应用动物模型REML法估计金华猪生长性状遗传参数

资料取自金华猪场 1979～ 1999年金华后备猪生长发育测定记录。采用动物模型约束性最大似然法 (REML) ,对该猪群的遗传参数进行估计。测定 14 18头金华后备猪的生长发育记录。结果表明 :4月龄、6月龄的体质量、体长、体高、胸围、腿臀围、膘厚、2～ 6月平均日增体质量的遗传力分别为 0 .4 8± 0 .12、0 .4 7± 0 .12、0 .4 9± 0 14、0 4 8± 0 .14、0 .4 3± 0 .12、0 .4 1± 0 .11、0 .4 8± 0 .14、0 .30± 0 .13,与国内外文献报道结果相近。初生与 6 0日龄、6 0日龄体质量与 4月龄体质量、6 0日龄体质量与 6月龄体质量、4月龄体质量与 6月龄体高、6月龄体质量与 6月龄体高的遗传相关分别为0 .5 3、0 .5 8、0 .4 2、0 .4 8和 0 4 3,为中高强度相关。而 4月龄体质量与 6月龄体质量 (rA0 .84、rp0 .78)、4月龄体质量与 6月龄体长 (rA0 .88、rp0 .71)、4月龄体质量与 6月龄胸围 (rA0 .6 1、rp0 .5 5 )、6月龄体质量与 6月龄体长 (rA0 .84、rp0 .82 )、6月龄体质量与 6月龄胸围 (rA0 .74、rp0 .82 )均呈强的正相关     

应用动物模型REML方法估计猪遗传参数的研究

本文以北京花猪为材料,采用动物模型非求导约束最大似然法（ＤＦＲＥＭＬ）对该猪群的遗传参数进行了估计。初生重、２１日龄体重、平均日增重、料重比、达１００ｋｇ日龄、６月龄体重、屠宰率、总产仔数、产活仔数和出生窝重的遗传力的估计值分别为０．２５、０．２１、０．３３、０．３１、０．３１、０．３４、０．４２、０．１４、０．１７和０．２１。出生重与出生窝重和２１日龄重、平均日增重与６月龄体重、出生窝重与产仔数、总产仔数与产活仔数之间存在着较强的遗传正相关;平均日增重与耗料增重比、达１００ｋｇ日龄与６月龄体重之间存在着较强的遗传负相关,出生重与产仔数之间存在着中等遗传负相关。     

金华猪繁殖性状的统计学分析

采用金华猪场1979～1999年金华猪的繁殖性能生产记录,测定了2355头金华母猪(纯繁)和金华猪(K)与约克夏(Y)、长白(L)、杜洛克(D)、汉普夏(H)杂交后代的繁殖性状。综合考虑各性状的各种固定效应,并建立各性状的固定效应模型,对其进行方差分析,计算各性状的最小二乘均数(LSM),对影响较大的固定效应在各观察水平上的LSM进行分析与比较。固定效应分析结果表明:品种、胎次、季节、年份对产活仔数、60日龄头数的影响极显著(P<0.01)。而产仔数受胎次、季节、年份的影响极显著(P<0.01)。金华猪纯繁组以及LK×D、K×L杂交组的产仔数、产活仔数较高,K×L、K×Y杂交组合的60日龄头数较高。而其他外来品种之间杂交组合的繁殖性状显著低(P<0.01)。说明金华猪具有高产的优良特性。金华猪产仔数、产活仔数随胎次逐渐递增,6～7胎达到高峰。金华猪夏季产仔数最高为15.72±1.66,显著高于秋、春、冬(P<0.01)。产活仔数春、夏、秋季无差异(P>0.05),但高于冬季(P<0.05)。1982～1987年间金华猪无论是产仔数还是产活仔数整体都维持较高的水平。     

梅山猪繁殖性状遗传参数及其影响因子分析

以纯种梅山猪25年的信息资料为基础,首次对梅山猪进行总体遗传结构的分析,用数量遗传学原理计算该品种的繁殖性状。结果显示,产仔性能的遗传力小于0.1,窝重的遗传力与同类研究相同。母体效应随仔猪的出生时间而下降,但产仔性能母体效应的比重达到10%。混合模型中固定因子普遍呈现显著差异,其中年度因子变化使产仔数25年间下降3头,其原因是遗传和环境的双重影响。     

