QTL for mohair traits in South African Angora goats

The aim of this study was to identify QTL associated with mohair production and quality traits in South African Angora goats. Limited research has been performed on QTL influencing the economically important mohair traits of Angora goats. Twelve half-sib Angora goat families with an average of 58 offspring per sire were genotyped for 88 microsatellites covering 22 autosomes. Phenotypic data was collected at second and third shearing for males and females respectively. A linkage analysis was performed under the half-sib model using the least squared regression approach of GridQTL. Three putative QTL were detected for fleece weight on CHI 2, 5 and 24, which corresponds with the locations of keratin and keratin-associated proteins. This study detected two putative QTL associated with mohair fibre diameter (on CHI 4 and 24, respectively), which is the most important price-determining trait. Four QTL were detected on CHI 8, 13, 18 and 20 which influence both comfort factor and spinning fineness. The variance explained by the QTL ranged between 6.9% for fibre diameter and 33.6% for standard deviation along the length of the staple. These results reveal segregation of QTL influencing mohair production and quality, and contribute to the understanding of the genetic variation of mohair traits.     

QTL affecting conformation traits in Angora goats

A genomic screen for quantitative trait loci (QTL) affecting conformation traits was performed by genotyping 288 Angora goats offspring from 8 half-sub families with 76 microsatellite markers. The following traits were recorded: weaning weight (WW, Kg); stature (S, cm); chest depth (CD, cm); shoulder width (SW, cm); rump length (RL, cm); rump width (RW, cm); head length (HL, cm); head width (HW, cm); shin circumference (SC, cm); chest circumference (CC, cm) and body length (BL, cm). Data were analyzed using the QTL Express program. A total of 5 QTL were detected in five chromosomes with chromosome wide significance level. For the 11 analysed traits the results were: evidence of two possible QTL for HL were found in chromosomes 1 and 4, a putative QTL for trait CD was found in chromosome 2, evidence for BL was found in chromosome 8 and a possible QTL was found for trait CC in chromosome 9. The results reported here show the existence of chromosomal regions in Angora goats involved in conformation traits and represent the first in depth search in some specific-genome sections in order to identify and characterize the genetic variability involved in these traits.     

QTL affecting fleece traits in Angora goats

With the aim to detect chromosome segment (quantitative traits loci, QTL) affecting fleece traits in Angora goats, a genome scan using 76 microsatellite markers spanning 1261 cM on 21 chromosomes was conducted. Eight paternal half-sib families were used, which included a total of 288 kids from a dispersed nucleus herd.Mid-side mohair samples were taken from kids at 4 months of age and eight phenotypic fleece traits were measured.We found putatives QTL for coefficient of variation of average fiber diameter (CVAFD) in chromosome 1 and 13, for kemp fiber (KEMP) in chromosome 5 and for discontinuous medullated fibers (DISC) and staple length (SL) in chromosome 2.These results demonstrate the segregation of quantitative traits involved in mohair production. Further studies will concentrate on these regions to characterize the variation of these QTL.     

The relationship between permanent incisor wear and mohair production and attributes in grazing adult Angora goats

We aimed to quantify if and to what extent permanent incisor wear affected mohair production in adult Angora castrate goats. The goats were grazed on annual temperate pastures for 6 years. During their sixth year mohair was harvested every 6 months and liveweight measured. Incisors were inspected at age 6 years and the amount and pattern of wear quantified. Restricted maximum likelihood (REML) base models were developed to account for background sources of variation. Once a base model had been selected for each fleece attribute, an extra term for the linear effect of the first and other permanent incisor wear were added to the model. During the year mean liveweight, greasy mohair production, clean mohair production and mean fibre diameter were (S.D.): 55.6 (5.85) kg, 4.97 (1.00) kg, 4.16 (0.87) kg, 34.8 (4.02) μm. Mean wear on permanent first incisors was 9% (range 0–30%). There was little wear on other permanent incisors. Greasy fleece weight, clean fleece weight, staple length and fleece entanglement were reduced significantly with increased wear of first permanent incisors. There were no significant effects of incisor wear detected for nine other fleece attributes or liveweight. The results indicate that 30% wear of the permanent first incisors reduced greasy fleece production by 20% and reduced clean fleece production by 30%. Given the magnitude of the effects detected it is clear that relatively small amounts of wear of permanent incisors in adult Angora goats reduce production of mohair and consequently will reduce financial returns from mohair sales. The clear implication is that managers of mohair producing enterprises should assess the incisors of adult Angora goats and use this information in determining which animals to cull from their flocks.     

