Evidence of differentiation and population structure in Charolais cattle of Mexico.

Charolais is one of the most important beef cattle breeds in the world. In Mexico, it was introduced almost a century ago, and it has been suggested that particular breeding management and genetic material origin have caused a process of divergence among the current population. By a high-density SNP array genome-wide analysis, this study aimed to assess the proposed differentiation and population structure of local populations by genetic distances and structure approaches, and a European Charolais sample was included as a reference population. The differentiation statistics indicated that local populations exhibit moderate divergence, confirming a significant differentiation process between northeastern and northwestern Charolais populations (Fst≥ 0.043, D≥ 0.031). These results were strongly supported by PCA and structure analysis. Genetic isolation and low genetic flow between populations and divergent origins of introduced genetic material (i.e., semen) are likely the main drivers of the outcomes. Some implications are discussed.

Presence of Toxoplasma gondii in Drinking Water from an Endemic Region in Southern Mexico.

Toxoplasmosis can be acquired through the ingestion of contaminated drinking water with oocysts of Toxoplasma gondii, highly resistant to the routinely disinfection processes; based on chlorination commonly used in the water supply industry. The aim of this study was to determine the presence of T. gondii DNA in samples of public drinking water from an endemic region of southern Mexico. In total 74 samples of water (5 L each) were collected from the three well fields (I, II, and III) and 71 independent wells, distributing public drinking water to the city of Merida Yucatan, after passing through the chlorination process. Water samples were filtered and concentrated by a sucrose solution, then DNA was extracted and evaluated through a nested-PCR (nPCR) specific for T. gondii. Positive samples were detected in 5.4% (4/74) of the water samples. This is the first report of the presence of T. gondii DNA in public drinking water from a large city in southern Mexico, where their consumption without any postpurification treatment could pose a risk for acquiring the infection in the urban population.

Effect of season and breed group on the follicular population and cyclicity of heifers under tropical conditions.

The aim was to determine the effect of season and breed group on follicular population, and presence and size of CL of heifers under tropical conditions. The seasons were hot-dry (March-June), hot-humid (July-October), and fresh-humid (November-February). Thirty Zebu (Brahman) and 38 F1 (Simmental × Brahman) heifers were used. Five evaluations were made in each season, at intervals of 7 days, to assess ovarian activity by ultrasound. Follicles were classified as small (≤4 mm), middle (4.1-8 mm), and large (≥8.1 mm) sizes, and also the size of CL, when present, was measured. Data were analyzed using analysis of variance and logistic regression procedures. Mean number of small follicles was 11.6 ± 2.3 with no effect of season, breed group, or their interaction (P > 0.05). Mean number of middle follicles was influenced by season and breed group; the highest average was found in the fresh-humid season (4.0 ± 0.2) and in F1 heifers (3.6 ± 0.2; P < 0.05). The highest mean number of large follicles was in the hot-humid season (1.4 ± 0.1; P < 0.05). The highest maximum follicle diameter (MFD) mean was registered in the hot-humid season (1.3 mm; P < 0.05) and the lowest proportion of heifers with CL occurred in fresh-humid season (33.3%; P < 0.05). No effect of season, breed group, and interaction on the maximum diameter of the CL was found. In conclusion, season was a very important source of variation. Heifers in the hot-humid season had the largest follicles and MFD, and better cyclicity.

Estimation of genetic parameters for preweaning growth traits of Brahman cattle in Southeastern Mexico.

