Amadeu Bona Filho

Características estruturais e produção de leite em pastos de capim-mombaça (Panicum maximum Jacq.) submetidos a diferentes alturas de pastejo

The herbage growth dynamics, plant community competition and grazing animal behaviour on grasslands can be affected by sward structure. This study was aimed at evaluating contrasting pre-grazing sward heights on milk production of cows and some morphophysiological characteristics of mombaca grass (Panicum maximum Jacq. Cv Mombaca) submitted to grazing. The experiment was carried out in a complete randomized design with two treatments (sward surface heights of 90cm and 140cm on pre-grazing) and four repilitions. Each plot was grazed by six Holstein-friesian cows with similar milk production and lactation time. The grazing method used was intermittent with a three days occupation period and six grazing cows were used as tester per treatment. The higher sward surface height presented greater tiller mass, leaf length and area, and tiller population density (P<0.10). Milk production was greater to the shortest sward height (P<0.10). Mombaca grass should be grazed at sward heights lower than 100cm.

Produção de cordeiros em pastejo contínuo de azevém anual submetido à adubação nitrogenada

It was evaluated the effect of nitrogen fertilization in ryegrass pasture (Lolium multiflorum Lam.) on the production of meat lamb under continuous grazing. Ryegrass pasture was established under no-tillage cropping in area of animal-crop integration system. The fertilization was held with 60kg of P2O5 ha-1 and 60kg of K2O ha-1. The treatments corresponded to the doses 0; 75; 150 e 225kg of N ha-1, in the urea form (45% de N) in single application, 35 days after seeding. The evaluation period was of 84 days. The forage was influenced quadratic ally by N rates, with minimum point at 182.75kg of N ha-1. However, the supply of leaf blades (LFM) was not influenced by doses of N (3.8kg LFM 100kg-1 live weight) or by the average daily weight gain, averaging 0.133 kg of LW an day. For stocking rate and live weight gain per area the doses of N increased 3.0 kg of LW-1 ha-1 and 1.1kg of LW ha-1, respectively for each kg of N applied. Nitrogen fertilization provides increases in animal productivity which results in increase kg of meat produced in this system.

Animal production in Tanzania grass swards fertilized with nitrogen

Nitrogen (N) at 100, 200, 300, and 400 kg ha-1 was applied to Tanzania grass swards to evaluate the animal response and relationships between sward characteristics and the performance of young Nellore bulls (Bos indicus) under continuous stocking. A completely randomized experimental design was used with two replications between 11 November 2001 and 15 April 2002 when the sward heights were maintained at 60 cm by using different stocking rates. The average daily gain (ADG) (0.73 kg d-1) was not affected by N doses while the number of animal days ha-1 increased linearly from 515 to 1267. On the other hand, the linear increase in the animal yield was 399, 653, 755, and 895 kg ha-1 for N at 100, 200, 300, and 400 kg ha-1, respectively, while the ratio between the liveweight gain (kg) and N (kg ha-1) decreased. Correlation coefficients between ADG and herbage mass, green leaf mass, green herbage mass, proportion of green leaf and leaf:culm ratio were low and nonsignificant. Under the conditions in Northwestern Parana, the application of N to swards of Tanzania grass is a management option for increasing beef cattle production.