The effect of stage of perennial ryegrass maturity at harvesting, fermentation characteristics and concentrate supplementation, on the quality and intake of grass silage by beef cattle

Two experiments were carried out in consecutive years to examine the influence of cutting date and restricting fermentation by carboxylic acid treatment on the nutrient intake from grass silage by beef cattle. In year 1, four cutting dates during July and August after a primary growth harvest and, in year 2, five cutting dates of primary growth between mid-May and early July were examined. Herbage was ensiled either untreated or treated with high levels of acid additive ('Maxgrass', mean 8.6 l t(-1)). Ninety-six (year 1) or forty-eight (year 2) continental cross steers were used in partially balanced changeover design experiments with each silage type either unsupplemented or supplemented with 4.5 (year 1) or 5.5 (year 2) kg concentrates head(-1) d(-1). Silage digestibility declined significantly between initial and final harvest dates (P < 0.001), whereas silage dry-matter (DM) and digestible energy (DE) intakes were significantly higher in the initial compared with final harvest dates in both years of the study (P < 0.01). Similarly, silage DM and DE intakes, and total DM intakes, of acid-treated and unsupplemented silages were greater than those of untreated and concentrate supplemented silages, respectively (P < 0.001). The results indicate that earlier cutting dates, and addition of acid to herbage before ensiling, can increase silage DM intake by beef cattle.