Forage Quantity and Quality Dynamics Due to Weathering over the Dry Season on California Annual Rangelands

Abstract

Livestock obtain forage by grazing on rangeland. In California annual rangelands, residual dry matter is commonly used to determine proper grazing levels. Rangeland forage biomass and quality can degrade dramatically during the dormant summer period. We examined 25 sites across an annual rainfall gradient (183-492 mm) over 3 contrasting rainfall yr (2015-2017) that varied from 57% to 152% of average annual precipitation. Overall fractional biomass loss was 54.4% (range = 46.5-61.5%) with greater fractional losses occurring in dry years. Biomass losses were related to the amount of peak standing crop and plant composition-both a function of annual precipitation. Fractional seasonal losses from the peak standing biomass in 2015 = 962 kg/ha (61.5% seasonal; 9.7% monthly), 2016 = 1 541 kg/ha (55.0% seasonal; 8.7%monthly) and 2017 = 1 923 kg/ha (46.5% seasonal; 7.3%, monthly). Forage quality metrics were strongly affected by summer weathering processes. Crude protein concentrations decreased by 33. 6%, 27.7%, and 21.0% in 2015, 2016, and 2017, respectively. In contrast, relative concentrations of fiber and lignin (acid detergent fiber [ADF] = cellulose + lignin) and in the weathered biomass showed increases for

Classification of Megathyrsus Maximus Accessions Grown in the Colombian Dry Tropical Forest by Nutritional Assessment During Contrasting Seasons

“…The protein content decline during low precipitation periods, similar to that found by Larsen et al (2021), might be caused by the lack of production of new leaves and tillers. Also, the senescent material decreases cellular content, in particular, protein (Vargas Junior et al, 2013).…”

“…Some studies suggest that in vitro and in vivo digestibility of organic matter increases with the rainy season (Vargas Junior et al, 2013;Silva et al, 2017), and others show that water stress did not significantly affect organic matter digestibility (OMD), (Fariaszewska et al, 2020). The findings in this research suggested that ADF decreased similar to that reported by Larsen et al (2021) and IVDMD increased slightly during the dry season vis-à-vis the rainy season. This condition might be related to the average height of germplasm of 130.7 vs. 55.2 cm during the rainy and dry seasons, respectively.…”

“…Plant height, flowering, DMB and crude protein of the collection were higher during the rainy season, contrasting with stress, growth, and production limitations during the dry season (Hare et al, 2015), which indicates that the water supply favors agronomic characteristics and protein content (Larsen et al, 2021). Weather characteristics have an effect on agronomic and nutritional parameters for M. maximus (Machado, 2013;Lemos et al, 2017;Maranhão et al, 2021;Marcillo et al, 2021).…”

Diet Type Impacts Production Performance of Fattening Lambs by Manipulating the Ruminal Microbiota and Metabolome

“…The high growth performance of feedlot lambs relies on a stable supply of nutrition-balanced feed ( Zhang et al, 2019 ). However, the deficiency of high-quality forage has severely restricted the development of intensive rearing system for lambs in farming areas ( Newell et al, 2020 ; Larsen et al, 2021 ). Due to the shortage of land and seasonal oscillations, it has become difficult to provide abundant and stable forage for livestock feeding ( Yang et al, 2018 ; Shen et al, 2020 ); low-quality crop stalks constitute the main source of roughage in the fattening lamb diet, which significantly impede lambs from achieving their productivity potential ( Blanco et al, 2014 ).…”

Cattle grazing reduces fuel and leads to more manageable fire behavior

“…The amount of herbaceous fuel on the ground during fire season in grazed California rangelands is largely a function of herbaceous growth in any given year, the number of livestock grazing per acre (grazing pressure), and vegetation biomass loss due to weathering (Frost et al 2008;Larsen et al 2021). Forage production is notoriously variable and unpredictable in California, both between years and across the landscape at a fine scale (Becchetti et al 2016;Devine et al 2019).…”