杂交对撒坝猪肉质的影响

本研究选用以撒坝猪为母本的三个杂交组合(杜×撒、约×撒、杜×约×撒)的肥育猪18头进行屠宰测定,分别对肉的pH值、大理石纹、肉色、失水率、贮存损失、熟肉率、嫩度、化学成分、组织学成分等进行测定,并与撒坝猪进行对比。结果表明,与撒坝猪相比,三个杂交组合的日增重和瘦肉率显著高于撒坝猪(P<0.01);在肉质方面:干物质含量下降,肌纤维直径变粗,失水率和嫩度变大,粗灰分、粗蛋白、pH值、肉色、大理石纹、贮存损失变化不明显,熟肉率有变高的趋向,但均属于优质肉的范围,未出现PSE肉和DFD肉。     

不同杂交组合羔羊6月龄体重和体尺的聚类与主成分分析

为研究不同杂交组合羔羊体尺和体重之间的关系,对 548 只不同杂交组合 6 月龄羔羊的体重、体高、体长、胸围、管围进行了聚类分析和主成分分析。 结果表明,主成分分析将体尺指标分为重量因子和宽度因子 2 个主成分,澳湖、杜湖和萨湖杂交一代羔羊累计贡献率分别为 73.265%、75.222%和 79.463%;聚类分析将体尺性状分为 2类,与主成分分析结果一致;建立其综合评价模型表达式,其中,澳湖杂交一代羔羊 F₁=0.576Y₁+0.156Y₂,杜湖杂交一代羔羊 F₂=0.603Y₁+0.150Y₂,萨湖杂交一代羔羊 F₃=0.658Y₁+0.136Y₂,综合得分萨湖杂交一代羔羊>杜湖杂交一代羔羊>澳湖杂交一代羔羊。     

15个柞蚕杂交组合部分数量性状主成分的评估分析

数量性状的主成分分析是评价杂交种综合性状优劣的重要手段之一。对15个柞蚕杂交组合的产茧量、千粒茧质量、收蚁结茧率、死笼率、发病率、不受精卵率6个数量性状进行主成分分析,将6个性状归纳为3个主成分,累计贡献率为93.170%。其中:第1主成分为产量因子,主要来自产量和生命力性状,其贡献率为57.924%;第2主成分为育性因子,主要来自不受精卵率,其贡献率为20.526%;第3主成分为生命力因子,主要来自生命力性状,其贡献率为14.719%。根据主成分值对供试杂交组合进行综合评价,结果是582×9906、582×抗大、8822×抗大、582×黑翅、8821×黑翅和582×8821的综合得分较高,为较优的柞蚕杂交组合。     

不同杂交组合商品猪的肉质研究

本研究选用二元长大(L×Y)、三元杜长大(D×LY)、四元皮杜长大(PD×LY)3个杂交组合猪群为试验动物,分别就各自肉质特性进行了测定。结果表明:D×LY肉色评分、嫩度测定结果最佳;PD×LY失水率、熟肉率、嫩度最差,其中熟肉率、嫩度与其他组间差异显著(P<0.05);D×LY肌肉剪切力值最小,与L×Y剪切力值差异不显著(P>0.05),但两者与PD×LY差异极显著(P<0.01)。肌纤维直径PD×LY>L×Y>D×LY,D×LY与L×Y肌纤维直径比较接近,差异不显著(P>0.05),而PD×LY与其他2个组合差异极显著(P<0.01)。粗蛋白含量PD×LY>D×LY>L×Y,其中PD×LY达23.49%,PD×LY与其余2组合间差异均极显著(P<0.01),其余2组合间差异不显著(P>0.05);肌内脂肪含量PD×LY最低,与其余2组合间差异均极显著(P<0.01),D×LY最高,为2.92%,与L×Y组合间差异不显著(P>0.05)。     

主成分分析在奶牛产奶量选择中的应用

应用主成分分析法分析了荷斯坦奶牛体尺及乳房性状的8个指标，选取了累计贡献率达85％以上的前5个主成分，并分析了5个主成分与产奶量的相关关系。结果表明，主成分Ⅰ有可能成为荷斯坦奶牛产奶量选择的指标。     

