Suplementação proteica ou energética de vacas F1 Holandês x Zebu lactantes mantidas no pastejo de ponta ou repasse

Abstract

The study was carried out at the experimental farm of Epamig in the municipality of Felixlândia-Minas Gerais, from March to April 2014, in order to evaluate the strategic combination of different supplementation (protein or energy) in primiparous cows, F1 H x Z associated with two grazing managements (first or last). We used 36 primiparous cows, F1 H x Z, with an average weight of 427 kg and average production of 10 kg day-1 of milk per cow. The experimental design was completely randomized in a factorial scheme (2 x 2), two grazing managements and two types of supplementation. The evaluations were performed for six consecutive weeks. Influences were observed in the grazing management (p <0.05) on the productive characteristics and chemical composition of the pasture. The first grazing showed better nutritional value, with higher content of crude protein (CP) 9.55%, non-fiber carbohydrates (NFC) 19.72%, neutral detergent fiber (NDFap) 63.88% and cellulose 26.68%. In addition to greater availability of mass kg ha-1 DM 5785, and a higher proportion of leaf blades 37.15% and smaller amount of stem and dead material in relation to the last grazing. The dry matter intake as % of body weight, and the diet digestibility was higher in the first grazing with both supplementation. The NDF and CP intake also differed (p <0.05) between treatments, with higher values at first grazing with protein supplementation and lower consumption first pasture with energy supplementation. However, differences in grazing and supplementation did not interfere in animal performance variables (p> 0.05), which are: milk production and composition, weight and body condition score and days open. The forage supply in both grazing systems, associated with the types of used supplements, maintained the milk production of primiparous cows, F1 H x Z, and did not interfere on animal performance variables. It is possible to maximize the use of pasture and adjust the concentrate composition depending on the quality of the pasture and milk production of cows.