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1.
Possibilities to include carcass traits recorded at commercial slaughterhouses in the genetic evaluation of sheep in Sweden were investigated by estimating direct and maternal genetic parameters for 4‐month weight (4MW), carcass weight (CW), carcass fatness grade (FAT), and carcass fleshiness (FLESH) using multiple‐trait animal models. Data included two sets of breeds, the so‐called white breeds (Swedish landrace breeds, Texel, Dorset, Oxford Down, Suffolk, East Friesian Milk Sheep, and Swedish crossbred) and the Gotland breed. There were 30 625 observations on 4MW and 5062 observations on carcass traits for the white breeds. For the Gotland breed the numbers were 43 642 and 7893, respectively. The results showed that it is feasible to use field‐recorded carcass traits in the genetic evaluation. To consider the effects of selection and to utilize all information in an optimal way multiple trait animal models should be used. Direct and maternal heritabilities for 4MW and CW varied between 0.04 and 0.18 and heritabilities for FAT and FLESH between 0.21 and 0.29. Direct and maternal genetic correlations between 4MW and CW were high (0.61–0.97). Genetic correlations were higher between the weights and FLESH (0.11–0.62) than between the weights and FAT (?0.23 to 0.40). Genetic correlations between FAT and FLESH were moderate (0.38–0.45). Heritabilities for CW were higher if 4MW was included in the analyses and the effect of selection on 4MW was stronger for CW than for FAT or FLESH. The importance of maternal effects on carcass traits was discussed.  相似文献   

2.
Abstract

Genetic parameters were estimated for pelt quality traits of the Gotland sheep breed using data from the Swedish Sheep Recording Scheme and multiple-trait animal models. Data on detailed pelt quality traits were available for 51,455 lambs born from 1991 to 2003. For 4,771 lambs there also was information about a subjectively measured overall score for pelt quality. Sex of lamb, age of ewe, litter size, age of lamb, and interactions between these had significant effects on pelt quality. Heritabilities were moderately high (0.20 to 0.48) and genetic correlations between the traits were low to highly positive (?0.18 to 0.95). Breeding for an increased overall score will in the short term improve score for quality of hair, score for curl, and score for nuance of colour. Size of curl and score for thickness of fleece may also increase and this is not always advantageous as these are traits with optimum values.  相似文献   

3.
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.  相似文献   

4.
Estimates of heritabilities and genetic correlations were obtained for weaning weight records of 23,681 crossbred steers and heifers and carcass records from 4,094 crossbred steers using animal models. Carcass traits included hot carcass weight; retail product percentage; fat percentage; bone percentage; ribeye area; adjusted fat thickness; marbling score, Warner-Bratzler shear force and kidney, pelvic and heart fat percentage. Weaning weight was modeled with fixed effects of age of dam, sex, breed combination, and birth year, with calendar birth day as a covariate and random direct and maternal genetic and maternal permanent environmental effects. The models for carcass traits included fixed effects of age of dam, line, and birth year, with covariates for weaning and slaughter ages and random direct and maternal effects. Direct and maternal heritabilities for weaning weight were 0.4 +/- 0.02 and 0.19 +/- 0.02, respectively. The estimate of direct-maternal genetic correlation for weaning weight was negative (-0.18 +/- 0.08). Heritabilities for carcass traits of steers were moderate to high (0.34 to 0.60). Estimates of genetic correlations between direct genetic effects for weaning weight and carcass traits were small except with hot carcass weight (0.70), ribeye area (0.29), and adjusted fat thickness (0.26). The largest estimates of genetic correlations between maternal genetic effects for weaning weight and direct genetic effects for carcass traits were found for hot carcass weight (0.61), retail product percentage (-0.33), fat percentage (0.33), ribeye area (0.29), marbling score (0.28) and adjusted fat thickness (0.25), indicating that maternal effects for weaning weight may be correlated with genotype for propensity to fatten in steers.  相似文献   

