Luis Cal-Pereyra

El fenómeno de aumento periparto de la eliminación de huevos de nematodos gastrointestinales constituye un desafío sanitario relevante en los sistemas ovinos, debido a su asociación con la consecuente contaminación de las pasturas por nematodos gastrointestinales. El objetivo de este estudio fue evaluar el efecto del momento del servicio y del biotipo ovino sobre el aumento periparto de la eliminación de huevos de nemátodos gastrointestinales, mediante el análisis de la dinámica posparto del recuento de huevos por gramo. Se utilizaron 20 ovejas Milchschaf y 60 mestizas Corriedale, adultas y gestando un solo cordero, asignadas a cuatro grupos experimentales: GM1 (n = 10; Milchschaf) y GC1 (n = 30; Corriedale), servidos entre el 1 y el 15 de febrero; y GM2 (n = 10; Milchschaf) y GC2 (n= 30; Corriedale), servidos entre el 2 y el 18 de abril. Los animales pastorearon en conjunto sobre campo natural. Quince días antes de la fecha prevista de parto, los grupos GM1 y GC1 fueron trasladados a la mitad de un potrero dividido en dos partes iguales, mientras que los grupos GM2 y GC2 fueron trasladados a la otra mitad. Se realizaron muestreos semanales de materia fecal desde dos semanas previas al parto hasta las 15 semanas posparto. Se observó un efecto altamente significativo del tiempo de muestreo sobre el recuento de huevos por gramo (P<0,001), con valores máximos entre las semanas 2 y 4 posparto (P<0,01). Asimismo, se detectó una interacción significativa entre el tiempo de muestreo y el momento de servicio (P<0,05). Las ovejas del tratamiento con servicio tardío presentaron un pico de recuento de huevos por gramo significativamente (P<0,05) menor. En conclusión, el fenómeno de alza de lactación determinó el patrón temporal de eliminación de huevos, con un pico en el posparto temprano. El biotipo y el momento de servicio mostraron una influencia limitada sobre su magnitud, destacando la importancia del manejo del período posparto para el control parasitario en sistemas ovinos extensivos.

Esta revisión sintetiza y discute información sobre los cambios en el metabolismo energético de ovejas gestantes y sus crías recién nacidas, y las modificaciones que induce la esquila preparto sobre el metabolismo y la termorregulación de ovejas gestantes y sus corderos. Durante la gestación la disponibilidad de glucosa en la sangre materna debe aumentar para ser dirigida a la unidad-feto placentaria, promoviendo el adecuado desarrollo fetal, el que es máximo durante el último tercio de la gestación. El aumento de la glucemia preparto en las ovejas se explica por una resistencia transitoria a la insulina. Luego del parto, los neonatos deben preservar su homeostasis, mantener su glucemia y su temperatura corporal en forma independiente en rangos compatibles con la vida. Los neonatos dependen principalmente de las reservas de glucógeno y de la gluconeogénesis para mantener la glucemia, y de las reservas de grasa parda para generar calor. El estatus metabólico de las ovejas durante la gestación influye directamente sobre la cantidad de glucógeno y de grasa parda del cordero al nacimiento. La esquila preparto es un manejo que está siendo cada vez más utilizado por los productores, ya que los corderos nacen más pesados y tienen mayores tasas de supervivencia que los nacidos de ovejas no esquiladas. La esquila preparto adelanta la resistencia a la insulina previa al parto, por lo que la unidad feto-placentaria comienza a captar más glucosa más tempranamente. Consecuentemente, los depósitos de glucógeno muscular y hepático y las reservas de grasa parda son mayores en los neonatos hijos de ovejas esquiladas, y son utilizados como combustibles para la generación de energía y de calor metabólico. En resumen, la esquilada preparto favorece características metabólicas y morfológicas del cordero que aumentan la tasa metabólica y por tanto la generación de calor, lo que reduce las muertes por hipotermia.

The objective of the study was to characterize differences in the time to onset of puberty and reproductive variables between East Friesian and Corriedale ewe lambs in an extensive pastoral system. The study was carried out for two consecutive years, and 73 pure-breed ewe lambs were evaluated (35 East Friesian and 38 Corriedale). Plasma progesterone was determined weekly between 4.5±0.5 and 7.2±0.5 months old. The time to onset of puberty was assumed when the progesterone levels were ≥0.6 ng/mL [...] ABSTRACT The objective of the study was to characterize differences in the time to onset of puberty and reproductive variables between East Friesian and Corriedale ewe lambs in an extensive pastoral system. The study was carried out for two consecutive years, and 73 pure-breed ewe lambs were evaluated (35 East Friesian and 38 Corriedale). Plasma progesterone was determined weekly between 4.5±0.5 and 7.2±0.5 months old. The time to onset of puberty was assumed when the progesterone levels were ≥0.6 ng/mL

