Effects of challenge dose and inoculation route of the virulent Neospora caninum Nc-Spain7 isolate in pregnant cattle at mid-gestation

International audienceAbstractParameters such as pathogen dose and inoculation route are paramount in animal models when studying disease pathogenesis. Here, clinical findings, including foetal mortality, parasite transmission rates and lesion severity, and immune responses were evaluated in Asturiana pregnant heifers at day 110 of gestation challenged with a virulent (Nc-Spain7) Neospora caninum isolate. Four different doses of parasite tachyzoites were inoculated intravenously (IV1, 107 parasites, n = 6; IV2, 105, n = 6; IV3, 103, n = 6; and IV4, 102, n = 5), and the subcutaneous (SC) inoculation route was also assessed for the dose of 105 tachyzoites (SC, n = 6). In addition, a control group (n = 4 pregnant heifers) was evaluated. Foetal death was observed in all infected groups from 25 to 62 days post-infection, varying with the dose (IV1:4/6, IV2:3/6; IV4:2/5, IV3:1/6), and was three times less frequently associated with the SC route than IV inoculation (1/6 vs. 3/6). A dose-dependent effect for parasite loads in placental and foetal brain tissues was also detected. After SC challenge, a reduced number of tachyzoites were able to reach foetal brain tissues, and no lesions were observed. In calves, specific IgG responses in precolostral sera were mainly associated with high-dose groups (IV1 [100.0%] and IV2 [66.7%]), and cerebral parasite DNA detection was scarce (3/18). In dams, IFN-γ production and the dynamics of anti-N. caninum IgG antibodies varied with the dose, and the cell-mediated immune response was also found to be route-dependent. Our results confirm the influence of parasite dose and inoculation route on the outcome and dynamics of bovine neosporosis at mid-gestation

Early Neospora caninum infection dynamics in cattle after inoculation at mid-gestation with high (Nc-Spain7)- or low (Nc-Spain1H)-virulence isolates

© The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.[EN] Early Neospora caninum infection dynamics were investigated in pregnant heifers intravenously inoculated with PBS (G-Control) or 107 tachyzoites of high (G-NcSpain7)- or low (G-NcSpain1H)-virulence isolates at 110 days of gestation. Serial culling at 10 and 20 days post-infection (dpi) was performed. Fever was detected at 1 dpi in both infected groups (P < 0.0001), and a second peak was detected at 3 dpi only in G-NcSpain7 (P < 0.0001). At 10 dpi, Nc-Spain7 was detected in placental samples from one animal related to focal necrosis, and Nc-Spain7 transmission was observed, although no foetal lesions were associated with this finding. The presence of Nc-Spain1H in the placenta or foetuses, as well as lesions, were not detected at 10 dpi. At 20 dpi, G-NcSpain7 animals showed almost 100% positive placental tissues and severe focal necrosis as well as 100% transmission. Remarkably, foetal mortality was detected in two G-NcSpain7 heifers. Only one animal from G-NcSpain1H presented positive placental samples. No foetal mortality was detected, and lesions and parasite transmission to the foetus were not observed in this group. Finally, 100% of G-NcSpain7 heifers at 20 dpi presented specific antibodies, while only 60% of G-NcSpain1H animals presented specific antibodies at 20 dpi. In addition, earlier seroconversion in G-Nc-Spain7 was observed. In conclusion, tachyzoites from Nc-Spain7 reached the placenta earlier and multiplied, leading to lesion development, transmission to the foetus and foetal mortality, whereas Nc-Spain1H showed delayed infection of the placenta and no lesional development or transmission during early infection.SIThis work was supported by the Spanish Ministry of Economy and Competi‑ tiveness (AGL2013-44694-R) and the Community of Madrid (PLATESA2-CM P2018/BAA-4370). Laura Jiménez-Pelayo was fnancially supported by a fellowship from the Complutense University of Madrid and Marta GarcíaSánchez was fnancially supported through a grant from the Spanish Ministry of Economy and Competitiveness (BES-2014-070723). Patricia Vázquez had a Juan de la Cierva-Formación post-doctoral contract (FJCI-2014-20982) from the Spanish Ministry of Economy and Competitiveness (MINECO). Alicia Román-Trufero was supported by a FPI-INIA fellowship from the Spanish National Institute for Agriculture and Food Research and Technology (INIA). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Authors gratefully acknowledge to: (1) SERIDA (Regional Service of Agri-food Research and Development of Asturias) Institution and Personal for their facilities and personal support. Special thanks to David Iglesias for their clinical assistance; (2) Mountain Livestock Institute (IGM), University of León CSIC-ULE for their histopathological specialist support, especially to Miguel Fernández for his help during the sampling; (3) Saluvet Group members, especially to Ale‑ jandro Jiménez-Meléndez and Roberto Sánchez-Sánchez; (4) Saluvet-innova members, especially to Paula García-Luna

