杜洛克猪遗传性跛行的体尺比较

COMPARISON OF BODY MEASUREMENTS IN DUROC SWINE GENETICALLY DIFFERENT FOR SEVERITY OF LEG WEAKNESS

试验采用96头杜洛克猪,这些猪是用反相选择跛行的方法所建立的两个品系的第7代后裔,测定其前肢的尺骨长,尺宽,足长和体长是否有差异。品系分为跛行组和健康组,后者表示在前肢结构上发育良好。所有猪都在二个特定日龄测定,平均117日龄和159日龄,并在每圈猪平均体重达到95kg时进行第三次测量,结束试验。资料用变量分析,混合方程包括品系、重复批次、饲料和性别的影响,并以体重或日龄作协方差分析。健康组猪比跛行组猪足长较长(P<0.01),在117日龄大7％,159日龄大14％,在试验结束时大30％。健康组猪的足宽则几乎和跛行组相等。对不同程度跛行选择的影响也表现在猪的体形方面,健康组猪比跛行组猪在159日龄时体长和尺骨长相对较短,在达到上市体重时体长轻短。对不同程度跛行的选择已使社洛克猪的结构发生了许多变化。

Ninety-six Duroc pigs, representing offspring of two lines from the seventh generation of an experiment for divergent selection ior leg weakness, were examined to determine if there were differences in the ulna length,foot ( claw ) width, foot ( claw ) length in the front leg and body length. The lines were designated as low and high lines, with the latter having superior front leg structure. All pigs were measured on two specific dates such that they averaged 117 days and 159 days of age and a third time when the pens averaged 95 kg. Data were analyzed using analysis of variance procedures with a mixed model that included the effects of line, replicate, diet, sex and weight or age as a covariate. The foot length of high-line pigs was significantly longer ( p<0.01 ) than that of low-line pigs at 117 days of age ( + 7 % ) , 159 days of age ( +14% ) or at the end of the test ( +30% ) . The foot width of high-line pigs was nearly the same as that of low-line pigs. Body conformation also seemed to be influenced by selection for different degrees of leg weakness. The high-line pigs had a relatively shorter body length and ulna length than low-line pigs at 159 days of age and shorter body length at market weight. Selection for differing degrees of leg weakness has changed a number of structural characteristics in these Duroc swine.