The genetic parameters for Brahman cattle under the tropical conditions of Mexico are scarce. Therefore, heritabilities, additive direct and maternal correlations, and genetic correlations for birth weight (BW) and 205 days adjusted weaning weight (WW205) were estimated in four Brahman cattle herds in Yucatan, Mexico. Parameters were estimated fitting a bivariate animal model, with 4,531 animals in the relationship matrix, of which 2,905 had BW and 2,264 had WW205. The number of sires and dams identified for both traits were 122 and 962, respectively. Direct heritability estimates for BW and WW205 were 0.41 ± 0.09 and 0.43 ± 0.09, and maternal heritabilities were 0.15 ± 0.07 and 0.38 ± 0.08, respectively. Genetic correlations between direct additive and maternal genetic effects for BW and WW205 were -0.41 ± 0.22 and -0.50 ± 0.15, respectively. The direct genetic, maternal, and phenotypic correlations between BW and WW205 were 0.77 ± 0.09, 0.61 ± 0.18, and 0.35, respectively. The moderate to high genetic parameter estimates suggest that genetic improvement by selection is possible for those traits. The maternal effects and their correlation with direct effects should be taken into account to reduce bias in genetic evaluations.

Echocardiographic Documentation of Dilated Cardiomyopathy Development in Dogs Naturally Infected with Trypanosoma cruzi.

We aimed to characterize the echocardiographic alterations in dogs from an endemic region that were naturally infected with T. cruzi. Dogs (n = 130) seropositive for antibodies against T. cruzi and/or with acute parasitemia were enrolled in the study. Indicators of changes in the structure and systolic and diastolic functions of the left ventricle (LV) and blood flow patterns were evaluated by echocardiography. The frequency and extent of alterations in these indicators were associated with the severity of the disease. Briefly, 15 (11.54%) dogs were diagnosed with dilated cardiomyopathy (DCM), and 115 (88.46%) dogs were diagnosed as being without DCM. Infected dogs with DCM exhibited structural features of LV dysfunction, e.g., a significant (p < 0.05) increase in the LV internal diameter at systole and diastole (LVID-s, LVID-d) and a decline in the LV posterior wall (LVPW-d) thickness at diastole. Despite an increase in stroke volume and cardiac output indicating contraction force, DCM resulted in a decreased ejection fraction, affecting systolic function. Dogs that were diagnosed as DCM-negative but were positive for T. cruzi by PCR exhibited a high frequency of an increase in the thickness of the interventricular septum in systole (IVS-s) and the LV posterior wall in diastole (LVPW-d), a decline in the LV inner diameter (LVID-d, LVID-s), and fractional shortening (FS). The thinning of the LVPW at systole was the most defining feature observed in chronically infected dogs. In summary, this is the first study reporting the echocardiographic changes occurring in dogs naturally infected with T. cruzi and developing DCM. Our data suggest that changes in LVID are a major indicator of risk of cardiac involvement, and the observation of changes in the IVS, LVPW, and FS have predictive value in determining the risk of DCM development in infected dogs.

Prevalence and Progression of Gingivitis in Domestic Cats in Subtropical Mexico.

With the objective to characterize the gingival index (GI) and its progression, 218 domestic cats in a subtropical region of Mexico were studied. All teeth of each cat were examined with a periodontal probe to determine the GI; in addition, the absence of teeth was recorded. Six months later, the teeth of the 38 cats were again examined to assess any progression of the GI and loss of teeth. From the 218 cats, 33.0% of them develop some degree of gingival inflammation; from those, 61.5% were classified as GI 1. Age, sex, and neutered status were associated with tooth affections. Missed teeth were observed in 35% of the cats, particularly for molars 109 and 209 in both sexes. After six months, the number of teeth with GI 1 decreased to 20%. The gingival problems in cats have not been well studied, particularly at the speed they progress and how this can affect the loss of teeth; under the conditions of this study, a high frequency of gingival inflammation even at early age was demonstrated, with a rapid tooth loss. Although young males were more prone to develop gingivitis, females tend to loss more teeth. Non-neutered cats tended to develop more dental affections.

Risk factors associated with the occurrence of the second-litter syndrome in sows in southeastern Mexico.

