Occurrence of antibodies against Neospora caninum in water buffaloes (Bubalus bubalis) on four ranches in Corrientes province, Argentina.

The aim of the present work was to describe the occurrence of antibodies to Neospora caninum in water buffaloes on four ranches located in Corrientes province in the northeast of Argentina. Antibodies against N. caninum were determined in sera of 449 water buffaloes by using an indirect fluorescent antibody test (IFAT). A Bayesian logistic regression mixed model was used to quantify the strength of association between positive serological results to N. caninum and gender, age and category (calf, steer, heifer, cow) as risk factors. Antibody titers were found in 287 (64%) buffaloes. All ranches had seropositive animals. Age was more strongly associated with positive results to N. caninum (OR: 1.4; CI 95%: 0.86-2.22) than gender (OR: 1.02, CI 95%: 0.40-2.59) and category (OR: 0.88, CI 95%: 0.57-0.88). Results suggest a high exposure of water buffaloes to N. caninum by postnatal transmission in these four ranches located in Corrientes province, Argentina. Further studies are needed to quantify the consequences of Neospora-infections in the water buffalo industry.

Ovum pick-up interval in buffalo (Bubalus bubalis) managed under wetland conditions in Argentina: Effect on follicular population, oocyte recovery, and in vitro embryo development.

The excellent adaptation of water buffalo (Bubalis bubalis) to swampy environments means that animals are frequently managed in areas with restricted access for reproductive procedures. The objective of this study was to evaluate the effect of the ovum pick-up (OPU) interval on follicular population, oocyte recovery, oocyte quality and in vitro embryo production. Twelve Murrah buffaloes were subjected to two consecutive dominant follicle reductions, and randomly assigned to either 7-day (n=6) or 14-day (n=6) OPU interval groups. Although there was no significant difference in the average number of small (<3mm) and large (>8mm) diameter follicles available per OPU, a higher proportion of medium-sized follicles (3-8mm) were observed in the 14-day interval group (5.129 vs 3.267; p<0.05). The number of recovered oocytes per donor was also significantly higher (4.51 vs. 2.8; p<0.05) in the 14-day interval group, although this was attributed to an increase in the proportion of lower quality oocytes (grades III and IV). After in vitro fertilization, embryo developmental competence from grade I and II oocytes was superior to that from grade III and IV oocytes, irrespective of OPU interval group. There was no significant difference in the proportion of grade I and II oocytes cleaved after sperm co-incubation; however, there was a higher proportion of blastocysts produced in 14-day interval group (28 vs. 6%, p<0.05). No blastocysts were produced from grade III and IV oocytes. This study indicates it is possible to use a 14-day interval for oocyte collection in water buffalo; this approach could be considered as an alternative when access to animals is restricted.

Neospora caninum serostatus is affected by age and species variables in cohabiting water buffaloes and beef cattle.

The aim of this study was to investigate how Neospora caninum serostatus may be affected by variables such as host species (water buffaloes or cattle) and age in animals cohabiting in the same ranch. A convenience cross-sectional study was performed on four ranches in the Northeast of Argentina, where water buffalo are cohabitating with beef cattle. Blood samples were collected from 1350 female water buffaloes (Bubalus bubalis) and 880 female beef cattle (Bos taurus and Bos indicus crossbreeds) from four ranches. Calving and weaning percentages at herd level for each ranch were also recorded. N. caninum antibody levels were measured by an indirect fluorescent antibody test (IFAT) (reciprocal antibody titers ≥ 100). Serological results were classified into 2 categories (0: negative; 1: positive). A logistic regression model was used to describe the relationship between N. caninum serostatus and specie (water buffalo or cattle), age or ranch and their interactions. Likelihood ratio tests were used to assess the significance of the model and their terms. Odds ratios were estimated and 95% profile likelihood (LR) and Wald confidence intervals (CI) obtained. Overall, specific antibody titers were found in 43.3% (584/1350) of water buffaloes and 28.6% (252/880) of cattle. Seropositive water buffaloes and cattle were observed on all ranches. Age was statistically significant (p=0.01) with an overall estimate of logit (log odds) of age of 0.03 for both species. This indicates that for every one year increase in age, the expected change in log odds of being seropositive increased by 0.03. On three of four ranches a water buffalo was 4.48, 1.54 and 2.25 times more likely to be seropositive than cattle for animals of the same age. The N. caninum serostatus was affected by age in the first place, but also by species on at least three of the four ranches. Calving and weaning percentages were higher in water buffaloes than in beef cattle (p<0.05). Even though the low pathogenicity that N. caninum seems to have in water buffaloes, this study reinforces the importance of this specie as maintenance of the disease.

Experimental inoculation of Neospora caninum in pregnant water buffalo.