Early Neospora caninum infection dynamics in cattle after inoculation at mid-gestation with high (Nc-Spain7)- or low (Nc-Spain1H)-virulence isolates

Early Neospora caninum infection dynamics were investigated in pregnant heifers intravenously inoculated with PBS (G-Control) or 107 tachyzoites of high (G-NcSpain7)- or low (G-NcSpain1H)-virulence isolates at 110 days of gestation. Serial culling at 10 and 20 days post-infection (dpi) was performed. Fever was detected at 1 dpi in both infected groups (P < 0.0001), and a second peak was detected at 3 dpi only in G-NcSpain7 (P < 0.0001). At 10 dpi, Nc-Spain7 was detected in placental samples from one animal related to focal necrosis, and Nc-Spain7 transmission was observed, although no foetal lesions were associated with this finding. The presence of Nc-Spain1H in the placenta or foetuses, as well as lesions, were not detected at 10 dpi. At 20 dpi, G-NcSpain7 animals showed almost 100% positive placental tissues and severe focal necrosis as well as 100% transmission. Remarkably, foetal mortality was detected in two G-NcSpain7 heifers. Only one animal from G-NcSpain1H presented positive placental samples. No foetal mortality was detected, and lesions and parasite transmission to the foetus were not observed in this group. Finally, 100% of G-NcSpain7 heifers at 20 dpi presented specific antibodies, while only 60% of G-NcSpain1H animals presented specific antibodies at 20 dpi. In addition, earlier seroconversion in G-Nc-Spain7 was observed. In conclusion, tachyzoites from Nc-Spain7 reached the placenta earlier and multiplied, leading to lesion development, transmission to the foetus and foetal mortality, whereas Nc-Spain1H showed delayed infection of the placenta and no lesional development or transmission during early infection.This work was supported by the Spanish Ministry of Economy and Competitiveness (AGL2013-44694-R) and the Community of Madrid (PLATESA2-CM P2018/BAA-4370). Laura Jiménez-Pelayo was financially supported by a fellowship from the Complutense University of Madrid and Marta García-Sánchez was financially supported through a grant from the Spanish Ministry of Economy and Competitiveness (BES-2014-070723). Patricia Vázquez had a Juan de la Cierva-Formación post-doctoral contract (FJCI-2014-20982) from the Spanish Ministry of Economy and Competitiveness (MINECO). Alicia Román-Trufero was supported by a FPI-INIA fellowship from the Spanish National Institute for Agriculture and Food Research and Technology (INIA). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe

Sistemas alternativos de producción de carne de vacuno en extensivo con razas autóctonas asturianas = Alternative extensive systems of beef production with Asturian local breeds