主成分分析在猪选种选配中的应用

用杭州种猪试验场1999年春产347头长白后备种猪性能测定记录，取平均日增重（X1）、达90kg日龄（X2）、6月龄体重（X3）、体长（X4）、体高（X5）、腿臀围（X6）、背膘厚度（X7）共7个性状作主成分分析。结果表明：主成分作为综合性状可用于选种，一个主成分可构成一个被选择的综合性状，也可用两个主成分构成一个选择指数，后备猪在主成的得分作为选择依据。个体在各个主成分上的得分能很好地反映出该个体在各综合性状上的优劣，因此能对每头后备猪作出较全面的评价，可作为制订选配计划的部分依据。     

灰色关联度分析在猪杂交组合综合评定中的应用

本文详细介绍了灰色关联度分析的使用过程,并把该法引用到猪的研究领域,对撒坝猪及其杂交组合的肥育性能进行了综合评定。结果表明,撒坝猪的肥育性能随选育世代的进展而提高;二元杂交以杜撒和约撒、三元杂交以约长撒和杜约撒肥育性能最好,可将这４个杂交组合作为商品猪杂交模式在云海滇中一带推广利用。     

不同杂交组合猪的肉质测定

选用地方猪、引进猪、培育猪、野猪作为杂交亲本,配置二元、三元共9个杂交组合和1个纯繁亲本,对其进行了10项肉质指标测定,并进行最小二乘分析。结果表明,在10个参试组合中,背最长肌的肉色和大理石纹评分分别为2.9～3.0和2.8～4.0;背最长肌的pH、失水率、减厚率、24h及96h贮藏率分别为6.20～6.79、8.78%～11.76%、33.49%～36.54%、97.04%～98.70%、92.98%～95.89%;臀肌及肋肌的熟肉率分别为69.40%～71.32%和76.96%～79.74%;背膘的含水率、皂价、碘价分别为6.36%～8.16%、175.69～182.40、65.73～66.80。除肉色、大理石纹、碘价外,肌肉pH、熟肉率、失水率、减厚率、24h、96h贮藏率、脂肪含水率、脂肪皂价指标各组合间存在显著(P<0.05)或极显著差异(P<0.01),表现出较大的父本影响。以组合中父本有利效应最高值出现的频率为根据,父本效应依序为杜洛克、湘黄、大约克、长白。同时也反映出湖南地方猪种的沙子岭猪与引进猪种和培育猪种杂交,均不会产生劣质猪肉。     

利用民猪提高猪肉质品质的研究

通过对含不同民猪基因杂交组合育肥猪90kg体重阶段进行屠宰,并进行肉质品质测定,测定指标包括:肌肉pH、肉色、滴水损失、肌肉剪切力值、肌肉大理石纹、肌内脂肪含量。结果表明,以民猪为母本的二元、三元杂交育肥猪屠宰后24h的pH、肉质嫩度、肌内脂肪含量、系水能力均优于不含民猪基因的外三元DYL组合。在优质肉猪生产中,考虑商品肉猪生长速度、饲料报酬等因素,YLM组合可用于优质特色猪肉的生产。     

主成分分析在猪育种工作中的应用

用主成分分析法对杭州大观山猪育种公司种猪场 ,1 999年春产 34 7头长白后备猪性能测定记录 ,分取 2月龄至 90kg体重平均日增重 (x1)、达 90kg体重日龄 (x2 )、6月龄体重 (x3)、体长 (x4 )、体高 (x5)、腿臀围 (x6)、背膘厚 (x7)等 7个性状进行分析。结果表明 :主成分分析能将测定性状综合成可反映生长速度 ,瘦肉率、体型状态等几个综合性状即主成分 ,后备猪在各主成分中的得分就是它们在综合性状上的表现 ,由此可对每头后备猪作出较全面的评价 ,利用主成分可以进行个体选择 ,制订选配计划     

