Resumo em Inglês:

ABSTRACT Cost and environmental restrictions limit the use of fishmeal (FM) in aquafeeds and plant protein (PP) sources. Soybean by-products are important alternative; however, their antinutritional factors may reduce fish growth. This study evaluates the effect of FM substitution for PP (soybean meal and soy protein concentrate) in diets of dourado (Salminus brasiliensis), a promising species for fish farming and empirically considered highly tolerant to PP-based diets. A control diet was formulated to contain 20 % of fishmeal and 61 % of plant protein (SBM) and other five diets with decreasing FM graded levels (16 %, 12 %, 8 %, 4 %, 0 %), which were replaced by soybean protein concentrate (SPC), comprising six treatments and four replicates. Fifteen dourados (6.73 ± 0.2 g) were stocked into 200 L tanks in a recirculating system, fed with experimental diets three times a day to apparent satiation for 90 days. Growth performance, food conversion ratio, protein efficiency ratio and protein retention efficiency of fish were impaired when FM substitution exceeded 13.05 % (the broken line analysis method). Histological analysis of intestinal mucosa showed a decrease in villus height when fishmeal was totally replaced by PP, which probably impaired digestive functions of fish and reflected in a severe loss on growth performance.

Resumo em Inglês:

ABSTRACT Whole-plant corn silage (WPCS) is a commonly used forage for feeding dairy cattle in Brazil. The aim of this study was to evaluate on-farm ensilaging practices and the nutritional value, microbiology and fermentation profiles of WPCS from dairy farms in the south of the state of Minas Gerais, Brazil. Silages from 54 dairy farms located in nine cities were sampled and a questionnaire was distributed for completion to describe the herd profile and ensilage practices. Herd size ranged from 8 to 1,000 lactating cows, and 52 % of the farms had fewer than 50 cows in lactation. The majority of the farms cultivated hard endosperm texture hybrids (52 %) and used pull-type forage harvesters (87 %). Double-sided plastic was the most used form of silo sealing (56 %) and 28 % used inoculants. Lactic acid bacteria count was greater than 6.01 log CFU g–1 in 60 % of the samples, and the mean populations of enterobacteria and Bacillus spp. were 4.23 and 4.09 log CFU g–1, respectively. Silo size ranged from 100 to 250 m3 in 44 % of the farms, and the silage removal rate was below 15 cm of the face/d in 41 % of cases. Silage dry matter (DM) concentration was 33 ± 3 % of fresh matter, NDF concentration was 57 ± 7 % of the DM, and in vitro NDF digestibility was 35 ± 11 % of the NDF. Silages with high DM concentrations had large particle size, affecting the nutritional value and the fermentative pattern. Improvements in ensiling practices can potentially inhibit the growth of spoilage microorganisms and raise the nutritional value of silages.

Resumo em Inglês:

ABSTRACT This study aimed to evaluate the production characteristics of pastures in integrated livestock production systems. For that, an experiment was carried out in São Carlos, SP, Brazil, from 2013 to 2015. Forage development, production and nutritive value were evaluated in five beef cattle production systems: extensive continuous stocking (Urochloa decumbens) = EXT; intensive = INT; crop-livestock = iCL; livestock-forest = iLF and crop-livestock-forest = iCLF. Rotational stocking pastures in INT, iCL, iLF and iCLF systems were established with Urochloa brizantha cv. BRS Piatã. In iCL and iCLF, pastures were renovated by resowing the grass simultaneously with corn. In iLF and iCLF, eucalyptus (Eucalyptus urograndis clone GG100) was planted in Apr 2011 in single rows with 15 × 2 m spacing. In the 2013/2014 crop season, INT, iCL, and iCLF pastures were more productive than in iLF and EXT. Shading increase in the 2014/2015 season reduced pasture production in iLF and iCLF, compared with INT and iCL, but increased crude protein content and digestibility. In the shaded systems, pasture production was affected by proximity to trees, mainly due to reductions in solar radiation transmission. The principal component analyses showed that forage accumulation and leaf area index were associated with the position in the middle of the inter-row, and nutritive value was associated with the position at 1.5 m from the trees. In iCLF, solar radiation transmission greater than 60 % maintained forage accumulation similar to iCL, while in iLF, it reduced forage accumulation, evidencing that pasture renovation minimized shading effects in these systems.

