Identification of genetic loci associated with growth traits at weaning in yak through a genome-wide association study

A multilocus GWAS was performed to explore the genetic architecture of four growth traits in yak. In total, 354 female yaks for which measurements of body weight (BW), withers height (WH), body length (BL) and chest girth (CG) at weaning were available underwent genotyping with the Illumina BovineHD BeadChip (770K). After quality control, we retained 98 688 SNPs and 354 animals for GWAS analysis. We identified seven, 18, seven and nine SNPs (corresponding to seven, 17, seven and eight candidate genes) associated with BW, WH, BL and CG at weaning respectively. Interestingly, most of these candidate genes were reported to be involved in growth-related processes such as muscle formation, lipid deposition, feed efficiency, carcass composition and development of the central and peripheral nervous system. Our results offer novel insight into the molecular architecture underpinning yak growth traits. Further functional analyses are thus warranted to explore the molecular mechanisms whereby these genes affect these traits of interest.     

Bayesian genome‐wide association analysis for body weight in farmed Atlantic salmon (Salmo salar L.)

We performed a genome‐wide association study to detect markers associated with growth traits in Atlantic salmon. The analyzed traits included body weight at tagging (BWT) and body weight at 25 months (BW25M). Genotypes of 4662 animals were imputed from the 50K SNP chip to the 200K SNP chip using fimpute software. The markers were simultaneously modeled using Bayes C to identify genomic regions associated with the traits. We identified windows explaining a maximum of 3.71% and 3.61% of the genetic variance for BWT and BW25M respectively. We found potential candidate genes located within the top ten 1‐Mb windows for BWT and BW25M. For instance, the vitronectin (VTN) gene, which has been previously reported to be associated with cell growth, was found within one of the top ten 1‐Mb windows for BWT. In addition, the WNT1‐inducible‐signaling pathway protein 3, melanocortin 2 receptor accessory protein 2, myosin light chain kinase, transforming growth factor beta receptor type 3 and myosin light chain 1 genes, which have been reported to be associated with skeletal growth in humans, growth stimulation during the larval stage in zebrafish, body weight in pigs, feed conversion in chickens and growth rate of sheep skeletal muscle respectively, were found within some of the top ten 1‐Mb windows for BW25M. These results indicate that growth traits are most likely controlled by many variants with relatively small effects in Atlantic salmon. The genomic regions associated with the traits studied here may provide further insight into the functional regions underlying growth traits in this species.     

Genetic analyses of metabolic body weight,carcass weight and body conformation traits in Nordic dairy cattle

Improving feed efficiency in dairy cattle by animal breeding has started in the Nordic countries. One of the two traits included in the applied Saved feed index is called maintenance and it is based on the breeding values for metabolic BW (MBW). However, BW recording based on heart girth measurements is decreasing and recording based on scales is increasing only slowly, which may weaken the maintenance index in future. Therefore, the benefit of including correlated traits, like carcass weight and conformation traits, is of interest. In this study, we estimated genetic variation and genetic correlations for eight traits describing the energy requirement for maintenance in dairy cattle including: first, second and third parity MBW based on heart girth measurements, carcass weight (CARW) and predicted MBW (pMBW) based on predicted slaughter weight, and first parity conformation traits stature (ST), chest width (CW) and body depth (BD). The data consisted of 21 329 records from Finnish Ayrshire and 9 780 records from Holstein cows. Heritability estimates were 0.44, 0.53, 0.56, 0.52, 0.54, 0.60, 0.17 and 0.26 for MBW1, MBW2, MBW3, CARW, pMBW, ST, CW and BD, respectively. Estimated genetic correlations among MBW traits were strong (>0.95). Genetic correlations between slaughter traits (CARW and pMBW) and MBW traits were higher (from 0.77 to 0.90) than between conformation and MBW traits (from 0.47 to 0.70). Our results suggest that including information on carcass weight and body conformation as correlated traits into the maintenance index is beneficial when direct BW measurements are not available or are difficult or expensive to obtain.     

