Doze vacas holandesas foram empregadas em um delineamento «switch— back», comparando 3 rações, as quais continham, como volumosos, silagem de sorgo var. Santa Eliza e feno de soja perene, nas seguintes proporções, em porcentagens de matéria seca: A) Silagem 100%; R) Silagem 75%; Feno 25%; C) Silagem 50c/; Feno 50%..-s rações eram completadas por misturas de concentrados, balanceadas de forma a torná-las isoproteicas e isoenergéticas.A observação recomenda o emprego de feno, na proporção de 2,5 kg de matéria seca por vaca por dia, quando as rações de volumosos se constituirem eni silagem fornecida à vontade .A substituição total da proteína proveniente da torta de algodão por proteína do feno de soja perene foi feita com inteiro sucesso.

Twelve Holstein — Friesian cows, were used in a “Switchback” lay-out to compare three different rations, in which varied proportions of Sorghum Silage (var. Santa Eliza) and perenial Soybean hay were combined (on a dry matter bassis), as follows:Treatment A) 100% Sorghum SilageTreatment B) 75% Sorghum Silage 25% Perennial soybean hay Treatment C) 50% Sorghum Silage 50% All rations were completed with a balanced concentrated mixture to meet the animals requirements for digestible protein and T . D N.A significant difference was observed among treatments being A inferior to B and C (P<0,01) when milk production (4% FCM) was anilysed (10.5 kg; 11 .2 kg and 11 .6 kg/cow/day for treatments A, B and e respectively).Significantly (P<05) higher dry matter intake occured as the percentage of perennial soybean hay increased in the rations (7.7 kg; 9.7 kg and 10.5 kg DM intake/cow daily for treatment A, B and C). However, as the DM intake was considered only with regard to silage consumption, no significant difference (P<05) was detected between treatments A and B.Based on these informations it is recommended to include 2.5 kg/cow daily of hay (on a DM basis) when silage is to be fed as the sole roughage (ad libitum).Replacement of cottonseed oil weal for perennial soybean as a source of protein resulted in a real sucess.