Genetic correlations between osseous fragments in fetlock and hock joints, deforming arthropathy in hock joints and pathologic changes in the navicular bones of Warmblood riding horses

The results of a standardized radiological examination of 5231 Hanoverian Warmblood horses were used to investigate heritability of and genetic correlations between prevalent radiographic findings in the equine limbs. Radiographic findings were categorized by joint location and type of visible alterations and analyzed as all-or-none traits. Heritabilities and correlations were estimated multivariately for most prevalent radiographic findings in equine limbs using Residual Maximum Likelihood (REML) and Gibbs Sampling (GS). Linear animal models and linear sire models were used for REML; sire threshold models were used for GS analyses. Heritabilities and residual correlations from linear model analyses were transformed from observed scale to underlying liability scale. Osseous fragments were seen in fetlock joints (OFF) of 23.5% and in hock joints (OFH) of 9.2% of investigated horses. Deforming arthropathy in hock joints (DAH) was diagnosed in 12.0% and pathologic changes in navicular bones (PCN) in 25.8% of investigated horses. Heritabilities differed little between analyses with animal and sire models and with REML and GS. Ranges of heritability estimates were h² = 0.16–0.44 with REML and h² = 0.07–0.43 with GS. Genetic correlation estimates were larger in GS than in REML analyses. Additive genetic correlation between OFF and DAH was positive (r_g = 0.25 to 0.77). Negative additive genetic correlations were determined between OFF and OFH (r_g = − 0.17 to − 0.82), between OFH and DAH (r_g = − 0.14 to − 0.81), and between OFH and PCN (r_g = − 0.19 to − 0.26). No relevant additive genetic correlations were estimated between PCN and OFF, and between PCN and DAH. The results of the present study indicate that the prevalences of common radiographic findings in the limbs of young riding horses are relevantly influenced by genetics and probably caused by different genes. Genetic correlations between radiological health traits therefore deserve closer attention in horse breeding. The quantitatively most important radiographic findings should be concurrently considered as individual traits in order to provide for general improvement of radiological health of the limbs of young Warmblood riding horses.     

New genetic parameters to exploit genetic variability in low input production systems

Under low input production systems, low heritabilities for growth traits have been a major limiting factor for recommending selection to improve animal productivity. Heritabilities low values were usually due to a large error variance leading to a dilution of the genetic variability. A total of 11,802 Barbarine lambs, from 606 breeding rams and 2428 breeding ewes, born during the period 1972–2002 and raised in a low production system were used in this study. The objective was to derive new genetic parameters that reflect in a proper way the available genetic variabilities for growth traits even under a low production system. Three classical heritability estimators and two new proposed genetic parameters (ratios) were computed and compared: the additive (h²a), the maternal (h²m), the total (h²t) heritabilities, the additive genetic ratio (a²) and the genetic maternal ratio (m²). Main results of this study showed that the direct animal model has led to higher heritability estimates than the animal maternal model. Estimates were 0.30, 0.30 and 0.31 for weights at 10 days, 30 days and 90 days, respectively. For average daily gains, estimates were 0.22 and 0.26 between 10–30 days and 30–90 days, respectively. Under maternal model, h²a varied from 0.05 to 0.08, h²m varied from 0.08 to 0.12 and h²t varied from 0.11 to 0.17. Maternal heritabilities were higher than additive heritabilities, but both remained relatively small. Values of additive genetic ratios were 0.20, 0.19, 0.20, 0.32 and 0.39 for W10, W30, W90 ADG13 and ADG39, respectively. The maternal genetic ratios were 0.41, 0.45, 0.37, 0.41 and 0.40 for W10, W30, W90, ADG13 and ADG39, respectively. These results showed that a² and m² describe better the contribution of the additive and maternal effects to the available genetic variability compared to classical heritability estimates because they remain unaffected by the residual error variance even under low-input production systems. These new parameters (ratios) represent, consequently, appropriate indicators for the contribution of the additive and maternal genetic effects to the total genetic variability and encourage breeders to find ways to exploit them.     

