美、英、新丹系长白猪生长性状比较试验

本试验旨在比较新丹系、美国、英系三个品系的肥育性能差异，用新丹系20头（公12、母8），美系27头（公17、母10），英系26头（公16、母10），采用群养单饲法，在一致的条件下试验猪从25kg体重养至90kg体重结束。结果表明：25－90kg平均日增重新丹系为920g,美系824g,英系820g；饲料报酬新丹系2．512、美系2．930、英系2．823；达90kg体重日龄新丹系145．5天、美系150．5天、英系152．5天。     

大约克夏猪生产性能的选育研究

通过群体继代选育法来提高大约克夏猪的生产性能,经过连续7年的选育,每个世代随机抽取24头猪作肥育试验,以测定大约克夏猪的生产性能。结果表明：大约克夏猪断奶体长增长7．66％,初配、初产体长分别增长16．90％和14．75％;肥育期平均日增重提高127．5g,料肉比下降19．72％;胴体瘦肉率则提高4.58个百分点;窝产仔数提高1．42头,初生重变化不大,断奶重则提高0.45kg。     

大约克夏猪肥育性状的选育研究

通过群体继代选育法来提高大约克夏猪的肥育性状，通过连续7个世代的选育，每个世代随机抽取24头猪作肥育试验。结果表明：大约克夏猪的断奶体长增长了7．66％，6月龄体长增长百10．19％；断奶体重增长了5．83％，60日龄体重增长了16．84％；育肥猪平均日增重提高了127．50g，科肉比下降了16．47％。     

不同来源大白猪在海南的适应性观察

观察比较了三个不同来源的大白猪在海南的表现。加系大白猪肢蹄粗壮结实，乳头和生殖器官发育好，发情明显，受胎率高，头胎产仔数显著高于英系，一般生产条件下170日龄达100kg体重，全群检测末查出氟烷基因，能适应海南气候，在配套系中宜作基础母本；丹系大白猪168日龄达100kg，料重比2．55，瘦肉率高达70％，高于加系、英系3个百分点，不携带氟烷基因，作母系父本具有优势；英系大白猪不适应海南湿热环境，对萎鼻特别敏感，表现增重极显著低于加系和丹系，且经氟烷基因检测，Hal^n基因频率达12．5％，相应肉质较差，在本场被淘汰。     

应重视保持和利用我国地方猪种的肉质优势

许振英教授组织全国协作．于1979-1983年对民猪，金华猪、内江猪、香猪、大花白猪、嘉兴黑猪、姜曲海猪、二花脸猪、大围子猪等地方猪种的种质特性进行了系统研究，其中肉质研究以长白、大白猪为对照，研究结果表明．中国地方猪：①肉色鲜红，无PSE肉；②pH比对照高( 0．32)；③系水力强(失水率比对照低5．59个百分点)：④肌肉大理石纹适中(3分和4分居多)；⑤肌肉水分少(-2．62个百分点)；⑥肌内脂肪含量高( 2．23个百分点)；⑦肌纤维直径小(一16．7l％)；⑧单位面积内肌纤维根数多( 26.3％)；     

英系大约克夏猪生产性能测定初报

对引进的英系大约克夏猪母猪40头、公猪3头进行了3年的扩繁生产,经测定,英系大约克夏猪年产胎次2.2胎,初产10.81头/胎,经产12.63头/胎,初生窝重、初生个体重分别为17.34kg、1.48kg,35日龄断奶个体重、断奶窝重分别为10.60kg、108.54kg。     

甘肃黑猪导血建系试验研究

甘肃黑猪导入1／4杜洛克血，选育瘦肉型品系（Ⅱ系），经过3个世代的选育，基本保持了甘肃黑猫的黑毛色、体型外貌和繁殖性能，较快的提高了生长速度和胴体瘦肉率。用新品系作母本，与长白和大约克夏公猪杂交，杂种猪平均日增重高14～24克，瘦肉率提高4．9～53个百分点，是比原甘黑更好的杂交母本，达到了建系要求。     

