Substituição de silagem de milho por cana-de-açúcar e caroço de algodão nos parâmetros ruminais, síntese de proteína microbiana e utilização dos nutrientes em vacas lactantes

Abstract

Five multiparous H olstein cows averaging 525.91 kg BW and 85 days in milk were assigned in a 5 x 5 Latin in the rumen and proximal duodenum and were fed a 50:50 concentrate:forage diet (DM basis). T reatments were defined by the replacement of corn silage by chopped sugarcane (whole plant) plus whole cottonseed in the following proportions: 100:0 (control); 75:25; 50:50; 25:75; 0:100 in the DM basis. D ry matter intake (DMI) of cows fed 100, 75, and 50% corn silage diets was higher (P<0.05) than DM I of cows fed 25 and 0% corn silage. Ruminal degradability and total tract digestibility of neutral detergent fiber and acid detergent fiber were not affected (P>0.05) by treatment diets. T otal digestibilities of crude protein in square to evaluate the effects of corn silage replacement by sugarcane plus whole cottonseed. C ows were cannulated diets containing up to 50% of sugarcane were lower than in diets containing 75 or 100% of sugarcane. Ruminal ammonia concentration decreased (P<0.05) with sugarcane and whole cottonseed inclusion. C oncentrations of acetic, propionic and butyric acids as well as total volatile fatty acids concentration were higher (P<0.05) with sugarcane inclusion up to 50% level. C orn silage can be replaced by sugar cane plus whole cottonseed up to 50% level of forage in the diet without negative effect on nutrient utilization by dairy cows producing up to 18 kg milk/day.