基于BLUP和GBLUP方法估计北京油鸡胴体和肉质性状遗传参数的差异

旨在比较不同方法对遗传参数估计的差异,为未来北京油鸡胴体和肉质性状选育方法的制定提供参考依据。本研究利用传统最佳线性无偏预测（best linear unbiased prediction,BLUP）和基因组最佳线性无偏预测（genomic best linear unbiased prediction,GBLUP）两种方法对北京油鸡的胴体和肉质等性状进行了遗传参数估计。从系谱较为完整的北京油鸡群体中,选择100日龄体重相近的公鸡615只,测定其100日龄体重（BW）、屠宰率（EP）、胸肌率（BMP）、腿肌率（LMP）、腹脂率（AFP）、嫩度（T,以剪切力值表示）和肌内脂肪（IMF）等性状,并用SNP芯片（Illumina,60K）进行个体基因分型。结果表明,除IMF和剪切力（SF）遗传力基于两种方法的估值存在较大差异外,其余性状利用两种方法得到的遗传力估值差异较小;除嫩度外,GBLUP方法估计的遗传力均低于BLUP方法。所有胴体相关性状中,除屠宰率遗传力为低遗传力外,其余性状均属于中等遗传力性状。嫩度呈现低遗传力,而IMF基于BLUP法和GBLUP法的估计遗传力分别为中等（h² =0.256）和低遗传力（h² =0.107）。基于BLUP方法,IMF与BW、BMP和SF 3个性状间均呈高度遗传负相关（-0.572、-0.420、-0.682）,与EP的遗传相关为中度负相关（-0.234）,与AFP的遗传相关为中度正相关（0.420）;基于GBLUP方法,IMF与BW、BMP和SF 3个性状间均呈高度遗传负相关（-0.808、-0.725、-0.784）,与EP的遗传相关为高度负相关（-0.626）,与AFP的遗传相关为低度正相关（0.097）。综上,对于某些性状,基于传统的BLUP方法与新的GBLUP方法得到的遗传力与遗传相关估值存在较大差异,实际育种工作中,为提高育种效率,需要综合考虑。     

Genetic correlations between competition traits and traits scored at breeding field-tests in Icelandic horses

Relationships between breeding field-test traits and competition traits were studied to investigate whether the latter could be usefully included in the genetic evaluation of Icelandic horses. The current method of genetic evaluation is based on records from breeding field-tests only. The breeding field-test data included 16 401 individual records of Icelandic horses evaluated in 11 countries during 1990–2005. Competition results included 18 982 records of 3790 horses competing in sport and gæðinga competitions in Iceland and Sweden during 1998–2004. In the breeding field-tests, eight conformation traits and eight riding ability traits were scored; height of withers was also recorded. These traits were analysed together with the competition traits tölt(comp), 4-gait, 5-gait and pace test, in bivariate analyses. Animal models were used; the fixed effects for breeding field-test traits included sex by age interaction and country by year interaction. For the competition traits the model included fixed effects of sex, age and event, and a random permanent environmental effect. Estimated heritabilities and genetic correlations for breeding field-test traits were consistent with earlier results; heritabilities ranged from 0.20 to 0.67, and moderate to high genetic correlations were estimated between many of the riding ability traits, and between riding ability traits and some conformation traits. The estimated heritabilities for competition traits were about 0.20, and genetic correlations between competition traits varied from − 0.12 to 1.00. In general, high genetic correlations were estimated between breeding field-test riding ability traits and competition traits. Moderately positive genetic correlations were found between some breeding field-test conformation traits and competition traits. Competition traits add information relating to the breeding goal of the Icelandic horse; they should therefore be added to genetic evaluation in future.     

