Genetic of fibre production and fleece characteristics in small ruminants, Angora rabbit and South American camelids

Abstract: This paper reviews genetics of fibre production and fleece characteristics in small ruminant, Angora rabbit and South American camelids with a special distinction between single coat and double coat species. About biology of fibre production there are variations in coat composition and structure, fibre growth pattern and fibre structure and quality between these two main kinds of fibre producing animals. In single coat species all fibres are nearly similar in dimensions and grow permanently while in double coat species coat comprises a coarse outer-coat and a fine inner-coat with variations of coat composition and structure, and fibre growth pattern according to the season with a well defined duration of fibre growth. Genetic basis of hair growth pattern, coat composition and fibre structure are different between species. In small ruminants, these coat characters are additive and due to several genes while in rabbit, several autosomal recessive genes are determining fibre growth, coat composition and structure. In alpaca, the fleece type (Suri or Huacaya) is determined by a single dominant gene. This paper also reviews genetic parameters of fibre production traits in angora goat, angora rabbit and alpaca in which many aspects of the genetic basis of fibre production are analogous. There are many traits controlling both fibre quality and fibre quantity, and most of these traits tend to be moderately to strongly inherited with differences between species so that a rapid genetic progress in any traits is possible and indeed has been achieved. However there are differences in breeding programmes between the double-coated Angora rabbit and the single-coated species Angora goat and alpaca. In double coat species, selection for one single trait, the easy measurable total fleece weight has general beneficial effects on fleece quality. On the opposite, due to antagonistic relations between qualitative and quantitative traits, achieving this goal requires a multi-trait selection index approach. Gene mapping studies have recently identified several putative QTL’s and major genes affecting fibre production and fleece characteristics in sheep, goat and rabbit and were reviewed. The whole genome sequence of sheep and rabbit which will be available in the near future and the use of high-density SNP chip will allow fine mapping and dissection of the genetic basis of many production traits including fibre and fleece characteristics and thus will contribute to improving the efficiency, profitability and sustainability of small ruminant and rabbit fibre production.