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An experiment was carried out to assess the effect of the incorporation of sun-dried foliage of Brosimum alicastrum into rations based on hay of Megathyrsus maximus on intake, rumen fermentation, kinetics of passage, microbial nitrogen supply to the small intestine, apparent digestibility in Pelibuey hair sheep. Four rations were randomly allotted to four rumen-cannulated lambs (BW = 37.4 ± 4.9 kg) using a 4 × 4 Latin square design to assess the effect of increasing levels (0, 15, 30 and 45% DM basis) of foliage of Brosimum alicastrum on a basal ration of M. maximus. Organic matter intake and water consumption increased linearly (p < 0.01) with increasing levels of B. alicastrum in the ration. The rate and potential extent of rumen fermentation of OM and CP of B. alicastrum were 10.6%/h and 86.6% and 11.4%/h and 95.2%, respectively, but no effect (p > 0.05) was found on the potential rumen degradation of DM (40.2%) or on the rate of degradation of DM (0.033%/h) of M. maximus, although a positive effect was found in the rumen degradation rate of NDF (p < 0.05). VFA and ammonia concentration in the rumen and the rate of passage of solids and liquids through the rumen (k1) increased linearly (p < 0.01) with increasing levels of B. alicastrum. Rumen pH was not affected by the incorporation of B. alicastrum (p > 0.05). Microbial nitrogen supply to the small intestine (p < 0.001), apparent digestibility of dry matter (p < 0.01) and NDF (p < 0.05) of the rations were also significantly increased as a result of the incorporation of B. alicastrum foliage. Results from this experiment suggest that the foliage of Brosimum alicastrum can be readily incorporated at around 30% of the ration of dry matter in hair sheep with beneficial effects on feed intake, rate of passage and microbial N supply to the lower tract.

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Abstract The aim of this study was to estimate allelic and genotypic frequencies of markers in the leptin (LEP), pituitary transcription factor (PIT-1) and luteinizing hormone receptor (LHR) genes and evaluate their effects on reproductive traits and milk yield of Holstein cattle. Data from 147 cows from department of Francisco Morazán, Honduras, were collected and PCR-Restriction Fragment Length Polymorphism (RFLP) assays were performed to characterize the PIT-1-HinfI, LEP- A59V and LHR-rs41256848 polymorphisms. To estimate the effect of genotypes on reproductive traits and milk yield fixed and mixed linear models were fitted. The frequencies of the genotypes CC, CT and TT of A59V, AA, AB and BB of HinfI, and CC, CG and GG of rs41256848 were 0.46, 0.33 and, 0.21; 0.09, 0.32 and 0.58; and 0.37, 0.61 and 0.02, respectively. The genotypes of LEP and LHR showed deviations from Hardy-Weinberg equilibrium. The A59V polymorphism was significantly associated with the calving to conception interval (CCI) (p=0.01), being the C allele favorable. The HinfI and rs41256848 polymorphism were significantly associated (p=0.08 and p=0.04) with age to first calving (AFC), being the A and G the alleles favorable associated, respectively. The results suggest that LEP, PIT and LHR polymorphisms can probably act as candidate to be used in marker-assisted selection for AFC and CCI traits.

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The study evaluates the effect of three hormonal protocols on ovarian dynamics and progesterone (P4) secretion of buffalo (Bubalus bubalis). Twenty-nine pluriparous Murrah buffaloes were used. The protocols were as follows: OVSYNCH (n = 10): 100 µg of gonadorelin (day 0), 500 µg of cloprostenol (day 7), and 100 µg of gonadorelin (day 9). CIDR+EB (intravaginal device (CIDR®) + estradiol benzoate; n = 10): CIDR plus 2 mg of EB (day 0), withdrew of CIDR, 500 µg of cloprostenol (day 7) and 1 mg of EB (day 8). CIDR+eCG (n = 9): CIDR plus 2 mg of EB (day 0), withdrew of CIDR, 500 µg of cloprostenol and 400 IU of eCG (day 7). Follicles were counted with an ultrasound and measured at 0, 24, and 54 h. The maximum follicle diameter and ovulation were evaluated at 70, 80, and 94 h after CIDR withdrew. Estrous was detected per 1 h three times daily. Blood samples were collected on days 0, 7, 10, 15, and 22 to determine P4 concentration. In CIDR+EB protocol, 50% of buffaloes presented estrous, at 69.6 h. All buffaloes ovulated. CIDR+eCG group had the shortest (69 h) ovulation time. No treatment differences for follicular population, maximum follicle diameter, and P4 concentration on days 7 and 10 (P > 0.05) were found. The P4 concentration in OVSYNCH and CIDR+eCG protocols were > 1 ng/ml, on days 15 and 22 (P < 0.05). There was no difference in ovarian activity; however, the P4 secretion was normal in the OVSYNCH and CIDR+eCG protocols compared to the CIDR+EB protocol.

