Services on Demand
Revista Brasileira de Zootecnia
On-line version ISSN 1806-9290
CARVALHO, Paulo César de Faccio et al. Advances in methods for determining animal intake on pasture. R. Bras. Zootec. [online]. 2007, vol.36, suppl., pp. 151-170. ISSN 1806-9290. http://dx.doi.org/10.1590/S1516-35982007001000016.
Methodological advances are usually a direct consequence of conceptual and technical advances. In the case of animal intake on pasture, recent conceptual advances regarding the process of searching and apprehension of the forage by the ruminant provide insight regarding the importance of the basic unit of intake, the bite, and the importance of processes limiting intake that occur before the forage reaches the rumen. Applying a reductionist approach to the grazing process, along with its spatial-temporal hierarchy, brought a new conceptualization of how an animal obtains feed from pasture. From the conceptual models emerged new variables that required new experimental and analytical procedures. Within this context, important advances have occurred. This article describes the new procedures that allow to estimate the consumption on the short-term, as well as that most utilized by the national scientific community for estimating the consumption on the long-term. Procedure for estimating fecal production and digestibility are discussed, as well as the use of n-alkanes and other emerging techniques. Consideration is given to the use of animals or paddocks as experimental units in grazing experiments. The conclusions presented in this article do not differ from those of preceding articles regarding this subject. In a grazing condition, continuous intake is the "black box" to be revealed, complex by nature with regard to the animal as well as the pasture, and there are important methodological barriers toward is determination. Nevertheless, recent advances in conceptualizing the grazind process, as well as in the analytical procedures, have been considerable and generate ambitious expectations over the short and long term.
Keywords : alkanes; bite size; chromic oxide; intake; pasture structure.