Resumo em Inglês:

ABSTRACT This study aimed to evaluate the effects of zinc oxide and a low level of encapsulated zinc oxide, with or without dietary fiber, on the performance and intestinal health of weaned piglets. A total of 112 piglets were used, divided into four treatment groups: basal diet with zinc oxide (ZnO); basal diet with zinc oxide and dietary fiber (ZnO+DF); basal diet with encapsulated low zinc oxide (LZnOE); and basal diet with LZnOE and DF (LZnOE+DF). Piglets were challenged with E . coli K88 + , weighed weekly and the fecal score was evaluated daily. One pig per pen was slaughtered to evaluate the production of volatile fatty acids, intestinal microbial populations, intestinal morphology, and digestibility. The encapsulated zinc resulted in lower body weight and average daily gain, but, when associated with dietary fiber, had similar results to zinc oxide. Until 49 days of age, zinc oxide reduced diarrhoea ( p < 0.05). At 63 days of age the piglets subjected to LZnOE+DF treatment had lower diarrhoea than the pigs subjected to LZnOE treatment but higher than the ZnO and the ZnO+DF groups. Final weight and incidence of diarrhoea of pigs receiving LZnOE was worse than ZnO. LZnOE associated with DF provided the same final weight of piglets from the ZnO group.

Resumo em Inglês:

ABSTRACT The slow rate of multiplication is one of the main constraints on the production of cassava (Manihot esculenta Crantz). This work aimed to evaluate the use of leaf buds for rapid propagation of cassava varieties. Leaf buds were excised from three cassava varieties (BRS Kiriris, 98150-06 and 9624-09) for plantlet generation. The experiment was completely randomized with a 5 (age of mother plant) × 3 (position of the leaf buds on the stems) × 2 (agrochemical treatments) factorial design. Data were collected on leaf sprouting percentage (Spro.Per), plantlet height (Plant.Hei) and total dry mass of plantlets (Dry.Mass.Plant). There was a difference between the three traits for most of the varieties, demonstrating significant effects on the agronomic attributes evaluated. Better agronomic performance (higher sprouting percentage, plantlet height and total dry mass) in plantlets was observed in leaf buds of: i) maturing plants up to six months old; ii) more herbaceous (upper) parts; and iii) plants treated with agrochemicals (fungicides and insecticides). Considering four-month-old plants, three annual cycles, and an 81 % average sprouting, it would be possible to reach an annual multiplication rate of 1:72, which is much higher than that achieved by traditional methods using mature stem cuttings from 12-month-old plants (around 1:5). These results are important because they demonstrate the possibility of using cassava leaf buds to produce high-quality plantlets rapidly for greater multiplication and diffusion of new varieties and cultivation on a larger scale.

Resumo em Inglês:

ABSTRACT In areas where the supply of water for irrigation is limited, tomato production is often subject to drought stress. In order to investigate the drought sensitivity of tomato (Lycopersicon esculentum Mill.) yield and quality during different growth stages, field and pot experiments were conducted in a high tunnel in southern China during the 2013 and 2016 growing seasons. The experiments consisted of four treatments. Crops were drip-irrigated to 100 % of field capacity at all growth stages divided into treatment T1 (control) and the treatment group T2, T3 and T4 receiving half the amount of irrigation as T1 when the soil water content reached 70 % of field capacity, the vegetative phase (stage I) T2, the flowering and fruit development phase (stage II) T3, and the fruit ripening phase (stage III) T4. Compared to the control treatment, drought stress at stages II and III caused a decrease in yield of 13 % and 26 %, respectively. Fruit firmness and color index were positively affected by drought stress, while fruit water content and shape index did not show any differences between treatments. Taste and nutritional quality parameters, such as total soluble solids, soluble sugar, organic acids and vitamin C improved in response to limited water supply (p ≤ 0.05). Despite having a negative effect on fruit yield, drought stress applied at stage III tended to enhance fruit quality traits. This study found that applying drought stress at stage I can be a positive management approach as it saves water and has fewer negative effects compared to applying drought stress at the other critical growth stages, thereby minimizing the adverse effects of drought stress.