撒坝猪繁殖性状的表型和遗传参数分析

对 6个世代共 2 31头撒坝母猪的繁殖性能数据资料进行了分析。在建立混合线性模型的基础上 ,采用HARVEY程序估计了总产仔数、活产仔数、初生窝重、 2 0日龄窝重、 60日龄断奶仔数和断奶窝重等 6个繁殖性状的表型和遗传参数。结果表明 ,撒坝猪繁殖性能在选育过程中有一定程度的提高 ,但速度平缓 ;上述 6个性状的遗传力分别为 0 0 37,0 0 75,0 1 1 1 ,0 1 55 ,0 1 0 3和 0 31 0 ,多为低遗传力性状 ;各性状间的遗传相关介于 0 532～ 0 773之间 ,表型相关和环境相关分别在 0 30 3～ 0 946和 0 442～ 0 972之间     

深县猪繁殖性状遗传参数的估计

应用动物个体模型和ASReml软件分析109头深县母猪繁殖性状的遗传参数,结果表明:总产仔数、产活仔数、初生窝重、断奶窝重、初生重和断奶重的遗传力分别是0.165、0.024、0.21、0.086、0.018和0.121,性状之间的遗传相关程度差别较大,遗传相关系数在-0.24~0.98之间,表型相关系数在-0.15~0.89之间。结果说明,深县猪的繁殖性能优良,产仔数高但差别大,尚需进一步探究影响繁殖性状的环境和遗传因素。     

多性状动物模型对考力代羊生长性状遗传参数的估计

用多性状动物模型估计考力代羊体重的遗传参数,从而获得较准确的遗传参数估值.使用1269只考力代羊的生长发育记录3332个,用多性状动物模型,分不考虑误差间协方差和考虑误差间协方差两种情况估计考力代羊生长性状的遗传参数.结果表明:不考虑误差间协方差时,直接遗传力估值依次为0.28、0.79、0.77、0.64和0.65;...     

估计猪早期生长性状和繁殖性状的动物模型比较

分析了三种模型对出生重，21、60、90日龄重，总产仔数，以及出生窝重性状遗传参数估计中的加性遗传效应、母体效应、窝效应和残差效应的方差组分、遗传力及其变化趋势。结果表明，出生重、21日龄重和60日龄重采用包含加性遗传效应、母体效应、窝效应和残差效应的模型进行估计比较适宜。90日龄重、总产仔、产活仔和出生窝重性状采用包含加性遗传效应、母体效应和残差效应的模型进行估计效果较好。     

猪繁殖性状的遗传改良策略

猪繁殖性能的提高将为养殖业带来巨大的经济效益，目前多数育种者将提高猪的繁殖力作为主要有种目标，并用数学遗传学方法和分子育种技术对繁殖性状进行改良。     

Estimation of Variances and Covariances of Milk Traits by REML with an Individual Animal Model

Abstract

Records form Finnish Ayrshire cattle were used to estimate variances and covariances of milk traits by the restricted maximum likelihood (REML) method using the individual animal model (IAM). Two data sets were analyzed. The first data set consisted of 1423 sires and 16363 cows, of which 11911 had records on first lactation. The heritabilities estimated from this data set for milk yield, protein yield, protein content and fat content were 0.40, 0.31, 0.63 and 0.68, respectively. The second data set was a subset of first data set with herds with less than ten observations excluded and consisted of 1335 sires and 11262 cows with 8140 first, 5688 second and 3717 third lactation records. The heritability estimates from the second data set under a repeatability model for milk yield, protein yield, protein content and fat content were 0.30, 0.26, 0.59 and 0.66, respectively. The repeatability estimates for the same traits were 0.53, 0.51, 0.67 and 0.76, respectively. The second data set was also used to estimate genetic and phenotypic correlations among milk traits in first lactation. Both genetic and phenotypic correlations among protein yield and protein and fat content traits were small. The genetic correlation between milk yield and protein content was -0.61, between milk yield and fat content -0.50 and between protein content and fat content 0.67. Absolute values of phenotypic correlations for the same pairs of traits were somewhat smaller than respective genetic correlations.     

