Abstract
Grasslands develop a multifunctional role to humanity, with unique fauna and flora, besides being the primary feed source for herbivores. However, grasslands are usually considered a low-efficiency production system, often converted into other land uses such as crops and forestation (e.g., south Brazil). This study aimed to evaluate the effect of two rest intervals between grazing occupations in rotational grazing on the grazing behavior and feed intake of beef heifers. Two grazing intervals, 375 and 750 DD (degree-days) were used; based on the cumulative thermal sum necessary for the leaf expansion of native grasses of two functional groups. The experiment was conducted as a completely randomized block design, with two treatments, three replications, and repeated measures over time. The grazing behavior was evaluated continuously for 18 hours (7 a.m. to 11h59 p.m.). Herbage intake was estimated using an external marker (Cr2O3) in four periods (one for each season). The green leaf mass was similar between treatments, with a mean of 40% of the pregrazing mass (kg DM ha-1). On average grazing, time was 50% of the period, and the bite rate was 38.7 bites min-1. The number of daily meals was 6.5, with an average of 84 minutes for each meal. The number of feeding times (feeding stations by minute) visited was 6.4. On average, there was a 2.23% difference in dry matter intake (% BW) among seasons. Neither ingestive behavior or forage consumption of heifers was affected by the treatments, both maintain similar chemical composition on natural grassland.
Highlights
Natural grasslands are on the decline on a global scale (Bengtsson et al, 2019; Haddock & Good, 2012)
Various grazing management tools are available for beef cattle farmers to use forage resources more effectively and compete with other land uses such as jas.ccsenet.org Journal of Agricultural Science
Our study evaluated two rest intervals between rotational grazing periods based on physiological characteristics of native grasses from the Pampa biome
Summary
Natural grasslands are on the decline on a global scale (Bengtsson et al, 2019; Haddock & Good, 2012). Some land uses (e.g., extensive grazing) are compatible with natural grassland functions but may not have the immediate economic return of more intensive land uses. One way to do this is to provide incentives that align long term sustainable land management decisions with a stable and competitive economic return (ELD Initiative, 2015). To improve the competitiveness with other land uses (e.g., crops), management of both forage and grazing animals is the key for successful livestock operations. A good goal is to develop a grazing system that uses properly managed and well-adapted forages while, at the same time, meeting the nutrient requirements of the animals. Various grazing management tools are available for beef cattle farmers to use forage resources more effectively (e.g., forage allowance, adjustment of stocking rate) and compete with other land uses such as jas.ccsenet.org
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