Influence of the time of the year on the nutritional value of forage consumed by beef cattle raised on grassland

Abstract

Due to the large territorial dimension used for the practice of livestock activity, Brazil has several pasture ecosystems, in which animals are subjected to different management conditions during their productive life. In this scenario, tropical forages present high production of dry mass, with marked seasonality between the “water”, “drought” and transition seasons. The objective of this work is to carry out a literature review on the interference of the time of year on the nutritional value of forages consumed by beef cattle raised on pasture. Seasonality determines the uneven distribution of forage production throughout the year, causing quantitative and qualitative changes in the chemical composition of pastures, resulting in lower quantity and quality in periods with lower rainfall. As the plant matures, the levels of crude protein, minerals and other components of the cellular content decrease, while those of the cell wall tend to increase, interfering with the digestibility of nutrients in the food. This digestibility will mainly determine the availability of nitrogen compounds in the rumen for microbial growth, as well as the availability of amino acids that reach the small intestine influencing the growth of animals. In this way, the pasture supplementation technique, associated with the deferral of pasture, presents itself as an alternative to low production and forage quality at critical times of production, making it possible to obtain adequate weight gain of the animals at different times of the year, resulting in efficient and sustainable animal production.