ZBTB38 gene polymorphism associated with body measurement traits in native Chinese cattle breeds

Body measurement traits, influenced by genes and environmental factors, play numerous important roles in the value assessment of productivity and economy. In this study, we investigated the association between genetic polymorphisms of the zinc finger and BTB domain containing 38 gene (ZBTB38) and body measurement traits in native Chinese cattle. Using direct DNA sequencing in 423 individuals of 8 different cattle subpopulations, 9 novel polymorphisms were identified for genotyping within 647 bp region of exon 1 of ZBTB38. Linkage disequilibrium and association analysis revealed that two coding exon polymorphisms (2323 G>A and 2325 C>T polymorphisms), missense mutations valine GTC(T) to isoleucine ATC(T), were associated with body length (BL), withers height (WH) and rump length (RL). Furthermore, the analysis of 2323 G>A and 2325 C>T SNP markers shows that there are significant effects on the BL (P = 0.0488), WH (P = 0.0044) and RL (P = 0.0314) in the total population. These results clearly suggest that the ZBTB38 gene is among the target genes for body measurement traits in bovine breeding, and provide data for establishment of an animal model using cattle to study big animal body type.     

Microsatellite polymorphism and its association with body weight and selected morphometrics of farm red fox (Vulpes vulpes L.)

Polymorphism of 30 canine-derived microsatellites was studied in a group of 200 red foxes kept on 2 Polish farms. 22 out of 30 microsatellites were selected to study association between marker genotypes and body weight (BW), body length (BL), body circumference (BC), tail length (TL), ear height (EH), length of the right front limb (FRLL), length of the right rear limb (RRLL), length of the right front foot (FRFL) and length of the right rear foot (RRFL). A total of 112 alleles and 243 genotypes were found at 22 autosomal microsatellite loci. Three monomorphic loci deemed as uninformative were excluded from the study. The association between marker genotypes and the studied traits was analysed using general linear model (GLM) procedure and least squares means (LSM). Linkage disequilibrium (LD) was estimated to assess non-random association between microsatellite loci. Out of 19 microsatellites studied four markers showed no association with the studied traits, three markers had a significant effect on one trait, and another three markers had significant effect on two traits. Among ten microsatellites with significant effect on four economically important traits (BW, BL, BC, TL) four were associated with two characters: marker FH2613 with BW and BC, marker FH2097withBL and BC, marker ZUBECA6 with BW and BC, whereas marker REN75M10 was associated with BL and TL. The strongest LD (r² ranged from 0.15 to 0.33) was estimated between nine loci with significant effect on economically important traits (BW, BL, BC, TL).     

Genome-wide association study of body weight in Australian Merino sheep reveals an orthologous region on OAR6 to human and bovine genomic regions affecting height and weight

Background

Body weight (BW) is an important trait for meat production in sheep. Although over the past few years, numerous quantitative trait loci (QTL) have been detected for production traits in cattle, few QTL studies have been reported for sheep, with even fewer on meat production traits. Our objective was to perform a genome-wide association study (GWAS) with the medium-density Illumina Ovine SNP50 BeadChip to identify genomic regions and corresponding haplotypes associated with BW in Australian Merino sheep.

Methods

A total of 1781 Australian Merino sheep were genotyped using the medium-density Illumina Ovine SNP50 BeadChip. Among the 53 862 single nucleotide polymorphisms (SNPs) on this array, 48 640 were used to perform a GWAS using a linear mixed model approach. Genotypes were phased with hsphase; to estimate SNP haplotype effects, linkage disequilibrium blocks were identified in the detected QTL region.

Results

Thirty-nine SNPs were associated with BW at a Bonferroni-corrected genome-wide significance threshold of 1 %. One region on sheep (Ovis aries) chromosome 6 (OAR6) between 36.15 and 38.56 Mb, included 13 significant SNPs that were associated with BW; the most significant SNP was OAR6_41936490.1 (P = 2.37 × 10⁻¹⁶) at 37.69 Mb with an allele substitution effect of 2.12 kg, which corresponds to 0.248 phenotypic standard deviations for BW. The region that surrounds this association signal on OAR6 contains three genes: leucine aminopeptidase 3 (LAP3), which is involved in the processing of the oxytocin precursor; NCAPG non-SMC condensin I complex, subunit G (NCAPG), which is associated with foetal growth and carcass size in cattle; and ligand dependent nuclear receptor corepressor-like (LCORL), which is associated with height in humans and cattle.

