Performance Traits In Cattle Research Articles

313 Many farmers want a prediction of future performance, not necessarily breeding potential

Abstract High heritability is a characteristic of many performance traits in cattle translating to a relatively strong correlation between an (accurate) estimated breeding value for an animal and its (future) production potential. However, the broad sense heritability (i.e., numerator in the formula includes both additive and non-additive genetic variance) is often larger than the narrow sense heritability (i.e., numerator includes only the additive genetic variance) especially for low heritability traits like reproductive performance. Moreover, the repeatability of a trait can be greater again, the difference between the heritability and repeatability is the inclusion of a permanent environmental variance in the numerator. Accurate and pertinent omic-based animal-level features can contribute to an increase in narrow sense heritability owing to a possible reduction in the residual variance; such data can also provide insights into both non-additive genetic variance and the permanent environmental variance. Even at the level of the contemporary group, omic-level data from the likes of bulk blood/saliva/milk sample, can improve how systematic environmental effects are modeled in the mixed model equations thus also reducing the residual variance. The greater heritability will contribute to a strengthening of the correlation between future phenotypic performance potential and estimated additive genetic merit. Importantly, omic measures for individual animals can help predict the permanent environmental effect of that animal capturing the yet untapped contributor to phenotypic variance. Irrespective, predictions need to be replaced by prescriptions; end users are inundated with data yet crave actionable information. Animal breeders have a lush (pardon the pun!) history of distilling estimates of genetic merit for a plethora of traits into a single value per animal (i.e., breeding indexes); this is the first step in transitioning from predictions to prescriptions. Given the familiarity of end users with breeding indexes, the potential exists to develop production indexes to rank commercial animals on future expected performance taking cognizance of genetic and non-genetic effects. Such production indexes align well with the associated breeding index but where the estimates of genetic merit for the traits in question are replaced by estimates of production merit; these estimated production values are the sum of the additive genetic, non-additive genetic and permanent environmental effects. The weighting factors in the production indexes are more short-term using current costs and prices as opposed to breeding indexes which are longer term. In comparison with the breeding indexes, the production indexes can include ancillary information like gender, age, and month of calving/birth. Like breeding indexes, they are updated in real time. Examples of the application of genome-enabled production indexes are guides for valuing animals for purchase or culling.

Association between Polymorphism in the Janus Kinase 2 (JAK2) Gene and Selected Performance Traits in Cattle and Sheep.

The Janus Kinase 2 (JAK2) tyrosine kinase is an essential component of signal transduction of the class II cytokine receptors, including the growth hormone receptor. Therefore, it may play a crucial role in the signaling pathway of the somatotropic axis, which influences growth, development, and reproductive traits in ruminants. For this purpose, for three breeds of cattle (Hereford, Angus, and Limousin; a total of 781 individuals), two polymorphic sites located in exon 16 (rs210148032; p.Ile704Val, within pseudokinase (JH2)) and exon 23 (silent mutation rs211067160, within JH1 kinase domain) were analyzed. For two breeds of sheep (Pomeranian and Suffolk; 333 individuals in total), two polymorphic sites in exon 6 (rs160146162 and rs160146160; encoding the FERM domain) and one polymorphic site in exon 24 of the JAK2 gene (rs160146116; JH1 kinase domain) were genotyped. In our study, the associations examined for cattle were inconclusive. However, Hereford and Limousin cattle with genotypes AA (e16/RsaI) and AA (e23/HaeIII) tended to have the highest body weight and better daily gains (p ≤ 0.05). No clear tendency was observed in the selected reproductive traits. In the case of sheep, regardless of breed, individuals with the AA (e6/EarI), GG (e6/seq), and AA (e24/Hpy188III) genotypes had the highest body weights and daily gains in the study periods (p ≤ 0.01). The same individuals in the Pomeranian breed also had better fertility and lamb survival (p ≤ 0.01). To the best of our knowledge, these are the first association studies for all these polymorphic sites. Single-nucleotide polymorphisms in the JAK2 gene can serve as genetic markers for growth and selected reproductive traits in ruminants given that they are further investigated in subsequent populations and analyzed using haplotype and/or combined genotype systems.