南方不同季节采用发酵床养猪技术饲养保育猪的研究

为探讨南方不同季节使用发酵床养猪技术饲养保育猪的效果，试验分2个阶段进行，每一试验阶段分别选择20kg左右的杜长大杂种猪230头，随机分为2组，每组5个重复，每个重复23头猪，其中1个组采用发酵床技术饲养，另1个组采用高床漏缝栏饲养。第1阶段试验在高温季节（2008年8—9月）进行，结果表明，高床漏缝栏组在日增重、采食量、料重比、呼吸道病发病率、腹泻率方面均好于发酵床组，但差异不显著；发酵床组死亡率3．48％，比高床漏缝栏组死亡率1．30％高2．18个百分点。第2阶段试验在低温季节（2008年12月至2009年1月）进行，结果表明，高床漏缝栏组在日增重、采食量、料重比、呼吸道病发病率方面均好于发酵床组，但差异不显著；高床漏缝栏组腹泻率低于发酵床组，差异显著；发酵床组死亡率为5．21％，比高床漏缝栏组死亡率3．04％高2．17个百分点。高温与低温季节使用发酵床饲养20妇保育猪的对比结果显示，高温季节的采食量高于低温季节，差异极显著；不同季节在日增重方面差异不显著；低温季节保育猪的料重比低于高温季节，差异极显著；呼吸道病发病率，高温季节与低温季节差异不显著；低温季节腹泻率比高温季节高，差异极显著；高温季节猪的死亡率是3．48％，比低温季节保育猪的死亡率5．21％低1．73个百分点。     

英系大约克与加系大约克相交后的繁殖性状

通过对英系大约克与加系大约克种猪杂交，比较１２４ 头分娩（ 经产） 母猪的繁殖性状（ 产仔总数、产活仔数、初生重、２０ 天成活数、２０ 天个体重、２８ 天断奶个体重）。观察结果显示：二品系杂交后比纯英系、纯加系种猪在２８ 天断奶个体重上有极显著的杂交优势。在产仔总数、产活仔数上加系大约克明显高于英系大约克种猪，在正反交组合中，从产仔总数、产活仔数两项看英加系比加英系略优一点，但无显著差异     

阳新猪生产性能测定报告

阳新猪是我国华北和华中两个类型的杂交后代经长期选育而形成的优秀地方猪种，已处濒危状态，亟需进行抢救性的保护。2008年经测定，阳新猪乳头数均值为13．96个，第2胎产活仔数10．11头，初生窝重10．07奴，繁殖性能有下降趋势。阳新猪15～80kg阶段日增重412g，杜阳猪451g，二者差异不显著。料重比阳新猪4．28，杜阳猪3．31，杂种优势明显。阳新猪屠宰率67．03％，比杜阳猪（73．07％）低6．04个百分点；瘦肉率47．6％，比杜阳猪（57.3％）低9．7个百分点；后腿比例27．82％，比杜阳猪（31．04％）低3．22个百分点，均差异显著。杂交有效地提高了商品猪的胴体性状。阳新猪的胃重比杜阳猪高16．7％，差异显著。阳新猪肌内脂肪为4．448％，系水力为89．71％，屠宰后45rain的pH均在6以上，无PSE肉，肌肉色值15．58％，大理石纹评分为3，肉色鲜红，表观有水晶样透明感，烹饪后口感细嫩多汁，肉香味浓。     

Performance of Duroc and Yorkshire boars and gilts and reciprocal breed crosses

Analyses of variance were computed for records on growth and body composition traits made in 1983 by 255 boars and gilts in selected and control lines of Durocs and Yorkshires and their reciprocal crossbreds. Previous selection over a period of several generations was mainly on an index of sow productivity including preweaning litter sizes and weight. Animals in the select lines were selected for high index values; animals in the control lines were selected to average near the mean index values of that year and line. Breeding animals in all four lines during that period were basically randomly selected with regard to growth rate or body composition traits. The same boars sired both purebred and crossbred litters in 1983. Traits analyzed were average daily gain (ADG) during a standard test period from 56 d of age to 90.7 kg and average backfat thickness (ABF) and longissimus muscle area (LMA) from ultrasonic scans at 90.7 kg. Crossbred pigs had greater (P less than .01) ADG than purebred pigs, but did not differ (P greater than .05) in ABF or LMA. Heterosis was 8.2% for ADG. Crossbreds with Yorkshire dams had thinner (P less than .01) ABF and larger (P less than .01) LMA than crossbreds with Duroc dams. Boars had greater (P less than .05) ADG, thinner (P less than .01) ABF and smaller (P less than .01) LMA than gilts. Correlations between 38 half-sib family averages of purebred and crossbred pigs of the same sex and the same sires were .07, .37 and .24 for ADG, ABF and LMA, respectively. Implications of the above and additional findings for swine breeding strategies are discussed.     

