Comparison of maize and alfalfa silages on milk production, milk composition and blood components of dairy cows.

Twenty multiparous Friesian cows, 60 to 100 days postpartum, were allotted to two groups of 10 cows according to calving date, lactation number, and daily milk production and were assigned randomly to one of two diets in a crossover design experiment. The control diet (maize diet) was 55% maize silage (dry basis), 20% soybean meal, 22% ground maize, and 3% mineral and vitamin mix. The treatment diet (alfalfa diet) was 55% alfalfa silage, 10% soybean meal, 32% ground maize, and 3% mineral and vitamin mix. The two diets contained similar quantities of crude protein and metabolizable energy. The diets were offered individually as total mixed rations in two equal portions at 09:00 and 20:00 h in amounts to achieve ad libitum intake. The two groups of cows were allowed exercise in an open lot without shade from 11:00 to 16:30 h and 22:00 to 05:30 h. The cows were milked daily at 06:00 and 17:00 h. The dry matter, metabolizable energy and crude protein intakes, milk production, and milk fat, protein, lactose, total solids and solids not fat contents, as well as milk fat and protein yields and body condition score, were not significantly affected when maize silage was given to lactating cows, compared with that of cows given alfalfa silage. No differences were observed in blood serum concentrations of glucose, total protein, albumin, urea, triglycerides, cholesterol, Na, K, Ca, P and Mg between maize and alfalfa silages.