The objective was to estimate the incidence of and to determine the effect of some risk factors on the decrease of litter size at parity 2 of sows in three commercial farms in Yucatan, Mexico. Data on 8,592 farrowing records of 4,296 sows were analyzed using a binomial logistic regression procedure. The model included the fixed effect of farm (1, 2, and 3), year of farrowing (2003-2011), season of farrowing (dry, rainy, and windy), number of pigs born alive at first parity (<9, 9-10, 11-12, and >12 piglets), lactation length (<18, 18-24, and >24 days), and weaning to conception intervals (<4, 4-11, and >11 days). Fifty-five point eight percent of all sows presented a reduced or similar litter size at parity 2. The odds of decrease in the second litter size were 1.56 and 2.01 for farms 2 and 3, respectively. Higher odds were found for sows farrowing during the rainy and dry seasons (1.20 and 1.24, resp.) and for sows with large litters at parity 1 (>12 piglets, odds = 33.2). Sows with weaning to conception intervals <4 days and between 4 and 11 days had higher odds of a decrease in the second litter (1.78 and 2.74 pigs, resp.).

Congenital Transmission of Trypanosoma cruzi in Naturally Infected Dogs.

Background: Congenital transmission (CT) of Trypanosoma cruzi in dogs has not been clearly demonstrated, even though dogs are important reservoirs of this agent. Materials and Methods: Seventeen late pregnant dogs seropositive for T. cruzi were selected, and a total of 84 fetuses were obtained. Blood and heart tissues from the fetuses and dams, and placental tissue from dam were collected. All tissues were analyzed by quantitative polymerase chain reaction (qPCR) for T. cruzi DNA (TcDNA) and inflammatory infiltrate and pathology by histological examination. CT was determined when physical, histological, or molecular evidence of T. cruzi was detected in blood or tissues of the fetuses. Results: A general transmission frequency of 59% was found, and 0.20 ± 0.24 of fetuses per litter were infected. Dams that were qPCR positive for TcDNA in cardiac tissue or blood displayed a transmission frequency of 100% and 67%, respectively. The highest parasite burden was noted in dams that were positive for TcDNA in both blood (82E-01 ± 1.54E-01) and cardiac (5.28E+03 ± 8.85E+03) tissues. In fetuses, higher parasitic burden in blood and cardiac tissue was found in those carried by dams that were seropositive and qPCR positive for TcDNA in cardiac tissue and blood. No amastigote nests were recorded in the cardiac tissue of fetuses in the histopathological studies, but typical lesions of T. cruzi infection were identified in all fetuses where CT occurred. Conclusions: CT of T. cruzi occurred at a high frequency in naturally infected pregnant dogs from the endemic areas.

Genetic parameters for birth weight, weaning weight and age at first calving in Brown Swiss cattle in Mexico.

Heritabilities and genetic correlations between birth weight (n = 13,741), adjusted 240-day weaning weight (WW, n = 8,806) and age at first calving (AFC, n = 3,955) of Brown Swiss cattle in Mexico were estimated. Data from 91 herds located in 19 of 32 states of Mexico from 1982 to 2006 were provided by the Mexican Brown cattle Breeder Association. Components of (co)variance, direct and maternal heritabilities were estimated for birth weight, WW and AFC using bivariate animal models. Direct and maternal heritabilities were 0.21 and 0.05 for birth weight, 0.40 and 0.05 for WW, whereas direct heritability for AFC was 0.08. The correlations between direct and maternal effects for birth weight and WW were -0.49 and -0.64, respectively. The genetic correlations between birth weight-WW and WW-AFC were 0.36 and -0.02, respectively. Under the conditions of this study, selection for increasing birth weight would increase WW, but increasing WW will not change AFC.

Detection of antibodies and risk factors for infection with bovine respiratory syncytial virus and parainfluenza virus 3 in dual-purpose farms in Colima, Mexico.