5.
The objective of this study was to estimate genetic correlations between calving difficulty score and carcass traits in Charolais and Hereford cattle, treating first and later parity calvings as different traits. Genetic correlations between birth weight and carcass traits were also estimated. Field data on 59,182 Charolais and 27,051 Hereford calvings, and carcass traits of 5,260 Charolais and 1,232 Hereford bulls, were used in bivariate linear animal model analyses. Estimated heritabilities were moderate to high (0.22 to 0.50) for direct effects on birth weight, carcass weight, and (S)EUROP (European Community scale for carcass classification) grades for carcass fleshiness and fatness. Heritabilities of 0.07 to 0.18 were estimated for maternal effect on birth weight, and for direct and maternal effects on calving difficulty score at first parity. Lower heritabilities (0.01 to 0.05) were estimated for calving difficulty score at later parities. Carcass weight was positively genetically correlated (0.11 to 0.53) with both direct and maternal effects on birth weight and with direct effects on calving difficulty score. Carcass weight was, however, weakly or negatively (-0.70 to 0.07) correlated with maternal calving difficulty score. Higher carcass fatness grade was genetically associated with lower birth weight, and in most cases, also with less difficult calving. Genetic correlations with carcass fleshiness grade were highly variable. Moderately unfavorable correlations between carcass fleshiness grade and maternal calving difficulty score at first parity were estimated for both Charolais (0.42) and Hereford (0.54). This study found certain antagonistic genetic relationships between calving performance and carcass traits for both Charolais and Hereford cattle. Both direct and maternal calving performance, as well as carcass traits, should be included in the breeding goal and selected for in beef breeds.  相似文献   

6.
Heritabilities of and genetic correlations between additive direct and maternal genetic effects for calf market weight, and additive direct genetic effects for carcass traits, were estimated for Japanese Black cattle by REML procedures under 2-trait animal models. Data were collected from calf and carcass markets in Hyogo and Tottori prefectures and analyzed separately by prefecture. Calf market weight was measured on 42,745 and 23,566 calves in Hyogo and Tottori, respectively. Only the fattening animals with calf market weight were extracted from the carcass database and used for estimation. The carcass traits analyzed were carcass weight, ribeye area, rib thickness, subcutaneous fat thickness, yield estimate, beef marbling score, and 4 meat characters (color, brightness, firmness, and texture). Direct and maternal heritabilities for calf market weight were estimated to be 0.22 and 0.07 in Hyogo, and 0.37 and 0.15 in Tottori, respectively. The estimates of heritabilities for carcass traits were moderate to high in both prefectures. The estimates of direct-maternal genetic correlations for calf market weight were positive (0.17) in Hyogo and negative (-0.63) in Tottori. The direct effect for calf market weight was positively correlated with the direct effect for carcass weight (0.87 and 0.56 in Hyogo and Tottori, respectively) but negatively correlated with the direct effect for beef marbling score (-0.10 in both prefectures). The estimates of genetic correlations between the maternal effect for calf market weight and the direct effects for carcass traits varied from -0.13 to 0.34 in Hyogo and from -0.14 to 0.15 in Tottori. Because direct and maternal genetic effects for early growth traits can be evaluated from calf market weight data in the production system of Japanese Black cattle, this information should be incorporated into selection and mating schemes of the breed.  相似文献   

