Evaluación productiva de la gestión del pasto, efecto del método de pastoreo y la oferta de forraje a campo natural

Understanding the influence of soil conditions, forage supply and grazing method on primary and secondary production, as well as on the quality of the natural cover is essential to develop prosperous and sustainable production systems. A 2x2 factorial structure experiment is being carried out on paddock 13 of the Mario Alberto Cassinoni Experimental Station (La -32.387511°S and Lo -58.033235°W), where two forage supply levels (low and high, 8% and 12%, respectively) and two grazing methods (rotation and continuous) are being evaluated. The work was done with Holstein steers. The supply was adjusted by monthly sampling that allowed the estimation of available dry matter (kg/ha), based on which changes of animals were made, destined to adjust the load, between pastures. These animals were also weighed monthly. The evaluation period covered from November 1, 2023 to April 25, 2024, so the end of spring, the entire summer, and the beginning of autumn were evaluated. Within this period, subperiods were constructed in such a way that the variability of the factors was evaluated monthly. The work was carried out with the objective of determining the botanical composition of the natural field in relation to the different treatments, as well as the primary and secondary production of the field. In order to take into account the edaphic influence, the pasture was divided into low, medium and lithosol zones, using cartographic bases and visual estimation. The variables determined were dry matter production (kg DM/ha), growth rate (kg/day/ha), dry matter availability (kg DM/ha), forage height (cm), forage use (% of available), botanical composition of the mat, daily gain of animals (kg LW/animal/day), live weight gain for the period per animal (kg LW/animal) and per hectare (kg LW/ha). Using the statistical program InfoStat, a qualitative analysis of the botanical composition was performed, allowing the construction of dendrograms, and a quantitative analysis of all variables was performed using the analysis of variance (ANAVA), subsequently performing a Tukey comparison with a 10% significance level. The results show that pasture height is strongly influenced by  forage supply and method, with high rotation being the one that allowed the highest heights, with a strong influence of soil conditions, with the highest heights being in the low pasture and the lowest in the lithosols. Botanical composition was strongly influenced by soil conditions, with contrasting communities found between the different areas, with the influence of  forage supply and method on the heterogeneity formed. Utilization was determined by forage supply, with a higher level of utilization under low supply. Area and forage supply were highly influential on growth rate, with a higher level of utilization under low forage supply areas. Animal productivity was not determined by the different management variables evaluated.