Sublethal concentrations of acetylcarvacrol strongly impact oocyte development of engorged female cattle ticks Rhipicephalus microplus (Canestrini, 1888) (Acari: Ixodidae).

Rhipicephalus microplus, commonly known as southern cattle tick, causes huge economic losses in the cattle industry. Its infestation affects the production of meat and milk and causes discomfort to hosts. In addition, it is the vector of Babesia spp. and Anaplasma spp. The most frequent method used to control these parasites is through synthetic acaricides. However, their indiscriminate use can be toxic for hosts and environment as well as cause selection of resistant ticks. Plant extracts and essential oils emerge as promising alternatives to manage tick infestation. Carvacrol, an aromatic monoterpene extracted from plants, has recognized antimicrobial, antioxidant, insecticidal, repellent and acaricidal activities. Acetylation of carvacrol is believed to enhance its nematicidal and acaricidal activities and to decrease its toxicity to hosts. Thus, the aim of this study was to evaluate the effect of different concentrations of acetylcarvacrol in the morphology of ovaries of engorged R. microplus ticks. The most remarkable morphological alterations found in the female germ cells were irregular and thicker chorion, decreasing in size and irregular shape of female germ cells (oocytes), cytoplasmatic vacuolization as well as ring-shaped nucleoli. These alterations were analyzed through a semi-quantitative method proposed in this study for ixodid ticks. Treatment group IV, which was exposed to 4.5 µL/mL of carvacrol acetate, showed the most significant alterations, and it was also statistically different when compared to control groups. Therefore, sublethal concentrations of acetylcarvacrol demonstrated to impact the reproductive system of R. microplus by causing several damages in the female germ cells. This would hinder the generation of new individuals, probably contributing for a long-term control of tick infestation.

Aspectos clínicos e laboratoriais da mastite induzida por inoculação intramamária de Staphylococcus aureus em vacas e búfalas / Clinical and laboratory aspects of mastitis induced by intramammary inoculation of Staphylococcus aureus in cows and buffaloes

Vários aspectos relacionados à mastite bubalina precisam ser esclarecidos. Muitas condutas são adaptadas a essa espécie pelo conhecimento adquirido com a espécie bovina. Com este experimento, objetivou-se evidenciar particularidades da mastite em búfalas e vacas que tiveram uma glândula inoculada com 1,0 x 103 UFC de S. aureus. Os animais foram monitorados por cultura bacteriana do leite, California Mastitis Test (CMT), e escores para avaliação da severidade da mastite. Foram utilizados os seguintes critérios: temperatura retal, apetite, produção de leite (resposta sistêmica à inflamação), contagem de células somáticas (CCS), aparência/consistência da glândula e aparência da secreção láctea (resposta localizada à inflamação). Todos os animais desenvolveram mastite clínica superaguda. A bactéria foi recuperada de todas as glândulas desafiadas, sem diferença significativa no percentual de isolamento entre as espécies até o 11º dia pós-inoculação, porém com diferença (P<0,001) no 30º dia pós-inoculação. A CCS pelo método eletrônico e o CMT detectaram nas búfalas resposta mais intensa logo após a inoculação e diminuição mais rápida da contagem ao final do experimento, quando se comparou essa espécie com as vacas. Ambos os testes demonstraram correlação com a cultura bacteriana. Na avaliação da severidade da mastite, as médias do escore total, do escore da resposta local e do escore da resposta sistêmica foram mais elevadas na espécie bovina (P<0,05). Ao longo do período de observação, verificou-se uma capacidade superior das búfalas em recuperar o status sanitário adequado, chegando, ao final do experimento, com os parâmetros avaliados mais próximos dos fisiológicos...

Several aspects related to bubaline mastits need to be clarified. Many conducts are adapted to this species by the knowledge adquired with the bovine species. This experiment aimed to evidence particularities of mastits in buffaloes and cows submitted to one-gland inoculation with 1.0 x 103 CFU of S. aureus. The animals were monitored through bacterial culturing milk, California Mastitis Test (CMT) and scores to assess the severity of mastitis. The following criteria were used: rectal temperature, appetite, milk production (systemic response to inflammation), somatic cell count (SCC), appearance/consistency of the gland and appearance of the milk secretion (localized response to inflammation). All animals developed hyperacute clinical mastitis. The bacteria was recovered from all challenged glands, with no significant difference in the percentage of isolation between the species until day 11 after inoculation, but with a difference (p<0.001) on day 30 post inoculation. The SCC with the electronic method and CMT, detected in buffaloes a more intense response right after the inoculation and a faster decrease of counting by the end of the experiment, when compared to cows. In both tests correlation with the bacterial culture was detected. In assessing the severity of mastitis, the averages of total score, of the score of local response and the systemic response score were higher in the bovine species (P<0.05). Throughout the observation period, there was a higher capacity of buffaloes in reaching the appropriate sanitary status, coming to the end of the experiment with the parameters closer to the physiological...