Eficiência nutricional da dieta de novilhos de corte mantidos em pastagem associada a suplementação

Pós-graduação em Zootecnia - FCAV

Early weaning and concentrate supplementation strategies for lamb production on Tifton-85 pasture

The influence of early weaning and concentrate supplementation strategies on sward characteristics, forage chemical composition and lamb productivity were evaluated in four production systems on Tifton-85 pasture: suckling lambs not supplemented until slaughter; suckling lambs supplemented with concentrate in creep feeding until slaughter; early-weaned lambs not supplemented until slaughter; and early-weaned lambs supplemented with concentrate until slaughter. Structural, morphological and productive characteristics of pasture were measured. The forage was chemically analyzed to estimate its composition. Lambs average daily gain and productivity were calculated. Sward height, forage and morphological components mass were lower in systems without weaning. Forage production was higher in systems with supplementation. Higher levels of neutral and acid detergent fiber were observed in forage ingested by lambs in creep feeding and by weaned and unsupplemented lambs. Average daily gain was higher for lambs in creep feeding (275 g/d) and lower for the weaned and unsupplemented animals (57 g/d). Productivity was higher for weaned and supplemented lambs (21 kg lamb body weight, BW gain/ha/d). Lower productivity was observed in systems without supplementation (5 kg lamb BW gain/ha/d on average). Ewes modify the sward conditions improving the pasture characteristics and the quality of forage produced. Changes in sward conditions affect the chemical composition of forage ingested by lambs. Early weaning may be an alternative to maximize pasture utilization in small areas. Concentrate supplementation may increase lamb performance and productivity in grazing systems. If the objective is to improve lamb individual performance, creep feeding should be used.

Desempenho e bem estar de bovinos Nelore na fase de recria mantidos em sistemas integrados de produção agropecuária

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Parâmetros nutricionais e metabólicos de novilhos nelore recriados em pastos de diferentes alturas e doses de suplemento

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Qualidade da carne de bovinos recriados em pastagens associada a suplementação e terminação a pasto ou no confinamento

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of stocking densities in the nursery phase on the growth of Macrobrachium amazonicum reared in net pens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Limnology of Macrobrachium amazonicum grow-out ponds subject to high inflow of nutrient-rich water and different stocking and harvest management

We evaluated the water characteristics and particle sedimentation in Macrobrachium amazonicum (Heller 1862) grow-out ponds supplied with a high inflow of nutrient-rich water. Prawns were subject to different stocking and harvesting strategies: upper-graded juveniles, lower-graded juveniles, non-graded juveniles + selective harvesting and traditional farming (non-grading juveniles and total harvest only). Dissolved oxygen, afternoon N-ammonia and N-nitrate and soluble orthophosphate were lower in the ponds in comparison with inflow water through the rearing cycle. Ponds stocked with the upper population fraction of graded prawns showed higher turbidity, total suspended solids and total Kjeldahl nitrogen than the remaining treatments. An increase in the chemical oxygen demand:biochemical oxygen demand ratio from inlet (4.9) to pond (7.1-8.0) waters indicated a non-readily biodegradable fraction enhancement in ponds. The sedimentation mean rate ranged from 0.08 to 0.16 mm day(-1) and sediment contained >80% of organic matter. The major factors affecting pond ecosystem dynamic were the organic load (due to primary production and feed addition) and bioturbation caused by stocking larger animals. Data suggest that M. amazonicum grow-out in ponds subjected to a high inflow of nutrient-rich water produce changes in the water properties, huge accumulation of organic sediment at the pond bottom and non-readily biodegradable material in the water column. However, the water quality remains suitable for aquaculture purposes. Therefore, nutrient-rich waters, when available, may represent a source of unpaid nutrients, which may be incorporated into economically valued biomass if managed properly.

Root system of Panicum maximum Jacq. cv. IPR-86 Mil(e)over-capnio fertilized with nitrogen and submitted to rotational stocking

The effect of nitrogen on the root system of the species Panicum maximum Jacq. cv. IPR-86 Mil (e) over cap nio, under grazing, was evaluated. The N rates were 0; 150; 300 and 450 kg/ha. year. The root density was evaluated during pregrazing at five years of successive N application, in three depths (0-10; 10-20 and 20-40 cm) and the root growth at 7, 14, 21, and 35 days after grazing. The grazing method adopted was rotational stocking. Root length and root mass densities in pre-and post-grazing presented maximum values at rates 204, 206, 192, and 197 kg/ha of N, respectively. The root growth (in root length density) increased, on average, until 29 days after grazing at rates 0, 150, and 300 kg/ha; at 450 kg/ha N rate, the increase was linear. Independently of N rates, around 60 and 25% of IPR-86 Mil (e) over cap nio cultivar root system was concentrated in 0-10 and 10-20 cm depth, respectively.

