Fernando Leandro dos Santos

A multi-season survey for infectious myonecrosis in farmed shrimp, Litopenaeus vannamei, in Pernambuco, Brazil.

Infectious myonecrosis (IMN), caused by infectious myonecrosis virus (IMNV), is the disease of greatest impact on shrimp farming in the northeast region of Brazil. The occurrence of IMN remained restricted to northeastern Brazil until 2006, when its presence was also confirmed in Indonesia. To determine the occurrence and evolution of IMN in Litopenaeus vannamei farmed along the coast of the state of Pernambuco, Brazil, histopathological examinations were performed on 60 samples collected from four farms in both predominant seasons in the northeastern region: dry and wet seasons. Samples made up of ten specimens were collected monthly from each pond. Histopathological results were associated to wet-mount exams and rearing performance data. Lesions suggestive of IMN (coagulative necrosis, hemocytic infiltration in the musculature, ectopic spheroids in the lymphoid organ) were identified in all the farms, with a higher occurrence during the dry season. Longer rearing periods and higher stocking densities were the variables with the most significant influence (p<0.05) in the occurrence of IMN.

Testicular measurements in Campolina stallions

Evaluation of the reproductive characteristics of Brazilian stallions is very important to the development of the national equine industry; however, breeders and breeders associations have more interest in methods to evaluate biometric or gait characteristics. Testicular evaluations are important to choose stallions and to develop local reproductive management. Knowledge of normal morphology is essential to recognize clinical problems and to develop a comprehensive breeding management program. When testicular measurements are evaluated, researchers get important information about daily spermatic production. 1,2, Testicular sizes and dimensions can be assessed manually by calipers or with ultrasound. These characteristics vary according to age, season of the year, nutrition and other factors. Allen 1 has observed that the size of the testes is roughly proportional to the size of the horse. Little and Holyoak 4 have found that sexual experience of breeding farm stallions also may be an important factor in determining the size of the testicles. This is because sexual stimulation alters the production of prolactic and gonadotropin-releasing hormone. In the mature horse, the testes are round, long, and of a size that would fill a cupped hand. The testes start life in the abdominal cavity and drop into the scrotum permanently by the time the animal is 12 months old or near puberty. Allen 1,4 determined that the onset of puberty happens between 12 and 18 months of age when the stallions ejaculate contains a minmum of 100 x 106 sperm. Other researchers have developed studies about testicular size in different horse breedsJ ,3,5 Allen I studied testicular size in Thoroughbred horses and obtained a mean of 10.0 cm for length and 6.0 for width. These results are similar to that of Rossdale and Ricketts. 5 In Brazil, Ribeiro Filho, Dantas, Lopes et al., 3 have studied testicular size in Quarter Horse stallion. Their results for testicutar size were similar to the results found by other researchers. They documented the correlation between age, length and width as more than 0.55. Another important aspect of the evaluation of testicular

AVALIAÇÃO DE POTENCIAL PROBIÓTICO FRENTE À INFECÇÃO EXPERIMENTAL POR VÍBRIOS EM PÓS-LARVAS DE CAMARÃO MARINHO

Bacillus spp. have been used against diseases caused by bacteria that affect cultured shrimp, providing beneficial effects on the host shrimps by altering their microbial community, and improving zootechnical indexes. The objective of this work was to evaluate the effects of a diet supplemented with Bacillus cereus—a bacterium with probiotic potential—on post-larvae Litopenaeus vannamei shrimps grown in laboratory. The experiment lasted for fifteen days and consisted of six treatments—control (T1), probiotic (T2), Vibrio parahaemolyticus (VP) (T3), probiotic and VP (T4), V. alginolyticus (VA) (T5), and probiotic and VA (T6). The survival rate, weight gain, colonization capacity of the probiotic bacteria, pathogen count, and histopathological lesions were evaluated. There was no significant difference (p≥0.05) in survival between treatments. The groups with pathogens and without probiotics presented lower weight gain. The result of the Bacillus cereus count in the treatments T2, T4 and T6 were significantly different (p<0.05), the probiotic bacteria were more aggressive in competing for space and nutrients when compared to V. parahaemolyticus than when compared to V. alginolyticus. Animals fed with the probiotic presented lower counts of these pathogens than those fed without the probiotic (p<0.05). No histopathological lesions were found in the organs and tissues of the shrimps. Bacillus cereus showed a high colonizing capacity in post-larvae shrimps, causing a significant reduction of pathogens, probably by secreting antimicrobial substances and the competitive exclusion, which justifies their use as probiotic bacteria.