Exploring molecular dynamic indicators associated with reproductive performance of Bos indicus cattle in blood plasma samples through data-independent acquisition mass spectrometry

Improving reproductive performance of cattle is of paramount importance for sustainable dairy farming. Poor reproduction performance (RP) hinders the genetic improvement of important Bos indicus cattle breeds. It is well known that incorporation of molecular information along with conventional breeding method is far better than use of conventional method alone for the genetic improvement of reproductive performance traits in cattle. Therefore, the present study sought to investigate the plasma proteome of the Deoni cows in cyclical (n = 6) and pregnant (n = 6) reproductive phases with varying reproductive performance (high and low). High-throughput data independent acquisition (DIA) based proteomics was performed to understand corresponding proteome. We identified a total of 430 plasma proteins. Among cyclic cows, twenty proteins were differentially regulated in low RP as compared to high RP. BARD1 and AFP proteins were observed upregulated in cyclical cows whose upregulation reported to affect reproductive performance in cattle. Among the pregnant cows, thirty-five proteins were differentially regulated, including the downregulation of FGL2 and ZNFX1 that modulates the maternal immune response mechanism which is required for successful implantation of the embryo. Also, proteins such as AHSG, CLU and SERPINA6 were upregulated in the pregnant cows whose upregulation reported to reduced reproductive performance. The results of this study will be helpful in establishing a framework for future research on the aspect of improving reproductive performance in Bos indicus cattle breeds. SignificanceThe Indian subcontinent is the center of domestication for Bos indicus cattle breeds and they are known for their disease resistance, heat tolerance, ability to survive in low input regime and harsh climatic conditions. In recent times, population of many important Bos indicus breeds including Deoni cattle is declining due to various factors, especially due to reproductive performance. Traditional breeding methods are not sufficient enough to understand and improve the reproductive performance traits in important Bos indicus cattle breeds. Proteomics approach is a promising technology to understand the complex biological factors which leads to poor reproductive performance in cattle. The present study utilized DIA based LC- MS/MS analysis to identify the plasma proteins associated with reproductive performance in cyclical and pregnant cows. This study if improved further, can be used to develop potential protein markers associated with reproductive performance which is useful for the selection and genetic improvement of important Bos indicus breeds.

Concordance rate in cattle and sheep between genotypes differing in Illumina GenCall quality score.

Proper quality control of data prior to downstream analyses is fundamental to ensure integrity of results; quality control of genomic data is no exception. While many metrics of quality control of genomic data exist, the objective of the present study was to quantify the genotype and allele concordance rate between called single nucleotide polymorphism (SNP) genotypes differing in GenCall (GC) score; the GC score is a confidence measure assigned to each Illumina genotype call. This objective was achieved using Illumina beadchip genotype data from 771 cattle (12428767 genotypes in total post-editing) and 80 sheep (1557360 SNPs genotypes in total post-editing) each genotyped in duplicate. The called genotype with the lowest associated GC score was compared to the genotype called for the same SNP in the same duplicated animal sample but with a GC score of >0.90 (assumed to represent the true genotype). The mean genotype concordance rate for a GC score of <0.300, 0.300-0.549, and ≥0.550 in the cattle (sheep in parenthesis) was 0.9467 (0.9864), 0.9707 (0.9953), and 0.9994 (0.99997) respectively; the respective allele concordance rate was 0.9730 (0.9930), 0.9849 (0.9976), and 0.9997 (0.99998). Hence, concordance eroded as the GC score of the called genotype reduced, albeit the impact was not dramatic and was not very noticeable until a GC score of <0.55. Moreover, the impact was greater and more consistent in the cattle population than in the sheep population. Furthermore, an impact of GC score on genotype concordance rate existed even for the same SNP GenTrain value; the GenTrain value is a statistical score that depicts the shape of the genotype clusters and the relative distance between the called genotype clusters.