Effects of stocking density on growth of channel catfish, Ictalurus punctatus, fingerlings in Southern Brazil

Channel catfish, Ictalurus punctatus, fingerlings (mean length: 4.0±0.5 cm) were stocked into sixteen 16-m2 tanks with cement walls and earth bottoms. Four stocking densities were used: 10, 15, 20, and 25 fish/m2. Fish were fed a prepared diet containing 36% protein according to a fish size/water temperature-dependant chart for 120 days. Fish were stocked on January 20, 1992. Average water temperature varied from 19.7°C to 28.5°C. Final mean values of individual fish length and weight were significantly higher (P < 0.05) for the density of 10 fish/m2 and averaged 19.4±2.6 cm and 70.0±16.9 g, respectively. Food conversion ratio was significantly higher (P < 0.05) for fish stocked at rate of 25 fish/m2. Survival rates averaged 91.4%, with no significant differences (P > 0.05) found among treatments. These results demonstrate the viability of channel catfish fingerling growth in southern Brazil.

Stocking density of Nile tilapia in cages placed in a hydroelectric reservoir

The Brazilian government has been encouraging fish farming in cages in federal water bodies, including hydroelectric reservoirs. Despite the government support, it is a new activity and the production model still needs some adjustment to reduce the production costs and achieve sustainability. The aims of this study were to determine the appropriate stocking density of Nile tilapia in cages in a hydroelectric reservoir and to evaluate to what extent fish size selection could improve their uniformity. Twelve cages (6m3) were placed at the Fish Farmers' Cooperative of Santa Fé do Sul and Region, Ilha Solteira reservoir, São Paulo, Brazil (20°12'10″S, 50°58'31.15″W). In stage I (initial fish weight, 78g), four stocking densities were tested: D1-800, D2-2000, D3-2500 and D4-3000 fish/cage, with three replicates. At the end of this stage (average fish weight, 255g), the fish were selected into three sizes, except for D1. In stage II, four stocking densities were tested, designed to obtain the following final production: D1-100kg/m3 (800 non-selected fish/cage), D2-80kg/m3 (600 fish/cage), D3-100kg/m3 (800 fish/cage) and D4-120kg/m3 (900 fish/cage). The trial ended when the fish weighed 800g. By reducing the initial stocking density from 2500 to 800 tilapia juveniles per cage, there was no need for selection. The growth performance was higher, the feed conversion rate was better and the time taken to reach harvesting was shorter. Consequently, the production cost reduced and the operating profit increased. Using the lowest initial stocking density, the risk of disease outbreak was also lower, and there was no need to use drugs for disease control since the mortality rate and occurrences of disease and deformity decreased and the dissolved oxygen level inside the cages was higher. © 2013 Elsevier B.V.

Stocking densities and feeding strategies in shrimp and tilapia polyculture in tanks

The objective of this work was to evaluate the performance of Pacific marine shrimp (Litopenaeus vannamei) and tilapia (Oreochromis niloticus), in a polyculture in tanks subjected to different stocking densities and feeding strategies, in comparison with monoculture. Two experiments were performed, at the same time, in a completely randomized design with three treatments and four replicates each. Treatments for experiment I were: monoculture with 10 shrimp per m² (10S:0T); polyculture with 10 shrimp and 0.5 tilapia per m² (10S:0.5T); and polyculture with 10 shrimp and 1 tilapia per m² (10S:1T). Shrimp was the main crop, and feed was provided based on shrimp biomass. Treatments for experiment II were: monoculture with 2 tilapia per m² (2T:0S); polyculture with 2 tilapia and 2.5 shrimp per m² (2T:2.5S); and polyculture with 2 tilapia and 5 shrimp per m² (2T:5S). Tilapia was the main crop, and feed was provided based on fish requirements. In the experiment I, tilapia introduction to shrimp culture resulted in lower shrimp growth and poor feed conversion rate. In experiment II, shrimp introduction to tilapia culture did not interfere with fish performance. Polyculture is more efficient with the combination of 2 tilapia and 2.5 or 5 shrimp per m² and feed based on fish requirements.

Stocking densities of juvenile Brycon orthotaenia: production parameters and economic benefits in net cages

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)