Genetic parameters for udder morphology traits either subjectively assessed or exactly measured, and a combination of both sets of traits were estimated using multi-trait animal model and algorithm REML （program VCE ...Genetic parameters for udder morphology traits either subjectively assessed or exactly measured, and a combination of both sets of traits were estimated using multi-trait animal model and algorithm REML （program VCE 4.0）. Purebred Tsigai and Improved Valaehian breeds, and crossbreds with Lacaune and East Friesian were studied. Subjectively assessed traits included udder depth （UD）, cistern depth （CD）, teat placement （TP）, teat size （TS）, udder cleft （UC）, udder attachment （UA） and udder shape （US）. Exact measurements included udder length （UL）, udder width （UW）, udder depth （UDEx）, cistern depth （CDEx）, teat length （TL） and teat angle （TA）. Heritabilities estimated for subjectively assessed traits were lower than those estimated for exact measurements and ranged from 0.090 （UA） to 0.294 （CD）. Heritabilities estimated for exact measurements ranged from 0.102 （UW） to 0.448 （CDEx）. In simultaneous evaluation of four subjectively assessed traits and corresponding exact measurements, heritabilities remained almost the same. High genetic correlations （0.855 to 0.937） between UD and UDEx, CD and CDEx, TS and TL and between TP and TA were found. These findings allow presuming that genetic evaluation based on subjectively assessed traits could become an effective tool in selection programs aimed at improvement of udder morphology in dairy ewes.展开更多
文摘Genetic parameters for udder morphology traits either subjectively assessed or exactly measured, and a combination of both sets of traits were estimated using multi-trait animal model and algorithm REML （program VCE 4.0）. Purebred Tsigai and Improved Valaehian breeds, and crossbreds with Lacaune and East Friesian were studied. Subjectively assessed traits included udder depth （UD）, cistern depth （CD）, teat placement （TP）, teat size （TS）, udder cleft （UC）, udder attachment （UA） and udder shape （US）. Exact measurements included udder length （UL）, udder width （UW）, udder depth （UDEx）, cistern depth （CDEx）, teat length （TL） and teat angle （TA）. Heritabilities estimated for subjectively assessed traits were lower than those estimated for exact measurements and ranged from 0.090 （UA） to 0.294 （CD）. Heritabilities estimated for exact measurements ranged from 0.102 （UW） to 0.448 （CDEx）. In simultaneous evaluation of four subjectively assessed traits and corresponding exact measurements, heritabilities remained almost the same. High genetic correlations （0.855 to 0.937） between UD and UDEx, CD and CDEx, TS and TL and between TP and TA were found. These findings allow presuming that genetic evaluation based on subjectively assessed traits could become an effective tool in selection programs aimed at improvement of udder morphology in dairy ewes.
