Non-hierarchical cluster analysis for determination of resistance to worm infection in meat sheep
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Non-hierarchical cluster analysis for determination of resistance to worm infection in meat sheep Johnny Iglesias Mendes Araujo 1 & Natanael Pereira da Silva Santos 2 & Max Brandão de Oliveira 3 & Luciano Silva Sena 4 & Daniel Biagiotti 5 & Aurino de Araujo Rego Neto 4 & José Lindenberg Rocha Sarmento 4 Received: 12 March 2020 / Accepted: 11 November 2020 # Springer Nature B.V. 2020
Abstract The aim of this study was to determine the resistance to worm infection in Santa Inês sheep by combining different sets of gastrointestinal parasite resistance indicator traits, using the k-means algorithm. Records from 221 animals reared in the MidNorth sub-region of Brazil were used. The following phenotypes were used: hematocrit (HCT); white blood cell count; red blood cell count (RBC); hemoglobin (HGB); platelets; mean corpuscular hemoglobin; mean corpuscular volume; mean corpuscular hemoglobin concentration; fecal egg count (FEC); coloration of the ocular mucosa (FAMACHA score); body condition score (BCS); withers height; and rump height. Two files with phenotypic information of animals were edited: complete, including all traits, and reduced, in which only FAMACHA score, HCT, FEC, and BCS were used. For determination of worm resistance, three groups were formed using the k-means non-hierarchical clustering by combining the traits of the complete and reduced analyses. The animals of the group in which individuals had the lowest values for FEC and FAMACHA score, as well as the highest values for HCT, RBC, HGB, and BCS were classified as resistant. In the group with opposite values for the aforementioned traits, the animals were classified as sensitive. The animals of the group with values between the other two groups were classified as moderately resistant. The results obtained in complete and reduced analyses were equivalent. Thus, it is possible to identify animals of the Santa Inês sheep breed according to their status of resistance to worm infection based on a reduced trait set. Keywords FEC . k-means . Multivariate analysis . Ovis aries . Parasite control . Selection
Introduction
* Johnny Iglesias Mendes Araujo [email protected] 1
Graduate Program in Animal Science, State University of Southwest of Bahia, Campus of Itapetinga, Itapetinga, Bahia, Brazil
2
Department of Agronomy, Federal University of Piauí, Campus Professora Cinobelina Elvas, BR 135, Km 3, Bom Jesus, Piauí Teresina, Brazil
3
Department of Statistics , Federal University of Piauí , Campus Universitário Ministro Petrônio Portella, Teresina, Piauí, Brazil
4
Department of Animal Science, Agrarian Sciences Center, Federal University of Piauí, Campus Universitário Ministro Petrônio Portella, Teresina, Piauí, Brazil
5
Technical College of Bom Jesus, Federal University of Piauí, Campus Professora Cinobelina Elvas, BR 135, Km 3, Piauí Bom Jesus, Brazil
The prevalence of gastrointestinal nematode infections is one of the major problems for sheep production in Brazil, as these infections may even cause death in heavily infe
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