A cross-sectional study was carried out, from November 2007 to March 2008, to estimate the prevalence of and to determine risk factors associated with bovine syncytial respiratory virus (BRSV) and parainfluenza 3 virus (PIV3) in dual-purpose herds in Colima, México. One hundred and seventy-six sera from 33 herds for PIV3 and 232 sera from 44 herds for BRSV were used. Sera were analyzed by indirect ELISA for the detection of antibodies against BRSV and PIV3 in cattle herds to determine the seroprevalence of respiratory diseases. The apparent and true prevalences for PIV3 were 60.8% and 54.4% and for BRSV 52.2% and 50.8%, respectively. The percentage of herds showing at least one positive animal was 78.7% for PIV3, and 93.2% for BRSV. Age (≤ 12, 13-48, and >48 months old) and respiratory signs (no, yes) showed significant association (P < 0.05) with PIV3 and age with BRSV. This study showed that animals were exposed to both viruses and that age was the main risk factor. The need to establish new vaccination plans to effectively protect cattle against those infections in the state of Colima, Mexico is suggested.

Frequency of removal reasons of sows in Southeastern Mexico.

The aim of this study was to describe the reasons for removal in three pig farms under the tropical conditions of Mexico. Data were obtained from the records from 2003 to 2009, including a total of 7,236 commercial culled sows. Farms 1 and 3 were full-cycle farms with 3,500 and 550 sows. Farm 2 was a two-cycle farm with 450 sows. The specific reasons for removal were grouped into six general categories. The descriptive statistics of the reasons for removal were obtained using cross tabulation tables. Chi-square was used to test between farm differences. Reproductive reasons accounted for the largest proportion of all removals (26.9%) of which anestrous and repeated estrous contributed with 34.2% and 20.8%, respectively. Locomotor problems were responsible for 15.5% of all removals, of which lameness was the main concern (56.3%) followed by "sow downer" syndrome (23.9%). Low production accounted for 12.8% of all removals of which 62.2% were due to small litter sizes and 37.8% due to disgalactia. Diseases were responsible for 13.0% of all removals of which respiratory problems was the most important (73.6%). Age as a cause of removal comprised 24.1% and the category "miscellaneous" 7.7% of all removals. Poor body condition and death reasons represented 2.6% and 1.6%, respectively. Differences between removal reasons were found between farms.

Length of productive life of sows in four pig farms in the tropics of Mexico.

The objective of this study was to determine the effect of some factors on the length of productive life (LPL), the number of parities (NP), and the culling interval (CI) of sows. The information from 2003 to 2009 of 3,746 sows with LPL and NP records and 5,819 sows with CI records from the four farms of Yucatan, Mexico was used. LPL was defined as the number of days between the first farrowing and culling or death and CI as the number of days between the last farrowing and culling. To determine the effects of farm, litter size at first farrowing (LSF1) and age at first farrowing (AF1) on LPL and NP, and of farm, LSF1 and culling reason on CI general linear models were used. Means and standard errors for LPL, NP, and CI were 496.4 ± 8.42 days, 3.35 ± 0.04 parities, and 48.3 ± 0.52 days, respectively. All factors had significant effects (P < 0.05) on LPL, NP, and CI. The sows from farm 2 stayed longer (806.0 days) and had more parities (5.25) than the sows from the other farms. Sows with the smallest litters (≤8 piglets) at first farrowing stayed the least time in the farm (675.1 days) and had the fewest parities (4.49). Gilts farrowing the first time before 331 days of age stayed longer time in the farm (726.4 days) and had more parities (4.81) in comparison with 331-348 and more than 348 days age groups. With respect to CI, the sows in farm 3 stayed the longest time in the farm. Sows with more than five parities were culled sooner after their last farrowing. In conclusion, differences between farms for LPL, PN, and CI were found. Females that farrowed at a short age and those with large litters stayed longer in the herd. Old sows and those culled for reproductive reasons stayed the least time in the herd after their last farrowing.

Effects of breed type and age at first calving on length of productive life in a cow-calf system in Southeastern Mexico.

