Comparison of a rotational grazing system in alfalfa (Medicago sativa, L.) with a confinement system for dairy cows

Abstract

A system of milk production from cows grazing lucerne as the only feed was evaluated and conpared with conventional system of total confinament. Data collected from April 1992 until January 1993 included forage production and quality; animal behavior at pasture and residual forage after grazing; milk yield and composition; liveweigth gain; feed intake; and economic feasibility of both systems, in terms of milk produced, feeds purchased, labor costs, and return on invested capital. Purebred Holsteins, of up to third lactation, were assigned to one of these two systems after 6 wk of lactation. Confined cows in free-stall housing were ad libitum a complete diet composed of maize silage and concentrate, with 14,4% CP and 46.1% NDF (dry basis). Lucerne paddocks (twice replicated) were managed using electric fences, with one day of grazing being followed by 24 to 36 days of regrowth. The pastures, established 8 mo before beginning the trial, were fertilized with PK and micronutrients after alternative grazing periods, and irrigated as needed. Daily production of 4% fat-corrected milk; milk fat content, tested weekly; and daily liveweigth change at 2-wk intevals, during the 294-d period, were 18.6±0.8 kg, 3.5±0.3%, and .132±.158 kg for grazing cows, and 21.4±0.4 kg, 4.1±0.27 and .116±.091 kg for confined animal, respectively. The two system differed (P<.10), except in liveweigth gain. The mean stocking rate of 3.1±0.8 animal/ha enabled daily production potential was shown to be an economic feasible option.