Genetic parameters in open pollination progenies of the acerola

A acerola (Malpighia emarginata D.C.) é uma cultura que vem despertando grande interesse por parte de consumidores, produtores, industriais e exportadores, dado o seu alto teor de vitamina C. No Brasil, não existem variedades recomendadas para o plantio comercial; por esta razão, os dados de produção são muito variáveis. O presente trabalho visa estimar e interpretar geneticamente a porção de variabilidade existente quanto a alguns caracteres, em uma população de plântulas de aceroleira obtidas de sementes, originalmente selecionadas em plantio comercial no Estado do Ceará. O experimento foi instalado no local definitivo em abril/96, na Estação Experimental da Embrapa-Centro Nacional de Pesquisa de Agroindústria Tropical (CNPAT), no município de Pacajus, CE, sob arranjo experimental de blocos casualizados, com 62 tratamentos, três repetições e quatro plantas por parcelas, no espaçamento de 4 m entre linhas e 3 m entre plantas. Os tratamentos são constituídos por progênies de polinização livre. No primeiro ano de idade das plantas, a maioria das progênies já tinha frutificado, sendo que a proporção de florescimento era menor do que a frutificação no período de avaliação. Pelas estimativas dos coeficientes de herdabilidade dos caracteres, pode-se afirmar que a seleção de progênies resultará em ganhos superiores em relação à seleção de plantas. Os índices b1 e b2, que quantificam a relação da variação genética em face da variação ambiental entre e dentro de progênies, respectivamente, revelam uma condição favorável à seleção dentro de progênies.Acerola (Malpighia emarginata D.C.), a typical tropical crop, has shown excellent adaptation in many Brazilian regions. Its high vitamin C content has attracted the interest of consumers, farmers, industries and exporters. Selected materials with desirable characteristics such as high productivity and high fruit quality must be planted to establish new orchards. The main purposes of this work were to estimate and genetically interpret the portion of variability among some characteristics of acerola plants within a population. Open pollination progenies from 62 mother trees previously selected within a commercial plantation were utilized. The experimental design used was a completely randomized block with three replicates, four plants per plot and spacing of 4 by 3 meters. The results showed that in the first year of evaluation the majority of the progenies had already fruited and the proportion of the flowering was lower than that of fruiting during the period of evaluation. The parameters used to evaluate genetic variation within the population showed high variability, which is favorable for selection

Performance and immunological resistance of Litopenaeus vannamei fed a β-1,3/1,6-glucan-supplemented diet after per os challenge with the Infectious myonecrosis virus (IMNV)

This study determined the efficacy of a β-1,3/1,6-glucan source on the survival, growth, and immunological responses of Litopenaeus vannamei challenged with infectious myonecrosis virus (IMNV). The work was conducted in 20 tanks of 500 L with clear water with constant recirculation and aeration. Shrimp weighing 2.6±0.4 g were stocked at 100 animals/m2 and reared for 10 weeks. Viral challenge occurred through oral administration of IMNV positive extract (1.82 £ × 103 copies of IMNV/µL RNA) during three consecutive days, twice a day. One treatment and three controls, with five replicatetanks each, were used, as follows: Com - commercial diet fed to non-challenged shrimp (NCS); Ref - lab-manufactured basal diet, deprived of β-1,3/1,6- glucan fed to NCS; IMNV-Ref - basal diet fed to IMNV-challenged shrimp; and, IMNV-BetG - basal diet with 1,000 mg/kg of a β-1,3/1,6-glucan. Per os challenge began on the 29th day of rearing (4.93-g to 6.92-g shrimp). Shrimp were effectively contaminated with IMNV. Animals were highly susceptible to IMNV four weeks after the first day of infection when mortality peaked. Shrimp in the Com treatment (69.5±12.7%) reached the highest survival, but it did not differ from the Ref group (57.9±9.21%). Shrimp under the IMNV-Ref treatment achieved the lowest survival (23.2±5.76%). Survival for IMNV-BetG (48.1±8.53%) was significantly higher than IMNV-Ref, and similar to the Ref group. Total hemocyte count was significantly affected by treatment and hemolymph sampling time, while serum protein concentration and phenoloxidase activity did not change. Addition of 1,000 mg/kg of β-1,3/1,6-glucan in a diet for L. vannamei enhances shrimp survival when orally exposed to IMNV. No signs of immunological fatigue or detriment in growth are detected when the species is continually exposed to this diet

Bioavailability of crude protein and lipid from biofloc meals produced in an activated sludge system for white shrimp, Litopenaeus vannamei

