Suchergebnisse

Abstract: The present study evaluates the economic viability of four different models of beef cattle production in the rio Vermelho hydrographic basin. The study focuses on the traditional extensive ranching system, which was compared to three intensive systems, one based on low levels of concentrated supplementation, a second with low levels of concentrated supplementation and confinement for fattening and an intensive grazing system, with supplementation during the dry and rainy seasons. The investments were estimated for the different levels of technical specifications of each system. The net present values and internal return rate were used for the assessment of the economic viability of the project, considering the minimum rate of attractiveness, equivalent to the inflation-adjusted savings interest rate (6.17%). The continuity of the sector was evaluated based on the gross and net margins, and profitability rates, where the system is already installed. All four systems had gross and net margins and profitability consistent with their economic sustainability over both the short and long terms. However, only two systems (reduced consumption of concentrated supplements and the intensive grazing system) were economically viable as start-ups.

The objective of this study was to investigate the relationships between energy, protein, enzymatic metabolism, and residual feed intake (RFI) in purebred Nellore bulls. A total of 120 Nellore bulls, individually housed, underwent performance trials while being fed a high-concentrate diet. The study utilized data from the 10 most efficient, least efficient, and moderately efficient animals. Blood samples were collected via venipuncture for a complete blood count, and serum was analyzed for albumin, total protein, urea, creatinine, glucose, cholesterol, gamma GT, AST, and alkaline phosphatase. The data were subjected to a completely randomized design with three treatments and 10 replicates, and treatment means were compared using the Tukey test. Pearson's linear correlation analysis was performed. The most efficient animals demonstrated a 27.62% reduction in feed intake compared to the least efficient ones. No significant differences were observed in the serum biochemistry between different RFI classes. Inefficient animals exhibited elevated mean corpuscular hemoglobin (MCH), a red blood cell index, which correlated with RFI, gain-to-feed ratio, and dry matter intake (r = 0.46, 0.42, and -0.42, respectively). Hemoglobin concentration showed correlations with RFI and gain-to-feed ratio (r = 0.36, -0.41, respectively). These findings suggest potential variations in oxygen-carrying capacity. Red blood cell parameters could serve as biomarkers for identifying inefficient animals.

This study was undertaken to examine production performance, pasture and milk intakes and nutrient digestibility in heifers supplemented with different levels of energy in a creep-feeding system on Urochloa decumbens Stapf pastures during the rainy-dry transition season. Fifty-one heifers with predominant Nellore genetic composition (average initial age and weight: 120 days and 133.4 ± 3.12 kg) and their respective dams were used in an evaluation of production performance, intake, and diet digestibility. Four treatments were evaluated, namely, MM - mineral mixture; T250 - 0.250 kg of supplement per head per day; T500 - 0.500 kg of supplement per head per day; and T750 - 0.750 kg of supplement per head per day, totaling three groups with 13 animals each and one group with 12 animals. All supplements were balanced to provide 100 g of CP animal-1 day-1. LIPE® and chromium oxide were used as external markers to estimate fecal excretion and individual DM and supplement intakes, respectively, whereas iNDF was used as an internal marker for pasture DM intake. Production performance did not differ between the supplemented and unsupplemented animals. Total DM intake and pasture DM intake were higher in the group supplemented with concentrate, and the same was observed for the digestibility of DM and NDFap consumed by the animals. The average cow milk yield was 5.33 kg/day, with average protein and fat contents of 3.51% and 4.85%, respectively. In conclusion, compared to the use of mineral mixture only, multiple supplementation at different levels containing 100 g of CP does not significantly improve performance in lactating beef heifers grazing on Urochloa decumbens Stapf and supplemented during the rainy-dry transition season.

An experiment was carried out to investigate the effects of supplementation strategies on intake, digestibility, and performance of Nellore cattle on pasture (Urochloa decumbens) during the rainy-dry transition period. The evaluated strategies were mineral supplementation (MS), self-feed supplementation (SF), and infrequent concentrate supplementation. Supplementation frequencies were three times per week (Mondays, Wednesdays, and Fridays - 3tw) and daily (7tw). Animals receiving concentrate supplementation had higher pasture DM and TDN intakes than those fed MS. There was no difference (P > 0.10) between concentrate supplementation strategies. Average pasture DM intake was 7.89, 8.09, and 8.10 kg day?1 for SF, 3tw, and 7tw, respectively. No effects were found (P > 0.10) between SF and infrequent supplementation, or for the supplementation frequencies tested. The lowest average daily gain (ADG) (P < 0.10) was found for animals fed MS, and there was no difference between concentrate supplementation strategies for this variable. Average daily gains for MS, SC, 3tw, and 7tw were 661.4, 812.7, 811.5 and 819.2 g/animal, respectively. During the rainy-dry transition period, grazing beef cattle receiving concentrate supplementation have higher pasture and TDN intakes and better performance than animals fed mineral supplement only. Self-feed supplementation or supplementation provided three days per week do not compromise pasture and TDN intakes, nutrient digestibility, or performance of grazing beef cattle.

This study was designed to evaluate the effects of different supplementation plans on the nutrient intake, apparent total-tract digestibility, grazing behavior, growth performance, and carcass characteristics of beef cattle under grazing conditions from ages 4 to 18 months old. The beef calves grazed Brachiaria decumbens in four seasons: rainy-dry transition, dry, dry-rainy transition, and rainy. Forty-four animals (11 per treatment) were randomly assigned to one of four nutritional plans of supplementation defined by the quantity of supplement offered: control, low, medium, and high supplementation. There was no difference (P > 0.10) in dry matter intake (DMI). However, animals receiving medium and high supplementation had decreased (P < 0.10) forage dry matter intake (FDMI) compared with those under non- and low supplementation. The DMI and FDMI were lower (P < 0.10) in the dry season. During the rainy season, the grazing time decreased (P < 0.10) for animals receiving supplementation compared with non-supplemented ones, but was similar between medium and high supplementation. The performance and carcass characteristics were greater (P < 0.10) for high and medium supplementation compared with low and control. In conclusion, increasing the supplementation plans for beef cattle in tropical pastures increases the nutrient intake but decreases FDMI. The performance also increases with the supplementation plan; however, the growth rate is affected by the grazing season.