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The objective was to determine the effect of some factors on pregnancy rate of fixed-time embryo transfer (FTET), in cows and heifers kept under Mexican tropical conditions. Recipients females (n=405) grazing in pastures were selected according to breed group (Zebu and crosses), parity (nulliparous and multiparous), body condition score (BCS) and the presence of a corpus luteum (CL). The females were synchronized on day 0 using a progesterone vaginal device and 2 mg estradiol benzoate (EB), two groups were established. Group 1 (conventional protocol) were animals in which the progesterone device was removed on day 7. At this time, also received an injection of 50 mg cloprostenol sodium and 1 mg estradiol cypionate. Animals also received 300 IU (heifers) or 360 IU (cows) of eCG. Group 2 (J-Synch protocol) were animals in which the progesterone device was removed on day 6. Cloprotenol and eCG injections were applied as in Group 1. Additionally, on day 9, animals of group 2 received 0.01 mg buserelin acetate. Embryo transfer of in vivo or in vitro was done on day 16 and pregnancy diagnosis was realized by ultrasonography on days 23 and 53 after FTET. Statistical analyses were carried out using Chi-square tests and logistic regression. Pregnancy rate varied between farms (P<0.05). The highest pregnancy rate was for multiparous cows (66%). The recipient utilization rate was better in the J-Synch protocol (85%), and in vivo embryos (75%) had higher pregnancy rate. The diameter of the follicle and the CL had no effect on pregnancy rate (P>0.05). However, the logistic regression determined that the only significant factor on pregnancy rate was the type of embryo. In conclusion, pregnancy rate in FTET females was higher for in vivo embryos than for in vitro embryos in cows evaluated under humid tropical conditions in Mexico.

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Paratuberculosis is caused by Mycobacterium avium subspecies paratuberculosis (MAP), a chronic disease of a negative economic impact on sheep production. In the state of Sonora, Mexico, there are no reports on the prevalence of MAP in sheep and risk factors associated with it. The objective of this study was to estimate the seroprevalence of MAP and risk factors associated by testing antibody-positive in sheep flocks located in the arid and hot region of Sonora, Mexico. A cross-sectional study was conducted from February 2012 to December 2014, in 43 flocks. Serum samples from 1178 individual sheep were obtained to detect antibodies against MAP by immunodiffusion in agar-gel. During blood sampling, information about animal and flock management risk factors were obtained by applying a questionnaire to the owners. Risk factors associated with seroprevalence of MAP were estimated using binary logistic regression. The true prevalence of MAP was 7.48% (95% CI 5.98, 8.98) and 53.5% of flocks had at least one seropositive animal. An animal was more likely to be seropositive if it was from a large flock (> 300 animals; OR 3.52, 95% CI 1.24, 9.99) and was born outside the farm (OR 6.24; 95% CI 2.9-1, 3.52). This is the first report of Mycobacterium avium subspecies paratuberculosis seroprevalence in sheep, in Sonora, Mexico. Large flocks and the entry of new animals to the flock were critical risk factors associated with MAP seropositivity.

