Summary Parasitic diseases of sheep involving gastrointestinal nematodes (GIN) are one of the main problems that affect fl ock productivity, especially during the peripartum period. Around lambing, the ewes are immunosuppressed and the nematode faecal egg count (FEC) increases at four weeks before lambing, reaching a peak between the fourth and sixth week postpartum and subsequently decreasing towards weaning. Prolactin has been credited with a suppressive effect on immune system, along with other hormones that intervene in metabolism, such as leptin, which has an important role in the activation of other hormones. Cortisol has also been included; this is stimulated by any stressful event and inhibits the proliferation of T-cells and alters the function of immunoglobulins. Another related hormone is pepsinogen, which is considered a marker of the integrity of the abomasum mucosa, as well as the albumin concentration that increases in the presence of a GIN infection. The humoral and cellular immune response, as well as inflammatory reactions, are the main mechanisms of action against GIN. Lymphocytes direct the effector mechanisms in a Th2 cell response, including interleukins (IL-4, IL-5, IL-9, IL-10) and transforming growth factor beta (TGF-β) together with immunoglobulins (IgA, IgG, IgM and IgE), which prevent the invasion of pathogens. Eosinophils with a cytotoxic effect are indicators of a parasitic infection, with importance in the immune protection of infected individuals. The genetic selection of resistant individuals measured by FEC is dependent on the heritability (h2), which is moderately inheritable and highly repeatable. Effects that influence the resistance or susceptibility of sheep to GIN infections in the peripartum period are determined by the interaction of various factors, such as genotype or breed, nutrition, age, type of birth, season and production system, etc., which are studied in this review.

SUMMARYThe aim of this study was to evaluate the reproductive performance and productivity of F 1 Pelibuey x Blackbelly (P x B) ewes and their crosses with Dorper and Katahdin (Synthetic). 1612 lambing intervals (LI), 1265 prolificacy (Pr), 1263 adjusted litter weaning weights to 91 days (WWa) and1200 productivity (PROD) data were analysed. The statistical model included the fixed effects of maternal breed group (MBG), year of lambing (YL), season of lambing(SL), parity number (PN), litter size at weaning (LSW), lambing interval group (LIG) and first-order interactions. The effect of dam nested within MBG was included as random effect. The means ± SE for Pr, LI, WWa and PROD were 1.2±0.01 lambs, 261.5 ±1.9 days, 18.5±0,1 kg and 16.8±0,2 kg, of lamb weaned, respectively. Repeatabilities for the traits were also calculated. Except by maternal breed group, all main effects in the models were significant (P < 0.001); only season of lambing did not affect Pr. Repeatabilities were 0.05±0.03, 0.13±0.03, 0.10±0.03 and 0.12±0.03 for LI, Pr, WWa and PROD, respectively. Partial correlations of PROD with WWa and LI were 0.84 and -0.56, respectively. In conclusion, the P x B ewes had similar performance to the Synthetic group. The environmental factors have more importance than the genetics effects.Key words: preweaning performance, productivity, hair sheep. RESUMENEl objetivo de este estudio fue evaluar el comportamiento reproductivo y productividad de ovejas F 1 Pelibuey x Blackbelly (P x B) y sus cruces con Dorper y Katahdin (Sintético). Se analizaron 1.612 datos de intervalos entre partos (IEP), 1.265 de prolificidad (Pr), 1.263 de peso de la camada al destete ajustado a 91 días (PCDA) y 1.200 de productividad (PROD). El modelo estadístico incluyó los efectos fijos de grupo racial materno (GRM), año de parto (AP), época de parto (EP), número de parto (NP) y tamaño de la camada al destete (TCD), grupo de intervalos entre partos (GIP) y las interacciones de primer orden. El efecto de la madre dentro de GRM fue incluido como efecto aleatorio. Se calculó el índice de constancia de IEP, Pr, PCDA y PROD. Las medias generales de Pr, IEP, PCDA y PROD fueron 1,2 ± 0,01 corderos, 261,5 ± 1,9 días, 18,5 ± 0,1 kg y 16,8 ± 0,2 kg de cordero destetado, respectivamente. Excepto por grupo racial materno, todos los factores considerados en este estudio afectaron a todas las variables de respuesta. Asimismo la época de parto no afectó la prolificidad. Los índices de constancia estimados fueron 0,05 ± 0,03, 0,13 ± 0,03, 0,10 ± 0,03 y 0,12 ± 0,03 para IEP, Pr, PCDA y PROD, respectivamente. Las correlaciones parciales de PROD con IEP y PCDA fueron -0,56 y 0,84, respectivamente. Se concluye que la productividad del grupo racial materno P x B es similar al grupo Sintético, y que los efectos ambientales tienen más importancia que los efectos genéticos.Palabras clave: comportamiento predestete, productividad, ovino de pelo. INTRODUCCIÓNLas razas ovinas tropicales están constituidas principalmente por animales de pelo cuya productividad difiere, ...