7.
为了解中国美利奴羊（新疆型）近年来遗传结构的变化趋势以及探讨毛用性状与繁殖性状的遗传关系,需要进一步研究这些性状的遗传力以及它们之间的关系。本研究收集额敏县聚鑫细毛羊养殖专业合作社1985-2018年中国美利奴羊（新疆型）共计9 428只羊毛生产记录和1987-2018共计5 887只年繁殖记录,运用BLUPF90软件结合Gibbs抽样方法,利用单性状模型对中国美利奴（新疆型）毛用性状（细度支数、等级、总评分、毛长、污毛重和鉴定时体重）和繁殖性状（配种次数、妊娠天数、胎产羔数和总产羔数）进行方差组分和遗传力估计,利用双性状模型分析毛用性状与繁殖性状之间的遗传相关与表型相关。结果显示,中国美利奴羊（新疆型）毛用性状细度支数、等级、总评分、毛长、污毛重、鉴定时体重的遗传力估计值分别为0.471±0.020、0.088±0.030、0.114±0.018、0.426±0.025、0.328±0.041、0.317±0.046;繁殖性状配种次数、妊娠天数、胎产羔数及总产羔数的遗传力估计值分别为0.056±0.009、0.022±0.010、0.120±0.018、0.163±0.016;毛用性状与胎产羔数、总产羔数之间的遗传相关范围为-0.031~0.286,鉴定时体重与胎产羔数（0.286）、总产羔数（0.204）遗传相关最高,细度支数与胎产羔数（-0.143）、总产羔数（-0.048）呈负的遗传相关;毛用性状与胎产羔数、总产羔数之间的表型相关范围为-0.210~0.216,毛长与总产羔数（0.216）表型相关最高,细度支数与胎产羔数（-0.137）、总产羔数（-0.210）呈显著负表型相关。本研究结果发现,毛用性状与繁殖性状之间存在一定的关系,这一结果可为今后制定中国美利奴羊育种规划提供数据基础,为选育优质高产、繁殖性能好的细毛羊提供理论依据,从而进一步提高细毛羊产业经济效益。  相似文献   

8.
Estimates of genetic parameters were obtained for body measurement traits of 648 animals at 4 months of age, of 545 at 8 months and carcass traits of 14 972 animals with the use of an animal model by the restricted maximum likelihood procedure. The estimated heritabilities for carcass traits were high (0.41 to 0.54). At 4 months the estimated direct heritabilities for body measurement traits were moderate to high (0.28 to 0.64), except for chest width (0.19); at 8 months they were also moderate to high (0.23 to 0.49), except for chest depth and chest width (0.18 and 0.06, respectively). Maternal heritabilities for all body measurement traits were low at both ages. The results indicate that because of their moderate direct genetic correlations with body measurement traits, carcass weight, rib thickness and subcutaneous fat thickness can be improved; however, rib eye area and beef marbling standard show little such possibility considering their correlation with body measurement traits.  相似文献   

9.
Our objectives were to estimate genetic parameters for carcass traits and evaluate the influence of slaughter end point on estimated breeding values (BV). Data provided by the American Simmental Association were divided into three sets: 1) 9,604 records of hot carcass weight (CW) and percentage retail cuts (PRC), 2) 6,429 records of CW, PRC, and marbling score (MS), and 3) 1,780 records of CW, PRC, MS, fat thickness (FT), and longissimus muscle area (LMA). Weaning weights (WW) from animals with carcass data and from their weaning contemporaries were used. Data were analyzed with a multiple-trait animal model and REML procedures to estimate genetic parameters and BV on an age-, CW-, MS-, or FT-constant basis. The model for carcass traits included fixed contemporary group and covariates for breed, heterozygosity, and slaughter end point and random additive direct genetic and residual effects. Weaning weight was preadjusted for founder effects, direct and maternal heterosis, age of dam, and age of calf. The model for WW included fixed contemporary group and random additive direct genetic, maternal genetic, maternal permanent environment, and residual effects. Heritabilities from data set 1 were 0.34 for CW and 0.25 for PRC on an age-constant basis and 0.25 for PRC on a CW end point. Heritabilities for data set 2 were 0.35, 0.24, and 0.36 for CW, PRC, and MS, respectively, on an age-constant basis. Data set 2 heritabilities were 0.25 for PRC and 0.34 for MS on a CW-constant basis and 0.33 for CW and 0.25 for PRC at a constant MS end point. Heritabilities on an age-constant basis for data set 3 were as follows: CW, 0.32; PRC, 0.09; MS, 0.12; FT, 0.10; and LMA, 0.26. Heritability estimates for data set 3 on a CW-, MS-, and FT-constant basis were similar to those on an age-constant basis. Heritabilities were 0.12 for PRC, 0.12 for MS, 0.14 for FT, and 0.22 for LMA on a CW-constant basis; 0.30 for CW, 0.09 for PRC, 0.10 for FT, and 0.28 for LMA at a constant MS end point; and 0.33, 0.17, 0.13, and 0.29 for CW, PRC, MS, LMA on a FT-constant basis. Genetic correlations among traits varied across groups and end points but suggested that it should be possible to select for improved lean yield without sacrificing quality grade. Correlations were calculated among BV computed at different end points. Adjustment to various end points resulted in some changes in BV and reranking of sires, especially for PRC; however, the number of records available had a larger influence than slaughter end point.  相似文献   