The correlation between passage rate of digesta and dry matter digestibility in various stages of swine

The relationship between passage rate of digesta (PRD) and apparent faecal dry matter digestibility (DMD) was investigated in five trials. In trial 1, 2, and 3, 36 weanling (16.9 ± 3.0 kg), 24 growing (51.3 ± 8.8 kg), and 23 finishing (104.8 ± 5.2 kg) barrows were housed in metabolic crates. The beginning and end of 5-day collection periods were marked by the addition of 0.5% indigo carmine to the feed for total faeces collection and PRD determination by observing the time required for the marker to appear. In trial 4 and 5, 21 gestating gilts (215.0 ± 15.0 kg), and 19 lactating sows were individually penned. Addition of 0.5% chromic oxide to the feed enabled indirect determination of DMD and PRD. The PRD, which ranged from 12 to 80 h, was positively correlated with DMD in weanling (R² = 0.483, P < 0.001), growing (R² = 0.425, P < 0.01), and finishing (R² = 0.553, P < 0.001) pigs. Body weight and DMD were not significantly correlated in weanling (R² = 0.001, P = 0.893), growing (R² = 0.000, P = 0.995), or finishing (R² = 0.092, P = 0.156) pigs. A positive correlation between PRD, which ranged from 27 to 102 h, and DMD occurred in gestating gilts (R² = 0.231, P < 0.05), but not in lactating sows (R² = 0.014, P = 0.633). The results indicate that longer retention times of digesta improve DMD in swine. Also the results indicate the importance of PRD as a potential independent variable in digestibility assessments.     

The effect of feeding antibiotic growth promoters on the performance of beef cattle consuming forage-based diets: A review

Scientific literature on the use of antibiotic growth promoters (AGP) in beef cattle consuming forage-diets was reviewed. Database summarizes 136 comparisons between untreated and AGP-treated cattle from 48 bibliographic references. Performance data of cattle receiving AGP either alone or in combination with 17 β-estradiol implants was statistically analyzed. Forage quality, in terms of average daily gain (ADG), differentially influenced (P = 0.1) the effect of AGP on beef cattle performance. As the quality of forage increased, the estimated net ADG response to monensin decreased and that to lasalocid increased. ADG increased quadratically (P < 0.01) with increasing doses of monensin (R² = 0.71) or lasalocid (R² = 0.63). Ionophore-dosage level quadratically improved (P = 0.01; R² = 0.52) feed conversion (FCONV) of cattle without affecting their dry matter intake (DMI; P > 0.1). A linear relationship (P < 0.01) between ADG and dose of tetronasin (R² = 0.64) or lysocellin (R² = 0.52) was also observed. The combination of monensin and 17β-estradiol implants resulted in an additive effect on ADG of grazing cattle. The experimental results reviewed show that, in beef cattle consuming forage-based diets, ionophores improve ADG and FCONV in a dose-dependent manner, with little or no effect on DMI. In addition, results suggest that forage quality influences the direction of the ADG response to AGP supplementation in cattle. Summarized data from beef cattle implanted with 17β-estradiol and/or supplemented with monensin indicate that the combined response of these two compounds on cattle grazing high-quality pastures has no effect on ADG over that obtained by 17β-estradiol alone.     

Genetic parameters in Finnish blue fox population: Pelt character and live animal grading traits

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.     

Association between butyrate and short-chain fatty acid concentrations in gut contents and faeces in weaning piglets

The concentration and composition of short-chain fatty acids (SCFA) in gastrointestinal and faecal samples were studied in weaning pigs fed different amounts and composition dietary fibre (DF). In Trial 1 a total of 50 castrated piglets were fed five experimental diets with varying contents of citrus pectin (soluble fibre) and barley hulls (insoluble fibre) and gastrointestinal contents were collected at euthanasia 9 days after weaning. In Trial 2, 120 pair-wise penned piglets were allocated to the same experimental diets as in Trial 1 (24 piglets per treatment), and fresh faecal samples were collected 5 and 32 days after weaning.

