Evaluación de estrategias de alimentación en sistemas pastoriles de producción de leche de alta productividad y bajo costo operativo durante la estación de otoño

The work was carried out in the department of Canelones, in the town of Progreso, on Folle road, Km 35,500, in the Southern Regional Center (CRS), belonging to the Faculty of Agronomy. The evaluation period covered from March 20 to June 20, 2023. The objective of the work was to compare and evaluate the effect of using contrasting animal loads in a dairy system with different feeding strategies. For the analysis, the production and harvest of forage in the platform area, direct grazing, consumption of forage reserves and supplementation needs according to the load level, animal performance in terms of milk production, solids, live weight and body condition, both individually and per hectare. Two systems that differ in the feeding and animal loading strategy were evaluated, one called High Productivity (AP) and the other Low Cost (BC). For this, two batches of animals were used, one for each treatment. The feed in general terms consisted of corn silage, corn and canola concentrate, and forage for the AP batch, and in the case of the BC batch, the corn silage was replaced by bales of ryegrass. The forage base belonged to a 6-year rotation, with a short-term meadow (2 years) and another phase of perennial pastures lasting 4 years. Regarding grazing, to estimate forage, the paddocks assigned to the experiment were visited once a week and always respecting the same day, measuring grass availability through the C-Dax pasturometer. A diagonal transect was carried out through each paddock with the C-Dax coupled to a tractor, recording the average height provided by the instrument. In this way, the forage stock and the growth rate were determined for all the paddocks, selecting those with the greatest available biomass for grazing. The days of occupancy of the strips depended on the system, since, in the case of AP, the strips were of daily occupancy, and for BC strips were created with at least approximately 3 days of occupancy. In addition to the weekly round, pre and post grazing was also measured with C-Dax, to estimate individual forage consumption per animal. The animals were milked twice a day (6:00 am and 3:00 pm). Forage consumption depended on the growth rate of the grazing area. The AP lot had 41 days of confinement and the BC 40 days, these enclosures had artificial shade and water. The systems did not show significant differences in terms of forage production, harvest efficiency, individual consumption of reserves, concentrates and forage, live weight, body condition, individual production and solids production. Regarding milk production and food consumption per hectare, a significant response to the load effect was shown.