基于主成分和聚类分析的优质鸡肉质评价模型的建立

为探讨优质鸡肉质合理评价模型,采用主成分和聚类分析方法对优质肉鸡7个新品系9个与肉质有密切联系的指标进行了分析。结果显示:9个原始指标依据主成分解释总变量和碎石图提取了4个主成分,反映原变量89.82%的信息。第一主成分主要综合了失水率、肌纤维面积、肌纤维密度和pH值信息,命名为质构因子;第二主成分主要综合了VB1、肌纤维密度、肌纤维面积和肌内脂肪(IMF)的信息,命名为作肉质因子;第三主成分综合了嫩度、肉色和肌内脂肪的信息即感官因子;第四主成分综合了肌苷酸、肌内脂肪含量和肉色的信息看作风味因子。聚类分析将9个肉质指标分为3类,聚类结果与主成分分析基本一致,综合利用主成分和聚类分析结果制定了优质鸡的肉质评价模型,为优质鸡选育和肉质评价提供了理论依据。     

基于主成分分析法建立鸭肉质的评估模型

对金定鸭、樱桃谷鸭、苏牧麻鸭和番鸭的失水率(X1)、剪切力(X2)、pH值(X3)、肉色(X4)、粗脂肪((X5)、多不饱和脂肪酸(PUFA,X6)、必需脂肪酸/(EFA,X7)、肌原纤维直径(X8)等8个肉质指标进行了测定,运用主成分分析对肉品质指标进行分析,并建立了主成分综合评价模型(y=-0.301zx1+0.367zx2-0.033zx3-0.223zx4-0.342zx5+0.250zx6+0.249zx7+0.267zx8).结果表明,选取前2个特征值作为2个主成分(累计贡献率达到85.15％),基本上反映了原所有肉质指标包含的全部信息;番鸭主成分综合得分最高,其次分别为金定鸭、苏牧麻鸭,樱桃谷鸭表现较低,结果与预期完全吻合.     

Production,performance, slaughter characteristics,and meat quality of Ziwuling wild crossbred pigs

Wild boars, because of their large size and ability to survive adverse conditions, are usually used to cross with domestic breeds to improve the quality of domesticated pigs. This study aimed to investigate the growth performance, slaughter performance, and meat quality of Ziwuling crossbred pigs. Crossbred pigs in four groups (n = 8 per group, 4 boars and 4 sows, all aged 100 days), F₁ [wild × B (Bamei)], F₁ × B, F₁ × Y (Yorkshire), and F₁ × F₁, were selected at a commercial pig farm. Growth performance, slaughter performance, and meat quality of these crossbred pigs were determined. Characteristics of fatty acids, amino acids, and longissimus muscle fiber in relation to growth, carcass, and meat quality traits were also investigated. Pigs in F₁ and F₁ × F₁ groups had lower average daily weight gain, water and storage loss rates, larger meat color score, higher muscle amino acid levels, larger muscle fiber diameter, and higher ratio of flavor amino acids to unsaturated fatty acids compared to other groups. Crossbred pigs with higher rate of wild boar’s consanguinity could improve production performance, slaughter performance, and meat quality. Thus, crossbreeding wild pig with domestic breeds might be an effective method to improve meat quality and flavor.     

Genetic parameters for performance and meat quality traits of crossbred pigs housed in two test environments

Genetic parameters were estimated for crossbred progeny of Bavarian Piétrain sires housed in two test environments on the two Bavarian test stations. The data contained 13,980 pigs housed in traditional pens for 2 pigs and 3,454 pigs housed in big pens for 10–14 pigs with automatic feeding system recorded between 2000 and 2004. In total, 584 sires having progeny in both housing systems were available to estimate genetic correlations between the two test environments. The analysis showed that the housing of pigs in big pens is more demanding with respect to the test design than in 2-pig pens. Further, the results show differences in both phenotypic performance and genetic parameters between the two environments. Daily gain is lower and lean meat content is higher in big pens with automatic feeding system. Therefore, it is suspected that pigs develop slower in the new housing due to a different feed intake behavior in comparison to 2-pig pens. This might be the main reason for the moderate genetic correlations among fattening performance traits (0.5–0.7 ± 0.13), which result in re-rankings of selection candidates depending which kind of information is utilized. Genetic correlations of slaughter and meat quality traits, however, are close to 1. Differences between the variance components in the two test stations have been found and simple pooling of data is problematic with respect to the breeding value estimation.     