Genetic and phenotypic parameters for lactation traits in a flock of Saanen goats in Mexico

Heritability, repeatability and genetic and phenotypic correlations of total milk production (TM), cumulated milk production to 120 days (M120) and lactation length (LL), were estimated from the analysis of 1413 records (566 does) obtained from a Saanen goat flock in Querétaro, Mexico, during 1991–1997. Variance components were estimated using a restricted maximum likelihood procedure and applying an animal model. The model included the fixed effects of year–season of kidding, litter size and age of doe, and random effects of animal, permanent environment and residual. For TM, M120 and LL estimates of heritability were 0.22 ± 0.07, 0.12 ± 0.05 and 0.04 ± 0.03, and of repeatability were 0.40, 0.27 and 0.11, respectively. Genetic correlations between TM and M120, TM and LL, and M120 and LL, were 0.98, 0.58 and 0.53, respectively. Phenotypic correlations ranged from 0.30 to 0.83. The correlated selection response for TM from indirect selection on M120 was 71.5% of that expected from direct selection. Efficient selection for TM is possible and M120 could be used as an early indicator of TM, due to the high indirect selection response calculated.     

A genetic linkage map for the South African Angora goat

Despite their economical importance, relatively few molecular studies have been made on goats compared to other livestock species. The most recent goat map was published in 1998, and lacks complete genome coverage. A large number of discrepancies and especially inter-chromosomal re-assignments were reported between the 1998 goat linkage map and the sheep map. In this study 94 microsatellite markers were amplified in 12 half-sib South African Angora goat families for compilation of a genetic map, aiming to confirm or reject previously reported rearrangements and to improve the alignment between the ovine and caprine maps. The number of informative meiosis per marker ranged from 69 to 836, with an average of 518. The microsatellites were mapped to 23 chromosomes, spanning 1352 cM and resulting in an average marker interval of 23.0 cM. Marker orders were compared to the previously published goat maps, as well as to the ovine map. Six chromosomes (CHI 2, 4, 5, 11, 13 and 19) showed rearrangements in marker order compared to the 1998 Schibler et al. goat map, while nine previously unmapped markers were conclusively assigned to eight chromosomes. Four of the previously reported intra-chromosomal rearrangements between the goat and sheep maps were confirmed to be either population specific or mapping errors. The verification of rearrangements in loci order will lead to improved alignment between the two maps, as well as improved efficiency of genome and fine mapping efforts in goats.     

The effect of dietary molybdenum supplementation on tissue copper concentrations,mohair fibre and carcass characteristics of growing Angora goats

