Silages of Brachiaria brizantha cv. Marandu harvested at two regrowth ages: Microbial inoculant responses in silage fermentation, ruminant digestion and beef cattle performance

• B. brizantha cv. Marandu nutrient intake was not affected by regrowth ages or microbial inoculant.
• Cattle performance with B. brizantha cv. Marandu was not affected by regrowth ages or microbial inoculant.
• Nutrient digestibility of B. brizantha cv. Marandu silage was not affected by regrowth ages or microbial inoculant.
• Sampling time had a positive linear relationship with the concentration of NH3-N in the rumen.
• Regrowth ages did not affect ruminal digestibility of nutrients in B. brizantha cv. Marandu silage.

Brachiaria brizantha cv. Marandu silages (BBS) were ensiled at two (35 and 70 d) regrowth ages (RA), with and without microbial inoculant (MI). No differences were observed regarding the chemical composition and fermentation parameters, with the exception of volatile fatty acids, which were affected by MI and RA interaction. No effects were observed on total nutrient digestibility in beef steers. The ruminal digestibility of ether extract and crude protein and the NH3-N concentration were affected by treatments. No effects were observed on total nutrient intake and beef steers performance. These findings were investigated by conducting three trials. Silage preparation and quality attributes were evaluated using a 2 × 2 factorial scheme in a completely randomized design. Rumen degradation and nutrient outflow to abomasum from silages were evaluated using four Nellore steers with a 267 ± 12 kg body weight (BW), which were fistulated in the rumen and abomasum and distributed in a 4 × 4 Latin square design. Beef steers performance was evaluated using a total of 32 Holstein × Zebu steers with a 364 ± 20 kg BW, which were distributed into eight randomized blocks. In a brief view, an earlier harvest of B. brizantha cv. Marandu grass, at 35 d of regrowth, did not increased the nutritional value of silage, nutrient digestibility, microbial or nitrogen use efficiency and beef cattle performance, when compared with a later harvest, at 70 d. The addition of microbial inoculant did not improve DM recovery, fermentation process, and did not influenced beef cattle nutrient intake and performance. Also, this inoculant was unable to reduce fermentation losses.