Meat quality of British crossbred pigs

Data for 3356 pigs taken from the first two years of MLC's Commercial Product Evaluation were used to examine the effects of genotype (commercial crossbred pigs from different breeding companies and a purebred Large White samples), sex, feeding regimen and slaughter weight on meat quality characteristics. Muscle pH at 45 min post mortem (pH₁) and after overnight cooling (pH₂), M. longissimus colour (MLD colour) and subjective assessment of muscle condition were examined.The overall means for pH₁ and pH₂ were 6.41 and 5.81, respectively and 7.8% of pH₁ values were below 6.0. Subjective assessment indicated that 4.7% of carcasses showed signs of pale, soft, exudative muscle (PSE) and 0.1% dark, firm, dry muscle. The effect of genotype was significant on all characteristics, although the differences were small: the percentage of subjectively assessed PSE carcasses ranged from 2.2 to 8.2. The effects of sex, feeding regimen and slaughter weight were negligible. Meat quality traits were poorly correlated with carcass dissection and assessment characteristics, the highest correlations being recorded between pH₁ and ham conformation score (?0.14) and between MLD colour and M. longissimus area (+0,17).     

基于主成分分析综合评价23份白沙枇杷果实营养品质

为了科学的评价不同白沙枇杷品种果实品质指标,建立高效白沙枇杷果实品质评价体系,本研究通过相关性分析法和主成分分析法对23份白沙枇杷果实的11个品质指标进行了系统分析。结果表明,不同品种的果实各个品质指标之间存在较大差异,且具有不同程度的相关性。采用主成分分析法从11个品质指标中提取出4个主成分因子。综合相关性分析和主成分分析,可溶性糖、可滴定酸、氨基酸(AA)和单果重作为白沙枇杷果实品质性状评价的核心指标。采用相关性分析和主成分分析综合评价方法为评价品质优良的白沙枇杷品种提供参考依据。     

Meat and nutritional quality comparison of purebred and crossbred pigs

Crossbreeding is an effective method of improving the efficiency and profit of production in commercial pig operations. To understand the effect of crossbreeding on meat and nutrient quality, a combination including three purebred (Duroc, D; Landrace, L; Yorkshire, Y) and two crossbred pig lines (Landrace × Yorkshire, LY; Duroc × (Landrace × Yorkshire), DLY) frequently used internationally were studied. The results showed that meat from the LY and DLY crosses had lower values for lightness , shear force and epinephrine and higher values for drip loss, C18:1, insulin, glucagon and monounsaturated fatty acids than D, L and Y pigs. Moreover, LY had higher values for post mortem pH and lower values for a* and b* than the purebreds. In contrast, DLY had lower values for pH and higher values for a* and b* than the purebreds. Meat quality‐related gene analysis showed that the CAST, IGF2 and MC4R gene expression levels in the LY and DLY pigs were significantly higher than those in the D, L and Y pigs. These results indicate that crossbreeding can alter the meat quality, nutritive value, energy metabolism and gene expression of pigs. Future research should focus on microRNA expression and DNA methylation that regulate gene expression and thus affect the meat quality.     

