farm with 510 Holstein cows in milk production, in which insecticide was not applied throughout the study, was visited weekly from march 1999 to march 2001, selecting on each occasion ten percent of the dairy cows for adult horn fly counts on direct observation. Weekly average fly numbers per cow were calculated so as to identify periods corresponding to the first population increment, fluctuation, second increment and decrement. Pearson's correlation analysis was calculated (P < 0.01) between climatic factors and temperature, relative humidity and rainfall, as well as fly counts for each of the population periods. The highest number of flies per cow was observed near the population peaks, in summer -- fall, but this was never greater than 120 flies per cow. Adult flies were not observed from january to march. High correlation indices, 0.80 and 0.85, were found in the first temperature increase, and 0.68 and 0.71 for relative humidity, in each year studied. In the decrease, high correlation indices, 0.79 and 0.80, for temperature, were found. There was not a significant correlation with rainfall. The annual distribution of H. irritans infestation was most influenced by temperature, limiting or promoting the population periods identified. [ABSTRACT FROM AUTHOR]

The intestinal parasite Cryptosporidium spp. is highly infectious in wild and domestic animals and humans. Infection frequency in dogs can vary between rural and urban environments. Cryptosporidium spp. infection frequency was quantified in dogs on dairy farms and in an urban area in the state of Aguascalientes, Mexico, and some possible risk factors analyzed. Feces samples were collected from 168 dogs at 30 dairy farms distributed among the state's ten municipalities (rural), and from 144 dogs at the Aguascalientes municipal Animal Control, Care and Welfare Center (urban area). Fecal smears were stained with Kinyoun to identify and count parasite oocysts. A questionnaire was applied to gather information on factors that could increase infection risk, and a risk analysis run using logistic regression. Overall infection frequency was 20.5 % (64/312; CI95% 16-25). In farm dogs it was 30 % (51/168; 95% CI 23-38) and in urban dogs 9 % (13/144; 95% CI 5-15). Seventy percent (70 %) of the dairy farms had positive dogs, average number of dogs per farm was 5.6, and dog density per farm was 2 to 12. Diarrheic feces was the only identified risk factor for Cryptosporidium infection, in both urban dogs (OR, 3.2; 95% CI 1.06-9.79 P<0.03) and farm dogs (OR, 2.7; CI95% 1.36-5.49 P<0.001). Infection frequency was highest in farm dogs, suggesting a consequently higher probability of cross-infection in this type of environment. [ABSTRACT FROM AUTHOR]

Contamination of agricultural and livestock products with aflatoxins (AF) is distributed worldwide. AFs are toxic, carcinogenic, and immunosuppressive; however, in Mexico, there is little information about Aspergillus flavus, the main fungus that produces them. The objective was to characterize the molecular and morphological, aflatoxigenic isolates of A. flavus and quantify the AFs in the feed and in the milk of Holstein cows in Aguascalientes (Mexico). A dairy production unit (2,749 cows) was selected for reasons of convenience, and monthly samples of food ingredients and total mixed ration (n= 267), raw milk (n= 288), and agricultural soil (n =40) were collected during 24 months and were cultivated (in PDA) using the pour plate technique with serial dilutions. The fungi were characterized using SEM, TLC and vapors of ammonium in coconut agar; the genes of calmodulin and a regulator of the biosynthetic pathway of AF, as well as the region of the internal spacer of the transcript, were sequenced. AFs were quantified in feed with HPLC and in milk, using ELISA. A total of 283 fungal isolates were characterized molecularly; of which 88 proved to be Aspergillus spp. Five of these were A. flavus with an aflatoxigenic capacity, and one was non-aflatoxigenic. 99.3 % of the samples of feed and 39.9 % of the milk samples exhibited detectable levels of AF (14.8 and 0,021 µg/kg). The cows ate daily 621 µg of AF and eliminated 0.09 % as AFM1 in milk. This suggests that the occurrence of aflatoxigenic A. flavus in the feed of dairy cows leads to a widespread contamination of the diets and food chain with AF. [ABSTRACT FROM AUTHOR]

The cyst-forming protozoan parasite Neospora caninum is one of the main causes of bovine abortion worldwide and is of great economic importance in the cattle industry. Recent studies have revealed extensive genetic variation among N. caninum isolates based on multilocus microsatellite genotyping. Currently, the most extensive study reported is based on the N. caninum genotyping of 96 samples from four countries on two continents (Spain, Argentina, Germany and Scotland) that demonstrate different clusters of multilocus genotypes (MLGs) implicated in cattle abortions as well as the population sub-structuring of N. caninum, which is partially associated with the geographical origin. The aim of this study was to genotype N. caninum from aborted bovine foetuses that originated from Mexico within the region of Aguascalientes and to investigate their genetic diversity. Parasite DNA was detected in 27 out of the 63 analysed foetuses recovered from 10 different herds. Complete or nearly complete profiles based on 9 microsatellite markers were obtained from 11 samples. Diverse N. caninum MLGs were implicated in the occurrence of abortion in each herd. All of the Mexican MLGs differed from the MLGs previously determined for the Argentinean, Spanish, German and Scottish N. caninum populations. The Mexican MLGs failed to cluster by eBURST analyses. The MLG relationships using PCoA showed a close genetic relationship between the Spanish population and a portion of the Mexican population, but a more distant genetic relationship with the Argentinean genotypes. These results demonstrate the genetic diversity of N. caninum in the studied areas that differed from other populations of N. caninum around the world. [ABSTRACT FROM AUTHOR]

