Theme 22: Grazing Management

Description

Although a decrease in the leaf-stem ratio affects the nutritive value of pastures, herbivores can reinforce selection for leaf blades to maintain the quality of their diets. This study evaluated whether the percentage of fragments with furrows in blades could be used to estimate the relative intake of this part of the leaves by herbivores grazing monoespecific pastures. It was worked with vegetation of kleingrass (Panicum coloratum L.) from paddocks with three deferment periods. Blade samples, and different plant part mixtures hand compounded were in vitro digested. The digestion residues were microhistological analyzed determining the number of fragment with furrows (#FWF), and the total number of fragments (T#F). The blade percentages in mixtures was computed as: Estimated %Blademixtures = ((#FWFmixtures*100/ %FWFblades)/ T#Fmixtures))*100. The %FWF in blade samples (19+ 1.5%) was not affected (P> 0.05) by changes in plant maturity determined by the length of the deferment period. The relationship between the actual blade percentages (y), and those determined by microanalysis (x) in mixtures was 1:1. This suggests that the microanalysis of feces or digestive contents could be used to estimate the percentages of blades in the diet of herbivores grazing monoespecific pastures.

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Microhistological Estimation of Leaf Blade Percentage in Diets from Monoespecific Pastures

Although a decrease in the leaf-stem ratio affects the nutritive value of pastures, herbivores can reinforce selection for leaf blades to maintain the quality of their diets. This study evaluated whether the percentage of fragments with furrows in blades could be used to estimate the relative intake of this part of the leaves by herbivores grazing monoespecific pastures. It was worked with vegetation of kleingrass (Panicum coloratum L.) from paddocks with three deferment periods. Blade samples, and different plant part mixtures hand compounded were in vitro digested. The digestion residues were microhistological analyzed determining the number of fragment with furrows (#FWF), and the total number of fragments (T#F). The blade percentages in mixtures was computed as: Estimated %Blademixtures = ((#FWFmixtures*100/ %FWFblades)/ T#Fmixtures))*100. The %FWF in blade samples (19+ 1.5%) was not affected (P> 0.05) by changes in plant maturity determined by the length of the deferment period. The relationship between the actual blade percentages (y), and those determined by microanalysis (x) in mixtures was 1:1. This suggests that the microanalysis of feces or digestive contents could be used to estimate the percentages of blades in the diet of herbivores grazing monoespecific pastures.