INFLUENCE DE LA FUMURE, DU CHARGEMENT ET DE L’ALIMENTATION A LA MOULEE SUR LA PRODUCTIVE HERBAGERE ET BOVINE DES PATURAGES

The influence of chemical fertilizers, stocking rate and meal supplementation on herbage and beef production was determined in a 3-yr pasture experiment. A stocking rate of 2.47 heads/ha was compared to one of 4.94 heads/ha. At the latter stocking rate, some of the steers were fed meal while on pasture. The fertilizer rates used were 1,121, 2,242 and 3,363 kg/ha of 10–10–10. All factors were combined in a factorial way. The fertility level of the soils was increased due to chemical fertilizer applications and at the highest rate, an excessive buildup of K occurred in soils. Phosphorus and potassium levels in soils were also increased at the highest stocking rate. An increase in fertilizer rate increased the total dry matter production of the herbage by 28%. Most of the increase in dry matter yields was accounted for by the harvesting of herbage surpluses obtained on the pastures fertilized with the highest rate of 10–10–10 and where the stocking rate was 2.47 heads/ha. At the stocking rate of 4.94 heads/ha, it was impossible to maintain the pasture dry matter production to meet the feed requirements of the grazing steers during the complete pasture season, even when the highest fertilizer rate was used. In the second half of the season, the daily body weight gains of the steers decreased by 50%. Feeding meal to the steers from mid-August compensated for the herbage shortage. The growth rate was markedly increased, while the carcasses had a thicker fat cover and a larger eye of lean. Finishing steers on grass pastures exclusively was possible at the stocking rate of 2.47 heads/ha. The maximum fertilizer rate appears to be at 200 kg/ha of each of N, P2O5 and K2O. The optimum rate would be half of this quantity.