There was no difference in the concentrations of SCFA caused by dietary treatments, but across treatments there was a correlation between concentration of SCFA and the proportion of butyrate. The correlation was lowest in the caecum (r² = 0.22, P = 0.0007) and highest in the distal colon (r² = 0.45, P = 0.0001). In faeces there was no relationship 5 days after weaning (r² = 0.004. P = 0.64) but a correlation of r² = 0.25 (P = 0.0001) 32 days after weaning. The results suggest that adaptive changes and differences between piglets in fermentative capacity immediately after weaning are associated not only with a higher concentration of SCFA but also a changed fermentation profile.     

Relationships between dairy cow mastitis and fertility management and farm performance

A field study was carried out on 38 dairy farms in the Netherlands to determine the relationship between mastitis and fertility management with 305-day milk production and gross margin. Questionnaires were used to get insight into the farmers' management. Out of 150 variables related to mastitis and fertility management, and technical and economic results, 44 variables were selected based on correlation of ≥0.25 or ≤−0.25 with milk production and/or gross margin. These variables were used in two separate partial least-squares (PLS) analyses. PLS has the advantage that it can handle a large number of variables in relation to the number of cases. The PLS-model of 305-day milk production had R² = 0.54 and showed a positive relation between 305-day milk production and awareness of the farmer regarding bulk somatic-cell count (BSCC), the goal level of the farmer for BSCC, and hygiene of the milking parlour. Fertility was negatively related to 305-day milk production, in spite of a relatively good fertility management on high-producing farms. R² = 0.46 for gross margin. The aspiration level of fertility did not seem to affect gross margin, but awareness of BSCC and calving interval (CI) had positive effects. Such awareness seemed a general parameter for good economic results, because it was correlated with different aspects of gross margin.     

Feed efficiency of rainbow trout can be improved through selection: different genetic potential on alternative diets

To assess the genetic potential for selection of increased feed efficiency in rainbow trout (Oncorhynchus mykiss), we estimated the heritabilities and correlations for BW, daily weight gain (DG), and daily feed intake (DFI). Body weight was recorded 5 times, and DG and DFI 3 times during a feeding trial lasting 22 mo. To test the hypothesis that phenotypic and genetic parameters were influenced by a nutritional environment, fish were fed either a modern normal protein diet (NP, 40 to 45% protein and 30 to 33% lipid) or an alternative high protein diet (HP, 50 to 56% protein, 20 to 24% lipid) in a split-family design. Results showed that there were no large differences in heritabilities between the diets. Average heritability for DFI over both diets and different fish ages was low (average h2 = 0.10), indicating that modest genetic changes in response to selection can be obtained. Average heritabilities for BW and DG over both diets and different fish ages were 0.28 and 0.33, respectively. The NP diet enabled fish to express a wide range of BW, as shown by the increased coefficients of phenotypic variation for BW. Fish fed the HP diet showed increased phenotypic variation for DFI in > 750-g fish. On the NP diet, genetic correlations of DFI with DG and BW were very strong for 750- to 2,000-g fish. In contrast, on the HP diet, the respective correlations were moderate to low, revealing more genetic potential to change growth and feed intake simultaneously in opposite directions. An analysis of the predicted selection responses showed that selection solely for high DG improved feed efficiency as a correlated genetic response. Simultaneous selection for high DG and reduced DFI, in turn, may increase genetic gain in feed efficiency by a factor of 1.2 compared with selection solely for DG. However, variation for growth and feed intake and the relationships between these traits were different in different nutritional environments, leading to divergent genetic responses on the alternative diets.     

Quality and production trait genetics of farmed European whitefish, Coregonus lavaretus