The purpose of this experiment was to better characterize the effects of the interaction between copper (Cu), molybdenum (Mo) and sulphur (S) in the diet on growth, metabolism and fibre characteristics in Angora goats. 15 Angora goats aged 9 months and weighing 21.5 kg on average were used in a ten-week study and allocated to three dietary treatments: Treatment C (10 MJ metabolisable energy, 178 g crude protein, 5.5 mg Cu, 0.57 mg Mo, and 3.4 g S): Treatment M1 (with 7.5 mg Mo) or Treatment M2 (with 15 mg Mo) per animal per day. Dose-dependent increases in the concentrations of Mo (P < 0.01) and Cu (P < 0.05) in plasma were recorded in response to increased dietary intake of Mo. Supplementation of the control diet with increased concentrations of Mo did not produce effects (P > 0.05) on growth rate, feed conversion efficiency, carcass weight or mohair fibre yield and diameter.Haematological status and concentration of Cu in liver and Cu and S in fibre at the end of the study were also not affected (P > 0.05).Concentrations of trichloroacetic acid (TCA) soluble “available” copper in plasma were not significantly different although significant (P < 0.05 and P < 0.01) reductions in the ratio of “available” to total Cu concentrations were observed. This effect was stabilised and maintained after 30 days. It is suggested that the additional Cu in plasma was largely TCA insoluble and possibly in the form of thiomolybdate complexes which may be poorly excreted and not available for uptake to the metabolic sites. It is evident that adequate “available” Cu was present in plasma and that exposure to elevated Mo intake was not severe or long enough to produce clinical symptoms or to affect growth, haematological status or fibre production.     

Genetic parameters for litter size at birth and kidding interval in the West African Dwarf goats

A total of 587 kidding records of West African Dwarf (WAD) goats over 10 years (1982–1991) were used. Mean kidding interval and litter size at birth were 275.68 ± 6.08 days and 1.79 ± 0.05 kids, respectively. Effects of parity, season and year of birth were significant (P < 0.05) for kidding interval. Parity also had significant effect (P < 0.05) on litter size at birth. Heritability estimates of 0.35 ± 0.05 and 0.32 ± 0.07 were obtained from sire and sire-dam groups, respectively, for litter size at birth. Heritability estimate for kidding interval was 0.03 ± 0.01 from sire-dam group. Repeatability estimates of 0.38 ± 0.05 and 0.33 ± 0.03 were obtained for litter size at birth while 0.06 ± 0.04 and 0.04 ± 0.02 were obtained for kidding interval from dam and sire-dam group, respectively. Selection for multiple birth is likely to result in larger litter size while culling of does for long kidding interval should be based on more than two records.     

Genetic analysis for physical nut traits in almond

Almond breeding is increasingly taking into account kernel quality as a breeding objective. Although information on nut and kernel physical parameters involved in almond quality has already been compiled, the genetic control of these traits has not been studied. This genetic information would improve the efficacy of almond breeding programs. A linkage map with 56 simple-sequence repeat markers was constructed for the “Vivot” × “Blanquerna” almond population showing a wide range of variability for the physical parameters of nut and kernel. A total of 14 putative quantitative trait loci (QTLs) controlling these physical traits were detected in the current study, corresponding to six genomic regions of the eight almond linkage groups (LG). Some QTLs are colocated in the same region or shared the same molecular markers, in a manner that reflects the correlations between the physical traits, as well as with the chemical components of the almond kernel. The limit of detection values for any given trait ranged from 2.06 to 5.17, explaining between 13.0 and 44.0 % of the phenotypic variance of the trait. This new genetic information needs to be taken into account when breeding for physical traits in almond. Increases in the positive quality traits, both physical and chemical, need to be considered simultaneously whenever they are genetically independent, even if they are negatively correlated. This is the first complete genetic framework map for physical components of almond nut and kernel, with 14 putative QTLs associated with a large number of parameters controlling physical traits in almond.     

Genetic parameter estimates for pre-weaning performance and reproduction traits in Markhoz goats