Aims: To evaluate the effects of early and late pre-partum shearing of Corriedale ewes carrying single fetuses on placental and lamb development and neonatal lamb behaviour. Methods: At 70 days of gestation, 37 multiparous Corriedale ewes with known gestation dates were randomly allocated into three groups: S70 (n = 12) and S110 (n = 12), shorn at Day 70 and 110 of gestation, and US (n = 13), that were not shorn pre-partum. Gestation length, lambing duration, placental expulsion time, placental weight, number and weight of cotyledons, and placental efficiency (lamb weight/placental weight) were determined. At birth, body temperature, weight, morphometric measurements, ponderal index (lamb weight/lamb crown-rump length) and behaviour were recorded, with weight remeasured 72 hours later. Four male lambs per group were slaughtered immediately after parturition, and organ weight and perirenal brown fat weight and energy content recorded. Results: Pre-partum shearing, regardless of timing, increased total dried placental weight per ewe. Pre-partum shearing at Day 70 of gestation increased the number and mean weight of the > 2 to <= 3-cm cotyledons, while pre-partum shearing at Day 110 of gestation increased only the weight of these cotyledons. At birth and at 72 hours, lambs from ewes shorn either at 70 days of gestation (birth: 5.5 (95% CI = 4.6-6.4) kg, p = 0.001; 72 hours: 6.4 (95% CI = 6.1-6.8) kg, p = 0.002) or at 110 days of gestation (birth: 5.4 (95% CI = 4.4-6.4) kg, p = 0.001; 72 hours: 6.5 (95% CI = 5.9-7.1) kg, p = 0.001) were heavier than lambs from unshorn ewes (birth: 4.0 (95% CI = 3.3-4.8) kg; 72 hours: 4.8 (95% CI = 3.5-6.1) kg). Lambs born to S70 and S110 ewes suckled sooner (31.5 (95% CI = 14.5-48.5) minutes, p = 0.001; and 39.3 (95% CI = 23.7-55.0) minutes, p = 0.001 respectively), than lambs born to the US group (70.3 (95% CI = 38.6-102.1) minutes). There was no evidence for an effect of pre-partum shearing on gestation length, parturition length, time of placental expulsion, placental efficiency, weight and energy of perirenal brown fat, and lamb temperature at birth. Conclusions and Clinical Relevance: Shearing ewes pre-partum may lead to placental changes affecting lamb development and behaviour and associated with higher survival. The findings suggest pre-partum shearing may improve lamb survival, farm profitability and sustainability.

The objective of the essay was to determine the influence of protein–energy supplementation on the gastrointestinal nematode population during spring rise in ewes and their offspring as a non–chemical alternative in Integrated Parasite Control. One hundred twenty six Corriedale ewes were divided into two groups, one supplemented with protein–energy blocks from one month before lambing until weaning and the other without supplementation. Every 17 days, faecal matter was randomly collected from 20 ewes and 20 lambs from both groups. Modified McMaster and coproculture were performed, estimating the pathogenicity index for each gender. Lambs´ weight at birth, marking and weaning were recorded and the daily weight gains from birth to marking and from marking to weaning were calculated. Eggs count per gram of faeces were higher (P<0.05) in the non–supplemented group and their lambs. The predominant genus in dams and lambs were Haemonchus contortus and Trichostongylus spp. The pathogenicity index in the non–supplemented dams was higher than 1 from the faecal egg count increase. The lamb body weights and average daily gains were higher in those lambs born to the supplemented dam group (P<0.05). In conclusion, the supplementation contributed to the non–chemical control of the most prevalent gastrointestinal nematode in periparturient ewes, H. contortus, and environmental contamination for lambs at the dam foot.

En el presente trabajo se describen los hallazgos macroscópicos y microscópicos de un mesotelioma pleural en un canino, ovejero alemán, macho, de 6 años que presentaba disnea y pérdida de peso por 20 días. El animal fue ingresado al Hospital Veterinario de la Facultad de Veterinaria de la Udelar, descompensándose y falleciendo durante la consulta. El cadáver fue remitido a la Unidad de Patología para su estudio post-mortem. La necropsia reveló hemoperitoneo, hepatomegalia, hemotórax abundante, se evidenció una gran masa en el mediastino, de forma irregular que se extendía por toda la cavidad, adherida a la pleura parietal y a la parrilla costal; dicha masa estaba formada por multi-nodulaciones de pocos milímetros de diámetro y coloración blanquecina, de consistencia friable. Además, se observó hemopericardio, se constató infiltración de diafragma, pericardio y epicardio. Al examen histopatológico de la masa y del tejido cardíaco, se identificaron células mesoteliales de gran tamaño, con forma cuboidal o poliédrica, agrupadas conformando estructuras arborizantes con una discreta cantidad de estroma conectivo. Las células presentaban citoplasma claro con vacuolas, núcleo grande e intensamente basófilo y algunas binucleadas, con nucléolo prominente, presentando pocas mitosis, y marcada anisocariosis y anisocitosis, diagnosticándose como un mesotelioma de tipo papilar. Este diagnóstico se confirmó mediante inmunohistoquímica, observándose inmunomarcación positiva a vimentina y pancitoqueratina en las células tumorales.

