The present invention refers to the use of a Salix babylonica (SB) extract and/or combined with the Leucaena leucoceohala (LL) extract or exogenous enzymes over the productive response in dairy cows and lambs. The use of the liquid extracts of S. babylonica shown to be an efficient alternative for increasing the production of milk and improving the use of feed for Brown Swiss cattle the results suggest that the administration of low doses of SB (150 ml/d) was better than high doses of (300 ml/d). The individual use (SB o LL) of these extracts, as additives in the feeding of lambs, improves the digestibility of dry matter, organic matter, ether extract and protein the consumption of feed was not modified and the daily weight gain was increased It is thus recommended the use of extracts in an individual manner and not in a combination thereof (SBLL). The supplements with Salix babylonica (30 mL/day) + exogenous enzymes (10g/day) have improved the digestibility of dry matter and organ ic matter and the daily weight gain in growing lambs, this may suggest that the combination of both additives has a beneficial impact on the use of nitrogen in the diet, therefore the synthesis of microbial protein is improved. On the other hand, high doses of Salix babylonica (1.8 mg/g dry matter) were useful to modify the ruminal fermentation variables in vitro, the combination of Salix babylonica and exogenous fibrolytic enzymes would not affect the production of gas or the fermentation parameters in vitro.La presente invención se refiere a la utilización del extracto de Salix babilónica (SB) o/y en combinación con otro extracto de Leucaena leucocephala (LL)) o enzimas exógenas sobre la respuesta productiva en vacas lecheras y en corderos de ovinos. El uso de los extractos líquidos de S. babylonica demostró ser una alternativa eficiente para aumentar la producción de leche y mejorar la utilización del alimento por vacas pardo suizo los resultados sugieren que la administración de dosis
