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Background: This work studied the natural infection of Neospora caninum during the first gestation of heifers in a dairy farm in animals consuming a ration contaminated naturally with Zearalenone (ZEA), and to find out effect of mycotoxin in the levels of estrogen (E) and progesterone (P4) and that`s relation to the infection to N. caninum and in the abortions. Methods: The study was conducted in a dairy farm located in El Llano municipality, in Aguascalientes, Mexico, in 2013. Two groups were formed, the group “A” with 20 seronegative animals to N. caninum, and group “B” with 20 seropositive. Once a month was determined the levels of total IgG to N. caninum, the serum concentration of E and P4, and the level of ZEA in the ration; in cases of abortion, fetal brain samples were taken to identify the presence of N. caninum DNA. Results: In group “A”, was observed two subgroups: seronegative (60%) and seroconverted (40%), and three abortions. In group “B”, all animals maintain their serostatus, and three animals aborted. All abortions were positive for N. caninum DNA. The level of ZEA in the ration has an average of 426 µg/kg; during the gestation did not identify that animals suffer any alteration in the levels of E or P4. No statistical differences among the studied variables (levels of E and P) in time (nine months of gestation) were detected. It was not identified any interaction with the natural exposure to ZEA intake in any of the groups under study. Conclusion: The chronic ingestion of ZEA does not affect serum concentrations of E and P4 during gestation of heifers under study and cannot be related to the infection for N. caninum and the abortion.

SRCRSP (Small Ruminant Collaborative Research Support Program) loci are polymorphic 100-300 base pair-long microsatellite sequences of repeated dinucleotides that can be amplified by the polymerase chain reaction (PCR). Alleles of a given locus are the PCR products of unique length amplified with a set of specific primers. SRCRSP loci have been used to identify individuals but not to assess paternity in goats. We have developed a method to assess caprine paternity by polymorphism analysis of SRCRSP loci in a herd of 20 goats from two breeds, nine Nubia and 11 Boer, respectively. Thirty six alleles were amplified: 6 SRCRSP-1; 5 SRCRSP-2; 4 SRCRSP-3; 5 SRCRSP-4; 5 SRCRSP-5; 6 SRCRSP-6 and 5 SRCRSP-9. four alleles appeared only in the Nubia group and eight only in the Boer group. Polymorphism analysis led to a 0.995 certainty for correct exclusion of the second parent. The loci described in this work could be used to control goat paternity as well as to identify individuals. Los loci SRCRSP (Small Ruminant Collaborative Research Support Program) son secuencias de microsatélites polimórficos de 100-300 pares de bases de dinucleótidos repetidos que pueden ser amplificados por la reacción en cadena de la polimerasa (PCR). Los alelos de un determinado locus son los productos de PCR de longitud única amplificados con iniciadores específicos. Los loci SRCRSP se han utilizado para identificar individuos, pero no para determinar la paternidad en el ganado caprino. En el presente trabajo se reporta el desarrollo de un método para evaluar la paternidad en caprinos mediante el análisis del polimorfismo de loci SRCRSP en un rebaño de 20 animales, que incluía nueve de raza Nubia y 11 Boer. Se amplificaron 36 alelos: 6 del SRCRSP-1, 5 del SRCRSP-2, 4 del SRCRSP-3, 5 del SRCRSP-4, 5 del SRCRSP-5, 6 del SRCRSP-6 y 5 del SRCRSP-9. Cuatro alelos aparecieron exclusivamente en el grupo Nubia, mientras que sólo ocho en el grupo Boer. El análisis del polimorfismo llegó a 0.995 de certeza en la exclusión correcta del segundo padre. Los loci descritos en este trabajo podrían ser utilizados para controlar la paternidad así como para identificar a los individuos en ganado caprino.