Efecto del color de la capa externa en la edad al primer parto, prolificidad e intervalo entre partos en un rebaño de ovejas de pelo en Campeche, MéxicoEffect of coat color on age at first lambing, prolificacy and lambing interval in a flock of hair ewes in Campeche, México SUMMARYThe main objective of the study was to evaluate the effect of the ewe's coat color (brown, white, spotted, Blackbelly, and black) on age at first lambing (AFL, n = 578), prolificacy (PRO, n = 475), and lambing interval (LI, n = 438) in a flock of hair sheep in Campeche, México. As a secondary objective, the effects of lambing year, lambing month, and the ewe's lambing number (primiparous, multiparous) were also evaluated. Data collected on reproductive characteristics during 5 years (2006)(2007)(2008)(2009)(2010) from 340 ewes and their lambs were analysed. The sheep were managed under semi-extensive conditions; ewes and their lambs were allowed to graze during the day and were penned overnight. The statistical analysis was performed with the GLM procedure of the SAS statistical package utilizing fixed effects models. Overall least-squares means for AFL, PRO, and LI were 463.9±13.0 days, 1.71±0.60 lambs born per ewe lambing, and 295,7±17,9 days, respectively. The ewe's coat color had a significant effect (P ≤ 0.05) on AFL and LI; the lowest averages for AFL were for white (435.8±1.4), brown (438.5±2,4) and spotted (439.7±3.6) ewes, while for LI the lowest averages were for spotted (284.9±6.9), white (288.8±1.6), and black (291.7±5.8) ewes. Significant effects ((P ≤ 0.05) of lambing year, lambing month, and lambing number were found on the three characteristics. Due to their lowest averages being obtained at first lambing and lambing interval, it is concluded that white and spotted ewes in this flock should be preferred for a selection program in an attempt to decrease the average of both characteristics.Key words: coat color, reproductive traits, hair sheep, humid tropic. RESUMENEl objetivo principal fue evaluar el efecto del color de la oveja (café, blanco, pinto, Blackbelly, y negro) en edad al primer parto (EPP, n = 578), prolificidad (PRO, n = 475) e intervalo entre partos (IEP, n = 438) en un rebaño de ovinos de pelo en Campeche, México. De manera secundaria se evaluaron año de parto, mes de parto, y número de parto de la oveja (primíparas, multíparas). Se analizaron datos de características reproductivas de cinco años (2006)(2007)(2008)(2009)(2010) de 340 ovejas y sus crías. El rebaño se manejó bajo condiciones semiextensivas; las ovejas y sus crías pastoreaban durante el día y se encerraban toda la noche. El análisis estadístico se efectuó con el procedimiento GLM del paquete estadístico SAS mediante modelos de efectos fijos. Las medias generales de cuadrados mínimos de EPP, PRO e IEP fueron 463,9±13,0 días, 1,71±0,60 corderos nacidos por oveja parida, y 295,7±17,9 días, respectivamente. El color de la oveja influyó (P ≤ 0,05) en EPP e IEP; los menores promedios para EPP fueron para las ovejas blancas (435,8±1,4), café (438,5±2...

Introduction: Dirofilaria immitis is a nematode that affects human health in several countries of the world. This study was conducted to examine whether serum samples from the owners of microfilaremic dogs present immunoreactivity to parasite proteins. Methodology: Eight serum samples from the owners of microfilaremic dogs were examined. Total proteins were extracted from adult worms and 12% SDS-PAGE was performed. The gel was electroblotted to a nitrocellulose membrane, and a Western blot (WB) was performed. Reactive bands of 22, 33, 39, 49, and 63 kDa in WB were excised from the gel and analyzed by mass spectrometry (MS). Results: The MS results showed the presence of 10 different proteins of D. immitis recognized by the human serum samples. Conclusions: These results indicate that in endemic areas of D. immitis, owners of infected dogs recognize specific proteins of the parasite, suggesting a possible infection.