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The objective was to determine the effect of some factors on pregnancy rate of fixed-time embryo transfer (FTET), in cows and heifers kept under Mexican tropical conditions. Recipients females (n=405) grazing in pastures were selected according to breed group (Zebu and crosses), parity (nulliparous and multiparous), body condition score (BCS) and the presence of a corpus luteum (CL). The females were synchronized on day 0 using a progesterone vaginal device and 2 mg estradiol benzoate (EB), two groups were established. Group 1 (conventional protocol) were animals in which the progesterone device was removed on day 7. At this time, also received an injection of 50 mg cloprostenol sodium and 1 mg estradiol cypionate. Animals also received 300 IU (heifers) or 360 IU (cows) of eCG. Group 2 (J-Synch protocol) were animals in which the progesterone device was removed on day 6. Cloprotenol and eCG injections were applied as in Group 1. Additionally, on day 9, animals of group 2 received 0.01 mg buserelin acetate. Embryo transfer of in vivo or in vitro was done on day 16 and pregnancy diagnosis was realized by ultrasonography on days 23 and 53 after FTET. Statistical analyses were carried out using Chi-square tests and logistic regression. Pregnancy rate varied between farms (P0.05). However, the logistic regression determined that the only significant factor on pregnancy rate was the type of embryo. In conclusion, pregnancy rate in FTET females was higher for in vivo embryos than for in vitro embryos in cows evaluated under humid tropical conditions in Mexico.

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The objective was to determine the effect of some factors on pregnancy rate of fixed-time embryo transfer (FTET), in cows and heifers kept under Mexican tropical conditions. Recipients females (n=405) grazing in pastures were selected according to breed group (Zebu and crosses), parity (nulliparous and multiparous), body condition score (BCS) and the presence of a corpus luteum (CL). The females were synchronized on day 0 using a progesterone vaginal device and 2 mg estradiol benzoate (EB), two groups were established. Group 1 (conventional protocol) were animals in which the progesterone device was removed on day 7. At this time, also received an injection of 50 mg cloprostenol sodium and 1 mg estradiol cypionate. Animals also received 300 IU (heifers) or 360 IU (cows) of eCG. Group 2 (J-Synch protocol) were animals in which the progesterone device was removed on day 6. Cloprotenol and eCG injections were applied as in Group 1. Additionally, on day 9, animals of group 2 received 0.01 mg buserelin acetate. Embryo transfer of in vivo or in vitro was done on day 16 and pregnancy diagnosis was realized by ultrasonography on days 23 and 53 after FTET. Statistical analyses were carried out using Chi-square tests and logistic regression. Pregnancy rate varied between farms (P<0.05). The highest pregnancy rate was for multiparous cows (66%). The recipient utilization rate was better in the J-Synch protocol (85%), and in vivo embryos (75%) had higher pregnancy rate. The diameter of the follicle and the CL had no effect on pregnancy rate (P>0.05). However, the logistic regression determined that the only significant factor on pregnancy rate was the type of embryo. In conclusion, pregnancy rate in FTET females was higher for in vivo embryos than for in vitro embryos in cows evaluated under humid tropical conditions in Mexico.(AU)

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The reproductive efficiency of sheep herds depends to a great extent on the ram. Male reproductive evaluation allows to select for the best and eliminate those with reproductive problems. The objective was to evaluate the effect of breed and age group on the reproductive behavior of hair sheep rams in the tropics of Mexico. Pelibuey (n = 42), Blackbelly (n = 30), Dorper (n = 44), and Katahdin (n = 30) rams of two age groups: young (n = 74, 1-1.5 years old) and adult (n = 72, 2-4 years old) were evaluated. Serving capacity (10-min duration) and breeding soundness evaluation (BSE) tests were carried out in each ram. In the first test, rams were classified as suitable and unsuitable, and in the BSE test, they were classified as satisfactory, questionable, or unsatisfactory. The response variables were analyzed using chi-square test or analyses of variance (ANOVA). ANOVA included the fixed effects of breed, age group, and their interaction. In the serving capacity test, 79.5% of the rams were considered suitable, with no breed differences (P > 0.05). Adult rams (90.3%) had the highest proportion of suitable rams (P < 0.05). In the BSE test, 80.2% of the rams were satisfactory; only breed being significant (P < 0.05). Pelibuey breed had the highest proportion of satisfactory rams (91.4%). Breed × age interaction was no significant for any trait. After serving capacity and BSE tests, a high proportion of rams was found not suitable for reproduction (36.3%), which is expected to cause low fertility in the flock.