Conclusions

The GWAS analysis detected 39 SNPs associated with BW in sheep and a major QTL region was identified on OAR6. In several other mammalian species, regions that are syntenic with this region have been found to be associated with body size traits, which may reflect that the underlying biological mechanisms share a common ancestry. These findings should facilitate the discovery of causative variants for BW and contribute to marker-assisted selection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12711-015-0142-4) contains supplementary material, which is available to authorized users.     

Detection of quantitative trait loci for body weights and conformation traits in Beijing ducks

Quantitative trait loci (QTL) for body weights and conformation traits were detected in Beijing ducks. Traits included body weights (BW) at hatching and at 1-7 weeks of age; lengths of the body (BL), keel bone (KBL), shank (SL) and neck (NL) at 7 weeks of age; width of breast (BTW) at 7 weeks; and girths of shank (SG) and breast (BG) at 7 weeks. Using a half-sib analysis with a multiple-QTL model, linkage between the phenotypic traits and 95 microsatellite markers was studied. Six genome-wide suggestive QTL for three body weights and two conformation traits were identified in CAU1, CAU2, CAU6 and CAU12. Chromosome-wide significant QTL influencing one body weight trait and one conformation trait were located in CAU4 and CAU10 respectively. Twelve chromosome-wide suggestive QTL for six body weight traits and four conformation traits were found in seven linkage groups (CAU1, CAU2, CAU3, CAU4, CAU6, CAU10 and CAU12). In addition, the QTL in CAU6 at 21 and 73 cM jointly affected SG and explained 10.6% of the phenotypic variation. This study provides the first evidence for QTL involved in body weights and conformation traits in ducks, and will stimulate further investigations into the genetic architecture of these traits in this species.     

Genome-wide scans identify known and novel regions associated with prolificacy and reproduction traits in a sub-Saharan African indigenous sheep (Ovis aries)

Maximizing the number of offspring born per female is a key functionality trait in commercial- and/or subsistence-oriented livestock enterprises. Although the number of offspring born is closely associated with female fertility and reproductive success, the genetic control of these traits remains poorly understood in sub-Saharan Africa livestock. Using selection signature analysis performed on Ovine HD BeadChip data from the prolific Bonga sheep in Ethiopia, 41 candidate regions under selection were identified. The analysis revealed one strong selection signature on a candidate region on chromosome X spanning BMP15, suggesting this to be the primary candidate prolificacy gene in the breed. The analysis also identified several candidate regions spanning genes not reported before in prolific sheep but underlying fertility and reproduction in other species. The genes associated with female reproduction traits included SPOCK1 (age at first oestrus), GPR173 (mediator of ovarian cyclicity), HB-EGF (signalling early pregnancy success) and SMARCAL1 and HMGN3a (regulate gene expression during embryogenesis). The genes involved in male reproduction were FOXJ1 (sperm function and successful fertilization) and NME5 (spermatogenesis). We also observed genes such as PKD2L2, MAGED1 and KDM3B, which have been associated with diverse fertility traits in both sexes of other species. The results confirm the complexity of the genetic mechanisms underlying reproduction while suggesting that prolificacy in the Bonga sheep, and possibly African indigenous sheep is partly under the control of BMP15 while other genes that enhance male and female fertility are essential for reproductive fitness.

     

Mapping quantitative trait loci (QTL) for body weight, length and condition factor traits in backcross (BC1) family of Common carp (Cyprinus carpio L.)