Genetic parameters and purebred–crossbred genetic correlations for growth,meat quality,and carcass traits in pigs

Growth, meat quality, and carcass traits are of economic importance in swine breeding. Understanding their genetic basis in purebred (PB) and commercial crossbred (CB) pigs is necessary for a successful breeding program because, although the breeding goal is to improve CB performance, phenotype collection and selection are usually carried out in PB populations housed in biosecure nucleus herds. Thus, the selection is indirect, and the accuracy of selection depends on the genetic correlation between PB and CB performance (rpc). The objectives of this study were to 1) estimate genetic parameters for growth, meat quality, and carcass traits in a PB sire line and related commercial CB pigs and 2) estimate the corresponding genetic correlations between purebred and crossbred performance (rpc). Both objectives were investigated by using pedigree information only (PBLUP) and by combining pedigree and genomic information in a single-step genomic BLUP (ssGBLUP) procedure. Growth rate showed moderate estimates of heritability for both PB and CB based on PBLUP, while estimates were higher in CB based on ssGBLUP. Heritability estimates for meat quality traits were diverse and slightly different based on PB and CB data with both methods. Carcass traits had higher heritability estimates based on PB compared with CB data based on PBLUP and slightly higher estimates for CB data based on ssGBLUP. A wide range of estimates of genetic correlations were obtained among traits within the PB and CB data. In the PB population, estimates of heritabilities and genetic correlations were similar based on PBLUP and ssGBLUP for all traits, while based on the CB data, ssGBLUP resulted in different estimates of genetic parameters with lower SEs. With some exceptions, estimates of rpc were moderate to high. The SE on the rpc estimates was generally large when based on PBLUP due to limited sample size, especially for CBs. In contrast, estimates of rpc based on ssGBLUP were not only more precise but also more consistent among pairs of traits, considering their genetic correlations within the PB and CB data. The wide range of estimates of rpc (less than 0.70 for 7 out of 13 traits) indicates that the use of CB phenotypes recorded on commercial farms, along with genomic information, for selection in the PB population has potential to increase the genetic progress of CB performance.     

Optimal definition of contemporary groups for crossbred pigs in a joint purebred and crossbred genetic evaluation

In the pig industry, purebred animals are raised in nucleus herds and selected to produce crossbred progeny to perform in commercial environments. Crossbred and purebred performances are different, correlated traits. All purebreds in a pen have their performance assessed together at the end of a performance test. However, only selected crossbreds are removed (based on visual inspection) and measured at different times creating many small contemporary groups (CGs). This may reduce estimated breeding value (EBV) prediction accuracies. Considering this sequential recording of crossbreds, the objective was to investigate the impact of different CG definitions on genetic parameters and EBV prediction accuracy for crossbred traits. Growth rate (G_P) and ultrasound backfat (BF_P) records were available for purebreds. Lifetime growth (G_X) and backfat (BF_X) were recorded on crossbreds. Different CGs were tested: CG_all included farm, sex, birth year, and birth week; CG_week added slaughter week; and CG_day used slaughter day instead of week. Data of 124,709 crossbreds were used. The purebred phenotypes (62,274 animals) included three generations of purebred ancestors of these crossbreds and their CG mates. Variance components for four-trait models with different CG definitions were estimated with average information restricted maximum likelihood. Purebred traits’ variance components remained stable across CG definitions and varied slightly for BF_X. Additive genetic variances (and heritabilities) for G_X fluctuated more: 812 ± 36 (0.28 ± 0.01), 257 ± 15 (0.17 ± 0.01), and 204 ± 13 (0.15 ± 0.01) for CG_all, CG_week, and CG_day, respectively. Age at slaughter (AAS) and hot carcass weight (HCW) adjusted for age were investigated as alternatives for G_X. Both have potential for selection but lower heritabilities compared with G_X: 0.21 ± 0.01 (0.18 ± 0.01), 0.16 ± 0.02 (0.16 + 0.01), and 0.10 ± 0.01 (0.14 ± 0.01) for AAS (HCW) using CG_all, CG_week, and CG_day, respectively. The predictive ability, linear regression (LR) accuracy, bias, and dispersion of crossbred traits in crossbreds favored CG_day, but correlations with unadjusted phenotypes favored CG_all. In purebreds, CG_all showed the best LR accuracy, while showing small relative differences in bias and dispersion. Different CG scenarios showed no relevant impact on BF_X EBV. This study shows that different CG definitions may affect evaluation stability and animal ranking. Results suggest that ignoring slaughter dates in CG is more appropriate for estimating crossbred trait EBV for purebred animals.