title: Testicular length as an indicator of the onset of sperm production in alpacas under Swedish conditions.
abstract: BACKGROUND
  The popularity of alpacas (Vicugna pacos) is increasing in Sweden as well as in other countries; however, knowledge about optimal management practices under Swedish conditions is still limited. The wide age range reported when the onset of puberty can occur, between 1 and 3 years of age, makes management decisions difficult and may be influenced by the conditions under which the alpacas are kept. The aim of this study was to find out when Swedish alpacas can be expected to start producing sperm, by using testicular length and body condition score as a more precise indirect indicator than age.
  
  
  RESULTS
  This study suggests that animals with a testicular length ≥3.8 cm would be producing sperm; however, if it is crucial to know that there is no sperm production for management purposes, the threshold level for testicular length used to differentiate between sperm-producing and non-sperm producing animals should be ≤1.6 cm instead. If only one variable is considered, testicular length appears to better than age alone to predict sperm production. Body condition score together with testicular length explains the individual onset of puberty and better guide management recommendations.
  
  
  CONCLUSIONS
  Using a combination of these parameters (testicular length, body condition score and age) as a tool for decision making for alpaca husbandry under Swedish conditions is suggested.
authors.affiliation: Division of Reproduction, Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 75007, Uppsala, Sweden. mariacelina.abraham@slu.se.
authors.forename: Maria Celina
authors.initials: MC
authors.lastname: Abraham
authors.affiliation: Division of Reproduction, Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 75007, Uppsala, Sweden. jopu0001@stud.slu.se.
authors.forename: Johanna
authors.initials: J
authors.lastname: Puhakka
authors.affiliation: Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, 75007, Uppsala, Sweden. aleruete@gmail.com.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Ruete
authors.affiliation: Division of Reproduction, Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 75007, Uppsala, Sweden. essraa.m.al.essawe@slu.se.
authors.forename: Essraa Mohsen
authors.initials: EM
authors.lastname: Al-Essawe
authors.affiliation: National Veterinary Institute, 75189, Uppsala, Sweden. kerstin.de-verdier@sva.se.
authors.forename: Kerstin
authors.initials: K
authors.lastname: de Verdier
authors.affiliation: Division of Reproduction, Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 75007, Uppsala, Sweden. jane.morrell@slu.se.
authors.forename: Jane Margaret
authors.initials: JM
authors.lastname: Morrell
authors.affiliation: Division of Reproduction, Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 75007, Uppsala, Sweden. renee.bage@slu.se.
authors.forename: Renée
authors.initials: R
authors.lastname: Båge
mesh_terms: D000375:Aging; D000818:Animals; D001823:Body Composition; D002161:Camelids, New World / Q000254:growth & development / Q000502:physiology*; D008297:Male; D013091:Spermatogenesis; D013094:Spermatozoa / Q000502:physiology*; D013548:Sweden; D013737:Testis / Q000033:anatomy & histology*
references.citation: J Reprod Fertil Suppl. 1979;(27):13-7
references.pmid: 289781
references.citation: Reprod Fertil Dev. 2013;25(4):683-90
references.pmid: 22951252
references.citation: Anim Reprod Sci. 2000 Mar 15;58(3-4):169-95
references.pmid: 10708894
references.citation: Anim Reprod Sci. 2004 Feb;80(3-4):353-61
references.pmid: 15036510
references.citation: Anim Reprod Sci. 2011 Apr;124(3-4):237-43
references.pmid: 20875933
references.citation: Theriogenology. 2012 Apr 15;77(7):1398-405
references.pmid: 22225693
references.citation: J Anim Sci. 1990 Apr;68(4):1087-96
references.pmid: 2185207
references.citation: Theriogenology. 2008 Aug;70(3):508-14
references.pmid: 18533244
references.citation: J Anim Sci. 1969 Jul;29(1):41-7
references.pmid: 5356694