The objective of this study was to determine the impact of metabolic changes occurring in induced subclinical gestation toxaemia in ewes on metabolic parameters and vigour in the first 72 h of their lambs’ life. Fifty-one adult Corriedale ewes of known gestation date and fed on a natural pasture were randomly divided into four groups at day 145 of gestation. Group A (ewes with single pregnancies) and group C (ewes with twin pregnancies) were fed on a natural pasture [...] ABSTRACT The objective of this study was to determine the impact of metabolic changes occurring in induced subclinical gestation toxaemia in ewes on metabolic parameters and vigour in the first 72 h of their lambs’ life. Fifty-one adult Corriedale ewes of known gestation date and fed on a natural pasture were randomly divided into four groups at day 145 of gestation. Group A (ewes with single pregnancies) and group C (ewes with twin pregnancies) were fed on a natural pasture

Sheep represent one of the main reservoirs of diarrheagenic Escherichia coli; this microorganism is an etiological agent of food-borne diseases; therefore, this work aimed to identify and characterize the principal pathotypes of diarrheagenic E. coli (DEC) obtained through rectal swabs and carcasses samples from sheep slaughtered in an abattoir at the central region of Mexico. The isolates were subjected to bacteriological identification, serotyping; phylogenetic classification; detection for virulence factors, and antimicrobial sensibility. A total of 90 E. coli isolates were obtained. It was observed through 49 E. coli isolates (54%), 8 of them from carcasses, and 43 from feces was DEC. DEC serotypes with health public relevance were found: O76:H19 (n = 5), O146:H21 (n = 3), O91:H10 (n = 1), O6:NM (n = 1), and O8:NM (n = 1). Regarding the presence of Shiga toxin-producing E.coli (STEC), 43/90 (47.7%) isolates have the stx1 w/o stx2 genes, and therefore were assigned as STEC non-O157; only one isolate expressed stx1 and eae genes and was classified as t-STEC (typical STEC). Additionally, 3/90 (3.3%) harbored only the eae gene and were classified as enteropathogenic E. coli (EPEC), the stp gene was found in 2/90 isolates (2.2%) and were classified as enterotoxigenic E. coli (ETEC); 1/90 (1.1%) isolates harboring the ipaH were classified as enteroinvasive E. coli EIEC. Regarding stx1 genes subtypes, stx1c only was found in 60.5% (26/43), followed by stx1a-stx1c 20.9% (9/43) and stx1a-stx1d 2.3% (1/43). The presence of both, stx1 and stx2 genes was found in 7/43 isolates (16.3%) from rectal swabs; the combination stx1c-stx2g was detected in 3/43 isolates (6.9%), while 4 (9.4%) isolates showed different patterns (stx1a-stx1c-stx2g; stx1c-stx2b-stx2g; stx1c-stx2b and stx1a-stx1c-stx2b-stx2g). STEC isolates showed the major diversity of phylogenetic groups, although phylogroup B1 was predominant in 90.6% (39/43) while there was only one isolate (2.3%) in each remaining phylogroup (A, B2, C, and F). All EPEC, ETEC, and EIEC isolates were clustered in phylogroup B1. We observed that 27.9% (12/43) of STEC isolates carried at least one antibiotic resistance: nine isolates expressed the tetB gene, one isolate the tetA gene, two isolates the sul2 gene, one isolate the sul1 and one isolate the sul1-tetB genes. These results highlight the importance of diarrheagenic E. coli as a potential risk for public health during the slaughtering process.

Polyunsaturated fatty acid (PUFA) deposition in lambs’ muscles could be influenced by their mothers’ diet. The aim was to study the profile of fatty acids in the muscle of lambs from ewes supplemented with different sources of PUFA to achieve a healthier meat for the consumer. On day 100 of gestation, pregnant ewes grazed on natural grass were divided into three groups (n = 20) and supplemented with PUFA: Group A: 700 g of a ration rich in PUFA, Group B: 700 g of a ration for sheep + 20 mL of fish oil and Group C: 700 g of the same ration. After parturition, each group was subdivided: ten ewes continued with the same diet until the end of lactation; the other ten were fed only natural grass. The values of n-3 and n-6 PUFA and alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), linoleic acid (LA) and arachidonic acid (AA) were analyzed in Longissimus lumborum muscles of lambs at 90 and 120 days of life. The feeding of ewes during lactation favorably influenced the lipid profile of the lamb muscle, increasing the concentration of n-3 and n-6 PUFA, ALA, LA, AA, DHA and EPA. The supplementation of ewes with fish oil and/or a ration rich in PUFA improved the LA/ALA ratio in lambs’ meat.