10.
The objective of this study was to estimate variance components related to imprinting for carcass traits and physiochemical characteristics in Japanese Black cattle. The carcass records obtained from 4,220 Japanese Black feedlot cattle included carcass weight (CW), rib eye area (REA), rib thickness, subcutaneous fat thickness, and beef marbling score (BMS), and the physiochemical characteristics were fat, moisture, glycogen per proportion of moisture content, oleic acid, and monounsaturated fatty acids (MUFA). To detect gametic effects, an imprinting model was fitted. High additive heritabilities were estimated for all traits (from 0.516 for glycogen to 0.853 for fat) and were reduced in Mendelian heritability. The range of the differences was from 0.002 (CW) to 0.331 (fat and moisture), and the reductions were due to their imprinting variances. The ratio of the imprinting variance to the total additive genetic variance for REA (0.374), BMS (0.291), fat (0.387), moisture (0.388), and MUFA (0.337) were large (p < 0.05). These imprinting variances were due to the maternal contribution and suggested the existence of maternally expressed genomic imprinting effects on the traits in Japanese Black cattle. Therefore, maternal gametic effects should be considered in breeding programs for Japanese Black cattle.  相似文献   

11.
Abstract

Finnish blue fox farmers breed for increased litter size and pelt size, and improved fur quality. Some farmers select pelt size and fur quality indirectly using live animal evaluations (grading traits). In order to be able to define breeding goals properly, heritabilities and genetic correlations were estimated for size traits and fur quality traits. There were four pelt character traits (pelt size, pelt colour darkness, pelt colour clarity and pelt quality) measured on dried skins, and six grading traits (animal size, grading colour darkness, grading colour clarity, underfur density, guard hair coverage and grading quality). The data included 54,680 animals born during the years 1987–2002, originating from seven farms. The heritabilities were high for pelt colour darkness and grading colour darkness, moderate for pelt size and low for other traits. In general, heritability of a pelt character trait was higher than its corresponding grading trait. Genetic correlations within the pelt character traits were low (～0.11) and within the grading traits mainly moderate or high (～0.44). There was high genetic correlation between pelt darkness and grading darkness, pelt quality and grading density, pelt size and animal size; between pelt quality and grading quality and between pelt colour darkness and grading guard hair coverage. This suggests that selection of pelt character traits via grading traits in most cases is relatively effective.  相似文献   

12.
Genetic parameters and genetic trends for birth weight (BW), weaning weight (WW), 6-month weight (6MW), and yearling weight (YW) traits were estimated by using records of 5,634 Makooei lambs, descendants of 289 sires and 1,726 dams, born between 1996 and 2009 at the Makooei sheep breeding station, West Azerbaijan, Iran. The (co)variance components were estimated with different animal models using a restricted maximum likelihood procedure and the most appropriate model for each trait was determined by Akaike’s Information Criterion. Breeding values of animals were predicted with best linear unbiased prediction methodology under multi-trait animal models and genetic trends were estimated by regression mean breeding values on birth year. The most appropriate model for BW was a model including direct and maternal genetic effects, regardless of their covariance. The model for WW and 6MW included direct additive genetic effects. The model for YW included direct genetic effects only. Direct heritabilities based on the best model were estimated 0.15?±?0.04, 0.16?±?0.03, 0.21?±?0.04, and 0.22?±?0.06 for BW, WW, 6MW, and YW, respectively, and maternal heritability obtained 0.08?±?0.02 for BW. Genetic correlations among the traits were positive and varied from 0.28 for BW–YW to 0.66 for BW–WW and phenotypic correlations were generally lower than the genetic correlations. Genetic trends were 8.1?±?2, 67.4?±?5, 38.7?±?4, and 47.6?±?6 g per year for BW, WW, 6MW, and YW, respectively.  相似文献   