El objetivo fue determinar la influencia del peso vivo (PV) de ovejas Blackbelly x Pelibuey sobre el consumo voluntario y digestibilidad del follaje de Erythrina americana, comportamiento productivo, cambios en variables hemáticas y en el número de huevos de nematodos gastrointestinales por gramo de heces (HPG). El diseño utilizado fue completamente al azar. Los factores fueron grupo de peso vivo (GPV, ligeras: 22.2 kg y pesadas: 34.4 kg) y periodo de evaluación (PE). Se evaluó PV, ganancia diaria de peso, índice de consumo de materia seca, consumo diario de materia seca (g kg-1 PV), proteína cruda (PC; g kg-1 PV), carbohidratos estructurales (CE, %), energía metabolizable (Mcal kg-1 PV), taninos condensados (TC; g kg-1 PV) y HPG. El GPV y PE afectaron (P<0.01) el consumo de todos los nutrientes estudiados. El GPV ligeras tuvo mayor consumo de nutrientes y TC con relación al de pesadas (P<0.01), sin incremento en su eficiencia productiva. Las variables hemáticas y el HPG no fueron afectados (P>0.05) por los factores estudiados y su interacción. El contenido de PC, CE y TC de E. americana, sugiere que su follaje puede utilizarse como alimento único durante periodos cortos. Las ovejas ligeras tuvieron mayor consumo de nutrientes y TC con relación a las pesadas. Sin embargo, este tipo de respuesta no permitió detectar un incremento en su eficiencia productiva. En ambos grupos de ovejas, el consumo de E. americana permitió un cambio positivo en su comportamiento productivo y no se afectó su estado de salud.

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In epidemiological studies are needed to identify the species of nematodes that parasitize ruminants, so the aim of this study was to describe morphologically two species of gastrointestinal nematodes found in abomasum of sheep and cattle in southeastern Mexico. Haemonchus contortus specimens were recovered from sheep from the states of Tabasco, Veracruz and Chiapas, and Mecistocirrus digitatus was obtained from Zebu cattle, from Tabasco. Identification of H. contortus was performed using a discriminant function measures the hooks of the male spicules. The morphology of the females of both species was recorded taking measures in an optical microscope at 10 and 40 X. Females and males of M. digitatus were larger (28.1 and 21.7 mm, respectively) than those of H. contortus (21.5 and 13.9 mm, respectively), with very contrasting morphological differences. Morphological measurements are in the ranges given in the literature.Key words: parasite nematode, abomasum. ResumenPara los estudios epidemiológicos se requiere de la identificación de las especies de nematodos que parasitan a los rumiantes, por lo que el objetivo de este trabajo fue describir morfológicamente dos especies de nematodos gastrointestinales encontradas en abomaso de ovinos y bovinos en el sureste de México. Los especímenes de Haemonchus contortus fueron recuperados de ovinos provenientes de los estados de Tabasco, Veracruz y Chiapas y Mecistocirrus digitatus se obtuvo de ganado Cebú de Tabasco. La identificación de H. contortus se realizó usando una función discriminante con las medidas de los ganchos de las espículas de los machos. La morfología de las hembras de ambas especies se registró tomando las medidas en un microscopio óptico a 10 y 40 X. Las hembras y machos de M. digitatus fueron más grandes (28.1 y 21.7 mm, respectivamente) que los de H. contortus (21.5 y 13.9 mm, respectivamente), con diferencias morfológicas muy contrastantes. Las medidas morfológicas se encuentran en los rangos indicados en la literatura.Palabras clave: Nematodos parásitos, abomaso.

Objective: To estimate the lactation curve and milk production of Pelibuey ewes andthe relationship with preweaning growth rate of the lambs.Design/methodology/approach: Forty five Pelibuey ewes were milked during 70days in Montecillo, México, in 2018, to estimate daily and total milk production. Thelactation curve was fitted with the incomplete gamma function. In addition, the effectsof type of birth and ewe weight at milking on milk production were analyzed, andcorrelations were calculated between ewe milk production and growth rate of thelambs, per week and for the entire lactation Results: A “typical” lactation curve was found, average ewe milk production for theentire lactation, weighted for the number of lambs suckling, was 131±8 L, with444±24 g d -1 . Ewe weight at milking had an effect (p&lt;0.01) on milk production.Positive correlations were found (p&lt;0.05) between ewe milk production andpreweaning growth rate of the lambs.Limitations on study/implications: There is a strong dependency of the lambs forthe milk production of the Pelibuey ewe, a factor of great relevance so that lambs cangain body weight and survive during lactation.Findings/conclusions: Pelibuey ewes produce less milk than dairy ewes. Therefore,lambs should be weaned at a maximum of 10 weeks of lactation.