Genetic parameters for growth, mortality and reproductive performances of Markhoz goats were estimated from data collected during 1993–2010 at Markhoz goat Performance Testing Station in Sanandaj, Iran. For kid performance traits 3763 records were available for birth weight (BW), 2931 for weaning weight (WW), average daily gain (ADG) and Kleiber ratio (KR) (approximated as ADW/WW^0.75) and 3032 for pre-weaning mortality (PWM). For doe reproductive performance traits there were 2920 records available for litter size at birth (LSB), litter size at weaning (LSW), total litter weight at birth (TLWB) and litter mean weight per kid born (LMWKB), and 2182 for total litter weight at weaned (TLWW) and litter mean weight per kid weaned (LMWKW). Genetic parameters were estimated with univariate and bivariate models using restricted maximum likelihood (REML) procedures. Random effects were explored by fitting additive direct genetic effects, maternal additive genetic effects, maternal permanent environmental effects, the covariance between direct and maternal genetic effects, and common litter effects in different models for pre-weaning traits of kids. Also, in addition to an animal model, sire and threshold models, using a logit link function, were used for analyses of PWM. Models for LSB, LSW, TLWB, TLWW, LMWKB, and LMWKW included direct additive genetic effects, permanent environmental effects due to the animal as well as service sire effects. Estimated direct heritabilities were moderate for pre-weaning traits (0.22 for BW, 0.16 for WW, 0.21 for ADG, and 0.27 for KR and 0.29 for PWM), and low for reproduction traits (0.01 for LSB, 0.01 for LSW, 0.02 for TLWB, 0.03 for TLWW, 0.07 for LMWKB, and 0.06 for LMWKW). The estimates for the maternal additive genetic variance ratios were lower than direct heritability for BW (0.07) and KR (0.04). The estimate for the maternal permanent environmental variance ratios (c²) varied from 0.01 for KR to 0.07 for WW and ADG. The magnitude of common litter variance ratios (l²) was more substantial for BW (0.46) than the PWM (0.19) and KR (0.16). The estimate for the permanent environmental variance due to the animal (c²) ranged from 0.03 for LMWKB to 0.07 for TLWB and LMWKW, whereas service sire effects (s²) ranged from 0.02 to 0.04. The correlation between direct and maternal genetic effects were negative and high for BW (?0.51) and KR (?0.62). The genetic correlations between pre-weaning growth traits were positive and moderate to strong, as were genetic correlations between reproductive traits. Between BW and PWM the correlation was ?0.35. Phenotypic and environmental correlations for all traits were generally lower than genetic correlations.     

Superovulation treatments and embryo transfer in Angora goats

A high incidence of early luteal regression after PMSG superovulation was associated with low recovery of embryos from reproductive tracts of Angora goats flushed later than Day 5 after onset of oestrus. Embryos were successfully recovered (mean 7.9/female) by flushing on Days 2-5. Mean ovulation rate after an FSH regimen (16.1 +/- 0.8) was significantly higher than that after a single injection of PMSG (10.8 +/- 1.2). Fertilization rate and survival of embryos following transfer to naturally synchronized recipient feral goats did not differ between the two gonadotrophin regimens: the mean number of kids born to 47 donors treated with FSH (7.5 +/- 0.6) was significantly greater than that to 28 donors treated with PMSG (4.8 +/- 0.6). Irrespective of hormonal treatment, the numbers of embryos recovered and of kids born were correlated with ovulation rate (r = 0.82, P less than 0.001 for both). Embryo survival was influenced by ovulation rate in recipients, with 52%, 63% and 75% of transferred embryos being carried to term by recipients with 1,2 and 3 CL, respectively (P less than 0.01). More embryos survived (65%) when 2 embryos were transferred to each recipient than when 1 (51%) or 3 (48%) were transferred. In recipients receiving 2 embryos, survival was significantly improved by transfer of both embryos to the same oviduct (70%) than when one was transferred to each oviduct (62%). The percentage survival of embryos was optimal when oestrus of recipients was synchronized within +/- 1 day of oestrus in donors.     

