Pesq. Vet. Bras. 33(4):469-475, abril 2013 Variability in the fecal egg count and the parasitic burden of hair sheep after grazing in nematode infected paddocks1 Roberto González-Garduño2*, Pedro Mendoza-de Gives3 4 ABSTRACT and Glafiro Torres-HernándezVa- riability in the fecal egg count and the parasitic burden of hair sheep after grazing in nematode infected.- González-Garduño paddocks. Pesquisa R., Mendoza-de Veterinária Gives Brasileira P. & Torres-Hernández 33(4):469-475. G.Universidad 2013. Autónoma Chapingo, Unidad Regional Universitaria Sursureste, P.O. Box 29 Teapa, 86800 Tabasco, México. E-mail address: [email protected] This study aimed to evaluate the variability in the fecal egg count (FEC) and the parasi- was carried out in Tabasco, Mexico, during two periods (August and December). In each periodtic burden 32 lambs of naive were hair grazed sheep for after one grazing month onin nematodeAfrican star infected grass ( Cynodonpaddocks. plectostachyus) The research and body weight (BW) were recorded. Gastrointestinal worms were recovered at necropsy. Datacontaminated were analyzed with gastrointestinalwith the MIXED procedureparasitic nematodes. of SAS using FEC, a model packed of repeatedcell volume measure (PCV)- ments over time. A higher number of Haemonchus contortus worms was found in Decem- ber (2814±838) than in August (1166±305). The opposite occurred with Cooperia curticei to the worm burden were higher in December (6516 ± 1599, r=0.83, respectively) than in(2167±393 August (4364±771, and 3638±441, r=0.44, respectively). respectively). The A highFEC variabilityand correlation in resistance-susceptibility coefficient in respect to gastrointestinal nematodes (GIN) occurred in Katahdin × Pelibuey lambs after grazing. INDEX TERMS: Haemonchus contortus, Cooperia curticei, Oesophagostomum columbianum, hair sheep, resistance-susceptibility. INTRODUCTION control these parasites (Torres-Acosta et al. 2012). Some The frequent and continuous use of chemical anthelmin- strategies to reduce the parasitic burden in the animals have been proposed: selective deworming (Besier et al. presence of lateral and multiple anthelmintic resistance intic thedrugs parasites. for deworming This resistance sheep leadsflocks to has a concerningresulted in inethe- ffectiveness of anthelmintics with large economic losses in al.2010), 2009) vaccination and biological (Arunkumar control (Waller et al. 2006). 2012), medicinal sheep productivity (Coles et al. 2006, Papadopoulos 2008, plantsSelection (Sawleha of sheep et al. 2010), that are cooper genetically oxide needlesresistant (Vatta to gas et- Sargison 2011). Twenty-four countries have reported the trointestinal parasitic nematodes is another possible stra- presence of nematodes resistant to several anthelmintics tegy that has been explored in recent decades (Eady et al. (Jabbar et al. 2006). - - ers around the world to search for alternative strategies to tive has been used in combination with other control me- This situation has motivated work thods,2003, Hutchingsespecially etwhen al. 2007, there Stear is the et problem al. 2007). of anthelminticThis alterna 1 Received on August 3, 2012. drug resistance (Molento 2009). The issue of resistance has Accepted for publication on March 18, 2013. increased mainly for sheep farming in humid, warm clima- 2 Universidad Autónoma Chapingo, Unidad Regional Universitaria Sur- te conditions such as in Brazil (Thomaz-Soccol et al. 2004). sureste, P.O. Box 29 Teapa, 86800 Tabasco, México. *Corresponding au- In these warm, humid areas the proliferation of nematode thor. [email protected] larvae in the grass increases, resulting in the possibility of 3 - larvae completing their biological cycles, thereby creating a ria, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Paseo Centro Cuaunahuac Nacional 8534, de Investigación Progreso, C.P. Disciplinaria 62550. Jiutepec, en Parasitología Morelos, México. Veterina major problem in the grazing sheep industry (Torres-Acos- 4 Colegio de Postgraduados, Programa de Ganadería, Instituto de Re- cursos Genéticos y Productividad, 56230 Montecillo, Estado de México. The genetic selection of sheep resistant to nematodes México. ta & Hoste 2008). - is based on phenotypic markers. For example, the elimi 469 470 Roberto González-Garduño, Pedro Mendoza-de Gives and Glafiro Torres-Hernández nation of eggs per g of feces in wool sheep breeds has been investigated for many years in Australia and New Zealand (Windon 1996, Gray 1997). In Merino, there are lines of sheep selected for both increased and reduced genetic re- sistance (Woolaston et al. 1990). These lines achieve ave- possible to reduce the use of anthelmintics in controlling nematodesrage counts in of sheep 2730 andwith 17400 genetic