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We evaluated the effect of some environmental factors on age at first lambing (AFL) and lambing to conception interval (LCI) of Pelibuey ewes under the humid tropical conditions of Mexico. Ewes grazed on Tanzania (Panicum maximum), Bermuda (Cynodon dactylon), and Brachiaria grass (Brachiaria humidicola) and received hay in the corral in the months of grass scarcity. Reproduction was continuous during the year. Data of 839 lambings from 334 ewes registered from 2009 to 2017 were analyzed using survival analysis procedures. The statistical model for AFL included the effects of year, season, and litter size at lambing, whereas that for LCI included year and season plus parity number of ewe and litter size at weaning. The overall means ± SD for AFL and LCI were 551.6±144.8 and 145.4±113.1 days, and their medians were 510 and 98 days, respectively. Only year of lambing had a significant effect on AFL, whereas LCI was affected by year, parity number, and litter size at lambing (P<0.05). Both AFL and LCI means did not show any trend with advancing years. The largest AFL and LCI means and medians corresponded to the first-parity ewes. In addition, single birth ewes had the longest LCI means and median. Therefore, year of lambing affects AFL, whereas year of lambing, parity number, and litter size at weaning affect LCI of Pelibuey ewes, indicating that these factors should be considered in the development of sound strategies to improve sheep production.(AU)

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The objectives of this study were to estimate the lifetime and per year productivity of sows and to determine the effect of some factor on those traits in four pig farms in the tropics of Mexico. Data from 7526 sows for lifetime number of piglets born alive per sow (LBA), lifetime kilograms of piglets at farrowing (LKF), number of piglets born alive per year (NPF/Y), and kilograms of piglets at farrowing per year (KPF/Y); and data from 7230 sows for lifetime number of piglets weaned (LPW), lifetime kilograms of piglets weaned (LKW), number of piglets weaned per year (NPW/Y), and kilograms of piglets weaned per year (KPW/Y) per sow were used. The statistical model for all traits included the fixed effects of farm, year of first farrowing, season of first farrowing, litter size at first farrowing, age at first farrowing, removal reason, simple interactions, and the error term. The means for LBA, LKF, NPF/Y, and KPF/Y were 45.1 piglets, 67.1 kg, 22.7 piglets, and 33.7 kg, respectively. The means for LPW, LKW, NPW/Y, and KPW/Y were 43.2 piglets, 251.9 kg, 21.5 piglets, and 125.1 kg, respectively. All factors were significant for all traits, except for age at first farrowing on LPW and LKW. Sows with large litter sizes and those that farrowed the first time, at an early age, had the highest lifetime and per year productivity. Therefore, more care and better management should be provided to those types of sows to improve the farms profit.

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The objective was to evaluate the reproductive performance and productivity of Pelibuey ewes in two flocks in Southeastern Mexico. Animals grazed on irrigated star grass (Cynodon plectostachyus). In flock 1, lambs grazed with their mothers from 7 to 70 days of age (weaning age), whereas in flock 2, they were confined and offered chopped grass, a commercial concentrated and managed under restricted suckling until weaning at 60 days of age.. The statistical model included the fixed effects of flock, year and season of lambing, parity number, litter size at weaning, first order interactions and the random effects of ewe and the error term. The means ± SD for age at first lambing, prolificacy, lambing interval (LI), weaning weight, and productivity were 477 ± 85.5 days, 1.41 ± 0.51 lambs, 255.9 ± 51.8 days, 16.5 ± 4 kg, and 18.1 ± 4.42 kg of lamb weaned, respectively. Repeatability estimates for the latter four traits were 0.09, 0.07, 0.11, and 0.13, respectively. All main effects in the models were significant (P < 0.001), except for year on LI. Prolificacy and productivity increased with parity number. The shortest LI was in the rainy season. Ewes with two or three lambs produced 8 and 14 kg of lamb more at weaning than single lamb ewes. In conclusion, reproductive performance and productivity could be improved, and the low repeatability estimates suggest that management should be used in a short term rather than genetic approaches.