193 p.Esta Tesis Doctoral plantea distintos sistemas alternativos a los convencionales para la producción de vacuno en extensivo. Como primera alternativa, estudiamos la producción de cebón de las dos razas autóctonas asturianas, Asturiana de los Valles (AV) y Asturiana de la Montaña (AM), comparando dos manejos, uno en el que los cebones añojos pastaban en puertos de montaña durante el verano, y otro en el que los cebones permanecían pastando en praderas de valle. Los pastos de montaña (a 1600-1800 m s.n.m.) en su mayor parte (70% de la superficie) consistían en pastos herbáceos dominados por Festuca rubra y Agrostis capillaris, siendo el resto matorrales de brecina (Calluna vulgaris) con arándano (Vaccinium myrtillus) junto con piornales de Genista florida. Las praderas de valle (a 65 m s.n.m.) eran sembradas con raigrás inglés (Lolium perenne) y trébol blanco (Trifolium repens). Utilizamos un total de 83 terneros nacidos en la paridera de invierno de cuatro años, desde 2010 a 2013, y que eran castrados cuando tenían alrededor de un año de edad. Los cebones se sacrificaban cuando tenían unos 33 meses. En general, las ganancias de peso fueron mayores para los cebones AV que para los AM. Sin embargo, durante el verano de su segundo año de vida, cuando se establecían los dos manejos, en los pastos de montaña los AV presentaron menores ganancias de peso que los AM (133 vs. 252 g/día), al contrario que en las praderas de valle, lo que resultó en una interacción genotipo x ambiente. En el puerto además, comparamos la conducta de pastoreo mediante controles visuales y la selección de dieta mediante la técnica de los n-alcanos (marcadores fecales) de ambas razas en julio y en septiembre de dos años. El tiempo de pastoreo de los cebones añojos aumenta de julio a septiembre (488 vs. 557 min/día) como adaptación a la disminución en la disponibilidad de pasto herbáceo. Aunque ambas razas tienen preferencia por el pasto herbáceo, los cebones de raza AM pastaron sobre los brezales en mayor proporción que los AV (21,5 vs. 12,5%). Sin embargo, estas diferencias en la selección de las comunidades vegetales no se reflejaron en diferencias en la composición de dieta entre las dos razas. Los cebones seleccionaron sobre todo las herbáceas (71-89%), mientras que entre las leñosas, el porcentaje de arándano en la dieta era mayor (10-21%) que el de brecina (2-8%), aumentando el porcentaje de ambas especies de julio a septiembre. Durante la segunda mitad del verano, cuando la disponibilidad de pasto herbáceo era muy baja, las ganancias de peso disminuyeron hasta el punto en el que los cebones AV perdían peso (120 vs. -12 g/día). Una vez que bajaban de puerto, los cebones mostraron un crecimiento compensatorio, alcanzando pesos similares a los cebones que permanecían en valles. En la fase de acabado, de 3-4 meses de duración, no se observaron diferencias en las ganancias de peso entre manejos o razas. El peso final al sacrificio resultó mayor en los cebones AV que en los AM (714 vs. 616 kg), al igual que el peso y el rendimiento de la canal, mientras que no se observaron diferencias entre los manejos salvo en el rendimientos de la canal, que mostró valores medios ligeramente superiores en los cebones manejados en praderas de valle. La segunda alternativa planteada es la del cebo de terneros en régimen semi-extensivo, comparando un sistema ecológico con uno convencional. Se utilizaron 67 terneros de raza AV nacidos en la paridera de invierno durante tres ciclos productivos, cada uno consistiendo en un pastoreo de otoño, tras el destete, invernada, pastoreo de primavera y acabado previo al sacrificio. Se establecieron tres repeticiones por tratamiento, distribuyendo a los animales en 6 parcelas de 1,6 ha con praderas de raigrás inglés y trébol blanco, y manejando lotes de 4-5 animales por parcela. Las parcelas del manejo convencional se abonaron con fertilizantes sintéticos (NPK), mientras que en las de ecológico se utilizó estiércol. No hubo diferencias entre tratamientos en los rendimientos individuales de los terneros, siendo las ganancias medias de 846, 786 y 1.381 g/día en el pastoreo de otoño, invernada y pastoreo de primavera, respectivamente. En las parcelas tratadas con fertilizantes sintéticos la producción de hierba en primavera era mayor, permitiendo manejar una mayor carga ganadera que en los pastos ecológicos (4,22 vs. 3,05 animales/ha). Esto se tradujo en mayores ganancias diarias de peso por superficie de los terneros manejados en convencional que en ecológico (5,62 vs. 4,27 kg/ha/día), y por tanto en una mayor producción animal por superficie al final del pastoreo de primavera en convencional que en ecológico (2.183 vs. 1.606 kg/ha). En la fase de acabado, dentro del manejo en ecológico se compararon tres tipos de alimentación: pastoreo, ensilado de hierba y ensilado de maíz, suplementados todos ellos con concentrado ecológico. El acabado convencional consistía en una alimentación a base de concentrado ad libitum y paja de cereal. Las mayores ganancias de peso en este periodo las obtuvieron los añojos del tratamiento convencional (1.340 g/día). Las ganancias de peso para los distintos acabados en ecológico fueron menores que en convencional, si bien es verdad que el acabado con ensilado de maíz conseguía ganancias (1.116 g/día) cercanas a las alcanzadas en convencional y superiores a las obtenidas en pastoreo (753 g/día) o con ensilado de hierba (664 g/día). Tras el sacrificio, se realizaron mediciones en la canal y disecciones para estudiar la composición. Aunque no había diferencias en el peso ni en la conformación de la canal debidas a los distintos tratamientos, la disección de la 6ª costilla reveló mayores porcentajes de grasa en los tratamientos convencional y de ensilado de maíz respecto a los de ensilado de hierba y pastoreo (10,2% vs. 7,5%)