13.
Genetic breed differences, heterosis, recombination loss, and heritability for reproduction traits, lamb survival and growth traits to 90 days of age were estimated from crossing D'man and Timahdite Moroccan breeds. The crossbreeding parameters were fitted as covariates in the model of analysis. The REML method was used to estimate (co)variance components using an animal model. The first estimation of crossbreeding effects for Timahdite and D'man breeds shows that breed differences in litter traits are mainly of maternal genetic origin: +1.04 lambs, +1.88 kg, +0.60 lambs, and +2.23 kg in favour of D'man breed for litter size at lambing, litter weight at lambing, litter size at weaning, and litter weight at 90 days, respectively. The breed differences in lamb growth and survival are also of maternal genetic origin for the majority of traits studied, but in favour of the Timahdite breed: +3.48 kg, +45 g day−1 and +0.19 lambs for weight at 90 days, for average daily gain between 30 and 90 days of age, and for lamb survival to 90 days, respectively. The D'man direct genetic effect was low and negative for survival and birth weight of lambs during the first month of life. All traits studied showed positive heterosis effects. Recombination loss effects were not significant. Therefore, crossbreeding of Timahdite with D'man breeds of sheep can result in an improved efficiency of production of saleable lambs. Heritability estimates were medium for litter size but low for the other reproduction traits. Direct heritabilities were low for body weights and lamb survival at 90 days and the corresponding maternal heritabilities showed, however, low to moderate estimates. For litter traits, the estimates of genetic and phenotypic correlations were positive and particularly high for genetic correlations.  相似文献   

14.
Sixty-four white-faced rams and wethers were dressed with the aid of a commercial pelt puller. The effects of age, castration, and season on difficulty of pelt removal and pelt damage were evaluated. Lambs were divided into two age groups (5 and 12 mo) within gender (ram and whether) and season (spring and fall). A greater force (P less than .05) was required to remove pelts from rams than from wethers in both 5- and 12-mo-old groups. Older lambs slaughtered in the fall required more force (P less than .05) to remove their pelts than did those slaughtered in the spring, but differences by season did not exist for 5-mo-old lambs. The difference between rams and wethers in percentage of live weight that was closely shorn pelt weight was not significant (P greater than .05). The area of grain crack in the flank expressed as a percentage of total area of the skin was lower (P less than .05) for skins from 5-mo-old lambs and ram lambs than it was for skins from 12-mo-old lambs and wether lambs, respectively. Factors involved in difficulty of pelt removal in ram lambs included crosscut shoulder weight, fat firmness, and carcass weight. Difficulty of pelt removal in wether lambs was best predicted by including crosscut shoulder weight and bodywall thickness in multiple regression equations.  相似文献   

