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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.

Background. The live weight (LW) and morphometric variables of sheep are useful characteristics to generate adequate criteria for genetic improvement and conservation of Creole animal resources. Objective. To establish morphological relationships and through them predict LW of females and males in Creole sheep of the Oaxacan Mixteca, Mexico. Methodology. LW, thoracic perimeter (TP), height at withers (HW), back length (BL), cane perimeter (CP), head length (HL), neck length (NL), abdominal perimeter (AP) and rump width (RW) were recorded in 720 Creole sheep in 24 production units, measured in animals of both sexes. First, they were analyzed using general linear model procedures to determine the effect of sex on the variables of interest, and then, they were analyzed using discriminant analysis. Simple correlations between morphometric variables were calculated and step-by-step multiple linear regression equations were generated to predict LW. Results. Differences were found between sexes for LW and morphometric measures, which were correlated (p ≤ 0.05). The variables TP, AP and BL had the highest correlations (0.92, 0.90 and 0.89, respectively) and the variables CP, NL and RW, the lowest (0.75, 0.82 and 0.83, respectively). The statistical models explained a large proportion of the total variability (R2 from 85 to 91 %). According to sex, males had R2 (0.90 to 0.94) higher than females (0.83 to 0.89). In both cases TP and HW were the most important characteristics for predicting LW. Conclusions. Under the conditions of this work, the model that included TP and HW was the one that best predicted the LW of the Creole sheep of the Oaxacan Mixteca. It is recommended to use different equations for each sex and training of sheep producers in the use of those equations.

Background: Sows’ lifetime reproductive performance is a key component for farm productive efficiency and profitability. Objective: To investigate associations between first parity wean-to-service interval (WSI) and sows’ lifetime reproductive performance traits. Methodology: Data were collected in a 3,900-sows farrow-to-finish farm in Yucatan, Mexico. Lifetime productivity records included parity number at culling (NCP), lifetime number piglets born alive (LNBA) from parity two until culling, lifetime non-productive days (LNPD) and length of productive life (LPL) for 4,175 sows. Association between WSI and sow lifetime productivity traits were analyzed using general linear models, including year and season at first service as categorical fixed effects and WSI as linear and quadratic predictor. Cut-off values for WSI were estimated using regression trees analysis. Results: WSI was negatively associated (P < 0.05) with LNBA and NCP, positively (P < .05) with LNPD and non-associated with LPL (P > 0.05). Cut-off values for WSI varied for each predicted variable: WSI > 5 days would translate into longer 13 more days of LPL, WSI < 7 days would increase LNBA by two extra pigs, WSI ≥ 9 days increase NCP by 0.2 parities and WSI

Background. Growth curves allow to predict the mature weight, the grow rate unto maturity, as well as the age and weight at inflexion point, to improve management on productive animals. Objective. To identify the best non-linear model (NLM), which best describe the growth curve of Creole sheep from the Mixteca region of Oaxaca, Mexico. Material and methods. The live weights of 720 sheep (438 females and 239 males) between 1 and 60 months of age were used. The NLM evaluated were: Logistic, Gompertz, Michaelis-Menten, Weibull and Mechanist. Analyzes were performed with SAS JMP software. The criteria used to select the best model were the corrected Akaike information criterion (AICc), Bayesian (BIC) and coefficient of determination (R2). Results. For females, the Mechanist and Weibull models adjusted better de data (lowest AICc, BIC), but not being differences with the Michaelis-Menten and Gompertz. For males the lowest AICc, BIC and the highest R2 (0.84) values were for the Logistic, Gompertz and Mechanist models. Implications. The knowledge of the parameters of the growth curves of the creole sheep of the Mixteca region could be used for taking better decisions on the management of this type of sheep. Conclusion. According to the models, the inflection point of the growth curves was reached at a young age and a lower body weight in females than in males; therefore, different models should be used to study the growth kinetics between sexes.

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.

Background. Fixed time artificial insemination is an important tool for the reproductive management of cattle. Objective. To determine the effect of two ovulation synchronization protocols and factors associated with the pregnancy rate of Zebu females using fixed time artificial insemination (FTAI) under tropical conditions. Methodology. Data of estrous and pregnancy from 129 multiparous Zebu cows and 257 heifers were used. All animals received an intravaginal device (new or used) CIDR® or DIB®, which remained in situ per 7 days. On the day of device removal, two treatments were established. I) Estradiol cypionate (EC; n = 192): 25 mg prostaglandin F2 alpha and 0.5 mg EC (estradiol cypionate); II) Estradiol benzoate (BE; n = 194): 25 mg PGF2α and 24 hours later (day 8), 1 mg BE. Estrous was detected by 1-hour; three times a day, and females inseminated 54-56 hours after removal of device, using thawed semen. Pregnancy diagnosis was by transrectal palpation with real-time ultrasound, 60 days after FTAI. Data were analyzed using Chi-square tests. Results. The overall estrous rate was 73.32%. The ovulation synchronization protocol affected the presence of estrous, where EC had a higher rate (79.39%) compared to EB (67.19%). Pregnancy rate for the females inseminated with thawed semen was 54.40%. All factors affected the pregnancy rate (p