波尔山羊繁殖性状遗传参数的估计

对 2 4 8窝波尔山羊的胎产羔数、羔羊初生重和 2月龄体重的资料进行了遗传分析。结果表明 :公羊和胎次均对母羊产羔数具有显著的影响(P <0 0 5)。不同产羔季节对羔羊初生重和 2月龄体重也具有显著影响。产羔数的遗传力为 0 1 52 ,属低遗传力 ,而羔羊初生重和 2月龄体重 2个性状 (0 433 ,0 347)有中等或较高的遗传力。波尔母羊胎产羔数与羔羊初生重、 2月龄体重之间存在显著或极显著的表型相关 ,但是它们之间却存在显著或极显著的负遗传相关 (P <0 0 5或 P<0 0 1 )。羔羊的初生重和 2月龄体重间 ,无论是表型相关还是遗传相关 ,都呈极显著的正相关(P <0 0 1 )。     

Season-dependent effect of daily frequency of feed distribution on the rate of feed consumption and reproductive performance in sows during lactation

The effects of the daily frequency of feed distribution (once, One; twice, Two; and four times, Four,) on the rate of feed consumption (RFC) and reproductive performance were investigated in Large White sows farrowing in the hot season from June to September (H sows) and in the rest of the year (R sows). The RFC was greater in feeding treatment Four than Two (P < 0.01) in H sows; however, bodyweight loss during lactation was not affected by the feeding treatment. No difference in effects of frequency of feed distribution for sows was observed on piglet growth. The survival rate of the piglets was not different between feeding treatments. The number of sows that came into estrus within 7 days post‐weaning was smaller in the feeding treatment Four than One (P < 0.05) in H sows and those of Four than One (P < 0.01) and Two (P < 0.05) in R sows. These results suggest that in sows during lactation increasing the daily frequency of feed distribution may have a negative effect on reproductive performance.     

ORIGINAL ARTICLE: Effects of dietary glucose inclusion on reproductive performance,milk compositions and blood profiles in lactating sows

Twenty‐four multiparous sows were used to investigate the effects of dietary glucose inclusion on reproductive performance, milk compositions, blood metabolites and hormones during lactation. The sows were randomly assigned to four treatments and each treatment had six replicates (sows). The diets were added with 0%, 1%, 3% or 5% glucose at the expense of corn and fed to sows for 24 days. The loss of backfat thickness during lactation was quadratically decreased (p = 0.008) and the wean‐to‐oestrus interval was shortened (linear, p = 0.013; quadratic, p = 0.009) with increasing levels of dietary glucose supplementation. The reproductive performance was not affected (p > 0.05) by different dietary glucose contents. Increased concentrations of total solid and fat in milk were noted (p < 0.05), whereas there was no difference on colostrum compositions. With increasing levels of dietary glucose inclusion, the concentrations of blood urea nitrogen (p = 0.004) and glucose (p = 0.029) were linearly increased at weaning. The concentrations of insulin were increased at post‐farrowing (linear, p = 0.027; quadratic p = 0.013) and weaning (linear, p = 0.029; quadratic, p = 0.017), respectively. Furthermore, the pulses of insulin and FSH at weaning were linearly (p = 0.049) and quadratically (p = 0.015) increased with the increasing levels of dietary glucose inclusion. In conclusion, this study indicated that inclusion of 3% glucose in lactating diet could reduce backfat loss, increase milk fat and have no negative effect on reproductive performance in multiparous sows.     

