Efficacy of pour-on dewormers on weight gain and fecal egg count in Hawaiian stocker cattle Jonathon Beckett 1, Tim Richards 2, Craig Reinemeyer 3 1 Animal Science Department, Cal Poly State University, Kahua Ranch 2, East Tennessee Clinical Research 3

What is a Parasite? u The Random House Dictionary defines it as an organism that lives on or within a plant or animal of a different species, from which it obtains nutrients.

Parasites of Concern Bunostomum phlebotomum (Cattle Hookworm) Causes itching of the leg and feet Irritate stomach and intestines Feed on blood in the intestinal wall Causes bloody, tar colored diarrhea Fasciola hepatica (Common Liver Fluke) Live in the bile ducts of the liver, and gallbladder Animals experience anemia and decreased growth Usually results in condemnation of the liver at slaughter Strongyloides papillosus (Intestinal threadworm) Most common in young calves Causes intermittent diarrhea, loss of appetite, and weight

Parasites of Concern Cooperia spp (Cattle Bankrupt worm) Lives in the Small Intestine Animals exhibit poor utilization of feed, taking a long time to reach market weight Ostertagia ostertagia (Brown Stomach Worm) Affected cattle not only lose weight but often die Cells damaged by the parasite are replaced by rapidly dividing cells that lack function The most commonly found and economically important internal parasite Toxocara vitulorum (Large Roundworm) Live in the Small Intestine Found especially in warm climates can travel through the lung and cause pneumonia Compete with host for food, causing diarrhea and weight loss

Clinical Parasitism u Diarrhea u Anemia u Rough hair coat u “Pot bellied” appearance u “Bottle jaw” u Less common

Subclinical Parasitism u Decreased milk production u Poor performance u More susceptible to disease u Infertility u Unthrifty

We Deworm Cattle For Only One Reason u FOR THE MONEY

Parasitism Economics of Parasite Control Calves v More efficient v Less susceptible to disease Cows v Increased milk production v Better body condition v Better breeding efficiency v Less susceptible to disease

Benefits of Deworming u Increased productivity u Increased efficiency u Better immune status u Increased breeding efficiency u Reduced pasture contamination

Importance of fecal egg counts? u Most commonly used technique u Usefulness depends on its precision and accuracy u Requires knowledge of parasite biology in area, experience with levels that are indicative of economic impact in a given situation

EPGs (Eggs Per Gram) importance? u An indicator, but only tell you that you have at least one female worm laying eggs u Can be used to determine potential parasite transmission levels in groups of animals, but not individual animals u Poor indicator of number of worms in an individual animal u Should not be used to measure production losses

Importance of Larval Cultures u Very few parasitologist are able to differentiate between different genera of the parasite eggs u Nematodirus is only “easy one” u Larval cultures let eggs hatch then the worms are identified

Macrocyclic Lactones u Avermectins –Ivermectin (Ivomec) –Doramectin (Dectomax) –Eprinomectin (Eprinex –Look alikes –Generic u Milbemycins –Moxidectin (Cydectin)

Macrocyclic LactonesMoxidectin Ivermectin Eprinomectin Doramectin

Types of Administration u Injectable –Advantage – Easy to administer –Disadvantage – Can create problems in the meat –Disadvantage – Must be re- dosed every 60 days u Pour-On –Advantage – Very quick to administer –Advantage – Noninvasive administration –Disadvantage – Must be re- dosed every 60 days u Drench –Advantage – Very quick to administer (not as quick as Pour-On) –Disadvantage – Must be re- dosed every 60 days –Disadvantage – Cow can spit out most of the product u Bolus –Advantage – Dosed only once in the cow’s life –Disadvantage – Much longer administration time –Disadvantage – Administration requires training

Just Some More Facts u Worms die after 5-8 wks in adult stage u Some products kill most of the worms present in the digestive tract at time of treatment u Some control only external parasites u Some control both internal & external u A few also kill the inhibited stages u A few offer persistence of several weeks

Hypothesis The effective drug in pour-on dewormers will affect growth and parasite infection throughout the grazing season in stocker cattle.

Control Ivomec Eprinex Dectomax Cydectin Protocol A B C D E Transported by boat to Canada -60 Transported to Feedyard, Bruneau, ID Transported to Swanton Pacific Ranch -14 Harvested at IBP, Boise, ID -21 Dewormed with Dectomax Days 0 Dewormed 70 Redewormed 156

Average Daily Gain Day a a a a b

Average Body Weight Day

Fecal Egg Counts Redewormed Dewormed

Carcass Weights

Yield Grade

Backfat

Ribeye Area a ab b

Marbling Score

Yield Grade 1 & 2’s

What does this mean? u It is important to deworm u Eprinex and Cydectin equally resulted in maximal growth u Ivomec is the weakest against internal parasites u Without adequate forage, no dewormer is fully effective

What does this mean? u Effect of dewormer during stocker phase is not significant at slaughter but effects are visible –Take advantage of cheap gain during stocker phase rather than pay more for the gain in the feedyard

What does this mean? u Other factors must be considered when selecting a dewormer –Cost –Persistency of Protection –Ease of Administration –Rain Fastness –Flame Resistance –Customer Service

Acknowledgements u Kahua Ranch – Thank you for allowing Cal Poly to conduct the trial on their cattle u Bruneau Cattle Company – Accommodating the feedlot phase u 2001 Swanton Pacific Stocker Enterprise group for participating in the data collection and organization of the trial u Brian Wetzel – Cal Poly Alumni for initiating this line of research as his senior project