Data from 2438 calvings born to 682 cows recorded from 2004 to 2015 in an extensive production system were used, to investigate factors associated with abortion and calf mortality until weaning. Cows belonged to Brahman, Nellore, Guzerat and Brown Swiss x Zebu breed groups. Data were analyzed using binary logistic regression, and the statistical model included the effects of year and season of calving (or abortion), parity number, breed group of the cow and sex (only for preweaning mortality). Abortion rate was 0.99% varying from 0.61% to 1.94% among year groups. First parity and Nellore cows had the greatest abortion rates (1.66 and 1.46%, respectively). The calf mortality rate was 9.65%, varying from 3.18% to 14.65% across all years. The major factors associated (P < 0.05) with mortality of calves included year and season of calving, parity number and breed group of the cow. Nellore cows had the highest odds of preweaning mortality (OR=4.41). Cow parity number and season of calving were also associated with calf mortality. First parity cows had the major calf losses overall. In conclusion, closer attention to the management of first parity cows could reduce calf mortality.

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.

A problem attributed to first parity sows is the second litter syndrome (the number of piglets of the second litter is lower or similar to the first litter). The objectives of this study were to estimate the frequency of sows showing the second litter syndrome and to determine the effect of some risk factors on the drop of the litter size of second parity sows in a commercial farm in La Piedad Michoacan, Mexico. Data on 6809 sows were used. The data were analyzed by a binomial logistic regression model. The model included the fixed effect of year and season of farrowing, breed group, weaning to service interval and pigs born alive at first parity. 48.1% of the sows showed the syndrome. Year of farrowing, weaning to service interval and pigs born alive had effect (P

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

The objectives of this study were to estimate the diversity of maize farmed by maize growers (“milperos”) of the Yucatan Peninsula, to review the state of maize conservation from 1948 to 2010, and to try out participative methods to best conservation and improvement of maize. Data of samples collected in 1948, 1974 and 1977 were analyzed; ethnobotanical explorations were carried out in 1999 and 2010; three cycles of visual stratified masal selection with four Creole maize were also practiced; and exhibition seeds in 44 localities were registered. The 1999 and 2010 explorations included 153 donors from 56 localities and 177 donors from 68 localities, respectively. Two-hundredth and thirty-six and 163 seed samples were collected from local populations of maize in the first and second exploration. The samples collected in 1999 and 2010 corresponded to the Tuxpeño, Dzit-Bacal, Nal-Tel landraces and crosses of them. In 1999 and 2010, it was found that 66.7% and 71.0% of the “milperos” interviewed, conserved and selected seeds from their maize populations for 6 or more years. The conservation of local maize increased 15.5%. However, the conservation of Dzit-Bacal maize decreased 14.2% in 10 years; therefore, its informal supply was strengthen in regional exhibitions of seeds and participative improvement of populations of that maize landrace was carried out, to reinforce its in-situ conservation and diversity.

Los objetivos del estudio fueron determinar el efecto de factores de riesgo sobre la ocurrencia del aborto, y su impacto sobre algunas medidas de eficiencia reproductiva en hatos de Aguascalientes. Se obtuvieron 353 sueros de vacas que abortaron y que no abortaron de 23 hatos con registros. La información de los hatos y animales se obtuvo por entrevistas. Además de factores relacionados con las condiciones de los hatos, se exploró la influencia de la seropositividad a rinotraqueitis infecciosa, diarrea viral bovina, neosporosis y brucelosis, determinada por pruebas comerciales de ELISA, y la última mediante las pruebas de rosa de bengala, rivanol e inmunodifusión radial. Se realizaron análisis de Ji-cuadrada, y posteriormente con las variables significativas (P

The aim of this study was to determine the prevalence and risk factors associated with Toxoplasma gondii infection in domestic cats using an indirect-ELISA (IgM and IgG) and PCR. Samples collected from 220 cats from Merida, Yucatan, Mexico, were analyzed. Cases were reported as acute or chronic. Cases when positive to IgM and IgG and PCR were considered as reactivated chronic infection. Risk factors (sex, age, body condition, diet access to hunting, and number of cats in home) were assessed with a multivariate analysis, 75.5% (166/220) of the cats were IgM and 91.8% (202/220) IgG-seropositive and 79% were PCR-positive (173/220). Number of cats per household and low body condition score were associated with reactivated chronic infection (𝑃

