Composição bromatológica e perdas de silagem de alfafa (Medicago sativa L.) elaboradas em dois estádios fenológicos

Abstract

In the dairy production based on pasture there are periods of off-season, where forage is insufficient. To reduce the impact of forage shortage, its conservation through ensilage is used. Alfalfa has a great potential of forage production for milk production, moreover, the stadium of this forage development can influence the increase of animal production. Thus, this study aimed to evaluate the effects on nutritional quality and the losses resulting from the alfalfa ensiling process, in two phenological stadiums: E1 - full vegetative (secondary tillering until first flower buds); E2 - reproductive (flower buds until first cut: 10% flowering). For that, the methodological process was based on an completely randomized experimental design with 2 treatments and 4 repetitions. The forage yield was estimated by five subsamples per plot, cut close to the ground, these were dried in a forced air oven at 55ºC until constant weight, to determine the partially dry matter contents. The alfalfa for silage was cut, withered and ensiled in polyethylene bag mini silos for 30 days. The samples taken from the field, pre-ensiled and from silage, were placed in air circulation ovens until constant weight, and then ground in a Willey mill for bromatological analysis: dry matter (DM), mineral matter (MM), digestible nutrients. (NDT), neutral detergent fiber (NDF), acid detergent fiber (ADF) and crude protein (CP). In addition, dry matter recovery (RMS) and buffer capacity (CP) were calculated. The results showed that there was no difference between the phenological stages in the yield (kg / ha) of DM, CP and NDT as well as in the nutritive value of fresh, pre-silage material and silage. It was observed that, even with high buffering capacity, the material was well preserved and without many DM losses, thus concluding that alfalfa silage is technically viable for feeding in dairy cattle.