DEHYDRATED ALFALFA AND CHEMICALLY PRESERVED ALFALFA SILAGE IN COMBINATION WITH SUNFLOWER MEAL OR UREA AS SOURCES OF PROTEIN FOR DAIRY-COWS

A 210 day feeding trial was carried out with 40 Holstein and Bulgarian Brown dairy cows divided into four groups. The basic forage was maize silage which was fed in combination with 1.7 kg dry matter (DM) of dehydrated alfalfa (DA) or with 3.2 kg DM of chemically preserved alfalfa silage (AS). Supplementary sources of protein were sunflower meal (SFM) and urea (U). Thus, the four treatments consisted of: DA+U, DA+SFM, AS+U and AS+SFM. The diets were isonitrogenous and were calculated to be isoenergetic. Milk yield, milk fat, milk protein, yield of fat and protein were respectively: 16.0 kg, 3.97%, 3.57%, 636 g day-1 and 572 g day-1 for DA+U; 16.2 kg, 4.09%, 3.64%, 662 g day-1 and 589 g day-1 for DA+SFM; 13.9 kg, 4.01%, 3.59%, 557 g day-1 and 498 g day-1 for AS+U; 15.2 kg, 4.03%, 3.56%, 611 g day-1 and 540 g day-1 for AS+SFM. Milk yield was significantly higher for cows with the dehydrated alfalfa in their rations than for those fed chemically preserved alfalfa silage. Differences in the calculated values of protein digestible in the small intestine (PDI) explained to a great extent the difference in milk production. Dehydrated alfalfa kept its superiority over the chemically preserved alfalfa silage during the whole lactation. The sunflower meal can be replaced successfully with cereals plus urea in rations with dehydrated alfalfa. Ration composition determines urea utilization, rather than the level of milk production.