Estimación de consumo de forraje mediante métodos indirectos para situaciones de altura residual contrastantes

A study was carried out at the Southern Regional Center (SRC) of the Faculty of Agronomy with the objectives of estimating the direct consumption of forage of dairy cows for two contrasting grazing managements using indirect methods, and comparing the methods used. The study was carried out during the spring of 2019, from September to December. Two grazing intensities were applied: intense management (A) of 4 cm and lax management (B) of 9 cm. For the determinations, two indirect methods were used, the C-Dax and the Measuring Plate, and the Double Sampling method was used as a reference. Four batches of 24 animals of the Holando, Jersey breeds and their crosses, calved in autumn, grouped by weight, body condition and number of lactations, were used. The forage base was composed of perennial pastures made up of Dactylis Glomerata and Trifolium Repens and winter greens made up of Lolium Multiflorum and Avena Byzantina. The pasture entry criterion was when the Dactylis reached the state of three fully expanded leaves. In addition to the forage, the animals were fed with reserves and concentrate. Two milkings were carried out per day (05:00 and 15:00), and grazing was carried out in daily strips, with a double shift of access to the pasture when the growth rate and forage stock allowed it, otherwise, they grazed in turn, remaining penned up after the second milking with the supply of reserves and water at will. The determinations were made three times a week, estimating with each indirect method the available forage pre and post grazing of the daily strip and with this information the direct consumption of the animals was calculated. In addition, there was information on the production of milk and solids of each batch that was determined biweekly. A randomized complete block design with factorial arrangement of treatments was used. The animals corresponding to management B had a greater direct consumption of forage with respect to the animals of management A. The C-Dax and the Measuring Plate presented a similar behavior, although they remained below the Double Sampling method in a large part of the period. experimental. Milk production and composition was similar between grazing managements. The results indicate that it would be possible to estimate the direct consumption of animals grazing daily strips with different post-grazing residual forage situations using indirect methods, taking into account the strengths and weaknesses of each one, as well as their requirements and manner of execution. Additional studies would be convenient to obtain more robust results and thus obtain more information about these useful tools for carrying out determinations and monitoring in pastoral production systems.