Incorporation of probiotic bacteria on larval culture of Macrobrachium amazonicum (Heller, 1862)

In this study, we evaluated the utilization of two probiotics incorporated into the water and in the diet in a larval culture system of Amazon River prawn. Autochthonous probiotic bacteria from the gut of wild juveniles of M. amazonicum juveniles and a commercial probiotic were tested and the following parameters were analyzed: survival, productivity, fresh weight, length, larval condition index (LCI) and larval stage index (LSI). The colonization of the larval gastrointestinal tract by probiotics took place when they were incorporated into diet, while probiotics in the water proved to be unsuccessful. The use of lactic acid bacteria had no significant effects (p>0.05) on survival, productivity, length, fresh weight, LSI and LCI, showing similar results in relation to the control group. However, we recommend the inclusion of probiotics into diet in larval culture of Amazon prawn since this method allowed bacterial gut colonization, which is important to evaluate the resistance to disease in further studies.

Biological control of nematodes by nematode-trapping fungi Duddingtonia flagrans in naturally infected sheep in southern Brazil

The aim of this study was to evaluate the anti-helminthic effect of a commercial formulation Bioverm® (Duddingtonia flagrans) in 28 sheep naturally infected with gastrointestinal nematodes. Animals were classified into two groups: G1 (n=14) treated with nematophagous fungi and G2 (n=14) untreated control. The efficacy of the anti-helminthic drug was assessed based on the egg count per gram of feces (EPG) of strongyles, larval culture, hemogram, leukogram, plasma protein levels, mucosal coloration using the FAMACHA© method, animals body weight, and evaluating the ocular mucosa for the FAMACHA© anemia guide were performed at days 0, 30, 60, 90, 120, 150, and 180. Additionally, the nematode larvae were quantified in the dry matter of the pastures of both groups. Results showed that the EPG was significantly decreased in animals receiving nematophagous fungi from D30 until the experiment end. The most common nematode genus was Haemonchus (63%), followed by Cooperia (23%) and Trichostrongylus (15%). Based on the fecal egg count reduction test (FECRT), treated animals showed a reduction of fecal egg count of 58.9%, 8.6, 92.8%, 96.4%, and 96.2%, at D30, D60, D90, D120, and D180, respectively. The absolute values of red blood cells and leukocytes were significantly increased at D60 and D90, respectively, in the treated animals. A significant weight gain was observed in the treated ewes at the end of the experiment; however, there was no correlation between the EPGs values and hematocrit with the FAMACHA© degrees of animals in both experimental groups. The mean EPG of both groups and the number of infectious larvae in the pastures were not directly proportional. In conclusion, nematophagous fungi contributed to decreased parasitic load in sheep, and consequently, improve animal performance; they can be a suitable alternative to reduce problems associated with nematode infections.

Effect of Copper Oxide Wire Particles with and Without Anthelmintic Treatment or Anthelmintic Treatment Alone on Gastrointestinal Nematode (GIN) Fecal Egg Counts in Goats

In two experiments (Exp), naturally parasite-infected 5–8 mo-old intact male Spanish goats were used to determine fecal egg count (FEC) reduction effects of copper oxide wire particles (COWP; 1 g bolus Copasure®) and levamisole (12 mg/kg; LEV; Prohibit®) alone or in combination with COWP; for Exp 2, albendazole (20 mg/kg; ALB, Valbazen ®, Exp 2 only) alone or in combination with COWP and an untreated control group (CON; n = 11) was also included. Animals were individually housed in 1.5 x 1.5-m pens (Exp. 1) or as a group on pasture (Exp. 2). For the studies, goats were selectively dewormed based on a FAMACHA© eyelid color score of 3, 4 or 5, with n = 12 and 13 for COWP in Exp 1 and 2, respectively, n = 14/Exp for LEV, n = 12/Exp for COWP and levamisole (LC), and (Exp, 2), n = 10 for COWP and albendazole (AC) and n = 12 for ALB. Fecal samples were collected using a gloved finger technique on D 0 and 14 in Exp 1 and Day 0 and 10 for Exp 2 for determination of FEC using a modified McMaster’s technique with a 50 egg per gram sensitivity and calculation of FEC reduction (RED; ((Day 0 FEC-Day 14 FEC)/Day 0 FEC)*100). Data were analyzed with a general liner model procedure using SAS. Larval culture (Exp 1) indicated 99.8% Haemonchus contortus on Day 0. Mean RED was greater for LC than LEV and COWP (P < 0.04) for Exp 1 (Day 14). For Exp 2, mean RED was greater (P < 0.04) for AC than ALB and CON, but not COWP, and was greater (P < 0.03) for LC compared CON and COWP, but not LEV. In these two studies, COWP resulted in > 93% reduction in FEC and the addition of a deworming drug did not improve effectiveness consistently (only in Exp. 1).

The influence of density on survival and larval development in the sea urchin Arbacia dufresnii (Echinodermata: Echinoidea)

Introduction: Density is one of the critical factors in echinoderm larvae for aquaculture purposes. Echinoplutei larvae are very sensitive to overcrowding. High culture density can lead to problems with bacteria or protozoa, decreasing survival and generating abnormal morphotypes. Objective: To evaluate the effect of culture density on survival and larval growth in the sea urchin Arbacia dufresnii. Methods: Two days after fertilization of A. dufresnii we we kept treatments at 1, 3, 5 and 10 larvae.ml-1, with three replicates each. We recorded survival and abnormal morphotypes periodically, as well as growth:somatic rod length, total length, and length of the post oral arms,. we applied generalized linear models. Results: Survival is dependent on density, time and replicates, and their interactions. Larval growth depended on density and time, also with interaction between the variables. The treatment of 5 larvae.ml-1 had the highest survival and larval condition. Conclusions: Larval culture of A. dufresnii had the best results at 5 larvae.ml-1.

Sheep nemabiome diversity and its response to anthelmintic treatment in Swedish sheep herds

Background A novel way to study the species composition and diversity of nematode parasites in livestock is to perform deep sequencing on composite samples containing a mixture of different species. Herein we describe for the first time the nematode community structures (nemabiomes) inhabiting Swedish sheep and how these are/were affected by host age and recent anthelmintic treatments. Methods A total of 158 fecal samples were collected (n = 35 in 2007 and n = 123 in 2013–2016) and cultured from groups of sheep on 61 commercial farms in the south-central part of the country where most animals are grazed. Among the samples, 2 × 44 (56%) were paired collections from the same groups pre- and post-treatment with anthelmintics such as macrocyclic lactones, benzimidazoles or levamisole. Samples were analyzed for their nemabiome using the PacBio platform followed by bioinformatic sequence analysis with SCATA. Species richness and diversity were calculated and analyzed in R. Results Nematode ITS2 sequences were found in all larval culture samples except two, even though the fecal egg counts were below the McMaster threshold in 20 samples. Sequencing yielded, on average, 1008 sequences per sample. In total, 16 operational taxonomical units (OTU), all with ≥ 98 % identity to sequences in the NCBI database, were recognized. The OTUs found represented nematode species of which ten are commonly associated with sheep. Multiple species were identified in all pre-anthelmintic treatment larval culture samples. No effects on nematode diversity were found in relation to host age. On the other hand, recent anthelmintic treatment lowered species richness, especially after use of ivermectin and albendazole. Interestingly, despite zero egg counts after use of levamisole, these samples still contained nematode DNA and especially H. contortus. Conclusions Our findings provide evidence that nemabiome analysis combined with diversity index analysis provides an objective methodology in the study of the efficacy of anthelmintic treatment as both high and low abundant species were detected.