Livestock production systems | [Sistemas de produccion de ganado]

A major reorganization of the Section's activities was undertaken in 1990. All of the section's research projects in Carimagua were either terminated or transferred to the Pasture Quality and Productivity Section. In turn, a number of on-farm projects of the latter were absorbed, thus consolidating all of the on-farm pasture research activities, in both the Andean piedmont savannas and "Llanos". In the Llanos, the section has been monitoring A. gayanus - S. capitata pastures for 11 consecutive years. The older pastures, sown in 1979-80, are in excellent condition despite not having received maintenance fertilization since planting. Two exploratory trials conducted this year in these old pastures showed that a combination of spelling from grazing and application of 10 kg P and 10 kg K can lead to substantial increases in biomass production. Newer pastures, mostly based on B. dictyoneura in association with several legumes, are also being monitored. Results of the first year of grazing are promising but require further confirmation. The same comment applies to A. gayanus - S. capitata and B. dictyoneura - C. acutifolium pastures initially established with rice in 1989. Weight gains in the former were extremely high (900 g/day with 2 head/ha). The Section continued providing technical support to the extension and promotion activities carried out by ICA's CRECED. The latter provided technical assistance to grazers that established 2500 has of pastures and seed lots, carried out field days and offered a very successful pasture establishment course aimed at professionals working in development institutions and private industry. On-farm activities in the Andean and Amazon Piedmont of Colombia and in Pucallpa, Peru has been continued. System performance in these dual-purpose farms is being monitored, with emphasis on the comparative performance of grass-alone versus associated pastures, evaluated with milking cows. Efforts were made in the course of the year to develop an appropriate analytical methodology for these situations. A short term collaborative experiment was carried out at the experimental station of La Libertad, ICA, to test the hypothesis that the animal genotype may be limiting the expression of differences between pastures. The initial results showed larger differences between pastures when evaluated with cows producing about 5 kg milk/d than with lower-yielding animals and no significant response to supplementation with Cottonseed meal. Interestingly, a non-significant but substantially larger response to the supplement was observed in the association than in the control pasture.