Relationship between Temperate Grass Sward Characteristics and the Grazing Behavior of Dairy Heifers

Sward architecture mediates ruminant grazing behavior in temperate grazing lands. Temperate grasses differ in their sward structure, which may influence the grazing behavior of cattle. We determined relationships between the grazing behavior of dairy heifers and the sward structure of the following temperate grasses: meadow fescue (Schedonorus pratensis (Huds.) P. Beauv.), orchardgrass (Dactylis glomerata L.), quackgrass (Elymus repens (L.) Gould), and reed canarygrass (Phalaris arundinacea L.). Vegetative-stage grasses were rotationally grazed by Holstein heifers (average initial body weight of 460 kg) during 5 day periods in the spring, summer, and fall of 2007 and 2008. The herbage dry matter (DM) allowance was twice the expected daily intake (11 kg DM animal−1 d−1). The sward characteristics were measured before grazing (e.g., the herbage height and mass, vertical distribution of leaf and stem fraction, and nutritive value). The grazing behavior of the heifers was quantified using automatic jaw movement recorders. In this study, the grass species had little effect on the grazing behavior. However, the bite rate was negatively correlated with the herbage mass, while the number of bites was positively correlated with the sward height and herbage mass. These results suggest that when herbage availability is not limited, grazing dairy heifers exhibit similar ingestive and rumination behavior across grass species and seasons, yet jaw movement dynamics may respond to the different characteristics of the swards. The results of this study provide the following benefits: (1) they inform managers about the jaw movement mechanics that can be expected of dairy heifers in temperate forage systems, showing that they are not limited by herbage allowance, and (2) they provide insight for future studies that employ on-animal sensors to evaluate foraging dynamics and animal performance outcomes in temperate forage pasture systems

Understanding Diet Selection in Temperate Biodiverse Pasture Systems

The first decade of the 21st century has been dominated by unprecedented environmental challenges. These challenges are associated with intense public awareness and interest in constructive environmental solutions. There is increasing interest by both consumers and producers of agricultural products in the development of a more sustainable agriculture system, with less dependence on external finite resources. Biodiverse pasture systems have the potential to serve agriculture in this regard. Thus, a symposium addressing contemporary, interdisciplinary research on plant-herbivore interactions, animal responses, and grazing management in temperate biodiverse pasture systems was sponsored by the American Society of Animal Science at the annual meetings of the society in July 2007. The resulting articles appear in this Special Feature of Rangeland Ecology Management. The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Dietary Selection by Domestic Grazing Ruminants in Temperate Pastures: Current State of Knowledge, Methodologies, and Future Direction

Ruminants grazing mixed-species pastures face many choices, including when and where to graze and how much herbage to consume. These choices affect not only the nutritional status of the animal, but also sward composition and nutritive value through selective defoliation. Limited research has been conducted in the area of dietary selection and preference, most of which has been limited to simple model systems often involving a choice between only two herbage species. Although these studies have provided a vital tool to allow understanding of the fundamental principles of foraging behavior, in reality, grazing ruminants are faced with more complex situations. Understanding and managing animal preferences in mixed swards and thereby altering dietary selection can result in greater primary (plant) and secondary (animal) productivity. Key issues to improve this understanding include a better linking of behavioral and nutritional studies, a better understanding of the genetic factors influencing diet selection, and the development of more explicit spatial models of foraging behavior that incorporate multiple scales of decision making. This article, as part of a set of synthesis articles, reviews the current state of knowledge and research methodologies related to diet selection of grazing domestic ruminants with particular reference to improved temperate grazing environments, including how well we understand each part of the complex decision-making process a grazing ruminant faces, the links with primary and secondary productivity, and developments in methodologies. Finally, we identify key areas where knowledge is lacking and further research is urgently required. The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Sustainability of US Organic Beef and Dairy Production Systems: Soil, Plant and Cattle Interactions

In 2010, the National Organic Program implemented a rule for the US stating that pasture must be a significant source of feed in organic ruminant systems. This article will focus on how the pasture rule has impacted the management, economics and nutritional value of products derived from organic ruminant systems and the interactions of grazing cattle with pasture forages and soils. The use of synthetic fertilizers is prohibited in organic systems; therefore, producers must rely on animal manures, compost and cover crops to increase and maintain soil nitrogen content. Rotational and strip grazing are two of the most common grazing management practices utilized in grazing ruminant production systems; however, these practices are not exclusive to organic livestock producers. For dairy cattle, grazing reduces foot and leg problems common in confinement systems, but lowers milk production and exposes cows to parasites that can be difficult to treat without pharmaceuticals. Organic beef cattle may still be finished in feedlots for no more than 120 days in the US, but without growth hormones and antibiotics, gains may be reduced and illnesses increased. Grazing reduces the use of environmentally and economically costly concentrate feeds and recycles nutrients back to the soil efficiently, but lowers the rate of beef liveweight gain. Increased use of pasture can be economically, environmentally and socially sustainable if forage use efficiency is high and US consumers continue to pay a premium for organic beef and dairy products

Projected heat stress challenges and abatement opportunities for U.S. milk production.

Cost-effective heat mitigation strategies are imperative for maintaining milk production and dairy farm profitability in the U.S. with projected climate change. This study investigated the cost-effectiveness of four heat abatement strategies, including Minimal (open barn or shading), Moderate (forced ventilation), High (fans and misting), and Intense (air conditioning). Heat stress and subsequent impacts on milk production per cow were predicted across nine climatic regions in the U.S. for early (2015 to 2034), mid (2045 to 2064) and late (2081 to 2100) 21st century, using downscaled climate projections. Heat abatements were used to adjust predicted milk production losses and illustrate the potential to reduce milk production losses due to heat stress. Economic analysis included a cost-benefit ratio calculation associated with the implementation of each heat abatement. Results showed that milk production losses were expected to accelerate across the U.S. at a mean rate of 174±7 kg/cow/decade, with the fastest rate in the Southeast region. Relative to Minimal heat abatement, Moderate, High, and Intense heat abatements increased annual milk production per cow by 3%, 4%, and 6% during early-21st century, 3%, 6%, and 11% during mid-21st century, and 3%, 8%, and 21% during late-21st century, respectively. The cost effectiveness of different heat abatement strategies generally increased with subsequently stronger heat abatements. In mid- and late-21st century, mean annual net values of High and Intense heat stress abatement implementation approached -$30 to$190 /cow and -$20 to$590 /cow, respectively, with the largest net annual benefit in late-21st century under Intense abatement. Findings from the study demonstrate the value of using downscaled climate projections to shed light on local and regional strategies to abate heat stress on cattle and mitigate potential milk production losses due to climate change

Forage Utilization for Pasture-Based Livestock Production (NRAES 173)

This 185 page publication (NRAES-173) was originally published by the Natural Resource, Agriculture, and Engineering Service (NRAES, previously known as the Northeast Regional Agricultural Engineering Service), a multi-university program in the Northeast US disbanded in 2011. Plant and Life Sciences Publishing (PALS) was subsequently formed to manage the NRAES catalog. Ceasing operations in 2018, PALS was a program of the Department of Horticulture in the College of Agriculture and Life Sciences (CALS) at Cornell University. PALS assisted university faculty in publishing, marketing and distributing books for small farmers, gardeners, land owners, workshops, college courses, and consumers.Essential information on grazing management and harvesting excess forage for livestock produced in a pasture-based system including chapters on fencing, watering systems, lanes and feeding pads, animal-handling facilities, and more