Genetic parameters of meat technological quality traits in a grand-parental commercial line of turkey

Genetic parameters for meat quality traits and their relationships with body weight and breast development were estimated for a total of 420 male turkeys using REML. The birds were slaughtered in a commercial plant and the traits measured included pH at 20 min (pH₂₀) and 24 h post-mortem (pHu) and colour of the breast and thigh meat. The heritabilities of the rate and the extent of the pH fall in the breast muscle were estimated at h² = 0.21 ± 0.04 and h² = 0.16 ± 0.04, respectively. Heritabilities ranging from 0.10 to 0.32 were obtained for the colour indicators in the breast muscle. A marked negative genetic correlation (r_g = -0.80 ± 0.10) was found between pH₂₀ and lightness (L*) of breast meat, both traits corresponding to PSE indicators. The pH₂₀ in the thigh muscle had a moderate heritability (h² = 0.20 ± 0.07) and was partially genetically related to pH₂₀ in the breast muscle (r_g = 0.45 ± 0.17). Body weight and breast yield were positively correlated with both initial and ultimate pH and negatively with the lightness of breast meat.     

Genetic parameters of meat quality traits in two pig breeds measured by rapid methods

To study genetic variation in meat quality traits measured by rapid methods, data were recorded between 2005 and 2008 on samples of M. longissimus dorsi (LD) in Landrace (n = 3838) and Duroc (n = 2250) pigs included in the Norwegian pig breeding scheme. In addition, ultimate pH levels in the glycolytic LD (loin muscle) and M. gluteus medius (GM, ham muscle), and in the oxidative m. gluteus profundus (GP, ham muscle) were recorded as an extended data set (n = 16 732 and n = 7456 for Landrace and Duroc, respectively) from 1998 to 2008. Data were analysed with a multi-trait animal model using AI-REML methodology. Meat from Duroc had considerably more intramuscular fat (IMF), less moisture and protein, appeared darker with higher colour intensity and had lower drip loss than meat from Landrace. The heritability estimates (s.e. 0.01 to 0.07) for pH in LD (0.19 and 0.27 for Landrace and Duroc, respectively), GM (0.12 and 0.22) and GP (0.19 and 0.38), drip loss (0.23 and 0.33), colour values: L* (lightness) (0.41 and 0.28), a* (redness) (0.46 and 0.43), b* (yellowness) (0.31 and 0.33), IMF (0.50 and 0.62), muscle moisture (0.31 and 0.50) and muscle protein content (0.40 and 0.54) in LD all demonstrated moderate-to-high genetic variation for these traits in both breeds. Near infrared spectroscopy and EZ-DripLoss are modern technologies used in this study for the determination of chemical components and drip loss in meat. These methods gave higher heritabilities than more traditional methods used to measure these traits. The estimated genetic correlations between moisture and IMF in Duroc, and pH and drip loss in Duroc were both -0.89. Interesting differences between the two breeds in numerical value of some genetic correlations were observed, probably reflecting the differences in physiology and selection history between Landrace and Duroc. The estimated genetic correlation between drip loss and pH was much stronger in Duroc than in Landrace (-0.89 and -0.63, respectively). This might be due to the high pH in Duroc, whereas Landrace had a lower pH closer to the iso-electric point for muscle proteins. The positive genetic correlation between the L* value in meat and IMF in Duroc (0.50) was an effect of differences in visible marbling, rather than meat colour. For Landrace, this correlation was negative (-0.20). IMF content showed favourable genetic correlations to drip loss (-0.36 and -0.35 for Landrace and Duroc, respectively).     

Genetic analysis of organoleptic quality in fresh market tomato. 1. Mapping QTLs for physical and chemical traits

