Aflatoxicosis is a growing problem in aquaculture. A 42‐day study was designed to evaluate the efficacy of conjugated linoleic acid (CLA) and curcumin (CUR) to protect juvenile Pacific white shrimp (Litopenaeus vannamei) from aflatoxins. Growth parameters along with alkaline phosphatase (ALP) and glutathione S‐transferase (GST) activities were measured. Shrimps (36) with an average weight of 76 ± 0.9 mg were randomly allocated in eight experimental groups. Non‐contaminated diet (NCD) and aflatoxin‐contaminated diet (ACD) at 200 μg/kg were prepared. ACD was used to prepare six diets supplemented with CLA (4, 5 or 6 g/kg) and CUR (0.15, 0.2 and 0.3 g/kg). ACD reduced feed intake, growth rate and nitrogen retention efficiency, and increased ALP and GST activity. Improved nitrogen retention was observed for all groups feed with CLA. CUR supplementation at 0.2 g/kg increased feed intake and growth rate while at 0.15 g/kg increased nitrogen retention. ALP activity was reduced in all CUR groups and in 5 and 6 g/kg CLA groups. Reduction in GST activity was observed in 0.15 and 0.2 g/kg CUR groups and 4 g/kg CLA group. CLA supplementation and CUR supplementation can be beneficial to protect juvenile shrimp against aflatoxins.
ABSTRACT. The natural nitrogen stable isotope signatures (δ 15 N) found in poultry by-product meal (PBM) and fish meal (FM) were used to estimate the relative contribution of dietary nitrogen supplied by both ingredients to the somatic growth of juvenile channel catfish Ictalurus punctatus. Six isonitrogenous and isoenergetic experimental diets were formulated using FM and PBM. Two of these diets consisted of isotopic controls having only one ingredient supplying dietary nitrogen, either FM or PBM. Four combined diets were formulated with varying proportions of these ingredients in order to supply high proportions of PBM (FM:PBM, 50:50, 35:65 20:80 and 5:95) on a nitrogen basis. There were significant differences in mean final weight of fish at the end of the trial. Lower growth was observed as the dietary level of PBM increased. In order to determine the relative contributions of the dietary nitrogen supplied by FM and PBM to catfish growth, an isotopic mixing model was applied. Results indicated that the incorporation of dietary nitrogen supplied by PBM was equivalent to the die tary proportions. The dietary nitrogen available in combined diets containing 50, 65 and 80% of PBM was incorporated in fish bodies as 50, 62 and 81%, respectively. However, high incorporation of dietary nitrogen from PBM was not always reflected in higher growth rates. Results demonstrate the viable use of stable isotopes to determine the allocation of dietary nitrogen and indicate that practical diets for catfish can be formulated with levels of PBM as high as 65% without affecting growth and survival.
The ixodicidal activity of the methanolic extracts of Artemisia ludoviciana (Astereceae), Cordia boissieri (Boraginaceae) and Litchi chinensis (Sapindaceae) against two field populations of Rhipicephalus (Boophilus) microplus from the state of Nuevo Leon (NL) and Veracruz (VER) was evaluated. The extract of L. chinensis in the concentration of 150 mg/ml showed efficacies of 100% and 99% against engorged females and mortalities of 98% and 99% against larvae. C. boissieri in the same concentration showed efficacies of 71% and 37% against engorged adults and mortalities of 33.04% and 10.33% against larvae and A. ludoviciana had efficacies of 94% and 83% in adults and mortalities of 89.39% and 89.21% against larvae in both populations respectively. The enzymatic activity of Acetylcholinesterase (AChE), Carboxylesterase (CaE), Glutathione-S-Transferase (GST) and Alkaline Phosphatase (ALP) was measured in both populations of ticks. As a result, a significant difference between both populations was shown, being the VER population the one that exhibited a higher enzymatic activity (p ≤ 0.05). It can be concluded that the methanolic extract of the seed of L. chinensis shows potential ixodicidal activity and can be used as an alternative source of tick control, however, prior characterization, toxicity and formulation studies are necessary.
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