We present here phenotypic and genetic parameters for the major quality and production traits of farmed European whitefish. A total of 70 families were produced by mating each of 45 sires to an average of 1.6 dams and each of the 52 dams to an average of 1.3 sires. A total of 2,100 individuals were recorded for survival, and 507 individuals for growth and quality-related traits. The 4 major results were as follows: first, all traits exhibited nonzero heritabilities except for fillet gaping and fillet protein%. The heritabilities for the production traits were harvest weight (0.42 ± 0.10), gutted weight (0.40 ± 0.10), fillet weight (0.36 ± 0.09), maturity score (0.27 ± 0.11, on liability scale), survival (0.19 ± 0.05, on liability scale), carcass% (0.14 ± 0.07), and fillet% (0.11 ± 0.06). The heritabilities for the quality traits were condition factor (0.49 ± 0.10), fillet lipid% (0.37 ± 0.10), muscle texture (0.30 ± 0.09), Distell lipid reading (0.26 ± 0.09), fillet lightness (0.16 ± 0.07), fillet gaping (0.04 ± 0.06), and fillet protein% (0.04 ± 0.06). Second, the quality traits that were significantly genetically correlated with each other were all related to lipid deposition. Increasing fillet lipid% (an undesired change in whitefish) was genetically related to desired lighter fillet color [genetic correlation (r(G)) = 0.70 ± 0.22] and to undesired greater condition factor (0.39 ± 0.17). None of the other genetic correlations between condition factor, fillet lipid%, muscle texture, fillet lightness, fillet gaping, and fillet protein% were significant. Third, BW and gutted weight were genetically related to the quality traits that were genetically related to lipid deposition. Increasing harvest weight was genetically related to high fillet lipid% (r(G) = 0.59 ± 0.14), lighter fillet color (0.61 ± 0.25), and to greater condition factor (0.60 ± 0.12). All other genetic correlations of harvest weights with the quality traits were nonsignificant, indicating that rapid growth was not genetically related to gaping and softer flesh. Fourth, none of the genetic correlations of carcass%, fillet%, maturity, and survival with the quality traits were significant, implying weak genetic integration between the traits. Yet, marginally significant genetic correlations were found for fillet lipid% with maturity score (r(G) = -0.46 ± 0.24) and survival (0.36 ± 0.19). These results provide the genetic basis for assessing the potential to improve product quality via selective breeding.     

Genetic parameters for carcass traits of field progeny and their relationships with feed efficiency traits of their sire population for Japanese Black cattle

Genetic parameters for carcass traits of 1774 field progeny (1281 steers and 493 heifers), and their genetic relationships with feed efficiency traits of their sire population (740 bulls) were estimated with REML. Feed efficiency traits included feed conversion ratio (FCR) and residual feed intake (RFI). RFI was calculated by the residual of phenotypic (RFI_phe) and genetic (RFI_gen) regression from the multivariate analysis of feed intake on metabolic weight and daily gain. Progeny traits were carcass weight (CWT), rib eye area (REA), rib thickness (RBT), subcutaneous fat, yield estimate (YEM), marbling score (MSR), meat quality grade, meat color, fat color, meat firmness and meat texture. The estimated heritability for CWT (0.70) was high and heritabilities for all the other traits were moderate (ranged from 0.32 to 0.47), except for meat and fat color and meat texture which were low (ranged from 0.02 to 0.25). The high genetic correlation (0.62) between YEM and MSR suggests that simultaneous improvement of high carcass yield and beef marbling is possible. Estimated genetic correlations of RFI (RFI_phe and RFI_gen) of sires with CWT (− 0.60 and − 0.53) and MSR (− 0.62 and − 0.50) of their progeny were favorably negative indicating that the selection against RFI of sires may have contributed to produce heavier carcass and increase in beef marbling. The correlated responses in CWT, REA and RBT of progeny were higher to selection against RFI than those to selection against FCR of sires. This study provides evidence that selection against RFI is preferred over selection against FCR in sire population for getting better correlated responses in carcass traits of their progeny.     

Estimation of additive and non-additive genetic parameters for reproduction, growth and survival traits in crosses between the Moroccan D'man and Timahdite sheep breeds

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.     

