The main pathogenic treponemes causing bovine digital dermatitis were identified from 17 infected herds in southern Brazil for the first time in this study using PCR. We did not find a relationship between treponeme phylogroup composition and clinical classification. Treponema phagedenis was present in all lesions. Rumen fluid was implicated as a reservoir location for these pathogens.A lthough bovine digital dermatitis (BDD) has been known to occur in Brazil since the early 1990s (1), there have been no attempts to describe the possible pathogens involved, apart from reports of histopathological (2) and electron microscopic (3) findings. Treponema species are difficult to culture, so molecular approaches are useful for detecting and identifying these spirochetes (4, 5). The present study describes, for the first time, the frequencies of the major treponeme species in BDD lesions in Brazil. Similar results in Europe, North America, and Asia (6-11) confirm the polytreponemal aspect of this clinical condition.Farms in southern Brazil where BDD infections are endemic (n ϭ 28) were identified by consulting veterinary records. Previously identified dairy cows (n ϭ 200) were individually reexamined and, if positive for BDD (n ϭ 22), were photographed and their lesions classified according to clinical stage, from M1 to M4 (12-14). Samples (n ϭ 22) were surgically excised, placed in phosphatebuffered saline (PBS) solution, and refrigerated (4°C to 8°C) until processing. The infected digit was then topically treated with antibiotics (oxytetracycline) and bandaged. Using a stomach tube, ruminal fluid (Ն50 ml of fresh fluid) was collected from 15 cows from seven different BDD-positive herds, which were chosen by convenience. From one BDD-free herd with a history of lameness but without any clinical BDD lesions detected on previous examinations of the whole herd, ruminal fluid from 10 cows was sampled for use as a negative control. All samples underwent extraction of bacterial DNA, as previously described (12,15). A nested-PCR method was used, as previously described (10). The treponeme-specific primers were called Treponema sp., Treponema medium/T. vincentii-like, Treponema phagedenis-like, and Treponema denticola/T. putidum-like (10). The research was approved by the Committee for the Ethical Use of Animals of Pontifícia Universidade Católica do Paraná (PUCPR) (registration no. 646) in 2011.Of the herds, 17 (60.71%) had BDD lesions on the day of examination and were positive for subsequent molecular BDD detection. The lesions were in different clinical stages (14) and were classified as follows: 13.64% were M1, 45.45% were M2, 22.73% were M3, and 18.18% were M4. However, certain lesions classified as M2 or M3 contained areas that were M4 or M1. In comparison, the cows in the present study exhibited considerably more M2 lesions (45.45% versus 21.03% in the previous study) and fewer M4 lesions (18.18% versus 50.03% in the previous study) ( Table 1). The reason for this observation or why the different forms can transition f...

The aim of this study was to evaluate the production performance of Nile tilapia post-larvae and fingerlings fed with increasing levels of alcoholic extract of propolis into diets. In Experiment 1, 1800 post-larvae were distributed in 30 tanks, in a completely randomized design with five treatments composed by the inclusion of 0, 1, 2, 3 and 4 g of dry propolis/kg of feed, and six replicates. In experiment 2, 1600 fingerlings were distributed in the same system and designed as experiment 1. No significant effect was observed between treatments, for final weight, total and standard length, survival, and intestinal villus height. However, the propolis extract inclusion of 1 g/kg in Nile tilapia post-larvae and fingerlings' feed resulted in a better body condition factor and higher body protein deposition (p<0.05). The condition factor is an estimate for the future growth of the animals, possibly the fish treated with propolis extract will present better growth, survival and greater reproductive potential rates. The results of the present study demonstrate that alcoholic extract of propolis improves the nutritional condition of Nile tilapia post-larvae and fingerlings, potentially leading to increased productivity in subsequent stages, as well as leading to improvement in fingerlings muscle deposition.

Crude glycerol and its purified and synthesized forms derived from biodiesel production are non‐toxic, biodegradable, biocompatible and versatile, and can be converted into various chemicals or products for biological use. Among the possible uses, there is its use in fish feeding, due to the chemical and nutritional composition, for being classified as energetic food and has low cost. The possibility of using glycerol in fish diets has been motivated by increasing maize prices, the excessive amount of glycerol produced and its processing costs for other purposes. Glycerol use in fish diet formulations is feasible, provided that certain factors be evaluated, such as digestibility and inclusion levels. In this context, this review discussed the main aspects that must be taken into account regarding glycerol use in fish diets, such as the characteristics and chemical composition of its categories, their fish metabolism pathways and their influence on fish plasma glucose. Crude glycerol or glycerine displays good potential for use in fish feed, as it contains adequate energy concentrations and can replace part of fish feed maize. However, it is evident that assessments concerning specific physiological phases, such as fish in reproductive phases, as well glycerol stability in water, are required.

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Chitosan foam can be used as a filter element for pollutants in Nile tilapia farming tanks to reduce the industrial chitin waste and value it. Another possibility is the inclusion of chitosan foam in fish feed. Therefore, this study aims at evaluating the apparent digestibility of nutrients and energy of chitosan foam for Nile tilapia. Apparent digestibility determination was carried out by the indirect fecal collection method, using chromic oxide as an inert indicator, a reference-diet and a test diet (70% reference-diet and 30% chitosan foam). Hence, 120 juveniles of Nile tilapia (50 ± 5 g) were used, divided into six replications. After the collection period, bromatological analyses of foam, diets and feces were carried out, as well as the determination of chromium concentration in feces. The coefficients of apparent digestibility concerning nutrients and energy were then calculated. Chitosan foam showed 83.7% digestible dry matter, 5.7% digestible protein, 7.9% digestible fat, 0.6% digestible ashes, 17.6% digestible crude fiber and 1021 kcal kg -1 digestible energy for juveniles of Nile tilapia. It can be concluded that chitosan foam is partially digestible for Nile tilapia and can be used mainly as a feed source of fiber and fat.

With the expansion of aquaculture production, the cultivation of fast-growing species, with good feed conversion and tolerance to adverse cultivation situations, has become widespread. In addition to these characteristics, Nile tilapia (Oreochromis niloticus) has great acceptance in the consumer market, due to the organoleptic properties of its meat and the absence of 'Y'-shaped intramuscular bones, currently being the third most-produced fish species worldwide, with 4,525,000 tons produced in 2018, representing 8.3% of all world fish production (FAO, 2020;Suresh & Bhujel, 2012).

Brazilian agriculture has undergone important changes since the 1960s, where public policies were responsible for building an institutional environment favourable to innovation and knowledge and technology adaptation (Vieira Filho & Fishlow, 2017). This has, in turn, led to dramatic increases in agricultural production (Schulter & Filho, 2017).Food security concerns and a growing interest in environmental sustainability are among the main challenges to be faced by countries in the coming decades, due to worldwide population growths (Schulter & Filho, 2017;Vieira Filho & Fishlow, 2017). The productive efficiency of agricultural activities, however, still requires improvements, driven by exponential food demand increases by the world's population (Food and Agriculture Organization of the United Nations [FAO], 2017). In this context, aquaculture has contributed effectively to animal production worldwide, displaying the greatest development in recent years among agricultural activities (FAO, 2020).It is estimated that the global fish production reached 179 million tons in 2018, of which 156 million were destined for human

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