A review of thoracolumbar vertebrae number variation in sheep breeding

Abstract

The variation in thoracic and lumbar vertebrae numbers (TLVn) affects economically important traits in sheep breeding. A wide variation of TLVn ranging from 17 to 21 was reported in different sheep breeds such as Texel, Scottish Blackface, Suffolk, Kazakh Fat Rumped, and Ujimgin. In general, highest TLVn were 44.87 % and 43.89 % for 13 thoracic vertebrae number (TVn) with 6 lumbar vertebrae number (LVn), and 13 TVn with 7 LVn formation for sheep breeds, respectively. Modern methods such as computed tomography (CT) or digital radiography (DR) technology can provide a significant solution for collecting phenotypes of TLVn variation in live animals. In addition, molecular studies have focused on identifying genetic markers of TLVn variation in sheep. Some specific variants in 9 genes (VRTN, NR6A1, ABCD4, SYNDIG1L, SFRP4, CPOX, KCNH1, CPQ and Hox) addressed the effects of TLVn variation in sheep breeds. Moreover, each segment of the TVn and LVn appears to have different effects on sheep performance, such as carcass composition, lion area, carcass length, and meat yield. Therefore, the concept of increased TVn and LVn needs to be clarified from a sheep selection perspective. There is potential for increasing TVn and LVn to improve meat yield and carcass quality in sheep breeding programs.