Genetic relationships between pelt quality, maternal ability, and lamb production in the Gotland sheep breed

The aim of the present investigation was to study the genetic relationships between pelt quality traits (shade of fleece, size of curl, score for fleece colour, score for curl, score for quality of hair, score for thickness of fleece, sum of pelt scores, and overall score) on one hand and maternal ability, live weight, and carcass traits on the other hand for the Gotland sheep breed. Data were received from the Swedish Sheep Recording Scheme and included observations on 4-month weight (4MW) and pelt quality for 51,402 lambs and on weight (CW), fatness (FAT), and fleshiness (FLESH) of the carcass for 12,440 lambs. The lambs were born during the period 1991–2003. When maternal genetic and permanent environmental effects were included in the model direct heritabilities for the pelt quality traits varied between 0.16 and 0.25. Maternal heritabilities (0.01 to 0.05) and common environmental variances as a fraction of the total phenotypic variances (0.07 to 0.10) were low. Maternal heritabilities were higher for 4MW (0.11) and CW (0.12) than for the pelt quality traits. Direct-maternal genetic correlations were both for the pelt quality traits and for 4MW and CW generally negative and low to medium high. Direct genetic correlations between pelt quality traits on one hand and 4MW, CW, FAT or FLESH on the other hand were low (− 0.16 to 0.12). Maternal genetic correlations between pelt quality traits and 4MW or CW were positive and high (0.38 to 0.96). It was concluded that breeding for increased growth and improved carcass quality would not influence pelt quality negatively or vice versa. If maternal genetic effects are considered for 4MW and CW in the breeding program for the Gotland sheep breed, selection for maternal effects on 4MW and CW will have positive effects both on lamb weight and pelt quality.     

Genetic correlations between ewe reproduction and carcass and meat quality traits in Merino sheep

Genetic correlations between reproduction traits in ewes and carcass and meat quality traits in Merino rams were obtained using restricted maximum likelihood procedures. The carcass data were from 5870 Merino rams slaughtered at approximately 18 months of age that were the progeny of 543 sires from three research resource flocks over 7 years. The carcass traits included ultrasound scan fat and eye muscle depth (EMDUS) measured on live animals, dressing percentage and carcass tissue depth (at the GR site FATGR and C site FATC), eye muscle depth, width and area and the meat quality indicator traits of muscle final pH and colour (L*, a*, b*). The reproduction data consisted of 13 464 ewe joining records for number of lambs born and weaned and 9015 records for LS. The genetic correlations between reproduction and fat measurements were negative (range ?0.06 ± 0.12 to ?0.37 ± 0.12), with smaller correlations for live measurement than carcass traits. There were small favourable genetic correlations between reproduction traits and muscle depth in live rams (EMDUS, 0.10 ± 0.12 to 0.20 ± 0.12), although those with carcass muscle traits were close to zero. The reproduction traits were independent of meat colour L* (relative brightness), but tended to be favourably correlated with meat colour a* (relative redness, 0.12 ± 0.17 to 0.19 ± 0.16). There was a tendency for meat final pH to have small negative favourable genetic correlations with reproduction traits (0.05 ± 0.11 to ?0.17 ± 0.12). This study indicates that there is no antagonism between reproduction traits and carcass and meat quality indicator traits, with scope for joint improvement of reproduction, carcass and meat quality traits in Merino sheep.     

Different models for evaluation of growth traits and Kleiber ratio in an experimental flock of Iranian fat-tailed Afshari sheep

Records for Afshari sheep were retrieved from data collected between 2000 and 2005 at the Zanjan University experimental flock, at Zanjan, Iran. (Co)variance components and corresponding genetic parameters for birth weight (BW), weaning weight (WW), 6-month weight (W6), average daily gain from birth to weaning (ADGa), from birth to 6 months (ADGb), from weaning to 6 months (ADGc), Kleiber ratio at weaning (WWKR) and Kleiber ratio at 6 months of age (W6KR) were estimated using univariate and bivariate analyses by the DFREML procedure. The Kleiber ratio, defined as growth rate/metabolic weight, has been suggested to be a useful indicator of growth efficiency and an indirect selection criterion for feed conversion. Estimates of direct heritability ( h ²) were 0.23, 0.27, 0.11, 0.22, 0.07, 0.01, 0.13 and 0.06 for BW, WW, W6, ADGa, ADGb, ADGc, WWKR and W6KR, respectively. Maternal genetic effects represented a relatively large proportion of the total phenotypic variance for BW ( m ² = 0.22), whereas maternal permanent environmental effects were significant for W6 ( c ² = 0.15), ADGb ( c ² = 0.16), ADGc ( c ² = 0.14) and W6KR ( c ² = 0.16). Results of bivariate analyses indicated the variable genetic correlations between traits. The largest positive genetic relationships were between adjacent measurements. The moderate estimates of h ² for early growth traits indicate that in Afshari sheep faster genetic improvement through selection is possible for these traits. In order to increase the efficiency of feed conversion, use of Kleiber ratio in selection programmes was recommended.     