Body weight and length are economical important traits in aquaculture species influenced by quantitative trait loci (QTL) and environmental factors. In this study, a backcross (BC1) common carp family, with 86 progeny, was utilized to construct genetic map for preliminary QTL mapping. The genetic map was constructed with 366 markers, including 191 SNP from gene, coverage 50 linkage groups with an average marker distance of 18.5 cM. A total of fourteen QTLs associated with body weight (BW), body length (BL) and condition factor (K) were detected on ten linkage groups (LGs). Among these QTLs detected, three (qBW8, qBL8 and qK8) were associated with BW, BL and K respectively, were mapped on LG8. qBW8 and qK8 were identified on similar interval neared locus HLJ2394 explained 14.9 and 20.9 % of the phenotype variance, while qBL8 was identified on separate nearby locus HLJ571 with 30.8 % of phenotype variance. Two QTLs, qBW13 and qK13, related with BW and K separately, were found on LG13 at different locus with phenotype variance of 25.3 and 20.9 %. Other two QTLs, qBW19 and qBL19, associated to BW and BL were mapped on same region near SNP0626 on LG19, and explained 10.3 and 15.6 % of phenotype variance. While other seven QTLs related with BW and BL were located on different LGs. Confidential interval was ranged from 1.1 to 10 cM in the present study. These markers, with lower QTL interval, have great influence on the body weight and length. Therefore, these QTLs will be helpful to find out the genes related with specific trait.     

Analysis of quantitative trait loci underlying the traits related to chlorophyll content of the flag leaf in rice

A population of 117 doubled haploid (DH) lines derived from the cross of Zhaiyeqing 8 (indica)× Jingxi 17 (japonica) was employed to map quantitative trait loci (QTL) underlying four physiological traits related to chlorophyll contents of the flag leaf. There were significantly positive correlations among chlorophyll a, chlorophyll b and chlorophyll a + b content. Chlorophyll a/b ratio was significantly negatively correlated with chlorophyll b content. These four traits were normally distributed with transgressive segregation, suggesting that they were controlled by multiple minor genes. A total of 11 QTLs were detected for the four traits and they lay on six chromosomes. Each of them explained 9.2%–19.6% of the phenotypic variations, respectively. Of these, two QTLs controlling chlorophyll a content were mapped on chromosomes 2 and 5; four QTLs underlying chlorophyll b content were mapped on chromosomes 2, 3, 5 and 9; three QTLs underlying chlorophyll a + b amount were mapped on chromosomes 3, 5 and 9; two QTLs underlying chlorophyll a/b ratio were mapped on chromosomes 6 and 11. The intrinsic relationship among the four traits and the practical implication in rice breeding are discussed. __________ Translated from Journal of Wuhan University (Science Edition), 2006, 52(6): 751–756 [译自: 武汉大学学报(理学版)]     

Polymorphisms of myostatin gene (<Emphasis Type="Italic">MSTN</Emphasis>) in four goat breeds and their effects on Boer goat growth performance

Polymorphisms of myostatin (MSTN) gene were investigated as a candidate marker for goat growth in 687 individuals by gene sequencing and polymerase chain reaction restriction fragment length polymorphism methods. Three potential genotypes (AA, AB and BB) of 5 bp indel (1,256 TTTTA/−) in 5′UTR were detected in four breeds. The polymorphism (CC, CD and DD) of substitution (1,388 T/A) in exon 1 was only segregating in Boer. Genotype AB resulted in significant increases in body weights at birth (BW0), 90 (BW90) and 300 (BW300) days of age, and birth body length compared to BB (P < 0.05). Whilst genotype CD contributed to heavier BW0 and BW90, and larger birth body height (BH) compared to CC (P < 0.05). Individuals either with AB or CD genotype also had greater values in other body sizes, although no significant differences appeared (P > 0.05). When in combination, the combined genotype ABCD displayed positive impacts on better growth traits in BW0, BW90, BW300, BH and BCG (P < 0.05). These results indicate that these markers in myostatin (MSTN) are associated with Boer growth and may be useful for marker assisted selection.     

