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Timely topic: July 2014

High quality forage helps maintain resilience to GI parasites

by Dr. Ken Turner
Research Animal Scientist
USDA-Agricultural Research Service
Grazinglands Research Laboratory
El Reno, Oklahoma


Introduction 
Control of gastrointestinal (GI) parasites (especially the blood feeder Haemonchus contortus) in small ruminants is a problem for sheep and goat producers.  Gastrointestinal parasite overloads reduce livestock performance and production efficiency, and can result in increased death losses of animals.  Oral anthelmintics (dewormers) are typically administered to reduce worm burdens; however, Haemonchus infesting sheep and goats have developed resistance to commercial anthelmintics. 

OK Boer Goats

Instead of monthly deworming, selective deworming of individual animals should be considered.  Use of the FAMACHA© eyelid score system in the control of Haemonchus can slow development of resistance of this GI parasite to commercial dewormers (Kaplan et al., 2004).  In addition, consideration must be given to maintaining healthy sheep and goats by satisfying dietary nutrients requirements, especially protein.

Grazing Management
Grazing management generally is a grazing plan that synchronizes duration of the grazing interval with plant growth characteristics of the sward.  This is accomplished by moving or adjusting the number of grazers on a given land area (Turner and Belesky, 2010).  There are a variety of forages used in grazing systems for sheep and goats.  In order to provide forages with high nutritive value (high crude protein [CP] and total digestible nutrients [TDN]) for livestock, grazing management should be used.  

Rotational Stocking
One management method commonly used for grazing livestock is rotational stocking.  With rotational stocking, a specified pasture is usually divided into two or more units termed paddocks, then a specified number of animals are allotted to the first paddock and allowed to graze for a period of time before being moved to the second paddock, and so on. Paddocks are rested to allow herbages time to re-grow; given adequate rainfall, 30-45 days is typically sufficient for most forages. Animals are moved between or among paddocks throughout the grazing (plant growing) season.

Grazing management using rotational stocking helps maintain desirable herbage with high nutritive value (high CP and TDN).  This is especially important for young or lactating animals which have a higher requirement for nutrients compared to mature or non-lactating animals.

Legumes
Establishing and maintaining legumes in pastures improves protein levels in the diet of grazing livestock.  In addition, legumes generally have higher levels of several minerals (calcium, copper, magnesium, phosphorus and zinc) in comparison to grasses.  These minerals can help maintain a healthy immune system in animals and thus improve tolerance to GI parasites.

Improving Resilience in Sheep and Goats
Maintaining forages with high nutritive value (including increased protein levels by utilizing legumes in pastures) helps to increase resilience in sheep and goats to GI parasites.  When grazing sheep and goats on pasture, resilience can be defined as the animal’s ability to tolerate higher GI parasite burdens and still remain productive (gain weight; produce milk). 

Turner et al. (2012) evaluated legume (alfalfa or red clover) or cool-season grass (orchardgrass) pastures maintained with rotational stocking to finish meat-goat kids.  Use of rotational stocking grazing management resulted in herbage with high nutritive value (high CP and TDN) in all pastures for finishing meat goats without supplementation. 

Meat-goat kids grazing alfalfa or red clover (legumes, high protein) pastures gained more weight compared to goat kids grazing orchardgrass pasture despite an increasing fecal egg count in all animals.  Meat-goat kids grazing alfalfa or red clover appeared to be more resilient to GI parasites than goat kids grazing orchardgrass.

Implication
Use of legume pastures and use of rotational stocking grazing management can provide herbages with high protein and energy levels, helping reduce effects from GI parasitism (especially Haemonchus) in sheep and goats.


Literature cited

Kaplan R.M., J.M. Burke, T.H. Terrill, J.E. Miller, W.R. Getz, S. Mobini, E. Valencia, M.J. Williams, L.H. Williamson, M. Larsen, and A.F. Vatta. 2004. Validation of the FAMACHA© eye color chart for detecting clinical anemia in sheep and goats on farms in the southern United States. Veterinary Parasitology 123:105–120.

Turner, K.E. and D.P. Belesky. 2010.  Terminology revisited: Effective communications for the agricultural community.  Journal of Extension vol.48 (no. 2). Available at: http://www.joe.org/joe/2010april/a5.php.

Turner, K.E., K.A. Cassida, and A.M Zajac. 2012.  Weight gain, blood parameters, and fecal egg counts when meat-goat kids were finished on alfalfa, red clover, or orchardgrass pastures. Grass and Forage Science 68:245-259.


Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.  USDA is an equal opportunity provider and employer.


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