Effects Of Pasture And Management Variables On Forage Intake By Grazing Sheep

Author : Jasmine Harris
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (127 download)

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Download or read book The Impacts of Pasture Management Techniques in Grazing Lamb Systems written by Jasmine Harris and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sheep production, including operations and sales, has increased in the Northeastern United States of America over the past 5 years (USDA NASS, 2017). As the population continues to increase, the demand for sheep meat remains parallel to the population. However, sheep producers have carved out a niche market, with access to over one-third of the nation's population in less than a 500 mile-radius (Indiana Business Research Center, 2021), by marketing young lambs, directly from pasture to ethnic and religious populations. Unfortunately, internal parasites are a major source of economic losses in small ruminants, and pasture-based small ruminant systems run greater risks of parasite-driven production losses than confined feeding systems (Stromberg and Gasbarre, 2006; Craig, 2018). Gastrointestinal nematodes (GIN) are becoming increasingly difficult to manage with anthelmintics due to increasing anthelmintic resistance (Mortensen et al., 2003). Regional surveys across the U.S., including the south (Mortensen et al., 2003), southeast (Howell et al., 2008), and Mid-Atlantic (Crook et al., 2016), suggest a greater prevalence of resistance to multiple anthelmintics on small ruminant farms. Haemonchus contortus, commonly known as the barber pole worm, is one of the most common and fatal GIN affecting small ruminants (Verocai et al., 2020). The increasing anthelmintic resistance and economic burden of GIN infection on producers emphasize the need for alternative methods of parasite control. Parasite prevalence is greatest in areas of the pasture where defecation occurred during previous grazing events. While removing the feces every time an animal defecates is implausible, proper management of grazing techniques can help to reduce the spread of parasites in grazing flocks (Coffey and Hale, 2012; Barkley, 2017). The efficacy of pasture rotation is a well-founded practice to reduce parasite loads; however, there are other mechanical pasture management techniques that may decrease the prevalence of GIN in grazing systems but have not been widely explored. Two such mechanical pasture management techniques are mowing and dragging. Pasture dragging, the pulling of a harrow or chain-link fence over the ground, is an agricultural process that spreads manure piles across pastures to accelerate manure desiccation and decomposition and enhance nutrient cycling (Missouri Agricultural Experiment Station, 1998). Pasture mowing is a mechanical process that more specifically impacts agronomic production by potentially reducing weed growth and allowing new growth of pasture (Penrose, 2018; Pampell, 2019). Dragging and mowing pastures, either alone or in combination, spreads manure piles and increases the exposure of that manure to sunlight. Sun exposure creates an unfavorable environment for parasite eggs to hatch and can kill hatched larvae. There are suggestions in published Extension literature that dragging and mowing can also help to increase forage production and soil fertility, allowing better quality forages to obtain the proper nutrients to grow (Williamson, 2015; Pampell, 2019). However, the peer-reviewed scientific publications in this area are lacking. While increased forage quality alone could increase nutrient availability for sheep, reducing susceptibility of those animals to parasite infection (Coop and Holmes, 1996; Coop and Kyriazakis, 1999; Houdijk et al., 2012), the efficacy of dragging and mowing to reduce parasite loads and spread among sheep have not been validated. We hypothesized that the use of mowing would improve overall pasture productivity and nutrient cycling while reducing parasite populations within growing lambs, thus increasing lamb growth, and that the magnitude of this response would be greater when mowing was conducted in combination with dragging. Therefore, the objectives of the experiment were to determine the impacts of mechanical pasture management techniques, mowing or mowing followed by dragging, in a rotational grazing system on botanical composition, forage mass, and soil fertility of the paddock and on growth and parasite status in growing lambs. Dorset and Suffolk x Dorset crossbred lambs (n = 36) were stratified by body weight and birth type (single versus twin) and randomly assigned to 12 pens across 4 blocks in the pasture. Each pen within block was randomly assigned to 1 of 3 treatments: no mechanical application to the paddock (CON), mowing application to the paddock post-grazing (M), or mowing followed by dragging application to the paddock post-grazing (MxD). Rotations (n = 11 ± 2) within paddocks occurred every 1 to 3 days, based on visual assessment of forage mass. There were no effects of treatment (P = 0.4), nor treatment x day interactions (P = 0.82) on fecal egg count (FEC). However, FEC increased (P 0.01) over time by 5.61 ± 0.58 log-transformed eggs per gram (epg) among all lambs, regardless of mechanical pasture treatments. There were no treatment x day interactions (P = 0.96) on packed cell volume (PCV). Although PCV decreased (P 0.01) over time by 2.15 ± 0.05% among all lambs, it remained above the threshold of 20%, thus, no lambs required parasite treatment over the course of the trial. There was a tendency (P = 0.09) for lambs grazed in the paddocks without mechanical treatment, CON, to maintain greater PCV than lambs in other mechanical treatments, M or MxD, suggesting that the lambs grazing CON paddocks may have been on a better plane of nutrition. However, there was no interaction of treatment x day (P = 0.82) on pre- or post-grazing forage mass. Pre- and post-grazing forage mass increased (P