EFFECT OF GRAZING Cratylia argentea ASSOCIATED WITH Brachiaria brizantha-Toledo ON QUALITY PASTURE AND WEIGHT GAIN IN HOLSTEIN × ZEBU HEIFERS

Abstract

The relationship between grazing a high quality shrub legume, blood serum urea (BSU) and daily weight gain (DWG) in F1 Holstein x Zebu heifers was evaluated. Two pastures were compared: 1) high crude protein diet (HCP): Cratylia argentea + Brachiaria brizantha Toledo grass, and 2) low crude protein diet (LCP): Brachiaria brizantha Toledo grass alone. Grazing of each treatment lasted 164 days. Dry matter yield (DMY), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin (LIG) were evaluated in both pastures. Before grazing, DMY at HCP and LCP was 1922 ± 405 and 770 ± 405 kg ha-1, respectively, and CP was 8.3 ± 0.85 and 8.7 ± 0.85 %, respectively. The NDF, ADF and LIG of Toledo grass at HCP and LCP were similar, averaging 73.1 ± 0.92, 42.7 ± 1.2 and 13.5 ± 0.7 %, respectively, while in C. argentea averages at HCP and LCP were 51.6 ± 0.58 % (NDF), 32.5 ± 0.85 % (ADF) and 16.7 ± 1.3 % (LIG). The BSU was 11.01 ± 0.35 (HCP) and 7.87 ± 0.35 (LCP) mg dL-1. Average DWG in HCP and LCP was 839 ± 258 and 580 ± 278 g day-1, respectively. In conclusion, in F1 Holstein x Zebu heifers DWG can reach over 800 g day-1 when grazing a high CP diet.