15.
Data from the first four cycles of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center (USMARC) were used to investigate genetic relationships between mature weight (MW, n = 37,710), mature weight adjusted for body condition score (AMW, n = 37,676), mature height (HT, n = 37,123), and BCS (n = 37,676) from 4- to 8-yr old cows (n = 1,800) and carcass traits (n = 4,027) measured on their crossbred paternal half-sib steers. Covariance components among traits were estimated using REML. Carcass traits were adjusted for age at slaughter. Estimates of heritability for hot carcass weight (HCWT); percentage of retail product; percentage of fat; percentage of bone; longissimus muscle area; fat thickness adjusted visually; estimated kidney, pelvic, and heart fat percentage; marbling score; Warner-Bratzler shear force; and taste panel tenderness measured on steers were moderate to high (0.26 to 0.65), suggesting that selection for carcass and meat traits could be effective. Estimates of heritability for taste panel flavor and taste panel juiciness were low and negligible (0.05 and 0.01, respectively). Estimates of heritability from cow data over all ages and seasons were high for MW, AMW, and HT (0.52, 0.57, 0.71; respectively) and relatively low for BCS (0.16). Pairwise analyses for each female mature trait with each carcass trait were done with bivariate animal models. Estimates of genetic correlations between cow mature size and carcass composition or meat quality traits, with the exception of HCWT, were relatively low. Selection for cow mature size (weight and/or height) could be effective and would not be expected to result in much, if any, correlated changes in carcass and meat composition traits. However, genetic correlations of cow traits, with the possible exception of BCS, with HCWT may be too large to ignore. Selection for steers with greater HCWT would lead to larger cows.  相似文献   

16.
In the present study, (co)variance components and genetic parameters in Nellore sheep were obtained by restricted maximum likelihood (REML) method using six different animal models with various combinations of direct and maternal genetic effects for birth weight (BW), weaning weight (WW), 6-month weight (6MW), 9-month weight (9MW) and 12-month weight (YW). Evaluated records of 2075 lambs descended from 69 sires and 478 dams over a period of 8 years (2007–2014) were collected from the Livestock Research Station, Palamaner, India. Lambing year, sex of lamb, season of lambing and parity of dam were the fixed effects in the model, and ewe weight was used as a covariate. Best model for each trait was determined by log-likelihood ratio test. Direct heritability for BW, WW, 6MW, 9MW and YW were 0.08, 0.03, 0.12, 0.16 and 0.10, respectively, and their corresponding maternal heritabilities were 0.07, 0.10, 0.09, 0.08 and 0.11. The proportions of maternal permanent environment variance to phenotypic variance (Pe2) were 0.07, 0.10, 0.07, 0.06 and 0.10 for BW, WW, 6MW, 9MW and YW, respectively. The estimates of direct genetic correlations among the growth traits were positive and ranged from 0.44(BW-WW) to 0.96(YW-9MW), and the estimates of phenotypic and environmental correlations were found to be lower than those of genetic correlations. Exclusion of maternal effects in the model resulted in biased estimates of genetic parameters in Nellore sheep. Hence, to implement optimum breeding strategies for improvement of traits in Nellore sheep, maternal effects should be considered.  相似文献   

17.
Maternal effects are an important source of variation in early growth and body traits in sheep but are often excluded from genetic analyses. Maternal additive genetic, maternal environmental, and cytoplasmic effects were investigated in a large Suffolk breeding scheme using a range of models involving different combinations of these effects with the direct additive genetic effect. Weights at 8 wk of age and at scanning (mean age 146 d) and ultrasonically measured muscle and fat depth were analyzed using an animal model on 55,683 (8-wk weight) and 28,947 (scanning traits) lamb records. Simple additive models always overestimated the heritability of all traits when compared to more complex models. The successive inclusion of maternal environmental, maternal genetic, and the covariance between direct and maternal additive effects in the model significantly improved the fit for almost all models and all traits, as indicated by a likelihood ratio test. Under the full model, the heritability of both weight traits was low (0.14 and 0.20 for 8-wk and scanning weight, respectively). The maternal additive and maternal environmental effects, as a proportion of the phenotypic variance, were similar (0.10 and 0.08 for 8-wk weight and 0.07 and 0.06 for scanning weight). The two scanning traits had higher heritabilities (0.29 and 0.27 for muscle depth and fat depth, respectively) with low levels of maternal genetic and maternal environmental variance. No evidence was found of a cytoplasmic effect on any of the traits studied under the full model. Breeding schemes for early growth and body traits in sheep should account for maternal effects in their genetic evaluations in order to improve their accuracy. The exact model to use will depend on the trait and individual circumstances of the scheme.  相似文献   