This study documents the presence of anti-Neospora caninum antibodies and their association with certain risk factors in 2 deer species from the central region of Veracruz State, Mexico. A total of 90 blood samples, 20 from temazate deer (Mazama temama) and 70 from white-tailed deer (Odocoileus virginianus), were taken from 3 farms, and serum samples were subjected to ELISA indirect test to detect N. caninum antibodies; the association between the serological status and the possible risk factors was then estimated. The overall presence of anti-N. caninum antibodies was 57.7% (52/90; 95% CI 46.9-67.9), with positive animals identified on all farms; in white-tailed deer it was 57% and in temazate deer 60%. Prevalence was higher in females than males. Adult animals had a higher prevalence than young ones. The risk analysis identified the age in the adult animal category (odds ratio 5.8) as being associated with the presence of anti-N. caninum antibodies. These results provide evidence of the significant contamination of oocysts in the environment and allow us to estimate the contribution of deer to the sylvatic cycle., (© American Society of Parasitologists 2024.)

The objective of this study was to describe the epidemiology of Toxoplasma gondii and Neospora caninum infection by estimating seroprevalence and its association with certain risk factors in goats from Aguascalientes, Mexico. A total of 150 blood samples was taken from 10 farms and serum samples were subjected to enzyme-linked immunosorbent assay indirect test to detect T. gondii and N. caninum antibodies; the association between seroprevalence and some potential risk factors was estimated through logistic regression analysis. The general seroprevalence for T. gondii was 12.6%, observed in the farms in a range of 6.6 to 60%, finding seropositive animals in 80% of them; for N. caninum the seroprevalence was 3.3% and in farms a range of 6.6 to 13.3% was identified and 30% of them had at least 1 seropositive animal. The coinfection was 0.66%. The risk analysis for T. gondii identified a history of abortions (odds ratio 9.25) as a factor associated with seroprevalence; for N. caninum, no risk factor was identified., (© American Society of Parasitologists 2023.)

Objective: To assess the prevalence of Mycobacterium bovis infection in cattle and wild ruminants (WRs) in a wildlife-livestock interface area (WLIA) of the Mexican highland plateau., Animals: 24,400 cattle from 793 herds (including 17,351 commercially slaughtered cattle) and 142 WRs (110 white-tailed deer [Odocoileus virginianus], 20 red deer [Cervus elaphus], and 12 North American elk [Cervus canadensis]) harvested via controlled hunting., Procedures: Cattle were serially tested for M bovis infection via caudal fold tuberculin and comparative cervical tuberculin tests during field surveillance. Carcasses of cattle and WRs were inspected for gross lesions; samples suggestive of tuberculosis were analyzed via histologic evaluation and mycobacterial culture (HMC). A PCR assay to detect Mycobacterium tuberculosis complex organisms was performed to confirm positive results of HMC., Results: WRs had inflammatory lesions in lungs and lymph nodes, although HMC results did not indicate M bovis infection. Eight cattle had positive results for both tuberculin tests, and 31 had positive results for HMC of grossly detected lesions; all were from 7 herds, and ≥ 1 cow in each herd had positive PCR assay results. These 7 herds were depopulated; adjacent herds and herds related via commerce were quarantined. Calculated true prevalence of M bovis infection was 0.86% (95% confidence interval, 0.24% to 1.49%) in cattle; M bovis was not detected in any WRs., Conclusions and Clinical Relevance: M bovis infection was present in cattle. Although transmission to WRs in this WLIA was not detected, diagnosis and prevention activities should be implemented and consolidated to prevent potential M bovis transmission between cattle and WRs.

The objective of this work was to study the reproductive behavior of two strains of R. (B.) microplus, one wild-caught (Native) and one reference strain (Media Joya) for two years, measuring the reproductive efficiency index (REI) and reproductive aptitude index (RAI). Engorged ticks from each strain were collected monthly from February 2002 to February 2004. These were weighed and kept in the laboratory until egg-laying. Oogenic masses were individually weighed and incubated until larvae emergence. REI and RAI were calculated from each sample, grouping ticks by weight in 100 mg range classes. An analysis of variance and Duncan's multiple rank tests were carried out on the data (P < 0.05). Pearson's correlation coefficients were estimated (P < 0.01) in order to determine the relationship between engorgement weight and the weight and number of laid and hatched eggs. The Native strain showed a higher engorgement weight than Media Joya strain. In both strains REI and RAI were similar in all weight classes; with a quadratic tendency in Media Joya and linear-quadratic in the Native strain (P < 0.05). Significant differences where observed when REI and RAI of both strains were compared along the duration of the study (P < 0.01) with the Native strain performing better in both indexes, including better performance during the dry season. All parameters studied showed highly significant correlation; eggs laid and eggs hatched were notably highly correlated, 0.94 and 0.91, for Media Joya strain and Native strain respectively.