Genome-Wide Association for Growth Traits in Canchim Beef Cattle

Studies are being conducted on the applicability of genomic data to improve the accuracy of the selection process in livestock, and genome-wide association studies (GWAS) provide valuable information to enhance the understanding on the genetics of complex traits. The aim of this study was to identify genomic regions and genes that play roles in birth weight (BW), weaning weight adjusted for 210 days of age (WW), and long-yearling weight adjusted for 420 days of age (LYW) in Canchim cattle. GWAS were performed by means of the Generalized Quasi-Likelihood Score (GQLS) method using genotypes from the BovineHD BeadChip and estimated breeding values for BW, WW, and LYW. Data consisted of 285 animals from the Canchim breed and 114 from the MA genetic group (derived from crossings between Charolais sires and ½ Canchim + ½ Zebu dams). After applying a false discovery rate correction at a 10% significance level, a total of 4, 12, and 10 SNPs were significantly associated with BW, WW, and LYW, respectively. These SNPs were surveyed to their corresponding genes or to surrounding genes within a distance of 250 kb. The genes DPP6 (dipeptidyl-peptidase 6) and CLEC3B (C-type lectin domain family 3 member B) were highlighted, considering its functions on the development of the brain and skeletal system, respectively. The GQLS method identified regions on chromosome associated with birth weight, weaning weight, and long-yearling weight in Canchim and MA animals. New candidate regions for body weight traits were detected and some of them have interesting biological functions, of which most have not been previously reported. The observation of QTL reports for body weight traits, covering areas surrounding the genes (SNPs) herein identified provides more evidence for these associations. Future studies targeting these areas could provide further knowledge to uncover the genetic architecture underlying growth traits in Canchim cattle.     

Resequencing and signatures of selection scan in two Siberian native sheep breeds point to candidate genetic variants for adaptation and economically important traits

Russian sheep breeds represent an important economic asset by providing meat and wool, whilst being adapted to extreme climates. By resequencing two Russian breeds from Siberia: Tuva (n = 20) and Baikal (n = 20); and comparing them with a European (UK) sheep outgroup (n = 14), 41 million variants were called, and signatures of selection were identified. High‐frequency missense mutations on top of selection peaks were found in genes related to immunity (LOC101109746) in the Baikal breed and wool traits (IDUA), cell differentiation (GLIS1) and fat deposition (AADACL3) in the Tuva breed. In addition, genes found under selection owing to haplotype frequency changes were related to wool traits (DSC2), parasite resistance (CLCA1), insulin receptor pathway (SOCS6) and DNA repair (DDB2) in the Baikal breed, and vision (GPR179) in the Tuva breed. Our results present candidate genes and SNPs for future selection programmes, which are necessary to maintain and increase socioeconomic gain from Siberian breeds.     

Genome-wide association study reveals the genetic basis of growth trait in yellow catfish with sexual size dimorphism

Sexual size dimorphism has been widely observed in a large number of animals including fish species. Genome-wide association study (GWAS) is a powerful tool to dissect the genetic basis of complex traits, whereas the sex-differences in the genomics of animal complex traits have been ignored in the GWAS analysis. Yellow catfish (Pelteobagrus fulvidraco) is an important aquaculture fish in China with significant sexual size dimorphism. In this study, GWAS was conducted to identify candidate SNPs and genes related to body length (BL) and body weight (BW) in 125 female yellow catfish from a breeding population. In total, one BL-related SNP and three BW-related SNPs were identified to be significantly associated with the traits. Besides, one of these SNPs (Chr15:19195072) was shared in both the BW and BL traits in female yellow catfish, which was further validated in 185 male individuals and located on the exon of stat5b gene. Transgenic yellow catfish and zebrafish that expressed yellow catfish stat5b showed increased growth rate and reduction of sexual size dimorphism. These results not only reveal the genetic basis of growth trait and sexual size dimorphism in fish species, but also provide useful information for the marker-assisted breeding in yellow catfish.     