18.
Heritabilities and genetic and phenotypic correlations were estimated from feedlot and carcass data collected from Brahman calves (n = 504) in central Florida from 1996 to 2000. Data were analyzed using animal models in MTDFREML. Models included contemporary group (n = 44; groups of calves of the same sex, fed in the same pen, slaughtered on the same day) as a fixed effect and calf age in days at slaughter as a continuous variable. Estimated feedlot trait heritabilities were 0.64, 0.67, 0.47, and 0.26 for ADG, hip height at slaughter, slaughter weight, and shrink. The USDA yield grade estimated heritability was 0.71; heritabilities for component traits of yield grade, including hot carcass weight, adjusted 12th rib backfat thickness, loin muscle area, and percentage kidney, pelvic, and heart fat were 0.55, 0.63, 0.44, and 0.46, respectively. Heritability estimates for dressing percentage, marbling score, USDA quality grade, cutability, retail yield, and carcass hump height were 0.77, 0.44, 0.47, 0.71, 0.5, and 0.54, respectively. Estimated genetic correlations of adjusted 12th rib backfat thickness with ADG, slaughter weight, marbling score, percentage kidney, pelvic, and heart fat, and yield grade (0.49, 0.46, 0.56, 0.63, and 0.93, respectively) were generally larger than most literature estimates. Estimated genetic correlations of marbling score with ADG, percentage shrink, loin muscle area, percentage kidney, pelvic, and heart fat, USDA yield grade, cutability, retail yield, and carcass hump height were 0.28, 0.49, 0.44, 0.27, 0.45, -0.43, 0.27, and 0.43, respectively. Results indicate that sufficient genetic variation exists within the Brahman breed for design and implementation of effective selection programs for important carcass quality and yield traits.  相似文献   

19.
T. Kvame  O. Vangen 《Livestock Science》2007,106(2-3):232-242
Genetic parameters for carcass traits in lambs at weaning (average age of 128 days) measured by ultrasound (n = 1821) and computer tomography (CT) (n = 234), and response to selection for ultrasound eye muscle depth (UMD) and carcass LEAN weight, were estimated. The research flock comprised a meat line (ML) and a control line (CL) of Norwegian White Sheep. The ML was crossed with Texel from 1998, and selected for UMD from 1993 to 2001, and for LEAN weight from 2001 to 2004. For CT scanning, a mean of 23 images was taken per animal. Genetic parameters were estimated with univariate and bivariate mixed-animal models using AIREML, including all animals with records and their relatives. The statistical models included fixed effects, live weight or age of lamb at weaning (covariate), and a random genetic effect.

Heritability estimates for weight of LEAN, FAT and BONE were 0.57, 0.29 and 0.51 using model corrected for live weight. The heritability estimates were lower when these traits were adjusted for age. High genetic correlation was found between LEAN and UMD (0.70), and between carcass FAT and ultrasound fat depth (UFD) (0.82). The genetic trend for UMD regressed on year of birth was significantly greater for ML than CL in 2004.  相似文献   


20.
The objectives of this study were to estimate genetic parameters for gestation length (GL), including estimation of maternal effects, and to investigate the genetic relationships of GL with birth weight and carcass traits in a Japanese Black cattle population. The original data comprised 34 775 records of animals born from October 1999 to August 2003. Two different models were used to analyze the data for GL. The first model (M1) included direct genetic effect of the calf and maternal genetic effect as random effects. The second model (M2) treated GL as a trait of the dam and included direct genetic effects only. M1 was used in bi-variate analysis. The direct and maternal heritabilities for GL estimated from M1 were 0.53 and 0.14, respectively. This result shows that GL is moderately inherited and can be controlled genetically. The direct × maternal genetic correlation for GL was −0.73. Direct genetic correlations of GL with carcass traits were close to zero. However, genetic correlation of maternal GL with carcass weight was moderate (0.25).  相似文献   

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