The aim of this study was to characterize the pathogenesis of Neospora caninum in experimentally inoculated pregnant water buffalo (Bubalus bubalis). Twelve Mediterranean female water buffaloes ranging in age from 4 to 14 years old and seronegative to N. caninum by indirect fluorescent antibody test (IFAT) were involved. Ten females were intravenously inoculated with 10(8) tachyzoites of NC-1 strain at 70 (n=3) or 90 (n=7) days of pregnancy (dp). Two control animals were inoculated with placebo at 70 and 90 dp, respectively. Serum samples were obtained weekly following inoculation to the end of the experiment. Three animals inoculated at 70 dp were slaughtered at 28 days post inoculation (dpi), three animals inoculated at 90 dp were slaughtered at 28 dpi and the remaining four animals inoculated at 90 dp were slaughtered at 42 dpi. Fetal fluids from cavities and tissue samples were recovered for IFAT and histopathology, immunohistochemistry and PCR, respectively. Genomic DNA from fetal tissues was used for parasite DNA detection and microsatellite genotyping in order to confirm the NC-1 specific-infection. Dams developed specific antibodies one week after the inoculation and serological titers did not decrease significantly to the end of the experiment. No abortions were recorded during the experimental time; however, one fetus from a dam inoculated at 70 dp was not viable at necropsy. Specific antibodies were detected in only two fetuses from dams inoculated at 90 dp that were slaughtered at 42 dpi. No macroscopic changes in the placentas and organs of viable fetuses were observed. Nonsuppurative placentitis was a common microscopic observation in Neospora-inoculated specimens. Microscopic fetal lesions included nonsuppurative peribronchiolar interstitial pneumonia, epicarditis and myocarditis, interstitial nephritis, myositis and periportal hepatitis. Positive IHC results were obtained in two fetuses from dams inoculated at 70 dp and slaughtered at 28 dpi. N. caninum DNA was detected in placentas and fetuses from all inoculated animals. The pattern of amplified microsatellites from placental and fetal tissues resembled the NC-1 strain. Water buffaloes, like cattle, are susceptible to experimental inoculation with N. caninum at early pregnancy.

Influence of fish oil in the concentration of conjugated linoleic acid and omega 6 and 3 in buffalo milk / Influência do óleo de peixe na concentração de ácido linoléico conjugado e Omega 6 e 3 no leite de búfalas

The aim of this research work was to investigate the influence of fish oil supplementation on the concentration of conjugated linoleic acid (CLA) and omega 6 and 3 in samples of buffalo milk. A total of 24 female buffaloes separated at random into three groups were fed for 49 days with: natural pasture (group I), supplemented with 70mL of fish oil (group II) and 140mL of fish oil (group III). In the experiment the concentration of CLA showed differences (P<0.05) among the three groups, with a maximum of 7.14mg/g fat in group II. No significant differences were found in omega-6 among the three groups. The highest value of 3.82mg/g fat corresponded to group I, whicht had not been supplemented with fish oil. Significant differences were observed in omega 3 (P<0.05) in groups II and III with respect to group I. The highest average value of 2.42mg/g fat was obtained in group III. The closest relationship omega 6/3 (1.37:1) was observed in group III. As a result, the diets of groups II and III, which included fish oil, increased significantly the content of CLA and omega 3 with reductions in levels of omega 6.

Estudou-se a influência da suplementação com óleo de peixe sobre a concentração dos ácidos graxos ômega 6 e 3, mostrado no leite de búfala. Foram utilizadas 24 búfalas aleatoriamente selecionadas e distribuídas em três grupos e alimentados com pastagem natural por 49 dias com: nenhum suplemento (grupo I), suplementado com 70mL de óleo de peixe (grupo II) e com 140mL de óleo de peixe (grupo III). A concentração de CLA diferiu (P<0,05) entre os três grupos, com valores máxima de até 7,14mg/g de gordura no grupo II. Não foram observadas diferenças significativas para os ácidos graxos omega 6, sendo o maior valor de 3,82mg/g de gordura no grupo I. Foi observada diferença significativa quanto aos ácidos graxos ômega 3 (P<0,05) nos grupos II e III em relação ao grupo I. O mais elevado valor, 2,42mg/g de gordura foi observado no grupo III. A relação ômega 6/3 mais estreita, 1,37:1, foi observada no grupo III. Os resultados mostram que os animais dos grupos II e III que receberam suplementação de óleo de peixe aumentou significativamente o teor de CLA e de omega 3, com diminuição de omega 6.

Aptidäo reprodutiva de touros da raça Nelore. Efeito das diferentes estaçöes do ano sobre as características seminais circunferência escrotal e fertilidade / Reproductive capacity of Nelore bulls. Effect of season on seminal characteristics, scrotal circunference and fertility

Nove touros da raça Nelore, selecionados de um total de 74, foram classificados segundo a qualidade de sêmen e a circunferência escrotal em superiores, bons e questionáveis e avaliados em três diferentes estaçöes (01.11.88, final da estaçäo seca; 26.04.89, durante a estaçäo chuvosa; 31.07.89, início da estaçäo seca). Os touros questionáveis apresentaram, durante o final da estaçäo seca, alteraçöes da qualidade espermática, características de um quadro de degeneraçäo testicular de grau médio. Entretanto, com a melhoria das condiçöes ambientais (clima e nutriçäo) os animais entraram em franca regeneraçäo, igualando-se aos demais por ocasiäo do 3§ exame. A circunferência escrotal, conforme se esperava, apresentou pequenas variaçöes uma vez que se tratava de animais adultos, portanto, com o desenvolvimento testicular já concluído. Submetidos a teste de fertilidade a campo, na proporçäo de 1:40, 3 vacas, os três grupos näo mostraram diferenças significativas, confirmando a hipótese de que os questionáveis se recuperaram da degeneraçäo ao longo da estaçäo de monta que durou 120 dias. A taxa média de gestaçäo alcançada foi de 68,4ñ5,2//, 80,5ñ4,6//, 88,3ñ6,1//e 89,9ñ4,6//aos 30, 60, 90 e 120 dias após o início da estaçäo, respectivamente