Assessment of the ideal ratios of digestible essential amino acids for pacu,Piaractus mesopotamicus,juveniles by the amino acid deletion method

The present study aimed to determine the ideal ratios of digestible essential amino acids (EAAs) for pacu (Piaractus mesopotamicus) juveniles by the amino acid (AA) deletion method. A completely randomized design which consisted of 11 treatments and three replicates each was used. The treatments included a control diet (CD) containing 55% of nonpurified natural ingredients and 45% of purified synthetic amino acids and ingredients, and other ten isonitrogenous and isoenergetic EAA limiting diets (LDs), each being deficient in 44.4 ± 0.02% of the respective EAA. Pacu juveniles with initial average body weight of 6.22 ± 0.09 g were distributed among 33 fiber glass tanks. Fish were fed with semipurified and extruded diets for 113 days two times a day until apparent satiation. The ideal ratio of each dietary EAA was calculated on the basis of the relationship between body N retention and amount of EAA deleted from the respective EAA LD. Based on the AA deletion method, the ideal ratios of digestible EAAs for pacu juveniles, relative to lysine requirement of 100% were estimated as: methionine 14.6%, threonine 35.0%, tryptophan 6.6%, arginine 62.8%, histidine 13.6%, isoleucine 26.3%, leucine 43.7%, phenylalanine 27.2%, and valine 35.8%.     

Assessing seed desiccation responses of native trees in the Caribbean

New Forests - Native trees from the Caribbean were tested for seed desiccation responses, by adapting the “100-seed test” protocol. Ninety-seven seed lots of 91 species were collected...     

How does water and salt stress affect the germination and initial growth of Brazilian soya bean cultivars?

The effects of water and salt stress on rate of germination and seedling growth were investigated under laboratory conditions in 46 soya bean genotypes from Central-West region of Brazil to verify how these stresses may limit crop establishment during the initial growth stage and also to identify the most tolerant genotypes to drought and salinity. Mild water and salt stresses were imposed by seed exposure to –0.20 MPa iso-osmotic solutions with polyethylene glycol—PEG 6000 (119.57 g/L) or NaCl (2.357 g/L) for 12 days at 25°C. The germination percentage, seedling length and seedling dry matter were measured, and then, salt or drought tolerance indexes were calculated. The “NS 5909 RG,” “NS 7000 IPRO,” “NS 7338IPRO,” “FPS Solimões RR,” “NS 5151 IPRO,” “SYN 13610 IPRO,” “LG 60177 IPRO,” “NS 6909 IPRO” and “BMX Desafio RR” were identified as the most drought-tolerant genotypes, whereas under salinity conditions, the genotypes “5D 615 RR,” “BMX Desafio RR,” “5D 6215 IPRO” and “BMX Ponta IPRO” were identified as tolerant. The “BMX Desafio RR” is the genotype most adapted to both stress conditions and, therefore, should be used under conditions of water shortage and excess salt in the soil at sowing time.     

Simulation of over-exploitation of ornamental fish and its consequences for the functional structure of assemblages of Amazonian streams

The consequences of over-exploitation may seriously impair the integrity and functioning of ecosystems. When loss of species is accompanied by the loss of ecological processes, the effects are no longer just taxonomic and may affect the stability of the environments. Ornamental fishing is one of the main economic activities of the middle Negro River. Such activity is directed to a small number of species and has the Cardinal Tetra (Paracheirodon axelrodi) as the main target species. Given the potential effects this pressure and the lack of information on its consequences, the present study analysed, through simulations, the possible effects of depletion of ornamental fish populations on the functional structure of fish assemblages, represented by functional diversity (FD) and functional redundancy (FR) indexes. We sampled 13 streams exploited by the ornamental fishery, where we collected 4,286 specimens of 110 species, of which 22 were targeted as ornamental fishing. We found that the ornamental species corresponded, on average, to 27.8% of the species and 33.3% of the FD of the assemblages. In a scenario of complete exclusion of ornamental species, local communities would lose 24.6% of the FD and reduce up to 12% of the FR. With these results, it is possible to infer that the local extinction of exploited species would cause negative impacts on the multifunctionality and the resilience of the streams ecosystems. In this way, we emphasise the need for proper management of the ornamental fisheries aiming to the sustainability of the activity and to the conservation of ecosystem functionality.     

Vacuum Drying for Extending Litchi Shelf-Life: Vitamin C,Total Phenolics,Texture and Shelf-Life Assessment

In an attempt to obtain shelf-stable litchi fruit with preserved nutritional quality and good sensory features, quarters of peeled and pitted fruits were vacuum dried at 50, 60 and 70 °C at a constant pressure of 8.0 kPa. The product was assessed for its vitamin C, total phenolics and texture (hardness). In addition, the product with the best texture was assessed for its shelf-life by means of accelerated testing. Results suggest that vacuum dried litchi retained almost 70% of the vitamin C and total phenolics when compared to frozen fruits (control). Vitamin C and phenolic compounds content significantly decreased with drying, while no difference was found between different drying temperatures. Hardness increased with drying temperature. The sample dried at 70 °C presented crispness, which is a desired quality feature in dried fruit products. This sample was subjected to shelf-life evaluation, whose result suggests a shelf-life of eight months at 23 °C. Total color change (CIE ΔE₀₀) was the expiry criterion. Vacuum drying was a suitable technique for producing shelf-stable litchi fruit with good texture while preserving its desirable original nutrients. Consumption of vacuum dried litchi may be beneficial to health due to its remarkable content of phenolic compounds and vitamin C.     