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Los objetivos de este estudio fueron estimar la prevalencia y determinar algunos factores de riesgo asociados con el virus del Síndrome Reproductivo y Respiratorio Porcino (PRRS) en sementales de granjas porcinas de Yucatán, México. El estudio se realizó en 30 granjas con 28 a 2.000 vientres y con diferentes niveles de tecnificación. Los verracos al llegar a la granja fueron sometidos a un periodo de adaptación al manejo y al estatus sanitario. En las granjas se empleaba la monta natural, la inseminación artificial o ambas técnicas. La alimentación de los verracos consistió en alimento comercial. Se realizó un estudio transversal por conglomerados desde septiembre 2005 hasta febrero 2006, muestreándose 170 verracos. La presencia de anticuerpos y partículas virales se determinó mediante las pruebas de ELISA y RT-PCR (Reacción en Cadena de la Polimerasa- Transcriptasa Reversa), respectivamente. Cincuenta y seis verracos fueron positivos a la prueba de ELISA, 21 a la prueba de RT-PCR y 67 a una o ambas pruebas. La prevalencia en los verracos fue 39,4% (67/170) y dentro de granjas varió de 0 a 100%. Veintiún granjas tuvieron al menos un animal positivo a la prueba de ELISA, 13 a la prueba de RT-PCR y 25 a una o ambas pruebas. El riesgo de un animal positivo a PRRS fue 3,6 veces mayor en granjas positivas al virus de PRRS y 2,6 veces mayor en granjas donde no se realizaban pruebas diagnósticas antes de introducir los sementales. Las granjas que utilizaban sementales en la detección de celo tuvieron 7,0 veces mayor riesgo de un verraco positivo al virus de PRRS.

The objectives of this study were to estimate the prevalence of and to determine some risk factors associated with the Porcine Reproductive and Respiratory Syndrome (PRRS) virus in boars from pig farms in Yucatan, Mexico. The study was carried out in 30 farms with 28 to 2,000 sows and different levels of technology. On arrival, boars were kept for an adaptation period to the farm conditions and management. Natural mating, artificial insemination or both techniques were used. Commercial feed was provided to the boars. A cluster cross-sectional study was carried out from September 2005 to February 2006, and 170 boars were sampled. The presence of antibodies and virus particles was determined using ELISA and RT-PCR (Reverse transcriptase- polymerase chain reaction) tests respectively. Fifty six out of 170 boars were positive to ELISA test, 21 to RT-PCR and 67 to one or both tests. Boar prevalence was 39.4% (67/170) and within farm varied from 0 to 100%. Twenty one farms (70%) had at least one ELISA positive animal, 13 positives to RT-PCR test (43.3%) and 25 (83.3%) to one or both tests. The risk of a PRRS virus positive boar was 3.6 times greater in the positive farms and 2.6 when no diagnostic tests were carried out before introducing the boar to the farm. Farms using the boars for estrus detection had 7.0 times greater risk of a PRRS virus seropositive boar.

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The purpose of this study was to estimate the seroprevalence of H. somni infection and to determine some risk factors associated with the seropositivity in beef cattle in the livestock region of Yucatan, Mexico. Furthermore, the intraherd correlation coefficient (r e) and the design effect (D) were estimated. The animals were selected using a two-stage random sampling. Blood samples were collected from 490 animals from 35 herds, and sera were tested for the detection of antibodies against H. somni, using the double agar gel immunodiffusion test. Information about each herd and animal sampled was recorded by a questionnaire personally applied in the farm. Data were analyzed by chi-square tests. Ten herds had zero seropositive animals, 19 had one and six had two seropositive animals. Thirty one out of 490 animals were seropositive. The animal seroprevalence adjusted to herd size was 5.5% (95% confidence interval = 3.5%, 7.5%). Animal seroprevalence in the six municipalities ranged from 3.6% to 9.5%, but no significant differences (P = 0.89) were found. The r e and D values for H. somni seroprevalence were 0 (SE = 0.01) and 1 (SE = 0.19), respectively. The chi-square test did not show association (P > 0.10) between the presence of antibodies against H. somni and the risk factors investigated.

