The use of ultrasonics in phenotype testing of rams

[摘要] An experiment in developing phenotype testing of rams was begun in 1975. One of the investigated characteristics was the area of the MLD measured ultrasonically. The experiment consisted of 130 rams on two feeding levels. In one group the rams were fed both hay and concentrates ad libitum, while in the other group concentrates were restricted. 124 of the rams were ultrasonically photographed, 61 from the ad libitum and 63 from the restricted feeding group. Weights (5 mths), daily gains and areas of MLD were approximately 39.3 kg (s.d. 4.4), 249 g (42), 11.6 cm2 (1.35) and 33.1 kg (4.6), 182g (32) and 9.4 cm2 (0.96) respectively. The ultrasonic area of the MLD correlated 0.52 and 0.32 with the area measured from carcasss. As a rule the ultrasonic area of the MLD correlated positively with other measures of live animals and slaughter results, but correlations with measures of relative meatiness were almost all nonsignificant. In completing the information concerning dressing weight and quantity of meat given by live weight, the ultrasonic area of the MLD proved to be the best of the measures on live animals. The rams in this experiment came from all over Finland but the next stage will consist mostly of progeny of the rams now selected (the two best and the two medium ones from both groups). With progeny testing the success of selection based on phenotype will be checked.