Genetic parameters for carcass and meat quality traits and their relationships to liveweight and wool production in hogget Merino rams.

Genetic parameters for carcass and meat quality traits of about 18-month-old Merino rams (n = 5870), the progeny of 543 sires from three research resource flocks, were estimated. The estimates of heritability for hot carcass weight (HCW) and the various fat and muscle dimension measurements were moderate and ranged from 0.20 to 0.37. The brightness of meat (colour L*, 0.18 +/- 0.03 standard error) and meat pH (0.22 +/- 0.03) also had moderate estimates of heritability, although meat relative redness (colour a*, 0.10 +/- 0.03) and relative yellowness (colour b*, 0.10 +/- 0.03) were lower. Heritability estimates for live weights were moderate and ranged from 0.29 to 0.41 with significant permanent maternal environmental effects (0.13 to 0.10). The heritability estimates for the hogget wool traits were moderate to high and ranged from 0.27 to 0.60. The ultrasound measurements of fat depth (FATUS) and eye muscle depth (EMDUS) on live animals were highly genetically correlated with the corresponding carcass measurements (0.69 +/- 0.09 FATC and 0.77 +/- 0.07 EMD). Carcass tissue depth (FATGR) had moderate to low genetic correlations with carcass muscle measurements [0.18 +/- 0.10 EMD and 0.05 +/- 0.10 eye muscle area (EMA)], while those with FATC were negative. The genetic correlation between EMD and eye muscle width (EMW) was 0.41 +/- 0.08, while EMA was highly correlated with EMD (0.89 +/- 0.0) and EMW (0.78 +/- 0.04). The genetic correlations for muscle colour with muscle measurements were moderately negative, while those with fat measurements were close to zero. Meat pH was positively correlated with muscle measurements (0.14 to 0.17) and negatively correlated with fat measurements (-0.06 to -0.18). EMDUS also showed a similar pattern of correlations to EMD with meat quality indicator traits, although FATUS had positive correlations with these traits which were generally smaller than their standard error. The genetic correlations among the meat colour traits were high and positive while those with meat pH were high and negative, which were all in the favourable direction. Generally, phenotypic correlations were similar or slightly lower than the corresponding genetic correlations. There were generally small to moderate negative genetic correlations between clean fleece weight (CFW) and carcass fat traits while those with muscle traits were close to zero. As the Merino is already a relatively lean breed, this implies that particular attention should be given to this relationship in Merino breeding programmes to prevent the reduction of fat reserves as a correlated response to selection for increased fleece weight. The ultrasound scan traits generally showed a similar pattern to the corresponding carcass fat and muscle traits. There was a small unfavourable genetic correlation between CFW and meat pH (0.19 +/- 0.07).     