Cellular activity and development of enteric,hepatic and muscle tissues of juvenile pacu Piaractus mesopotamicus (Holmberg 1887) fed with lyophilized bovine colostrum

Bovine colostrum, an alternative food of animal origin provided as partial protein source, may constitute an innovative ingredient in fish feeding. Serum insulin‐like growth factor 1 (IGF‐1) and cellular activity of enteric, hepatic and muscle tissues of juvenile pacu Piaractus mesopotamicus fed with lyophilized bovine colostrum (LBC) were evaluated. Pacu (8.46 ± 0.74 g; 7.75 ± 0.27 cm, n = 18 in triplicate) were stocked into 18 tanks (300 L; 18 fish per tank, in triplicate) and fed with control diet containing 0% of LBC or experimental diet containing 10% and 20% of LBC inclusion for either 30 or 60 days of experiment. IGF‐1 serum concentration was not affected (P > 0.05) by the diet containing LBC and experimental period. The intestinal and hepatic cellular activity was not influenced by LBC (P > 0.05); however, intestine protein/RNA decreased at 60 days (P < 0.05). The muscle cellular activity was affected by LBC, highest in fish fed with diet containing 10% of LBC (P < 0.05). Between the periods DNA and protein/RNA increased at 60 days, while RNA, protein/DNA and RNA/DNA ratio decreased in this same period (P < 0.05). Increased DNA muscle content indicates fish growth by hyperplasia. The results of the present study is related with suitable development of enteric, hepatic and muscle tissues and proper condition of juvenile pacu fed with LBC considering the absence of differences in relation to juveniles that consumed diet without colostrum.     

Post‐hatching development of the ornamental ‘Red Cherry Shrimp’ Neocaridina davidi (Bouvier, 1904) (Crustacea,Caridea, Atyidae) under laboratorial conditions

The ‘Red Cherry shrimp’, Neocaridina davidi is a small freshwater caridean shrimp living, originally, in various kinds of inland water bodies around Asian countries. This shrimp has reached several countries for ornamental use; however, basic information on the biology of the species is still scarce in the literature. Its early post embryonic development morphology has not yet been described. This paper focused on the production and the development of early post‐hatching stages of N. davidi, its male secondary sexual features, observation of the gonads and the presence of females with embryos. The larval development of N. davidi was almost suppressed as noted by the presence of relatively large‐sized eggs, first stage hatching as a decapodid; and the tail fans were present only from the 2nd post‐hatching stage. A biological important consequence of the presence of this Red Cherry shrimp species in the Neotropics is its potential release into nature, which could cause its rapid dispersion affecting populations of other indigenous caridean freshwater shrimps.     

Single nucleotide polymorphisms in the growth hormone gene of Oreochromis niloticus and their association with growth performance

Polymorphisms in the growth hormone (GH) gene that is associated with the growth rate of farmed fish have been the target of many breeding programmes. The present study aimed to identify single nucleotide polymorphisms (SNPs) in GH gene regions to evaluate the association of SNP variations with the growth rate of two Nile tilapia: Oreochromis niloticus (Linnaeus, 1758) strains. The targeted regions were amplified, sequenced, aligned and screened for the presence of SNPs; thereafter, performance tests were used to check for the association between SNPs and weight. Allele and genotype frequencies were estimated for each SNP and genotype. Genotype blocks or sets of SNP genotypes and frequencies were also estimated. Association between SNPs and growth rate was statistically evaluated using a univariate linear mixed model that included both fixed and random effects. A total of 10 SNPs were identified, nine in the proximal promoter and one located in the 5′ UTR, forming 10 genotype blocks. In all weight recordings, five genotype blocks were significantly associated with the highest weights. Single nucleotide polymorphisms 6‐10 were also found to be significantly associated with growth (p‐value < .05). Genotypes with higher additive genetic values for weight were identified in the Chitralada strain, suggesting a possible impact of these additive effects of the GH SNP genotype on the growth rate of Nile tilapia. These findings may be used as part of marker‐assisted selection in tilapia breeding programmes.     

Dietary roughage sources affect lactating Holstein x Zebu cows under experimental conditions in Brazil: a meta-analysis

Tropical Animal Health and Production - To reduce costs, lactating cows are often fed a higher proportion of roughage and alternative feeds; however, such protocols may not lead to optimal milk...