Chemical composition and dry matter digestion of some native and cultivated grasses in Mexico

Abstract

The objective of the study was to quantify differences in nutritive value, over four seasons, of native grasses such as <i>Bouteloua curtipendula, Bouteloua trifida, Brachiaria fasciculata, Chloris ciliata, Digitaria insularis, Leptochloa filiformis, Panicum hallii, Panicum obtusum, Paspalum unispicatum, Setaria grisebachii, Setaria macrostachya, Tridens eragrostoides, Tridens muticu</i>s and naturalized <i>chrus ciliaris</i> and <i>Rhynchelytrum repens</i> that are used as forages for grazing beef cattle. <i>Cenchrus ciliaris</i> was included as a reference grass of good nutritional quality. Plants were collected in autumn 2001 and in winter, spring and summer 2002. The nutritive value was assessed in terms of nutrient content, effective rumen degradable dry matter (EDDM), metabolizable energy (ME) and metabolizable protein (MP). Most grasses had crude protein (CP) content comparable to the reference <i>C. ciliaris</i> grass (grand mean = 120 g/kg) and some of them had a higher content (140 g/kg). Cell wall (NDF) and lignin contents were lower in <i>C. ciliaris</i> (650 g/kg, 30, respectively) than in the other grasses (mean = 700 g/kg, 60, respectively). All grasses had less EDDM (mean = 420 g/kg) than <i>C. ciliaris</i> (470 g/kg). All grasses had the ME content (mean = 5.6 MJ/kg DM) that was lower for maintenance requirements of growing beef cattle. Conversely, mean MP values (67 g/kg DM) were sufficient. Lower content of P (annual mean = 120 g/kg DM), Na (0.3) and Cu (40 mg/kg DM) was detected in all grasses to meet the requirements of growing cattle. All grasses, in all seasons, had sufficient CP and MP content to meet the maintenance requirements of growing beef cattle. Higher levels of EDDM occurred in summer and autumn. Because of their good nutritional quality, grasses such as <i>B. fasciculata, C. ciliata, P. hallii, P. obtusum, S. grisebachii, S. macrostachy</i> and <i>T. eragrostoides</i> can be considered as good forages for ruminants.

Nutritional Quality of Herbaceous Vegetation in a Phryganic Mediterranean Ecosystem During the Grazing Period

“…All herbage samples during the grazing period had adequate K levels to meet the optimum maintenance requirements for beef cattle (6 g/kg DM; NRC, 1996) and sheep (5 g/kg DM; NRC, 1985). Herbage biomass with sufficient K content to meet the maintenance requirements for beef cattle and sheep was also found by Ganskoop and Bohnert (2001), Ramirez et al (2009) in grasslands of northern Great Basin and Mexico, respectively, and by Roukos et al (2011a) in adjacent grasslands.…”

“…Thus, it can be assumed that there is an increased risk of Mg deficiency to occur in grazing livestock, a result also found by Roukos et al (2011a). Conversely, Ramirez et al (2009) reported that 13 grasses in Mexico had marginal sufficient levels of Mg to meet growing beef cattle requirements. Minson (1990) stated that seasonal variation of Mg content within species are relative small and Mg concentration in herbage is affected by its botanical composition and climatic conditions Suttle, 2010;Roukos et al, 2011a).…”

“…Climatic conditions, botanical composition, soil properties and topography may differentiate the nutritional quality of herbage, which needs to be precisely estimated in order to determine a proper management plan (Vazquez-de-Aldana et al, 2000;Ayan et al, 2006;Bovolenta et al, 2008;Ramirez et al, 2009;Holechek et al, 2010;Mountousis et al, 2011;Roukos et al, 2011a).…”

“…Roukos et al (2011a) reported higher values of Ca and P in herbage collected from grasslands in adjacent area. On the contrary, Ganskoop and 152 Bohnert (2001) and Ramirez et al (2009) found inadequate levels of P in forages to meet maintenance requirements of sheep and cattle in grasslands of arid environments of USA and Mexico, respectively.…”

Chemical composition, intake, ruminal fermentation, plasma metabolites and hormones in range steers

“…However, these evaluations may be complemented with studies of intake, ruminal fermentation and metabolites and hormones concentrations to more precisely establish dietary supplementation needs. As the rangelands mature, digestibility decreases because of decreased nitrogen and increased fibre and lignin contents (Ramı´rez et al 2009). These changes may be accompanied by a decrease in intake, ruminal ammonia and total volatile fatty acid (VFA) concentrations.…”