Bereskin B, Hetzer H O
J Anim Sci. 1986 Aug;63(2):395-408. doi: 10.2527/jas1986.632395x.
Two Duroc and two Yorkshire lines of pigs that had been selected at Beltsville Agricultural Research Center for 12 and 10 generations, respectively, for either thinner or thicker backfat were mated to produce all possible pure lines and reciprocal crosses in 1967, 1969 and 1970. Data for littermate gilts and barrows from 136 litters were analyzed to estimate genetic and maternal influence on individual pig weights at birth, 21 d, 56 d and 140 d of age; age at 79.4 kg; average backfat thickness at 79.4 kg and postweaning average daily gain (56 d to 79.4 kg). Pure-line gilts differed among breed-lines (P less than .05 or P less than .01) for all traits except weight at 56 d. Gilts of the two low-fat lines were heavier than gilts of the two high-fat lines through 56 d of age, but Yorkshire low-fat gilts were lightest at 140 d, were oldest at 79.4 kg and had the slowest daily gain, in addition to the least backfat. The Duroc low-fat line gilts were heaviest at 140 d, youngest at 79.4 kg and were second thinnest in backfat. Among pure-line barrows, the low-fat lines were heaviest at birth, at 21 d and at 140 d and were thinnest in backfat. Line-cross gilts were heavier than pure-line gilts at all four ages, were younger at 79.4 kg and higher in daily gain. Among barrows, line crosses were heavier in all weights except at 21 d, were younger at 79.4 kg and were higher in daily gain than pure lines. Differences between pure lines and line crosses in backfat were not significant for either sex. Heterosis varied from 6.5 to 16.7% among weights and growth traits. Pigs of both sexes differed among breed-lines in general combining ability for all traits except 21-d weight, and differed in maternal ability for weights through 56 d and for backfat. Specific combining ability (SCA) was significant only for intra-breed crosses for weight at 21 d, and for inter-breed, intra-line crosses for 21- and 56-d weights and for age at 79.4 kg among gilts, with no significant effects in SCA for any trait among barrows. General combining ability was not correlated with maternal effects for any trait except 21-d weight, for which they were positively correlated (r greater than .80).
1967年、1969年和1970年，将在贝尔茨维尔农业研究中心分别经过12代和10代选育的两个杜洛克猪品系和两个约克夏猪品系（分别选作背膘更薄或更厚的品系）进行交配，以产生所有可能的纯系和正反交组合。对来自136窝的同窝小母猪和小公猪的数据进行了分析，以估计遗传和母体对出生时、21日龄、56日龄和140日龄个体猪体重；79.4千克时的年龄；79.4千克时的平均背膘厚度以及断奶后平均日增重（56日龄至79.4千克）的影响。除56日龄体重外，所有性状的纯系小母猪在品系间均存在差异（P小于0.05或P小于0.01）。两个低脂系的小母猪在56日龄前比两个高脂系的小母猪重，但约克夏低脂小母猪在140日龄时最轻，在79.4千克时年龄最大，日增重最慢，背膘也最少。杜洛克低脂系小母猪在140日龄时最重，在79.4千克时最年轻，背膘厚度排第二薄。在纯系小公猪中，低脂系在出生时、21日龄和140日龄时最重，背膘最薄。品系杂交小母猪在所有四个年龄阶段都比纯系小母猪重，在79.4千克时年龄更小，日增重更高。在小公猪中，品系杂交猪除21日龄外，在所有体重阶段都更重，在79.4千克时年龄更小，日增重比纯系更高。纯系和品系杂交猪在背膘方面的差异对两性均不显著。杂种优势在体重和生长性状方面从6.5%到16.7%不等。除21日龄体重外，所有性状的两性猪在一般配合力方面在品系间存在差异，在56日龄前的体重和背膘方面在母体能力上存在差异。特殊配合力（SCA）仅在21日龄体重的品种内杂交以及小母猪中21日龄和56日龄体重及79.4千克时年龄的品种间、品系内杂交中显著，对公猪的任何性状在SCA中均无显著影响。除21日龄体重外，一般配合力与任何性状的母体效应均无相关性，21日龄体重二者呈正相关（r大于0.80）。
