东北民猪、长白猪和三江白猪主要组织异速生长模式的研究

文中指出,考察的组织的早熟性顺位,民猪为骨骼>肌肉>皮肤>腹外脂肪>总脂肪>板油,而长白猪和三江猪为骨骼>皮肤>肌肉>腹外脂肪>总脂肪>板油。肌体组成在多数情况下长白猪具有较高瘦肉率和较低脂肪率,所有各屠宰期长白猪与三江猪之间在瘦肉率和总脂肪率上差异均不显著。各组织阶段增重比值:随着活重的增长各脂肪性状的阶段增重比值相应增加,而肌肉组织的相对增长比值在活重15—30公斤阶段各品种猪均达最高值,此后,民猪显著递降,三江猪缓慢递降而长白猪为降—升—降的态势。

COMPARATIVE STUDY ON THE ALLOMETRIC GROWTH PATTERN OF MAJOR TISSUES OF MIN ZHU, LANDRACE AND SANJIANG WHITE PIG BREEDS

Data for the present study were obtained from the dissection of 90 pig carcasses of three breeds, Min Zhu(M), Landrace(L) and Sanjiang White(SW). 3 barrows and gilts of each breed were serially slaughtered at either 15, 30, 60, 90 and 120 kg liveweights. The left side of the carcass (half carcass) was dissected into muscle, total fat (subcutaneous + intermuscular+perirenal fat), bone and skinto study tissue growth and carcass composition. Data for individual tissues and the half carcass weights were transformed to logarithms to establish part-to-whole regression from the allometric growth equation y= ax~b) taking either half carcass weight or the weights of muscle + bone in the half carcass as independent variables. The data for growth coefficients obtained from the said calculations indicated that the ranking of tissue maturity for M was: bone>muscle>skin> external abdominal fat>total fat>perirenal fat; those for L and SW were: bone> skin>muscle>external abdominal fat>total fat>perirenal fat. The specifity of tissue growth pattern for M was that, muscle was earlier developing than skin. Growth coefficient (b=0.935) of the skin was almost similar to the b (0.953) of muscle for L and for SW (b = 0.932). There was a tendency for the fattest breed (M) to have a lower coefficient of muscle growth and the leanest (L) to have a higher one, and for SW to occupy an intermediate position with an inclination toward the L. At most slaughter weights, the L pigs had higher percent lean and lower percent fat in the side. However, differences in percent lean and total fat between L and SW at all slaughter weights were not significant. Carcasses of SW slaughtered at 120kg liveweight were almost equal in composition to those of L. Percent skin of M slaughtered at all weights exceeded the corresponding values of L and SW. Data for the relative growth rate defined as unit weight gain of individual tissues relative to each kg half carcass weight gain between two slaughter weight intervals indicated that as liveweight increased from 15 to 120kg, the proportionate growth rate for all fat traits increased linearly, and that the proportionate growth rate of muscle in all breeds studied reached a maximum during the 15 to 30kg period, after which the rate of M decreased significantly, that of SW slightly, while that of L tended to increase slightly at first, followed by a decrease. The L pigs exhibited a higher growth rate for muscle and lower for fat than either M or SW pigs at between 60 and 90kg liveweignts, but at heavier (90-120kg) liveweight the SW pigs had a higher growth rate of muscle than the L and M pigs. Results suggested that selection for increasing percent lean in the carcass of SW pigs progressed by 1.112 percentage unit per generation. Progenies of the 3 rd generation had 4.446 percentage units more lean than the backcross progenies. Results of present study confirmed that selection for improved lean productivity on the basis of the selection index used has thus been effective. Problems for further increase of percent lean were discussed.