Key Findings

• There is a large breadth of research exploring antemortem factors that impact meat quality outcomes in finished cattle.
• Geographic location influences research focus (i.e., studies on Nellore cattle concentrated in South America, studies including bulls mostly conducted outside of North America).
• pH and meat color were the most commonly measured meat quality parameters in the reviewed studies, likely due to their ease of measurement and their close relationship with dark cutting.
• Dark cutting, despite its economic impact, is under-researched, particularly in regions where it's a priority (e.g., the US), necessitating focused funding and research initiatives. While current research heavily emphasizes feeding practices, a multi-factorial approach is crucial for improving meat quality, requiring greater exploration of less-studied areas like transport, plant management, and weather impacts, along with a critical appraisal of existing intervention studies

background

Dark-cutting beef, or DFD (dark, firm, and dry) beef, is a quality defect characterized by an abnormally dark color due to high pH levels, typically caused by pre-harvest stress depleting muscle glycogen. This undesirable color leads to consumer rejection and significant economic losses for the beef industry, currently averaging $36.85 per hundred pounds in discounts in the US, with an estimated annual loss of $288 million. While the incidence of DFD has decreased since the 1990s, recent rates have plateaued, remaining a persistent issue. Beyond color, DFD can also negatively impact flavor and raises animal welfare concerns due to the stress-related nature of the condition. Numerous factors, including breed, sex, handling practices, transportation, and environment, contribute to DFD, making it a complex challenge to mitigate. Currently, a systematic mapping review of the current literature has not been conducted. The objective of this study was to identify trends, knowledge clusters, and knowledge gaps in research exploring antemortem factors that impact dark cutting and associated measurements in fed beef cattle (i.e., pH, meat color, and glycogen content of meat) in order to contribute to the efforts of lowering DFD incidence. The research question that this review was designed to answer was: what are the antemortem factors (i.e., cattle management, live animal characteristics, environment) associated with dark cutting, pH, meat color, and glycogen content in fed beef cattle? 

methodology

This systematic mapping review used a structured methodology to identify research trends, clusters, and gaps related to dark cutting beef. Following established guidelines, the review searched four databases (Agricola, CAB Abstracts, Medline, and Web of Science) using robustly developed search strings and inclusion criteria, focusing on peer-reviewed, English-language studies of antemortem factors affecting meat quality (dark cutting, pH, meat color, and glycogen content) in fed cattle. Two independent reviewers screened titles and abstracts, followed by full-text screening by three reviewers. Data extraction was conducted using a pre-tested tool, with reviewers independently coding articles and resolving inconsistencies through discussion. Extracted data were then synthesized and visualized using EPPI-Reviewer and EPPI-Mapper, systematic review software programs, to create summaries and an interactive map of the research landscape.

findings

The initial search retrieved 16,506 citations. After removing duplicates and performing the above-described screening steps, 460 articles were included in this systematic map. The majority of studies (61.1%) involved 21-150 animals with few studies over 1,500 animals. The majority of studies were conducted in Europe (28.5%) and bulls and steers were the most common sex class included in studies (34.8% and 33.3%, respectively). pH (73.2%) and meat color (77.2%) were the most frequently measured outcomes, while glycolytic potential (5.4%) and dark cutting frequency (10.9%) were less common. Feeding was the most studied intervention (53.6%). An interactive evidence gap map, available for download here: https://mountainscholar.org/items/f6e8713b-4234-41e6-94f6-4d618a98328f, visualizes the distribution of studies across interventions and outcomes by region.

industry Implications

This research provides a framework for identifying future research potential to address meat quality concerns in fed cattle. Dark cutting was relatively infrequently represented in the literature base and if this is a priority area, from the standpoint of reducing economic losses from this defect, in certain regions of the world (i.e., the United States), there should be an intentional effort to fund, request, or identify research needs in this space. There are many antemortem factors that have been explored as having potential impacts on meat quality and thus making improvements and changes in this area requires a multi-factorial approach. Currently, much of the research base focuses on manipulating feeding practices but there is more opportunities to explore less studies areas such as transport, plant management, and weather impacts. A deeper exploration and critical appraisal of studies associated with interventions of interest should be conducted.