Botanical composition and nutritive value of the diet consumed by cattle in an area invaded by natal grass [Melinis repens (Willd.) Zizka]

Abstract

The objective was to evaluate the botanical composition and nutritional value in the diet of bovine cattle in areas invaded by natal grass [Melinis repens (Willd.) Zizka]. The research was conducted at the Salinas Ranch, in the municipality of Satevó, Chihuahua, in a brush grassland. Botanical composition of the area was determined by the line-point intercept method. Sampling was conducted from August 2013 to February 2014. The botanical composition of the diet (microhistological technique) and the nutritional value were determined using two esophageal-fistulated Hereford/Angus heifers (350 ± 5 kg). The data were subjected to a variance analysis, and the chemical composition of the diet was fitted using the PROC MIXED procedure of SAS to a mixed model. The average available forage during the four phenological stages was 1,279 kg DM ha -1 , with a presence of 87.5 % natal grass (1,119.13 kg DM ha -1 ). The highest preference indexes were for Aristida divaricata (8.43) and Croton pottsii (12.95) during the growing stage; whereas the least preferred species was Melinis repens (0.33 to 0.41). The highest crude protein content was observed during the growing (13.23 %) and flowering stages (10.71 %). During this study the best quality of the diet was determined during the growing and flowering stages and was mainly composed of Melinis repens during four stages.