Foraging behaviour and performance of steers from two local breeds (Asturian Valley and Asturian Mountain) grazing in Cantabrian (N Spain) summer pastures

Steer meat production in northern Spain is deficient to attend market demand. This research aimed to compare the foraging behaviour and production of yearling steers from two local breeds differing in body weight (BW), Asturian Valley (AV, 372 kg) and Asturian Mountain (AM, 307 kg), grazing in summer pastures consisting of 70% grassland and 30% heathland. Bodyweight gains from a total of 42 steers were recorded during four grazing seasons (from June to October). In two years, in July and September, plant community selection and diet composition were estimated by direct observation and using faecal markers, respectively. Grazing time increased from July to September (488 vs. 557 min/day; p<0.001) as sward height in the grassland decreased. Although AV steers grazed proportionally for longer on herbaceous pastures than AM steers (81.3 vs. 73.3%; p<0.05), no differences between breeds were found in diet composition. AM steers showed greater mean daily BW gains than AV steers (252 vs. 133 g/day; p<0.01). From June to August, steers from both breeds gained BW (487 vs. 360 g/day for AM and AV, respectively; p<0.01), but thereafter BW gains decreased (120 vs. –12 g/day for AM and AV, respectively; p<0.05), because of reduced availability of grassland herbage. Yearling steers from AM breed seem to be better suited to mountain conditions than those from AV breed, probably because of their smaller body size and lower total nutrient requirements for maintenance

Foraging behaviour and performance of steers from two local breeds (Asturian Valley and Asturian Mountain) grazing in Cantabrian (N Spain) summer pastures

Steer meat production in northern Spain is deficient to attend market demand. This research aimed to compare the foraging behaviour and production of yearling steers from two local breeds differing in body weight (BW), Asturian Valley (AV, 372 kg) and Asturian Mountain (AM, 307 kg), grazing in summer pastures consisting of 70% grassland and 30% heathland. Bodyweight gains from a total of 42 steers were recorded during four grazing seasons (from June to October). In two years, in July and September, plant community selection and diet composition were estimated by direct observation and using faecal markers, respectively. Grazing time increased from July to September (488 vs. 557 min/day; p<0.001) as sward height in the grassland decreased. Although AV steers grazed proportionally for longer on herbaceous pastures than AM steers (81.3 vs. 73.3%; p<0.05), no differences between breeds were found in diet composition. AM steers showed greater mean daily BW gains than AV steers (252 vs. 133 g/day; p<0.01). From June to August, steers from both breeds gained BW (487 vs. 360 g/day for AM and AV, respectively; p<0.01), but thereafter BW gains decreased (120 vs. –12 g/day for AM and AV, respectively; p<0.05), because of reduced availability of grassland herbage. Yearling steers from AM breed seem to be better suited to mountain conditions than those from AV breed, probably because of their smaller body size and lower total nutrient requirements for maintenance