The present study compared the bioavailability of crude protein and lipid from biofloc meals generated with an activated sludge system using two water sources: wastewater from shrimp experimental culture (BFL-W) and, artificially, using clean seawater (BFL-C). The sludge system operated by chemical and organic fertilization three times per week. Sampling of bioflocs occurred every two days during 81 days. To evaluate digestibility, each type of biofloc meal was incorporated into a reference diet (REF) at 300 g/kg. Another diet acted as a negative control (NEG) by using fish waste meal. The apparent digestibility of bioflocs was estimated by the indirect method using chromic oxide (Cr2O3) as the inert marker at 10 g/kg of the diet. Juvenile L. vannamei of 5.09±0.79 g (n = 440) were stocked at 10 shrimp/tank in 44 tanks of 61 L each that operated under a water recirculating regime. Biofloc meals contained a high ash content (591.0-649.2 g/kg) combined with a low crude protein content (95.9-137.3 g/kg). After 26 days, shrimp achieved a final survival of 93.2±0.8% and a biomass gain of 37.1±1.8 g/tank. Final shrimp body weight ranged from 9.01±0.15 to 9.45±0.13 g. The apparent digestibility coefficient (ADC) of crude protein in the biofloc produced from BFL-W, BFL-C and fish waste meal (NEG) reached 26.0, 25.7, and 64.1%, respectively. Similarly, the lipid ADC was 78.9, 67.9, and 85.8%, respectively. This study indicated that biofloc meals had a low protein availability for L. vannamei. However, although low levels of lipid were present, it proved to be available for the species. The dietary inclusion of biofloc meal appears to have a growth-promoting effect on shrimp, which may be associated with trace minerals, or other nutrients not identified in this study

Increasing feed allowance in low-fish meal diets allows for a reduction in dietary methionine for juvenile Litopenaeus vannamei raised in green-water tanks

A 10-week study was conducted to evaluate the effect of feed allowance and graded levels of dietary methionine (Met) on growth performance of Litopenaeus vannamei. Juvenile shrimp of 1.83±0.14 g were stocked in 42 outdoor green-water tanks of 1 m3 under 120 shrimp m−2. Animals were fed under two feed allowances, regular and 30% in excess. Five diets with 30 g kg−1 fishmeal were designed to contain 318±2 g kg−1 crude protein and a minimum amount of protein-bound Met. To achieve graded levels of dietary Met, a control diet with 4.6 g kg−1 Met or 8.9 g kg−1 methionine + cysteine (M+C) was supplemented with 1.2, 2.2, 3.2, and 4.2 g kg−1 of DL-methionylDL-methionine to result in total dietary Met of 5.6, 6.9, 7.9, and 9.2 g kg−1 (10.0, 11.2, 12.1, and 13.5 g kg−1 M+C, respectively). A final survival of 86.5±3.6% was reached with no significant influence from feed allowance or dietary Met. Feed inputs significantly affected apparent feed intake, weekly shrimp growth, final body weight (BW), and gained yield. Larger meals and a higher dietary Met had no impact on feed conversion ratio. There was a significant interaction between feed allowance and Met over shrimp BW. By feeding animals in excess, BW was enhanced at 6.9 g kg−1 Met. A dietary Met of 7.9 g kg−1 was required to achieve a maximum BW under a regular feed allowance. Thus, shrimp required less amounts of dietary Met to maximize BW when higher feed inputs were delivered. Our findings demonstrate a sparing effect of dietary Met for L. vannamei when a higher feed allowance is adopted. Shrimp farmers should consider adjusting feed allowance to dietary Met to maximize shrimp growth performance and yiel

VARIABILIDADE GENÉTICA EM CARACTERES MORFOLÓGICOS DE POPULAÇÕES DE PLANTAS JOVENS DE ACEROLA

Com o objetivo de estimar e interpretar geneticamente a porção de variabilidade genética existente em populações de plantas juvenis de acerola obtidas de sementes, originadas de populações submetidas a processo de seleção, foi instalado um experimento com três tipos de populações, em blocos ao acaso, com 45 progênies, três repetições e número variável de 4 a 6 plantas por parcela. Tendo em vista os resultados obtidos, conclui-se que a avaliação da variabilidade genética em populações de plantas jovens de aceroleira não se constitui em material adequado para esse tipo de estudo. Também não foi possível fazer uma interpretação genética da porção de variabilidade existente nas populações, haja vista não seguirem um padrão que possibilitasse estabelecer associações entre as populações nas condições em que o trabalho foi desenvolvido