Fixed versus variable rest period effects on herbage accumulation and canopy structure of grazed 'Tifton 85' and 'Jiggs' Bermuda grass

Abstract

The objective of this work was to evaluate the effects of variable and fixed rest periods on the forage production, plant-part composition, and canopy structural characteristics of 'Tifton 85' and 'Jiggs' Bermuda grass (Cynodon spp.) pastures under rotational stocking. The treatments were two grass cultivars (Jiggs and Tifton 85) and two rest periods (grazing starting whenever the canopy reached 25 cm or every 28 days, regardless of canopy height). A completely randomized experimental design, with a 2×2 factorial arrangement (two grass cultivars and two managements), was used with three replicates. The experiment was carried out during the summer growing season in Piracicaba, SP, Brazil. Pre- and post-grazing forage mass chacteristics were evaluated. 'Jiggs' and 'Tifton 85' canopies had similar light interception (96.8%) at pre-grazing, for fixed and variable rest periods; however, they showed different canopy structural characteristics. 'Jiggs' had greater stem proportion, greater canopy height during pre-grazing, and lower leaf area index. There were no differences between strategies and between grass cultivars for total yield, which averaged 16.8 Mg DM ha-1. Fixed and variable rest periods can be used for 'Tifton 85' and 'Jiggs' Bermuda grass.

Forage and animal production on palisadegrass pastures growing in monoculture or as a component of integrated crop–livestock–forestry systems

“…The reduction in HA during the dry season has been reported as the main reason for low animal performance in palisadegrass grazing systems (Domiciano et al, ; Euclides, Montagner, Barbosa, Do Valle, & Nantes, ). However, well‐planned systems with adequate management of grazing (Pedreira et al, ) associated with strategic supplementation and fertilization (100 kg/ha of N and K) may result in a ADG level that maintains animal development. In addition, although the dry season presented the least rainfall (523 mm; Figure ), it allows some HA and tissue turnover (Brougham, ), especially at the end of the dry season (September).…”

“…While integrated systems may increase land‐use efficiency and, under favourable soil and climatic conditions (e.g., central Brazil), maintain productivity throughout the year, the proper arrangement of system components is fundamental for capitalizing on existing synergies and increasing animal productivity (Pedreira, Silva, Guimarães, Pequeno, & Tonato, ). In the Amazon biome, the radiant heat load varied ~ 250 W/m 2 from 7 a.m. to 3 p.m., while in the shaded areas, the amplitude was 73 W/m 2 (Domiciano et al, ), supporting greater animal thermal comfort due to the reduction in the exposure to thermal stress and radiant thermal load (Pezzopane, Nicodemo, Bosi, Garcia, & Lulu, ).…”

Management of Aries and Aruana Guinea grass cultivars under rotational stocking based on canopy light interception

“…Pedreira et al . (2018), evaluating Cynodon cultivars in the summer under two distinct management strategies – 95% LI (pre-grazing height 25 cm) and a fixed period of 28 days – found similar FA values in the summer for both strategies, a direct reflection of the strategy employed.…”

“…Pedreira et al . (2018) and Silva (2015) mentioned that the pre-grazing target height at LI above 95% causes grass senescence, a drastic increase in the stem growth rate and decreases in the nutritional value and the proportion of leaves in grasses, thus reducing grazing efficiency and animal productivity.…”

Canopy characteristics and tillering in \'Zuri\' guineagrass pastures in response to grazing frequency and severity

“…Approaches using "calendar-based" (fixed) rest periods (PEDREIRA et al, 2007(PEDREIRA et al, , 2017PEQUENO et al, 2015;SILVA et al, 2015) is the most common and practical approach for producers. Research, however, has proven that the use of this technique may not optimize many processes and forage characteristics, mainly for species with vigorous stem elongation, resulting in varying forage characteristics through the course of the grazing season PEDREIRA et al, 2017;PEDREIRA et al, 2018).…”