Association genetics,geography and ecophysiology link stomatal patterning in Populus trichocarpa with carbon gain and disease resistance trade‐offs

Stomata are essential for diffusive entry of gases to support photosynthesis, but may also expose internal leaf tissues to pathogens. To uncover trade‐offs in range‐wide adaptation relating to stomata, we investigated the underlying genetics of stomatal traits and linked variability in these traits with geoclimate, ecophysiology, condensed foliar tannins and pathogen susceptibility in black cottonwood (Populus trichocarpa). Upper (adaxial) and lower (abaxial) leaf stomatal traits were measured from 454 accessions collected throughout much of the species range. We calculated broad‐sense heritability (H²) of stomatal traits and, using SNP data from a 34K Populus SNP array, performed a genome‐wide association studies (GWAS) to uncover genes underlying stomatal trait variation. H² values for stomatal traits were moderate (average H² = 0.33). GWAS identified genes associated primarily with adaxial stomata, including polarity genes (PHABULOSA), stomatal development genes (BRASSINOSTEROID‐INSENSITIVE 2) and disease/wound‐response genes (GLUTAMATE‐CYSTEINE LIGASE). Stomatal traits correlated with latitude, gas exchange, condensed tannins and leaf rust (Melampsora) infection. Latitudinal trends of greater adaxial stomata numbers and guard cell pore size corresponded with higher stomatal conductance (g_s) and photosynthesis (A_max), faster shoot elongation, lower foliar tannins and greater Melampsora susceptibility. This suggests an evolutionary trade‐off related to differing selection pressures across the species range. In northern environments, more adaxial stomata and larger pore sizes reflect selection for rapid carbon gain and growth. By contrast, southern genotypes have fewer adaxial stomata, smaller pore sizes and higher levels of condensed tannins, possibly linked to greater pressure from natural leaf pathogens, which are less significant in northern ecosystems.     

A novel 62‐bp indel mutation in the promoter region of transforming growth factor‐beta 2 (TGFB2) gene is associated with body weight in chickens

Transforming growth factor‐beta 2 (encoded by TGFB2) is a growth factor that regulates a plethora of cellular functions. In this study, we sequenced the promoter and full‐length exon region of the chicken TGFB2 and found two mutations (g.‐640C>T and g.‐851_‐790del) within the promoter. The two polymorphisms were genotyped in 1030 pedigreed hens recorded for body weight at 7 (BW7), 9 (BW9), 11 (BW11), 13 (BW13), 17 (BW17) weeks old, egg weight at 36 weeks of age (EW36) and egg numbers from the age at first egg (AFE) to 40 weeks of age (EN40). Despite the fact that no mutations were found to have statistically significant genetic effects on egg production, the association results of growth traits showed that both g.‐640C>T and g.‐851_‐790del had significant effects on body weights and that both genotype g.‐640TT and g.‐851_‐790wt/wt were positive for body weight performance. Therefore, the polymorphisms of TGFB2, especially the g.‐851_‐790del mutation associated with body weight at almost all periods, could be potential useful genetic markers to improve the growth of Beijing You chickens.     

Association between temperament related traits and single nucleotide polymorphisms in the serotonin and oxytocin systems in Merino sheep

Animal temperament is defined as the consistent behavioral and physiological differences that are seen between individuals in response to the same stressor. Neurotransmitter systems, like serotonin and oxytocin in the central nervous system, underlie variation in behavioral traits in humans and other animals. Variations like single nucleotide polymorphisms (SNPs) in the genes for tryptophan 5-hydroxylase (TPH2), the serotonin transporter (SLC6A4), the serotonin receptor (HTR2A), and the oxytocin receptor (OXTR) are associated with behavioral phenotype in humans. Thus, the objective of this study was to identify SNPs in those genes and to test if those variations are associated with the temperament in Merino sheep. Using ewes from the University of Western Australia temperament flock, which has been selected on emotional reactivity for more than 20 generations, eight SNPs (rs107856757, rs107856818, rs107856856 and rs107857156 in TPH2, rs20917091 in SLC6A4, rs17196799 and rs17193181 in HTR2A, and rs17664565 in OXTR) were found to be distributed differently between calm and nervous sheep. These eight SNPs were then genotyped in 260 sheep from a flock that has never been selected on emotional reactivity, followed by the estimation of the behavioral traits of those 260 sheep using an arena test and an isolation box test. We found that several SNPs in TPH2 (rs107856757, rs107856818, rs107856856 and rs107857156) were in strong linkage disequilibrium, and all were associated with behavioral phenotype in the nonselected sheep. Similarly, rs17196799 in HTR2A was also associated with the behavioral phenotype.     