Resumo em Inglês:

ABSTRACT Some germplasm collections have a high number of accessions, which makes it difficult to explore the genetic variability present in the germplasm bank due to the redundancy and the difficulty of detailed analysis of all conserved accessions. Therefore, our study aimed to analyze the genetic diversity of 153 lima bean (Phaseolus lunatus) accessions for the purpose of constructing a core collection. Eleven SSRs were used for this purpose. The 153 lima bean accessions can be represented by low redundancy using a minimum of 34 accessions, thus representing 22 % of the size of the entire germplasm bank. The core collection had a higher Shannon diversity index and expected heterozygosity (1.906 and 0.811, respectively) than those presented by the entire germplasm bank (1.605 and 0.713, respectively), indicating a higher polymorphism of the representative cultivars in relation to the entire collection. The accessions selected for the core collection may be used in future studies of genome association as well as in genetic crosses in breeding programs aimed at developing improved cultivars with high genetic diversity which can meet current and future market needs.

Resumo em Inglês:

ABSTRACT Drought is likely the main abiotic stress that affects wheat yield. The identification of drought-tolerant genotypes represents an effective way of dealing with the continuous decrease in water resources as well as the increase in world population. The aim of this study was to identify single nucleotide polymorphisms (SNP) associated with drought tolerance indices in wheat by using a genome-wide association study (GWAS) under fully irrigated and rain-fed conditions. The drought tolerance indices (i.e., Stress Susceptibility Index, Stress Tolerance Index, Tolerance Index and Yield Stability Index) were calculated based on grain yield, 1,000-kernel weight and kernels per spike. The association panel was genotyped using genotyping-by-sequencing (GBS). A total of 175 SNPs exhibited statistical evidence of association with at least one drought tolerance index, explaining up to 6 % of the phenotypic variation. Forty-five SNPs were associated with more than one tolerance index (up to 4 agronomic traits). Most associations were located on chromosome 4A, supporting the hypothesis that this chromosome has a key role in drought tolerance which should be exploited for wheat improvement. In addition, statistical analysis detected SNPs associated with tolerance indices in both growing seasons, providing information about genetic regions with stable effects under different environmental conditions. This GWAS experiment serves as one of the few studies on association mapping for drought tolerance indices in wheat, which could increase the efficiency of rain-fed and irrigated crop production.

Resumo em Inglês:

ABSTRACT Sugarcane orange rust caused by Puccinia kuehnii has recently become an important disease in sugarcane crops and its spread is causing great concern to growers. In this study, we analyzed spores from symptomatic orange rust sugarcane leaves collected in multiple locations in Cuba in a 4-year-period in order to characterize morphological traits of P. kuehnii, establish an adequate molecular technique to characterize it, and determine its infection court in sugarcane. Orange rust caused by P. kuehnii was confirmed by polymerase chain reaction (PCR) and morphological characterization. AFLP markers detected high diversity in P. kuenhnii samples. Sequencing of rDNA regions, as expected, did not reveal differences and SSR markers designed for P. melanocephala could not be transferred to P. kuehnii. In addition to stomata, entry through prickles was also detected as a new infection court in sugarcane. Although the presence of pustules on the adaxial leaf surface was frequently detected, no clear correlation between this presence and density of stomata and/or prickles was found.