Use of microsatellite markers to detect quantitative trait loci in Yorkshire pigs

To identify genetic markers associated with economic traits in pigs, 157 microsatellite markers were examined in Yorkshire pigs. Thirty eight female Yorkshire pigs were initially examined and six of them were selected as progenitors; half were more than 1.5 standard deviations (SD) above the mean for average daily gain (ADG) and backfat thickness (BFT), and the remaining half were more than 1.5 SD below the mean. These pigs were then mated to male Duroc pigs, and 200 F2 pig offspring were examined for the association of specific alleles with ADG and BFT. To confirm the specific markers identified in the initial analysis, associations of significant markers with economic traits were further examined in 228 additional performance-tested purebred pigs. Twenty-five microsatellite markers were significantly associated with either ADG or BFT, and among these, 17 were associated with both traits. The markers with the highest association to ADG were also associated with BFT. Our study reveals that specific markers could be used to predict economic significance, and confirms several quantitative trait loci (QTL) identified in previous studies. However, further analysis with more closely-spaced microsatellite markers is required to refine predictive values for economic traits and positions of QTL that are reliable for actual phenotypic prediction.     

Comparisons of blood biochemical parameters,digestive enzyme activities and volatile fatty acid profile between Meishan and Yorkshire piglets

This study was conducted to compare physiological characteristics between Meishan and Yorkshire piglets in their early lives. Six healthy purebred Meishan sows and Yorkshire sows with close farrowing dates were used in this research. The piglets sucked their respective sow's milk for 14 days, then they were slaughtered to collect samples of blood, pancreas, contents of stomach, jejunum, cecum, colon as well as feces for analysis of blood biochemical parameters, digestive enzymes, and volatile fatty acid(VFA). The results showed that Yorkshire piglets had higher concentrations of high-density lipoprotein cholesterol(HDL-C) and total cholesterol(TC)(P 0.05). Gastric lipase activity was higher in Meishan piglets but Yorkshire piglets had higher lactase activity(P 0.05). The total VFA together with acetate and propionate in cecum and colon were higher in Meishan piglets than in Yorkshire piglets(P 0.05),but acetate in jejunum and ratio of acetate to propionate in colon were lower in Meishan piglets than in Yorkshire piglets(P 0.05). In conclusion, in early suckling period, significant differences exist in host metabolism and intestinal microbial metabolism between Meishan and Yorkshire piglets.     

Comparisons of carcass traits,meat quality,and serum metabolome between Shaziling and Yorkshire pigs

This study aims to compare the meat quality of Shaziling and Yorkshire pigs and to find the potential indicator in serum for superior meat quality. Six Shaziling and Yorkshire pigs at 30, 60, 90, 150, 210, and300 d of age were selected to examine carcass traits, meat quality, and serum metabolome. The results showed that the body weight, carcass length, and loin eye area of Shaziling pigs at 150, 210, and 300 d of age were significantly lower than those of Yorkshire pigs (P <0.05). Shaziling ...     

Some Factors Influencing the Losses of Pigs Prior to Weaning

Analyses of the records of 244 litters of purebred Yorkshire, Landrace, the crosses, backcrosses and crisscrosses of these two breeds were carried out to evaluate some of the factors influencing the losses of piglets prior to weaning.

There were differences in percentage survival between mating systems, with crossbred Landrace x Yorkshire piglets showing the highest rate of survival.

A direct relationship existed between the duration of farrowing and the incidence of stillbirths. The incidence of stillbirths was higher for male piglets than for female piglets.

Litter size at birth and weight loss of sow from parturition to weaning were important factors in determining litter size at weaning. Litter size at birth however, exerted a more important influence on litter performance than weight loss.

Age of sow had no significant effect on the number of piglets alive at weaning and implied that gilts were apparently as good mothers as sows.

From computed least squares estimates, it was implied that in general, piglets of low birthweights had much less chance of survival than those born with heavier weights.

     

Breed prenatal, breed postnatal and heterosis effects for postweaning traits in swine

Crossfostering techniques were used to evaluate breed prenatal, breed postnatal and heterosis effects in Duroc and Yorkshire swine. Traits analyzed for these effects were: age adjusted to 104 kg (DAYS), backfat adjusted to 104 kg (AJBF), average daily gain (ADG), weight/day of age (WDA), unadjusted backfat (BF) and weight at 154 d (WT154). Breed prenatal (genetics and prenatal maternal) effects were important for BF and WT154 (P less than .10). Pigs gestated by Duroc dams tended to be fatter and weigh more at 154 d than pigs from Yorkshire dams. Breed postnatal effects were important only for AJBF (P less than .05). Pigs reared by Duroc nurses were fatter than pigs reared by Yorkshire nurses. Prenatal dam x postnatal nurse interaction effects were important for BF (P less than .10) and AJBF (P less than .05). Heterosis values were -10.2, 8.0, 13.7, 13.6, 14.1 and 7.7% for DAYS, AJBF, ADG, WDA, WT154 and BF, respectively. Differences between purebred and crossbred pigs were larger when purebred and crossbred pigs were reared in the same litter than when reared separately. These data suggest that intra-litter competition between purebred and crossbred pigs may have a detrimental effect on postweaning growth for purebred pigs.     

