Improving forage nutritive value and livestock performance with spatially-patchy prescribed fire in grazed rangeland

Authors: WANCHUK, MEGAN - North Dakota State University; McGranahan, Devan; SEDIVEC, KEVIN - North Dakota State University; BERTI, MARISOL - North Dakota State University; SWANSON, KENDALL - North Dakota State University; HOVICK, TORRE - North Dakota State University; LIMB, RYAN - North Dakota State University

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Rangelands are under increasing pressure to simultaneously support livestock production and conservation objectives. We compared how patch-burning compares to conventional grazing systems (rotational and continuous grazing) in supporting livestock production in a controlled, ranch-scale experiment comparing forage quality and livestock weight gains. Fire increased crude protein, neutral detergent fiber digestibility, and energy, and decreased acid detergent fiber, neutral detergent fiber, and lignin components of forage nutritive value relative to unburned patches and grazing systems without fire. Recently-burned patches had the best forage nutritive value throughout the grazing season. Cows spent more time in recently-burned patches compared to other patches in pastures managed with patch-burning. Recently-burned patches had the highest proportion of points that met grazing animal requirements throughout the grazing season. As such, cows from patch-burned pastures performed better over the course of the grazing season. Patch-burn grazing can benefit livestock production and performance while supporting rangeland conservation. Patch-burning best met the nutritional requirements of grazing cattle, which resulted in better weight gains on patch-burning pastures.

Technical Abstract: Rangeland ecosystems can meet both livestock production and conservation objectives, but managers often prioritize one over the other. The conservation benefits of patch-burn grazing are established. But patch-burning remains understudied from a livestock production standpoint, with most work restricted to crude protein content from limited timeframes and few direct comparisons to alternative grazing systems. We conducted a controlled, ranch-scale experiment to compare forage nutritive value and livestock performance on patch-burned pastures to rotational and continuous grazing. From permanently-established sample points, we clipped available forage and counted fecal pats at monthly intervals during four grazing seasons in pastures with identical stocking but assigned to either patch-burn, rotational, or continuous management (N = 4 each). We used Near-Infrared Spectroscopy to determine multiple components of forage nutritive value, which we reduced via ordination into a single Forage Composition Index. We also weighed cows before and after the grazing season to assess livestock performance for each grazing system. Fire increased crude protein, neutral detergent fiber digestibility, and energy, and decreased acid detergent fiber, neutral detergent fiber, and lignin components of forage nutritive value relative to unburned patches and grazing systems without fire. While many components followed seasonal trends, recently-burned patches had the best forage nutritive value throughout the grazing season. Cows spent more time in recently-burned patches compared to other patches in pastures managed with patch-burning. Patch-burning created heterogeneity in forage nutritive value and grazer selection throughout the duration of the study. Recently-burned patches had the highest proportion of points that met grazing animal requirements throughout the grazing season. As such, cows from patch-burned pastures performed better over the course of the grazing season. Patch-burn grazing can benefit livestock production and performance while creating heterogeneity necessary to achieve rangeland conservation goals. Patch-burning best met the nutritional requirements of grazing cattle, which resulted in better weight gains on patch-burning pastures.