Estimation of genetic parameters and genome scan for 15 semen characteristics traits of Holstein bulls

A QTL detection experiment was performed in French dairy cattle to search for QTL related to male fertility. Ten families, involving a total of 515 bulls, were phenotyped for ejaculated volume and sperm concentration, number of spermatozoa, motility, velocity, percentage of motile spermatozoa after thawing and abnormal spermatozoa. A set of 148 microsatellite markers were used to realize a genome scan. First, genetic parameters were estimated for all traits. Semen production traits were found to have moderate heritabilities (from 0.15 to 0.30) while some of the semen quality traits such as motility had high heritabilities (close to 0.60). Genetic correlations among traits showed negative relationships between volume and concentration and between volume and most quality traits such as motility or abnormal sperm while correlations between concentration and these traits were rather favourable. Percentages of abnormal sperm were negatively related to quality traits, especially with motility and velocity of spermatozoa. Three QTL related to abnormal sperm frequencies were significant at p < 0.01. In total, 11 QTL (p < 0.05) were detected. However, the number of QTL detected was within the range of expected false positives. Because of the lack of power to find QTL in this design further analyses are required to confirm these QTL.     

Genetic relationship between different measures of feed efficiency and its component traits in Japanese Black (Wagyu) bulls

Genetic parameters of average daily gain (ADG), metabolic body weight (MWT), body weight at finish (BWF), daily feed intake (DFI), feed conversion ratio (FCR), and residual feed intake (RFI) were estimated in 740 Japanese Black bulls. RFI was calculated as the difference between actual and expected feed intake predicted by the residual of multiple regression (RFI_phe) and genetic regression (RFI_gen) from the multivariate analysis for DFI, MWT, and ADG. The estimations were made for the test periods of 140 days (77 bulls) and 112 days (663 bulls). The mean for RFI_phe was close to zero and RFI_gen was negative. Most of the traits studied were moderately heritable (ranging from 0.24 to 0.49), except for ADG and FCR (0.20 and 0.15, respectively). The genetic correlations among growth traits (ADG, MWT and BWF) and between DFI and growth traits were high, while the phenotypic correlations between them were moderate to high. The genetic and phenotypic correlations between RFI_phe and RFI_gen were > 0.95 implying that they are regarded as the same trait and the genetic correlations of RFI (RFI_phe and RFI_gen) with FCR and DFI were favorably high. RFI_phe was phenotypically independent of its component traits, MWT (r_p = − 0.01) and ADG (r_p = 0.01). RFI_gen was genetically independent of MWT (r_g = − 0.07), while there was a weak genetic relationship (r_g = 0.18) between RFI_gen and ADG. These results provide evidence that RFI_gen should be included for genetic improvement of feed efficiency in Japanese Black breeding program.     

The use of purine derivatives/creatinine ratio in spot urine samples as an index of microbial protein supply in Yerli Kara crossbred cattle

Three experiments were conducted to evaluate the use of purine derivatives (PD)/creatinine ratio in spot urine samples as an index of microbial protein supply in Yerli Kara crossbred cattle (YK-C). In Experiment I, response of daily PD excretion to feed intake in YK-C at state farm was measured. In Experiment II, spot urine sampling techniques was applied at state farm and four YK-C bulls were used. In Experiment III, spot urine sampling technique was applied at small-holder farms. There were significant correlations (R² = 0.99) between PD excretion (mmol/day) and digestible organic matter intake (DOMI) (kg/day) in Experiment I, Y = 12.5 (± 0.5) + 19.7 (± 3.5)X (R² = 0.99, n = 16). The equation obtained from Experiment I could be expressed as: Y = − 2.3 (± 0.3) + 0.953 (± 0.06)X, (R² = 0.99, n = 49) where Y is PD excretion (mmol/day) and X is the PDC index. The PDC index was calculated as the molar concentration ratio of PD to creatinine times the metabolic body weight (kg). The corresponding microbial-N values to PDC index of groups I, II and III in developed banding system are 15–25 g/day. Experimentally estimated DOMI was 2.21 ± 0.15 kg/day. Estimated DOMI of groups I, II, and III were 2.8 ± 0.6, 2.6 ± 0.7 and 2.7 ± 0.7 kg/day, respectively. In conclusion, the PDC index in spot urine samples could be used under similar farm condition as an indicator of microbial protein supply in YK-C cattle. Estimated DOMI from PDC index in spot urine samples under defined field conditions may help the development of feeding strategies for YK-C cattle held by small holders.