Genome‐wide detection of genetic loci and candidate genes for teat number and body conformation traits at birth in Chinese Sushan pigs

Body conformation at birth and teat number are economically important traits in the pig industry, as these traits are usually explored to evaluate the growth and reproductive potential of piglets. To detect genetic loci and candidate genes for these traits, we performed a GWAS on 269 pigs from a recently developed Chinese breed (Sushan) using 38  128 informative SNPs on the Affymetrix Porcine SNP 55K Array. In total, we detected one genome‐wide significant (P = 1.31e‐6) SNP for teat number on chromosome X and 15 chromosome‐wide significant SNPs for teat number, body weight, body length, chest circumference and cannon circumference at birth on chromosomes 1, 3, 4, 6, 7, 9, 10, 13, 14, 15, 17 and 18. The most significant SNP had an additive effect of 0.74 × total teat number, explaining 20% of phenotypic variance. Five significant SNPs resided in the previously reported quantitative trait loci for these traits and seven significant SNPs had a pleiotropic effect on multiple traits. Intriguingly, 12 of the genes nearest to the significant SNPs are functionally related to body conformation and teat number traits, including SPRED2, MKX, TMSB4X and ESR1. GO analysis revealed that candidate genes proximal to the significant SNPs were enriched in the G‐protein coupled receptor and steroid hormone‐mediated signaling pathway. Our findings shed light on the genetic basis of the measured traits and provide molecular markers especially for the genetic improvement of teat number in Sushan and related pigs.     

Crude glycerin in the supplementation of crossbred heifers in tropical pastures

Crude glycerin (CG) is a biodiesel byproduct that has been tested as an alternative feed additive for use in beef production. After being absorbed, it is used in the liver to produce glucose, an important precursor of intramuscular fat in ruminants. This study aimed to evaluate the effect of CG (439 g/kg glycerol) on the performance and meat quality of crossbred heifers finished in Urochloa brizantha cv. Marandu. Thirty-six heifers with an initial BW of 301.5 ± 23.02 kg were used. They were supplemented for 154 days with the following levels of CG: mineral mixture (without CG), 33.3, 66.6 and 99.9 g/kg CG in the DM of the supplement. Supplement or pasture DM intakes, slaughter BW and carcass traits were not influenced (P > 0.05) by increasing levels of CG. The total fat content of the meat, the vaccenic (18:1 n-7t) and conjugated linoleic acid (18:2 c9-t11) increased with the addition of CG in the diet (P < 0.05). Crude glycerin can be included up to 99.9 g/kg of the total diet without changing the performance of crossbred heifers finished in the tropical pasture.     

Divergent compensatory growth responses within species: linked to contrasting migrations in salmon?

Animals often exhibit accelerated or “compensatory” growth (CG) after periods of environmentally induced growth depression, raising important questions about how they cope with environmental variability. We tested an underexplored hypothesis regarding the evolutionary consequences of CG; namely, that natural populations differ in CG responses. Common-garden experiments were used to compare subadult growth following food restriction between groups (control, treatment) of two Atlantic salmon (Salmo salar) populations and their first-generation (F₁) hybrids. The populations are found at similar latitudes but characterized by differences in migration distance. We predicted that long-distance migrants would better maintain growth trajectories following food restriction than short-distance migrants because they: (1) require larger body sizes to offset energetic costs of migration and (2) face greater time constraints for growth as they must leave non-breeding areas earlier to return to breeding areas. Long-distance migrants grew faster, achieved quicker CG (relative to controls), and their overall body morphology was more streamlined (a trait known to improve swimming efficiency) than slower growing short-distance migrants. F₁ hybrids were generally intermediate in “normal” growth, CG, and body morphology. We concluded that CG responses may differ considerably among populations and that the conditions generating them are likely interconnected with selection on a suite of other traits.