Improving organoleptic quality is an important but complex goal for fresh market tomato breeders. A total of 26 traits involved in organoleptic quality variation were evaluated, in order to understand the genetic control of this characteristic. A recombinant inbred line (RIL) population was developed from an intraspecific cross between a cherry tomato line with a good overall aroma intensity and an inbred line with a common taste but with bigger fruits. Physical traits included fruit weight, diameter, color (L,a,b), firmness and elasticity. Chemical traits were dry matter weight, titratable acidity, pH, and the contents of soluble solids, sugars, lycopene, carotene and 12 aroma volatiles. RILs showed a large range of variation for most of the traits and many of them were transgressive. Some correlations between aroma volatiles were in accordance with the metabolic pathway they originated from. A total of 81 significant QTLs were detected for the 26 traits by simple and composite interval mapping. They were mainly distributed in a few regions on chromosomes 2, 3, 4, 8, 9, 11 and 12. Major QTLs (R²>30%) were detected for fruit weight, diameter, and color, and for six aroma volatiles. Co-localization of QTLs controlling correlated traits was mainly found on chromosome 2. QTLs for fruit weight and sugar content or dry matter weight were often co-localized. However, a QTL for soluble-solids content and dry matter weight have been detected on chromosome 9 in a region without fruit weight QTLs. QTLs for seven aroma volatiles, lycopene content and fruit color were also co-localized. The QTL localizations were compared with those detected in crosses between Lycopersicon esculentum and wild tomato species. Received: 19 January 2000 / Accepted: 26 May 2000     

Genetic parameters and selection efficiency using part-records for production traits in strawberries

Summary The efficiency of selection for yield and fruit size using parts of the complete-season record was evaluated using data collected for individual strawberry seedlings (Fragaria x annanasa) in four genetic tests. Part-records were generated for each trait using cumulative weekly sums, and these were compared with complete records to assess the value of extended data collection. In addition, part-records were generated using data from alternate weeks of harvest. Scoring separate sets of seedlings in alternate weeks was assumed to allow a doubling of the unselected population size, halving the selection proportion and increasing selection intensity. Heritabilities estimated for part-records were often larger for mid-season cumulative part-records than for the complete-season records. Seasonal patterns for broad-sense and narrow-sense heritabilities differed, suggesting temporal expression of genes that condition yield and fruit size. Predicted genetic gains were largest using cumulative part-records between 4 and 12 weeks of the 15-week season, depending on trait and breeding objective (breeding value versus clonal value), with 8–9 weeks as a reasonable compromise. Selection using alternate-weeks records was identified as an efficient alternative to selection using total complete-season records. Superiority of the alternate-weeks option depends on the balance between increased selection intensity and decreased individual genetic information, and will differ for specific traits and program designs.     

Genetic parameters for direct and maternal effects on body weights of Draa goats

Genetic parameters and (co)variance components were estimated for weights at birth and at 30, 90 and 180 days of age for Draa goat maintained at Ouarzazate station over a period of 18 years (1988–2005). Records of 1498 kids, the progeny of 46 sires and 404 dams were used in the study. Analyses were carried out by restricted maximum likelihood. Six different animal models including or ignoring maternal genetic or permanent environmental effects were fitted for all traits. The Model 2 with only permanent environmental maternal effects seemed most suitable. Estimates of direct heritability from this model were 0.16 for birth weight and 0.07, 0.11 and 0.11 for weights at 30, 90 and 180 days, respectively. Maternal heritability estimates varied from 0.00 to 0.24 for all traits according to the model used (Models 4–6). Bivariate analysis by Model 2 was also used to estimate genetic correlations between traits. The estimates of genetic and phenotypic correlations among weights were positive and intermediate to high in value. Despite the low estimated heritabilities of body weight traits of Draa goat, there is a small genetic variability that may be exploited to improve growth performance.     

Genome-wide CNV analysis revealed variants associated with growth traits in African indigenous goats

Using the CaprineSNP50 data generated by the AGIN consortium, we detected common CNVs in 126 samples from four African indigenous goat breeds. A total of 30 CNVs ranging from 30,237 bp to 4,910,757 bp were identified. These CNVs were then associated with six growth traits by a linear regression analysis. Three significant associations were identified between two CNVs and two body traits after false discovery rate (FDR) correction (P < .05). One of them (CNV27) was significantly associated with both chest width and width of pin bones. It overlaps the SNX29 gene, the Gene Ontology (GO) annotations of which indicate CNV27 could be a potential functional candidate for meat production, health and reproduction traits. To our knowledge, this study is the first CNV-based association test of growth traits using SNP chip data in African meat goats.