Suchergebnisse

We examined the production performance of Nellore heifers fed high-concentrate (90%) diets in which ground corn (GC) was substituted by ground soybean hulls (SH) at increasing levels (0, 33, 66, and 100%), in the concentrate portion. A total of 144 heifers (263.40 ± 13.90 kg average initial weight; 27 months old) received the test diets in a feedlot for 112 days. The experiment was set up as a completely randomised design with four treatments. Data were subjected to ANOVA and orthogonal contrasts, adopting ? = 5%. The sum of squares of treatments in the contrast analysis was decomposed into two orthogonal contrasts (L - linear and Q - quadratic effect) for the level of SH substituting GC. Dry matter intake was not changed by the GC substitution levels, averaging 2.51% of body weight. There was a linear increase in neutral detergent fibre intake (1.08, 2.03, 2.92, 3.78, 4.85 kg/day) and feed conversion (6.20, 7.08, 7.77, and 8.67 kg/kg); and a linear decrease in total digestible nutrient intake (5.78, 5.16, 5.03, 5.12, and 3.66 kg/day), average daily gain (1.24, 1.11, 1.02, and 0.89 kg/day), and slaughter weight (383.52, 374.71, 363.25, and 366.27 kg) as the substitution level was increased (0, 33, 66, and 100%, respectively). Subcutaneous fat thickness and loin-eye area were not influenced (P > 0.05), averaging 5.30 mm and 53.09 cm2, respectively. Substituting ground corn by ground soybean hulls in high-concentrate diets determined a reduction in production performance of feedlot-finished Nellore heifers.

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.

The objective of this study was to evaluate the replacement of 0, 25, 50, 75 and 100% of ground corn (GC) with pelleted soybean hulls (SH) in the concentrate portion of cattle diets. The evaluation was conducted using five 13-month-old Nellore steers cannulated in the rumen, with a mean body weight of 265.00 + 11.60 kg. The steers received a diet composed of 90% concentrate and 10% sugarcane bagasse as the only source of roughage. The statistical design used was a 5x5 Latin square. There was no effect (p > 0.05) of replacement levels or interaction (p > 0.05) between replacement levels and sampling time on ruminal pH, which ranged from 5.8 to 6.0. The apparent digestibility of DM, CP, EE, CHOT and CHONF were not influenced (p > 0.05) by the replacement levels, showing mean values of 67.88 + 2.02; 67.43 + 2.89; 68.29 + 4.11; 70.54 + 1.68 and 80.21 + 1.85%, respectively. The NDF digestibility increased linearly (p < 0.05) with the replacement of corn with soybean hulls. There was no effect (p > 0.05) of replacement levels on time spent feeding (F) and total idle time (TI), with mean values of 10.51 and 4.61% of the day, respectively. However there was a quadratic effect (p < 0.05) of soybean hull inclusion on the time spent ruminating. It was concluded that although the replacement of corn with soybean hull does not improve the ruminal pH of steers fed diets with a high proportion of concentrate, pelleted soybean hulls improve the digestibility of the fibrous fraction of the diet and increase the time spent ruminating, indicating that this ingredient can be included in high-concentrate diets to improve economic efficiency.

There are no studies evaluating the virginiamycin (VM) doses under tropical conditions. So, the present study was conducted to evaluate the optimal dose of VM for growing Nellore bulls on tropical pasture. Two experiments were conducted. The first experiment, one hundred and two Nellore bulls (307 ± 25 kg body weight [BW]; 22 months) were used. Animal performance was evaluated using a randomized block design, with group as experimental unit (n = 8; 12 animals each). The second experiment, a double 4 × 4 Latin square, eight animals were used to evaluate the ruminal parameters. Four doses were evaluated: 0, 35, 55, and 75 mg VM per 100 kg BW. The average daily gain (P = 0.08) and carcass gain (P = 0.05) exhibited a trend of quadratic behavior. An increased dose of VM did not affect supplement intake (P = 0.64), rumen pH (P = 0.96), acetate: propionate ratio (P = 0.73), or the total concentration of volatile fatty acid (P = 0.63). The concentration of rumen ammonia nitrogen exhibited a quadratic effect (P = 0.01). A quadratic behavior was found for volatile fatty acid, except for propionate (P < 0.01). In conclusion, the dose of 47 mg VM per 100 kg BW is recommend for growing Nellore bulls on tropical pasture.