The effect of age at first calving (AFC) and breed type (BG) on cow length of productive life in the herd (LPL) and cumulative kilograms of calves weaned per cow (KWC) was studied. Data on 313 Brahman, 183 Nellore, and 269 crossbred cows (undefined crosses of European × Zebu cattle) born from 1986 to 2002 were used. Three hundred and ninety-one out of the 765 cows had non-censored data. LPL curves by BG and AFC (<2.5, 2.5 to <3, 3 to <3.5, and ≥ 3.5 years of age) were obtained using life table procedures. The magnitude of the effect of AFC and BG on LPL was determined using Cox proportional hazard regression procedures. KWC data (n=359) were analyzed by a linear model that included the effects of period of birth of the cow (in years), BG, and AFC. There was no difference in the survival curves between BG (p>0.05), but there was for the hazard ratio of culling (p<0.05). Brahman and Nellore cows produced more kilograms of calves (p<0.05) than crossbred cows. AFC influenced LPL (p=0.014) and KWC (p=0.012). Cows with AFC <3 years of age stayed longer in the herd and weaned more KWC than those with a higher AFC (p<0.05).

Seroconversion to bovine viral diarrhoea virus and infectious bovine rhinotracheitis virus in dairy herds of Michoacan, Mexico.

Bovine viral diarrhoea virus (BVDV) and infectious bovine rhinotracheitis virus (IBRV) are important viral diseases around the world. The objective of this study was to estimate the incidence of seroconversion to BVDV and IBRV and to identify associated risk factors in dairy herds of Michoacan, Mexico. The longitudinal study included 62 herds and ran from December 2001 to November 2002. The total number of animals enrolled and completing the study were 392 and 342 animals for BVDV and 925 and 899 animals for IBRV. Animals were tested monthly for 12 months, for the presence of antibodies. Risk factors were: herd size (2-9, 10-25 and 26-55 animals), herd serostatus (seropositive or seronegative, only for IBRV), age group of the animal (6 to 12, 13 to 24, 25 to 48 and > 48 months) and animal origin (born in farm, purchased). The cumulative incidences for BVDV and IBRV were 16.4% and 3.4%, respectively; whereas, the incidence density rates for BVDV and IBRV were 15.9 and 2.9 per 1000 animal-months at risk, respectively. Seroconversion curves were statistically different for age group for BVDV and IBRV and for herd status for IBR. The relatively high incidence of seroconversion for BVDV suggests that a successful control programme should be oriented towards the identification and elimination of the PI animals and towards avoiding the introduction of PI cattle to the farm. The scenario of IBRV is favourable to implement a programme directed to reduce the number of new seropositive herds.

Prevalence of abortion and stillbirth in a beef cattle system in Southeastern Mexico.

Prenatal mortality is an important cause of production losses in the livestock industry. This study estimates the prevalences of abortion and stillbirth in a beef cattle system and determines the significance of some risk factors, in the tropics of Mexico. Data were obtained from a Zebu cattle herd and their crosses with Bos taurus breeds, in Yucatan, Mexico. The logit of the probability of an abortion or stillbirth was modeled using binary logistic regression. The risk factors tested were: year of abortion (or calving), season of abortion (or calving), parity number and dam breed group. The effect of twins on stillbirth was tested using Fisher exact test. Of the 4175 calvings studied 49 were abortions (1.17%). Significant factors in the logistic regression analysis for abortions were season of abortion and parity number. The risk of abortion was lower in the dry seasons compared to the rainy and windy seasons (P = 0.009). The risk of abortion was higher in second parity cows followed by the third and first parity cows, as compared to older cows (P = 0.015). Of the 4126 births, 87 were stillbirths (2.11%). Significant factors in the logistic regression analysis for stillbirth were year of calving (P = 0.0001) and parity number (P < 0.001). The risk of stillbirth in first parity cows was 2.6 times that of old cows. Of the total births, 15 were twins (0.36%) of which 7 were born dead calves. Herd owners must focus on the significant risk factors under their control to reduce the prevalence of prenatal mortality.