epg, resistance. respectively, The searchmaking for it genes or Quantitative Trait Loci (QTL) related to resistan- ce against parasites in sheep is considered a major aspect countries, i.e. UK (Davies et al. 2006, Bishop & Morris 2007) andto be Kenya investigated (Silva et (Beraldi al. 2012). et al. Despite 2007) theby workers development in some of Fig.1. Rainfall and temperature averages from 1971 to 2000 re- modern molecular techniques, traditional productive as- corded at the Meteorological Center, 27068 Puyacatengo, Ta- basco, Mexico. et al. 2004) and egg faecal count have been used to diagno- sispects parasites such as (Cringoli weight gain, et al. packed 2010). cell volume (Vanimisetti The study was divided into two periods. In each period, 32 Studies indicate that hair breeds are more resistant to Katahdin × Pelibuey three- month-old weaned male lambs were parasitic nematodes than wool breeds. For instance, in a used. The lambs of each period had never been in contact with GIN because they were reared in house with ewes during the pre- - weaning period. At weaning, they were negative to gastrointes- tinal nematodes; consequently, no acquired resistance against work published by Notter et al. (2003), authors recorded bs. Meanwhile, in hair lambs maintained under the same nematodes would be expected. conditions,4011 FEC average only 1135 after FEC four was to found.eight weeks On the in other wool hand, lam lambs were grazed for one month in a rotational system with 15 gastrointestinal parasitic nematodes with values of 5170 daysThe grazing first periodin each wasone ofcarried two 7500m out in2 August (rainy season) and Katahdin and St Croix have been identified as resistant to lambs were given 250g of a commercial feed with 14% crude pro- Miller 2004). Also, one hair sheep breed from the Canary tein. Also, they were provided with a mineral paddocks. mixture During and grazing, water Islandsand 4217 (Canaria FEC and hair Dorper breed lambs sheep) with (González 8602 FEC et (Burkeal. 2008) & ad libitum. After grazing, lambs were housed for 21 days to allow and another from Mexico (Pelibuey) are also recorded as the larvae to evolve into adult worms. Lambs from this group resistant against gastrointestinal nematodes (Morteo-Gó- were slaughtered to recover the nematode parasites. mez et al. 2004). Other studies also indicated the presence 38 infected sheep were grazed on the pastures for three months of resistance in the following breeds: Florida (Amarante et fromAfter September completing to November the first grazing (rainy season)period, anto continuously“extra” group in of- al. 1999, Díaz et al. 2000), Gulf Coast native (Li et al. 2001), fect the prairie with gastrointestinal nematodes. In the second period, another group of 32 grazing lambs with the same characteristics, origin and management, previously indi- BlackbellyThe high (Amount variability et al.observed 2003), betweenRed Maasai and (Baker within et bre al.- cated, was introduced. This group grazed for a month (December) eds2003) allows and Dorperfor selection (Vannimiseti based on et theal. 2004). nematode egg count and was then housed for 21 days. The January group was slau- despite the heritability and repeatability being close to 0.3 ghtered to recover the nematode parasites. Individual body weight (BW) was recorded at the beginning alternative for controlling parasitic nematodes. The aim of and at days 35 and 42 of each period, and the average daily wei- the(Jackson present 2002). study Nevertheless, was to identify it should the variabilitybe considered between as an ght gain (DWG) was estimated. On the same dates, blood samples the fecal egg count and the parasitic burden of hair sheep - were taken from the jugular vein to measure the packed cell volu Parasitologicalme (PCV) by the micro-haematocrit method technique (Benjamin 1991). after grazing MATERIALSin nematode infected AND METHODS grazing paddocks. Experimental site This study was carried out in the Unidad Regional Universita- 21, During35 and grazing,42. The fecalMcMaster samples technique were taken was onused days to determine14, 21, 35 ria Sursureste of the Universidad Autónoma Chapingo in the Muni- theand FEC 42. valuesDuring (Thienpont the housing et period,al. 1986). samples Fecal samples were taken were on pooled days cipality of Teapa, Tabasco, Mexico, at 60 meters above sea level and and then cultured to obtain nematode infective larvae for taxono- located 17° 31’ 38” North latitude and 92° 55’ 50” West longitude. The prevalent climate of this region is Af (m) wi’g, hot and humid At the end of the housing time in each period, lambs were with rainfall throughout the year (Fig.1). The average annual tem- mic identification (Niec 1968). perature is 25.8ºC and