Diagnóstico nutricional de una especie del pastizal natural del área medanosa de San Luis – Argentina.

Abstract

Sorghastrum pellitum (“pasto de vaca”) is a perennial grass of spring-summer growth, native to the “sandy area with grasslands and “chañar” (Geofroea decorticans) groves in “San Luis” (Argentine). It was our aim to make the nutritional assessment of its growing cycle (the end and winter deferred), simulating its ingestion by a breeding cow and using the CNCPS (Cornell Net Carbohydrate and Protein System). The use of CNCPS Showed that the amounts of metabolic protein (MP) and the metabolic energy (ME) available for nourishing the cow were as follows: 477g./an./day and 17 Mcal/an./day respectively. The available MP amount was higher than that required to nourish the breeding cow. But at the flowering-fruit setting period, it did not fulfill the end of lactation requirements. The ME amount available to the cow, both at the plant vegetative stage and when dispersing, turned out to be equal to or lower than the cow requirements at the end of lactation and higher than pregnancy requirements when winter deferred. We conclude that Sorgastrum pellitum is a species that exhibits a deficiency of energy and protein at the end of the lactation period but proves to be a useful native forage resource when it is winter deferred.