约×荣杂种仔猪生长发育性状特点及杂种优势研究

通过对约×荣杂种仔猪生长发育性状特点及杂种优势的研究,发现约×荣杂种仔猪与其亲本品种相比,在平均个体重、日增重和生长强度方面具有明显的杂种优势,在其生长发育过程中,生长发育快,断奶体重大,适应性和抗应激能力比两亲本品种强,是理想的杂交组合。     

大约克夏生长肥育期生长规律的研究

对60头大约克夏从70～190日龄,每隔15d测定体重和背膘厚,分析其生长发育规律。结果表明:①大约克夏生长肥育期的各阶段日龄与体重间的相关系数r≥0.67(P<0.0001)。②Logistic模型和Compertz模型均可拟合大约克夏在生长肥育期的生长曲线(P<0.0001),但Logistic模型(R2=0.9967)优于Compertz模型(R2=0.9694)。③大约克夏130￣160日龄间的背膘厚度与体重保持极小的比值(约0.11),160日龄前背膘厚的分化生长率小于1(0.2653￣0.7711);大约克夏190日龄时体重为119.31kg,背膘厚为14.59mm。     

Follicular development during the prepuberal period of different morphological types of ovaries in Hampshire and Yorkshire gilts fed two planes of nutrition

Changes in follicular development of the ovary at 105, 140 and 175 d of age were observed on 48 prepuberal Yorkshire and Hampshire gilts raised on two planes of nutrition. The follicles from the left ovary were counted and measured by histological techniques. Both the nonatretic and the atretic (more than four pyknotic bodies) antral follicles were classified into six categories according to size, and each category was expressed as percentage of the total number. The proportion of nonatretic follicles belonging to the first category (.19 to .36 mm in diameter) was higher in Hampshire than Yorkshire gilts at d 105 (65.4 vs 47.6%; P less than .05), but not at d 140 and 175. The proportion of atretic follicles to the total number observed was higher in Yorkshire at d 175 than at d 140 and 105 (38.6 vs 21.9 vs 11.6%, respectively; P less than .05), whereas in Hampshire, significant differences were observed only between d 140 and 105 (25.2 vs 3.9%, respectively). The low-plane regimen reduced the percentage of nonatretic follicles of the third (.63 to 1.12 mm) and fourth (1.13 to 2.00 mm) categories in Yorkshire gilts from 14.4 and 7.2% to 9.7 and 4.0%, respectively (P less than .05). According to grouping, size and number of antral follicles, three morphological types of ovaries could be distinguished: honey-comb, grape-like and an intermediate class. Reanalyzing the data accounting for types resulted in radical reduction in the residual variation, hence many significant differences between the two breeds could be identified. At 140 and 175 d of age, Hampshires with honey-comb- and grape-like ovaries had greater numbers of medium and large follicles than Yorkshires (P less than .001). It is concluded that the slower follicular development observed at 105 d of age in Hampshire, as compared with Yorkshire gilts, allows accumulation of greater numbers of antral follicles at 140 and 175 d for both morphological types of ovaries.     

Estimation of direct and maternal heritability and genetic correlation for backfat and growth rate in swine using data from centrally tested Yorkshire boars.

The purpose of this study was to estimate components of variance and covariance for backfat and growth rate in swine tested in central test stations in the United States. Data were collected from 26 central boar test stations from 1984 through 1990. The traits analyzed were backfat adjusted to a 104.5-kg basis and ADG adjusted to a 36-kg on-test weight. Records from 7,951 purebred Yorkshire boars were analyzed. Contemporary groups were defined as boars of a breed that were tested and sold as a common group in a test station. Variance components were estimated using a pseudo-expectation method with a multiple-trait, sire-maternal grandsire model. Direct heritabilities for backfat and ADG were estimated to be .56 and .24, respectively. Direct maternal effects were significant for both backfat and ADG; they accounted for 11 and 23% of the variance, respectively. The additive genetic correlation between backfat and ADG was approximately zero. Within this population of centrally tested Yorkshire boars, heritability seems to be high for backfat and moderate for ADG, with a significant maternal effect on each trait.