Improvement of alfalfa forage quality by maceration at harvest

Abstract

A series of trials were conducted to evaluate benefits of alfalfa maceration at the time of cutting on wilting, storage and feed characteristics under prairie conditions. Early bloom alfalfa was harvested with either a conventional roller-co ditioner (CONV) or a macerator with four degrees of maceration (LIGHT, LIGHT+, SEVERE and SEVERE+). Maceration of alfalfa from LIGHT+ to SEVERE reached an 80% DM during wilting in 9-11 h, relative to CONV, which reached the same DM content in 54 h. Exposure to 2 cm precipitation shortly after cutting and maceration resulted in 24.2 to 26.8 h shorter wilting time relative to conventionally-conditioned alfalfa. Lactic acid bacteria population of alfalfa tended to be higher with maceration at 0-1 h post-cutting (P = 0.10). Alfalfa harvested with a macerator had a lower (P < 0.05) CP content at the time of baling. Macerated alfalfa conserved as silage had more colony forming units (cfu, P < 0.05) of lactic acid-producing bacteria at the initial day of ensiling. At day 80 of storage, macerated alfalfa conserved s hay had a higher content of soluble carbohydrates (P < 0.05) and a tendency toward a lower glucosamine content (P = 0.07) compared to alfalfa harvested with a conventional mower-conditioner. The benefits of maceration in this study appeared to be related to the shortening of wilting time and increasing the quality of conserved alfalfa as silage or hay compared to conventionally conditioned alfalfa. Decreased in CP at post-harvest was not followed with a significant increase in fibre content. Dry matter intake for steers fed SEVERE hay tended (P = 0.08) to be lower and ADF and NDF digestibilities were 22.0 and 16.7% lower (P < 0.05) compared to CONV hay. Dry matter and CP digestibilities were 8.1 and 32.4% higher, respectively, (P < 0.05) for steers fed the SEVERE hay compared to those fed CONV hay. Beef calves consumed 13% more DM of silage made from the macerated alfalfa compared to those fed CONV silage or hay and achieved 22.7% greater average daily gain (ADG) at the initial 21 day growing trial (P < 0.05) but overall ADG was unaffected by treatment. Holstein cows were used in an early lactation trial and fed silage-based TMR's which contained either CONV or SEVERE alfalfa with similar level of concentrate, 58 and 59%, DM basis, respectively. Daily DMI, milk yield and milk composition were not affected by alfalfa harvest treatment. Cows fed the TMR containing macerated alfalfa had a greater (P < 0.05) ADG and tended to achieve a better body condition score (BCS) at the end of 14 week lactation trial.