Abstract
The objective of this study was to evaluate the morphogenetic traits and chemical composition of Tanzania grass using a fixed rest period or according to light interception at 95%. The treatments consisted of evaluations of two Tanzania-grass pasture-management strategies: (1) LI95 - animals entered the paddocks when the pasture reached 95% of light interception (LI), with three days of paddock occupation; and (2) FR - the pasture was managed with a defoliation interval (DI) of 30 days, and three days of paddock occupation. The experimental area consisted of 4 ha, with 22 paddocks per treatments. Ten recently-calved cows were used per treatment in year 1, and eight cows were used per treatment in year 2. Sward height, forage mass, and morphological components and their chemical composition were evaluated. The management strategies used on the Tanzania grass pasture did not affect pasture mass or height in the pre- and post-grazing conditions, or the proportion of stems. However, the proportion of leaves was greater in the paddocks with 95% light interception. The crude protein content was higher in the paddocks with 95% light interception; the other nutrients were not affected. In conclusion, management adopting 95% light interception does not influence morphogenetic traits. Nevertheless, it promotes an increase in the crude protein content of grasses.
Highlights
In Brazil, a large proportion of studies on grazing management focusing on plant characteristics and environment conditions are primarily grounded on rest intervals, stocking rates, and/or cutting intensity/fixed grazing, and they seldom respect the plant physiology, with no proper control of the structural characteristics of the forage sward, which are essential variables for proper defoliation management and use of the produced forage (SANTOS et al, 2013)
Treatments consisted of evaluations of two Tanzania-grass pasturemanagement strategies: (1) LI95 - animals entered the paddocks when the pasture reached 95% light interception (LI), with 3 days of paddock occupation; and (2) FR - the pasture was managed with a 30-day defoliation interval (DI) and 3 days of paddock occupation
The treatments employed, and the duration of grazing cycles varied in the LI95 treatment
Summary
In Brazil, a large proportion of studies on grazing management focusing on plant characteristics and environment conditions are primarily grounded on rest intervals, stocking rates, and/or cutting intensity/fixed grazing, and they seldom respect the plant physiology, with no proper control of the structural characteristics of the forage sward (e.g., leaf area index), which are essential variables for proper defoliation management and use of the produced forage (SANTOS et al, 2013). Intraspecific competition for light increases progressively; stem elongation, leaf senescence and tiller mortality elevate; whereas leaf accumulation decreases. These morphophysiological changes occur after interception of 95% of the incoming light by the sward, which has characterized this moment as ideal for an interruption of regrowth (ZANINE et al, 2016), since all the energy used by grass throughout the growing season is obtained from solar radiation (RAY; SINCLAIR, 1998)
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