title: FAMACHA(©) scores history of sheep characterized as resistant/resilient or susceptible to H. contortus in artificial infection challenge.
abstract: With the aim of validating the FAMACHA(©) as a method for phenotypic selection of sheep resistant/resilient to gastrointestinal nematodes, 27 Suffolk ewes with known FAMACHA(©) score histories were experimentally infected with 25,000 larvae of Haemonchus contortus. From the day of infection (day 0) to 60 days post-infection, at intervals of 7-15 days, ewes were evaluated for packed cell volume (PCV) and fecal egg counts (FEC). A statistically significant increase (p<0.05) in FEC occurred between day 0 and day 60. PCV values showed a decrease (p<0.05) starting from day 21, compared to day 0. Based on the changes in FEC and PCV values from day 0 to day 60, 15 ewes (55.56%) were classified as susceptible (S) and 12 ewes (44.44%) as resistant/resilient (RR). A comparison of the average FEC after infection between susceptible (4487.6 eggs per gram-epg) and resistant/resilient (1317.9epg) ewes showed a significant difference (p<0.05) between the two groups. The difference in average PCV values after infection (24.8% and 30.3% for S and RR, respectively) was also significant (p<0.05). Data from 980 previous evaluations of FAMACHA(©) scores from the 27 ewes showed that 58.33% of the ewes classified as RR and 46.67% of the S group had a history of only F1 and F2 scores. In the RR group, only one animal (8.33%) had an F4 score, occurring one time out of the 61 evaluations of this ewe. In contrast, 40.0% of S group ewes had F4 and/or F5 scores. During the period of FAMACHA(©) score history that was evaluated, 69.56% of the total number of anthelmintic treatments in the flock were administered to ewes from group S. Since ewes with F4 and/or F5 scores during the FAMACHA(©) score time period were classified as susceptible during the experimental infection (with the exception of one ewe), we conclude that the FAMACHA(©) score history is a useful tool for the selection of ewes that are resistant/resilient, as well as for the identification of susceptible animals that should be culled.
authors.affiliation: Graduate Program in Animal Science, School of Agricultural Sciences and Veterinary Medicine-Pontifícia Universidade Católica do Paraná (PUCPR), São José dos Pinhais, Paraná 83010-500, Brazil.
authors.forename: J F S
authors.initials: JF
authors.lastname: Pereira
authors.affiliation: Graduate Program in Animal Science, School of Agricultural Sciences and Veterinary Medicine-Pontifícia Universidade Católica do Paraná (PUCPR), São José dos Pinhais, Paraná 83010-500, Brazil.
authors.forename: J B
authors.initials: JB
authors.lastname: Mendes
authors.affiliation: School of Agricultural Sciences and Veterinary Medicine-Pontifícia Universidade Católica do Paraná (PUCPR), São José dos Pinhais, Paraná 83010-500, Brazil.
authors.forename: G
authors.initials: G
authors.lastname: De Jong
authors.affiliation: Graduate Program in Animal Science, School of Agricultural Sciences and Veterinary Medicine-Pontifícia Universidade Católica do Paraná (PUCPR), São José dos Pinhais, Paraná 83010-500, Brazil.
authors.forename: D
authors.initials: D
authors.lastname: Maia
authors.affiliation: School of Agricultural Sciences and Veterinary Medicine-Pontifícia Universidade Católica do Paraná (PUCPR), São José dos Pinhais, Paraná 83010-500, Brazil.
authors.forename: V N
authors.initials: VN
authors.lastname: Teixeira
authors.affiliation: School of Agricultural Sciences and Veterinary Medicine-Pontifícia Universidade Católica do Paraná (PUCPR), São José dos Pinhais, Paraná 83010-500, Brazil.
authors.forename: A S
authors.initials: AS
authors.lastname: Passerino
authors.affiliation: Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV 26505, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Garza
authors.affiliation: Graduate Program in Animal Science, School of Agricultural Sciences and Veterinary Medicine-Pontifícia Universidade Católica do Paraná (PUCPR), São José dos Pinhais, Paraná 83010-500, Brazil. Electronic address: cristina.sotomaior@pucpr.br.
authors.forename: C S
authors.initials: CS
authors.lastname: Sotomaior
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D004198:Disease Susceptibility / Q000175:diagnosis / Q000662:veterinary*; D005243:Feces / Q000469:parasitology; D005260:Female; D006188:Haemonchiasis / Q000175:diagnosis / Q000469:parasitology / Q000662:veterinary*; D006189:Haemonchus / Q000502:physiology; D006400:Hematocrit / Q000662:veterinary; D010270:Parasite Egg Count / Q000662:veterinary; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology*
keywords: Experimental infection; FAMACHA(©); Haemonchus contortus; Selection; Sheep