Resumo em Inglês:

ABSTRACT Bud rot (BR) caused by Phytophthora palmivora and lethal wilt (LW) whose causal agent is unknown, are two diseases currently posing a threat to the oil palm ( Elaeis guineensis . Jacq) industry. BR, first reported in 1964, has destroyed more than 85,000 ha. LW, first reported in 1994 in the Llanos Orientales in Colombia, has destroyed more than 5,000 ha. Chlorophyll a fluorescence is useful as a provider of information about the efficiency of the photosynthetic process when plants are subjected to biotic or abiotic stresses. Oil palms affected by BR and LW showed anomalies in the photosynthetic system, manifested by reductions in Fv / F M and ΦPSII. Changes in ΦPSII, variable fluorescence yield ( Fv ) and maximum fluorescence in light-adapted leaves ( F M ’ ) were observed from the start of BR infection. The most sensitive and early indicators of LW disease were leaf temperature and basal fluorescence ( F 0 ). Fv/F 0 significantly changed in diseased palms, indicating problems with movement of electrons through the electron transport chain. Leaf temperature changed in response to both diseases, but variation was greater in LW. We concluded that damage to the photochemical system caused by the diseases affected the processes by which the plant captures and transports energy, causing a physiological imbalance in the plant reflected in the observed variations in chlorophyll a fluorescence and leaf temperature. The two parameters began to change early in the onset of BR and before visual symptoms appeared in LW, which is very important to the management of both diseases, the foundation of which is early detection.

Resumo em Inglês:

ABSTRACT The interaction of Zn with soil compartments influences its bioavailability and uptake by plants. In this study, rice and soybean were cultivated under greenhouse conditions with the aim of evaluating Zn bioavailability and fractionation in a clayey-textured Typic Hapludox as a function of Zn rates (4 or 8 mg kg –1 Zn). The experiment was conducted until grain filling. Two soil subsamples (t 1 and t 2 ) that referred to the seeding and flowering stages, were collected and compared with two single extraction schemes, DTPA (Zn DTPAt1 and Zn DTPAt2 ) and Mehlich-1 (Zn Mt1 and Zn Mt2 ) for Zn available contents. Zn fractionation was carried out with t 2 soil subsamples for the testing of the following fractions: exchangeable Zn (Zn Exc ), Zn bound to carbonates (Zn Carb ), Zn bound to organic matter (Zn OM ), Zn bound to oxides (Zn Oxi ) and residual Zn (Zn res ). Zn applied to soil increased the Zn concentration in labile fractions in decreasing order as follows: Zn Exc > Zn OM > Zn Carb . There was no difference between the lesser or unavailable fractions, Zn Oxi and Zn res, when there was no correlation between the rates either with total accumulated Zn in plants (Zna total ), or the contents extracted by DTPA or Mehlich-1. Total cumulative Zn content in rice and soybean affected by the ZnCl 2 rates applied were positively correlated with Zn content extracted by both solutions. Both extractant solutions presented positive correlation between available contents of Zn with Zn bound to labile fractions.

Resumo em Inglês:

ABSTRACT This review aims to demonstrate the possible formation of Ethyl carbamate (EC) in different production stages of cachaça. EC is a carcinogen confirmed in animal experiments and possibly carcinogenic to humans. EC incidence below relevant health limits naturally affects many fermented foods and beverages. Concentrations above 1 mg L–1 are often detected in certain spirits derived from cyanogenic plants. In Brazil, cachaça is widely consumed and therefore consumers are at health risk if they drink EC beverages at high concentrations, since the amount of EC in cachaça (sugar cane brandy) constantly exceeds the threshold 0.21 mg L–1, damaging the health of consumers and hindering exportation to North America and Europe. Many studies have reported on EC formation at different stages of the cachaça production process. Most studies refer to EC formation during fermentation and distillation. In fermentation, reaction occurs between ethanol and nitrogen precursors, such as urea (H2NCONH2) and cyanide (CN–) to form EC. In distillation, cupric ions catalyze cyanide conversion from EC; however, in discontinuous distillation, the bottling fraction of cachaça reduced EC concentration. Although this review describes the possible routes of EC formation at different production stages of cachaça, it presents some studies on EC reduction in alcoholic beverages.