El objetivo de este estudio fue estimar la prevalencia y determinar el efecto de localidad y tamaño del hato sobre la presencia de mastitis subclínica en cabras lecheras en Michoacán, México. Asimismo se estimó el coeficiente de correlación intraconglomerados y el efecto de diseño. Todas la cabras lactantes de 25 hatos lecheros de cuatro localidades de Tanhuato, Michoacán fueron muestreadas (n=1795 cabras lactantes). En dos localidades, el sistema de producción era semi-intensivo con pastoreo durante el día y estabulación durante la noche y los rebaños en las otras dos localidades pertenecían al sistema intensivo. La detección de mastitis se realizó mediante la prueba de California. Prevalencias fueron estimadas para cada ubre y por animal. Modelos de regresión logística mixta fueron usados para determinar la asociación de localidad (fijo), o tamaño de rebaño (fijo) con la presencia de mastitis; la identificación del rebaño se incluyó como efecto aleatorio. El tamaño de rebaño se definió como el número de cabras (secas y lactantes) por rebaño y se agrupó en tres categorías (0,05) en la prevalencia de mastitis entre la ubre derecha (18,6%) e izquierda (16,7%). La prevalencia dentro de rebaño varió de 9,52 a 72,41% y la prevalencia animal fue 30,5% (548/1795). La localidad de San José Vargas tuvo la más alta frecuencia de mastitis (55,48%) y Tinajas de Vargas la más baja (21,13%). Las razones de probabilidades ajustadas (OR) e intervalos de confianza al 95% (IC95) por localidad fueron: 4,76 (2,86; 7,93), 1,20 (0,37; 3,86), 1,02 (0,19; 5,26) para San José Vargas, Cieneguitas y Rancho Nuevo, respectivamente, comparado con la localidad de Tinajas de Vargas. Los OR e IC95 para los rebaños pequeños y grandes, comparados con los rebaños medianos, fueron: 3,94(0,85; 17,41) y 1,58(0,99; 2,53), respectivamente. En conclusión, la prevalencia de mastitis fue relativamente alta, la cual es afectada por la localidad y el número de cabras en el rebaño.

 El objetivo de este estudio fue evaluar los cambios de peso corporal (PC) durante la lactancia de vacas Holstein x Cebú (HC) y Suizo x Cebú (SC) en un sistema de doble propósito en el bosque tropical húmedo de México. Vacas de tres hatos comerciales se pesaron al parto y cada mes hasta el secado. Los datos comprendieron 3.356 pesajes de 234 vacas tomados durante los años de 2002 a 2005. Un análisis preliminar, no mostró diferencias entre grupos genéticos, por lo tanto, los datos se analizaron según el número de parto (1; 2; 3 y 4 o más partos), utilizando modelos mixtos para medidas repetidas. Los modelos incluyeron los efectos fijos de hato, año de parto y mes de medición y los efectos aleatorios de vaca y residual. La gráfica de PC de las vacas mostró un ligero incremento continuo en las primeras dos lactancias y una tendencia a mantenerse constante en los grupos de vacas con 3 y 4 o más partos. El peso al parto (PP) y el promedio de todos los pesos de una vaca durante la lactación (PVL) incrementaron con el número de parto. El peso adulto de las vacas se alcanzó en la tercera lactancia. Los coeficientes de correlación de los PC de una misma lactancia para los cuatro grupos de parto fluctuaron de 0,51 a 0,89 (P

Se realizó un estudio longitudinal para determinar la frecuencia e incidencia de Lawsonia intracellularis en cerdos de engorde en una granja de múltiples sitios y otra de un sitio en Yucatán, México. Se utilizaron 59 y 58 lechones negativos a L. intracellularis de las granjas de múltiples sitios y un sitio, respectivamente, los cuales se monitorearon cada 14 días de la semana, 1 a la 21 de edad. La bacteria en heces se detectó utilizando la prueba de la reacción en cadena de la polimerasa. Todos los cerdos de ambas granjas eliminaron L. intracellularis al menos una vez hasta la semana 11 de edad, encontrándose el mayor número de animales positivos a la semana 7. La incidencia acumulada fue del 100% en ambas granjas y la tasa de incidencia en las granjas de un sitio y múltiples sitios fueron 0,31 y 0,26 cerdos por cada 14 días a riesgo, respectivamente. Los resultados de este estudio proporcionan información para la implementación de esquemas de prevención control y erradicación de L. intracellularis

El objetivo de este estudio fue determinar el efecto de algunos factores ambientales sobre las constantes de curvas de crecimiento de becerros cruzados en un sistema de doble propósito en el trópico húmedo (SDPT) de México. Los becerros eran animales ¾ Europeo (Holstein, Simmental, Suizo) ¼ Cebú, igual que sus madres. Los becerros apoyaban a las vacas en el ordeño y tomaban la leche residual después de éste por 30 minutos (amamantamiento restringido) y se mantenían en un potrero de Estrella de ífrica, teniendo acceso a un complemento energético-proteico (1 kg/becerro/día). Trescientos sesenta y un becerros (190 machos y 171 hembras) se pesaron (4.678 pesajes) al nacimiento y a intervalos de 28 días, hasta el destete. Las constantes (lineales y cuadráticas) para cada animal se analizaron mediante modelos lineales generales. Año y época de nacimiento tuvieron efectos (P

El estudio se llevó a cabo en una explotación comercial del Municipio de Panabá, Yucatán, con clima Aw(o), con el objeto de analizar el comportamiento reproductivo de hembras cebú y encastadas con Bos taurus mantenidas en condiciones de pastoreo y bajo un