Molecular characterization of bacterial microbiota associated with infectious bovine keratoconjunctivitis in Michoacán, Mexico / Caracterización molecular de la microbiota bacteriana asociada con queratoconjuntivitis infecciosa bovina en Michoacán, México / Caracterização molecular da microbiota bacteriana associada à ceratoconjuntivite bovina infecciosa em Michoacán, México

Abstract Background: The most common ocular disease affecting cattle worldwide is infectious bovine keratoconjunctivitis (IBK), which has been associated with Moraxella bovis bacterium. Objective: To report the molecular characterization of the ocular bacterial microbiota and its relation to IBK in cattle in two dairy regions in Michoacán, Mexico. Methods: A total population of 761 bovines were evaluated, of which 17 (2.23%) showed symptoms of IBK. Thirty-eight bacterial isolates from ocular samples of bovines with IBK were characterized by Gram-staining and antimicrobial sensitivity. In addition, isolates were identified by sequence comparisons of the 16S ribosomal gene. Results: The genus Moraxella was one of the most abundant bacteria and M. bovoculi was the most predominant species. Conclusion: The bacterial isolates identified in eye lesions of cattle and associated to IBK are diverse. To the author´s knowledge, this is the first study on the subject in Mexico; therefore, more research is needed to estimate the incidence of IBK and determine its associated microbiota.

Resumen Antecedentes: la enfermedad ocular más común que afecta al ganado en todo el mundo es la queratoconjuntivitis infecciosa bovina (IBK), que se ha asociado con la bacteria Moraxella bovis. Objetivo: reportar la caracterización molecular de la microbiota bacteriana ocular y su relación con IBK en ganado de dos regiones lecheras en Michoacán, México. Métodos: se evaluó una población total de 761 bovinos de los cuales 17 (2,23%) mostraron síntomas de IBK. Se obtuvieron treinta y ocho aislamientos bacterianos de muestras oculares de bovinos con IBK, los cuales se caracterizaron por tinción de Gram y sensibilidad antimicrobiana. Además, los aislamientos se identificaron mediante comparaciones de secuencias del gen ribosomal 16S. Resultados: el género Moraxella fue una de las bacterias más abundantes y M. bovoculi fue la especie más predominante. Conclusión: los aislamientos bacterianos identificados en lesiones oculares de bovinos y asociados a IBK son diversos. Hasta donde sabemos, este es el primer estudio sobre el tema realizado en México; por lo tanto, es necesario ampliar esta investigación para estimar la incidencia de IBK y determinar la microbiota asociada con la misma.

Resumo Antecedentes: a doença ocular mais comum que afeta o gado no mundo é a ceratoconjuntivite bovina (IBK), que tem sido associada à bactéria Moraxella bovis. Objetivo: relatar a caracterização molecular da microbiota bacteriana ocular e sua relação com a IBK em bovinos de duas regiões leiteiras de Michoacán, México. Métodos: foi avaliada uma população total de 761 bovinos, más apenas 17 (2,23%) apresentaram sintomas de IBK. Trinta e oito isolados bacterianos de amostras de olho bovino com IBK foram caracterizados por coloração de Gram e sensibilidade antimicrobiana. Além disso, os isolados foram identificados por comparação de sequências do gene ribossômico 16S. Resultados: a microbiota bacteriana associada à IBK foi diversa, sendo o gênero Moraxella uma das mais abundantes e M. bovoculi a espécie predominante. Conclusão: de acordo com o conhecimento dos autores, este é o primeiro estudo sobre o tema no México até o momento, portanto é necessário expandir essa pesquisa para estimar a incidência de IBK e determinar a microbiota associada à mesma.