Estimation of genetic parameters of conformation traits in Iranian Thoroughbred horses

The aim of this study was to estimate the genetic parameters of conformation traits in Iranian Thoroughbred race horses. The data set included the conformation records of 607 Thoroughbred horses. In this study, 10 conformation traits were recorded. The effect of sex was significant for length of back line (P < 0.05), withers height (P < 0.05), circumference of front cannon (P < 0.001), and circumference of hind cannon (P < 0.001). The effect of age was significant for all traits (P < 0.01). The genetic parameters were estimated by the restricted maximum likelihood (REML) method using DFREML program. The heritability estimates were for head length 0.39, length of back line 0.41, length of shoulder 0.24, heart girth 0.49, chest width 0.22, withers height 0.38, front cannon height 0.27, circumference of front cannon 0.30, hind cannon height 0.29 and circumference of hind cannon 0.34. The estimates of genetic correlation ranged from 0.18 to 0.96 and those of phenotypic correlation varied from 0.16 to 0.83.     

Estimates of genetic parameters for growth traits in Kermani sheep

Birth weight (BW), weaning weight (WW), 6-month weight (W6), 9-month weight (W9) and yearling weight (YW) of Kermani lambs were used to estimate genetic parameters. The data were collected from Shahrbabak Sheep Breeding Research Station in Iran during the period of 1993-1998. The fixed effects in the model were lambing year, sex, type of birth and age of dam. Number of days between birth date and the date of obtaining measurement of each record was used as a covariate. Estimates of (co)variance components and genetic parameters were obtained by restricted maximum likelihood, using single and two-trait animal models. Based on the most appropriate fitted model, direct and maternal heritabilities of BW, WW, W6, W9 and YW were estimated to be 0.10 +/- 0.06 and 0.27 +/- 0.04, 0.22 +/- 0.09 and 0.19 +/- 0.05, 0.09 +/- 0.06 and 0.25 +/- 0.04, 0.13 +/- 0.08 and 0.18 +/- 0.05, and 0.14 +/- 0.08 and 0.14 +/- 0.06 respectively. Direct and maternal genetic correlations between the lamb weights varied between 0.66 and 0.99, and 0.11 and 0.99. The results showed that the maternal influence on lamb weights decreased with age at measurement. Ignoring maternal effects in the model caused overestimation of direct heritability. Maternal effects are significant sources of variation for growth traits and ignoring maternal effects in the model would cause inaccurate genetic evaluation of lambs.     

聚类分析确定荣昌猪繁殖性状选育指标

对荣昌猪的 12个繁殖性状进行了测定 ,计算了各表型参数和性状间的相关系数 ,探讨了应用聚类分析方法确定繁殖性状选育指标。结果表明 ,荣昌母猪繁殖性状选育和性能评定的适宜指标中 ,应至少包括断奶窝重、存活率和育成率。本研究为猪繁殖性状选育提供了新的参考     

Estimation of direct and maternal genetic parameters for growth and carcass traits in a herd of Japanese Black cattle in Miyagi prefecture, using a multitrait animal model

Data from 1170 records of fattening calves were collected on growth and carcass traits from a Japanese Black cattle herd located in Miyagi prefecture, Japan. The objective was to determine direct and maternal heritabilities, direct and maternal genetic correlations and phenotypic correlations between bodyweight at the beginning of the fattening period (BWS), bodyweight at the end of the fattening period (BWF), carcass weight (CW), average daily gain during the fattening period (ADG), rib eye area (REA), rib thickness, subcutaneous backfat thickness (SFT), yield estimate (YE) and beef marbling score (BMS). Direct heritability estimates of 0.16 (SFT) and 0.07 (BMS) were low, whereas estimates of the other traits were medium to high and ranged between 0.44 (REA) and 0.78 (CW). Direct genetic correlations were all positive, except those that were between BWS and SFT, and between BWS and YE (?0.49 and ?0.14, respectively). The lowest positive genetic correlation was between BWS and BMS (0.04) and the highest was between BWF and CW (0.99). The phenotypic correlation coefficients ranged between ?0.41 (between SFT and YE) and 0.96 (between BWF and CW). Maternal heritability estimates were generally low and ranged between 0.00 for BMS and 0.08 for BWS, CW and ADG. Selection programs comprising information on growth and carcass traits of calves and maternal traits of dams were suggested.