Nutritional quality of pasture, body condition and blood metabolite levels of dual-purpose cows throughout the year in northern Veracruz, Mexico

Abstract

The objective was to evaluate the seasonal variations in production and quality of four grasses, as well as the body score condition (BSC) and metabolite concentration in blood serum of lactating dual purpose cows from the North of Veracruz, Mexico. Samples of four grasses were collected every 28 days they and processed to determine dry matter (DM) production, crude protein (CP) and neutral detergent fiber (NDF). In addition, blood samples of 25 lactating cows were obtained, to determine the BSC and the glucose and urea nitrogen serum concentration. Production values for DM, CP and NDF were 908 kg ha-1, 7.6 and 78.3%, respectively. In spring, DM was greater (1230 kg ha ^-1) than in winter (450 kg ha-1), a similar situation observed for NDF (P<0.05). In addition, CP content, within season was affected (P<0.05) by grass species. Pangola grass samples showed the smallest CP concentrations (4.6%) in winter. Mean BSC was 4.4, and it was affected (P<0.05) by season. During the summer the cows showed the lowest BSC (3.3). The concentrations of glucose and urea nitrogen were affected by the season (P<0.05), being highest in winter with 74.2 and 20.0 mg dL ^-1, respectively. The DM yield for hectare was smaller in winter and the grass CP content was not modified by the season. The metabolic profiles of glucose and urea nitrogen were within the established ranges for lactating grazing cows.