Factores ambientales asociados con los días no-productivos de cerdas en el trópico mexicano / Environmental factors associated with lifetime non-productive days of sows in the Mexican tropics

RESUMEN Objetivo. Estimar el número de días no productivos (DNP) de por vida, la proporción de DNP (%DNP) y días no productivos por cerda por año (DNP/Y), y determinar el efecto de factores de hato y cerda sobre las características aquí estudiadas en tres granjas comerciales en el trópico mexicano. Materiales y métodos. Los datos de 6703 cerdas de tres granjas comerciales fueron usados. El modelo que describió las características de interés incluyeron los efectos fijos de granja, año de primer parto, época de primer parto, edad al primer parto, causa de desecho, interacción de año por época y error residual. Resultados. Las medias de DNP de por vida, %DNP y DNP/Y fueron 64 días, 12% y 39.3 días, respectivamente. Todos los factores tuvieron efectos significativos (p<0.01) en todas las características. Las cerdas con primer parto a mayor edad y las eliminadas por razones reproductivas tuvieron más DNP en el hato. Además, las cerdas eliminadas en el primer parto tuvieron menor DNP y mayor %DNP que las cerdas desechadas en partos subsecuentes. Conclusiones. La eliminación temprana de cerdas incrementó la proporción de días no productivos, que a su vez podrían reducir la rentabilidad de las granjas.

ABSTRACT Objectives. To estimate the lifetime non-productive days (NPD), lifetime proportion of NPD (%NPD) and non-productive days per sow per year (NPD/Y), and to determine the effect of herd and sow level factors on the traits here studied in three pig farms in the Mexican tropics. Materials and methods. Data from 6703 sows from three commercial farms were used. The model that described the traits studied comprise the fixed effects of farm, year and season of first farrowing, age at first parity, reasons of removal of sows, year x season interaction and the residual error. Results. The means for lifetime NPD, %NPD and NPD/Y were 64 days, 12.0% and 39.3 days, respectively. All fixed factors had significant effects (p<0.01) on the characteristics evaluated. Sows having their first parity at an old age and sows culled because of reproductive reasons had the highest lifetime NPD. In addition, sows culled at first parity had lower lifetime NPD and higher %NPD than sows culled in subsequent farrowing. Conclusions. The early culling of sows increased the percentage of non-productive days, which in turn is expected to reduce the profit of farms.

Risk factors for Aujeszky's disease in pig herds and detection of field virus antibodies in fattening pigs in the state of Yucatan, Mexico.

Two epidemiological studies were conducted from August 1997 to May 1998: a case-control study to identify herd level risk factors for antibodies to Aujeszky's disease virus (ADV) in sows in the state of Yucatan, Mexico and a cross-sectional study to determine the prevalence of antibodies against ADV in fattening pigs. In the case-control study, data on herd management and biosecurity were obtained from all the 27 ADV known field-virus-seropositive farms (cases) and 62 randomly selected seronegative farms (controls) by questionnaire. Breeding animals of these seropositive farms had received a gE-deletion vaccine. In the cross-sectional study, 26 farrow-to-finish farms of the 27 seropositive farms were used and blood samples taken from 60 fattening pigs per herd (15 pigs for each stage of production). Serum samples were analyzed by the screening-ELISA and gE-ELISA tests. In the case-control study, three of the 15 risk factors were significant. Odds ratios for distance to the nearest farm (< or = 2.5km), not sampling for the detection of ADV and herds with origin of breeding animals within the state were 9.5, 18.1 and 8.7. In the cross-sectional study, 11 (42.3%) of the 26 sampled farms were seropositive to vaccine antibodies. None of the piglets were positive to antibodies against field virus risk--suggesting that the strategy of vaccinating only the breeding animals reduced the ADV infection of the piglets.