El propósito de este estudio fue investigar la seroprevalencia de la infección por H. somni y determinar algunos factores de riesgo asociados con su seropositividad en ganado para carne en la región ganadera de Yucatán, México. Asimismo, se estimó el coeficiente de correlación dentro de hatos (re) y el efecto de diseño (D). Los animales se seleccionaron usando un muestreo aleatorio en dos etapas. Las muestras de sangre se recolectaron de 490 animales en 35 hatos, y los sueros se sometieron a análisis para detectar anticuerpos contra H. somni, mediante la prueba de inmunodifusión doble en agar. La información acerca del hato y de cada animal muestreado se obtuvo mediante una encuesta aplicada personalmente en el rancho. Los datos se analizaron mediante pruebas de Ji-cuadrada. Diez hatos tuvieron cero animales seropositivos, 19 tuvieron uno, y seis tuvieron dos animales seropositivos. Treinta y uno de los 490 animales fueron seropositivos. La prevalencia animal ajustada por el tamaño del hato fue 5.5% (intervalo de confianza al 95% = 3.5%, 7.5%). La seroprevalencia de los animales en los seis municipios varió de 3.6% a 9.5%, pero no se encontraron diferencias significativas (P = 0.89). Los valores de r e y D para la seroprevalencia de H somni fueron 0 (EE = 0.01) y 1 (EE = 0.19), respectivamente. Las pruebas de Ji-cuadrada no mostraron asociación (P > 0.10) entre la presencia de anticuerpos contra H. somni y los factores de riesgo investigados.

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El objetivo de este estudio fue comparar los resultados de regresiones logísticas para datos correlacionados obtenidos mediante tres procedimientos del sistema de análisis estadístico (SAS). Se utilizó la información de un estudio transversal sobre rinotraqueitis infecciosa bovina en el estado de Yucatán, México, donde la unidad de muestreo fue el hato y la unidad de interés el animal. Los datos se analizaron mediante los procedimientos LOGISTIC, GENMOD y NLMIXED del SAS. El modelo logístico utilizado incluyó los factores de riesgo: tamaño de hato (<=75, 76-147, 148-261, 262-480 animales) y etapa de vida del animal (crecimiento, desarrollo y producción). Se obtuvieron las razones de probabilidad (OR) e intervalos de confianza al 95% (IC95). También se calcularon las razones de probabilidad (OR) e IC95 utilizando regresiones logísticas estándar como referencia. Los ORs para tamaño de hato: <=75, 76-147, 148-261 y 262-480 animales, utilizando los procedimientos LOGISTIC, GENMOD y NLMIXED fueron: 0,34; 0,68; 0,62 y 1; 0,34; 0,63; 0,63 y 1; y 0,29; 0,62; 0,57 y 1, respectivamente; y para los animales en crecimiento, desarrollo y producción fueron: 0,12; 0,15 y 1; 0,15; 0,17 y 1; y 0,12; 0,14 y 1, respectivamente. Los menores IC95 fueron para los ORs de la regresión logística estándar y los mayores para los OR obtenidos mediante el procedimiento NLMIXED. En conclusión, los tres procedimientos ajustaron por el efecto de hato siendo el más estricto NLMIXED.

The objective of this study was to compare the results of logistic regressions for correlated data obtained by using three procedures of the Statistical Analysis System package (SAS). Information from a cross sectional study on infectious bovine rhinotracheitis in Yucatan state, Mexico, was used; where the sampling unit was the herd and the unit of interest was the animal. Data were analyzed by using the LOGISTIC, GENMOD and NLMIXED procedures of the SAS. The logistic model used included the risk factors: herd size (<=75, 76-147, 148-261, 262-480 animals) and stage of life (growth, development and production). The odd ratios (OR) and 95% confidence intervals (CI95) were obtained. Also the OR and CI95 for the risk factors were estimated using ordinary logistic regression as a reference. The ORs for herd size <=75, 76-147, 148-261 y 262-480 animals, using LOGISTIC, GENMOD and NLMIXED procedures were: 0.34, 0.68, 0.62 and 1; 0.34, 0.63, 0.63 and 1; and 0.29, 0.62, 0.57 and 1, respectively; and for the animals in the stage of growth, development and production were: 0.12, 0.15 and 1; 0.15, 0.17 and 1; and 0.12, 0.14 and 1, respectively. The narrower CI95 were for the ORs from the ordinary logistic regression and the widest for the OR obtained using the NLMIXED procedure. In conclusion, the three procedures adjusted for herd effect, being the most precise those of the NLMIXED procedure.