Describing the growth curve of local turkey using non-linear models / Descripción de la curva de crecimiento de pavos locales usando modelos no lineales

ABSTRACT Objective. Determine the best non-linear model to fit the growth curve of local turkeys managed under confinement in Michoacan, Mexico. Material and methods. Twenty-four and 43 female and male turkeys, reared under commercial conditions were given commercial feed. Birds were weighed weekly from hatch to 29 weeks of age. The Gompertz, Brody, Richards, von Bertalanffy and Logistic models were chosen to describe the age-weight relationship. Results. The best fitting model was selected based on the multiple determination coefficient (R2), the Akaike information criterion (AIC) and visual analysis of the observed and predicted curves. In both female and male, von Bertalanffy was the best model. The highest estimates of parameter A (mature weight) for both females and males were obtained with the von Bertalanffy model followed by the Gompertz and Logistic. The estimates of A were higher for males than for females. The highest estimates of parameter k (rate of maturity) for both females and males were, in decreasing order, for the Logistic, Gompertz, and von Bertalanffy models. k values for female turkeys was higher than for males. The age at the point of inflection (ti) and body weight at the age of point of inflection (WI) varied with the model used. The largest values of TI and WI corresponded to the Logistic model. Between sexes, the largest TI and WI values corresponded to males. Conclusions. The best models to describe turkey growth was the von Bertalanffy because it present the highest R2 and lowest AIC values.

RESUMEN Objetivo. Determinar el modelo no lineal que mejor ajuste la curva de crecimiento de pavos locales criados en confinamiento. Material y métodos. Veinticuatro y 43 pavos hembras y machos, respectivamente, criados en confinamiento fueron alimentados con dietas comerciales. Cada animal se pesó desde el nacimiento hasta la semana 29 de edad. Los modelos de Gompertz, Brody, Richards, von Bertalanffy y Logístico fueron elegidos para describir la relación edad-peso. El mejor modelo se seleccionó con base en el coeficiente de determinación (R2), el criterio de información de Akaike (AIC) y el análisis visual de las curvas observadas y predichas. Resultados. El mejor ajuste (machos y hembras) correspondió al modelo von Bertalanffy. El más alto valor del parámetro A (edad a la madurez), para hembras y machos correspondió al modelo von Bertalanffy, seguido de Gompertz y Logístico. El estimador A fue mayor para machos que hembras. El mayor valor del parámetro k (tasa de madurez), para hembras y machos, variaron según el modelo utilizado. Los valores de k fueron más altos para hembras que para machos. La edad al punto de inflexión (T:) y peso vivo al punto de inflexión (W:) también variaron de un modelo a otro. Los valores más altos de T, y Wj correspondieron al modelo Logístico. Entre sexos, los valores mayores de T: y WI correspondieron a los machos. Conclusiones. El mejor modelo que describió la curva de crecimiento de los pavos locales fue el de von Bertalanffy.

Toxoplasma gondii presence in women with spontaneous abortion in Yucatan, Mexico.

The objective of this study was to estimate the seroprevalence of anti- Toxoplasma gondii antibodies and DNA of women with spontaneous abortions in 2 hospitals located in Yucatan, Mexico. Between June 2008 and May 2009, blood samples were taken from 100 women with spontaneous abortion attending the Ticul City Communitarian Hospital and the Merida Mother-Kid Hospital. The sera were tested for anti- T. gondii IgG and IgM antibodies. Blood samples (5 ml with anticlotting agent) were also used for polymerase chain reaction (PCR) assay, to detect T. gondii DNA. Forty-two of the 100 samples were negative. Of the positive samples (n = 58), 32 were positive to IgG, 2 to IgM, 5 to IgG and IgM, 6 to IgG and PCR, 1 to IgM and PCR, and 12 to IgG, IgM, and PCR. Accordingly, 55% of the women were seropositive to at least IgG, 20% to at least IgM, and 19% via PCR. Differences between hospitals were significant (P < 0.05) only for IgM. The risk of infection (IgM positive) was 2.85 (odds ratio [OR] 95%, confidence interval [CI]; 1.03-7.87) times greater in women patients at the Merida Mother-Kid Hospital, than those at the Ticul Communitarian Hospital. More studies are needed to evaluate the impact of this disease and to establish strategies to follow in order to reduce congenital toxoplasmosis in the populations at risk.