Cytoplasmic inheritance and its effects on development and performance

In contrast to nuclear inheritance, cytoplasmic inheritance in mammals is derived mostly, if not exclusively, from the maternal line. Mitochondria, and their DNA molecules (mtDNA), are the genetic units of this method of inheritance. Mammalian mtDNA codes for 13 enzymes used in the mitochondrial energy-generating pathway, oxidative phosphorylation, 22 tRNAs and two rRNAs. Although all transcripts of mtDNA and their translational products remain in the mitochondria, most proteins used in mitochondria are from nuclear DNA and are imported after synthesis on cytoplasmic ribosomes. Spermatozoa introduce a small number of mitochondria into the cytoplasm of the egg at fertilization, which appear to be digested soon after penetration. Although the paternal contribution of mtDNA to the offspring is not believed to occur in mammals, some interspecific crosses have suggested that it does occur. Experiments with animals derived from reconstituted embryos, using nuclear or cytoplasmic transplantations, suggest that nuclear-mitochondrial interactions are important but not essential in the survival and replication of exogenous mitochondria introduced into the egg. As the levels of heteroplasmy varied in several tissues of animals derived from reconstituted embryos, it is suggested that differential partitioning of mitochondria occurs during embryogenesis. Mitochondrial morphology changes substantially during oogenesis and throughout early cleavage stages. Somatic morphology and normal replication patterns are regained at the blastocyst stage. In pig oocytes and embryos, mitochondria aggregate and are closely associated with endoplasmic reticulum, lipid granules and large vesicles. Although the direct correlation of mitochondrial genes with reproductive traits is still unclear, some human degenerative diseases and performance traits in cattle can be related directly to specific mtDNA polymorphisms. In pigs, reciprocal-cross comparisons have indicated greater offspring parent similarity with dam than sire for lean:fat ratio. A difference was also observed for oxygen consumption and oxidative phosphorylation, but not for anaerobic energy metabolism, in a pig reciprocal-cross experiment. Information on the transmission of mtDNA and its effects on performance will have many implications not only for our understanding of mitochondrial genetics but also for the increased productivity of animals. There are also potential ramifications to the animal cloning industry.

Breed- and trait-specific associations define the genetic architecture of calving performance traits in cattle.

Reducing the incidence of both the degree of assistance required at calving, as well as the extent of perinatal mortality (PM) has both economic and societal benefits. The existence of heritable genetic variability in both traits signifies the presence of underlying genomic variability. The objective of the present study was to locate regions of the genome, and by extension putative genes and mutations, that are likely to be underpinning the genetic variability in direct calving difficulty (DCD), maternal calving difficulty (MCD), and PM. Imputed whole-genome single-nucleotide polymorphism (SNP) data on up to 8,304 Angus (AA), 17,175 Charolais (CH), 16,794 Limousin (LM), and 18,474 Holstein-Friesian (HF) sires representing 5,866,712 calving events from descendants were used. Several putative quantitative trait loci (QTL) regions associated with calving performance both within and across dairy and beef breeds were identified, although the majority were both breed- and trait-specific. QTL surrounding and encompassing the myostatin (MSTN) gene were associated (P < 5 × 10−8) with DCD and PM in both the CH and LM populations. The well-known Q204X mutation was the fifth strongest association with DCD in the CH population and accounted for 5.09% of the genetic variance in DCD. In contrast, none of the 259 segregating variants in MSTN were associated (P > × 10−6) with DCD in the LM population but a genomic region 617 kb downstream of MSTN was associated (P < 5 × 10−8). The genetic architecture for DCD differed in the HF population relative to the CH and LM, where two QTL encompassing ZNF613 on Bos taurus autosome (BTA)18 and PLAG1 on BTA14 were identified in the former. Pleiotropic SNP associated with all three calving performance traits were also identified in the three beef breeds; 5 SNP were pleiotropic in AA, 116 in LM, and 882 in CH but no SNP was associated with more than one trait within the HF population. The majority of these pleiotropic SNP were on BTA2 surrounding MSTN and were associated with both DCD and PM. Multiple previously reported, but also novel QTL, associated with calving performance were detected in this large study. These also included QTL regions harboring SNP with the same direction of allele substitution effect for both DCD and MCD thus contributing to a more effective simultaneous selection for both traits.

Genomic Regions Associated With Skeletal Type Traits in Beef and Dairy Cattle Are Common to Regions Associated With Carcass Traits, Feed Intake and Calving Difficulty.

Linear type traits describing the skeletal characteristics of an animal are moderately to strongly genetically correlated with a range of other performance traits in cattle including feed intake, reproduction traits and carcass merit; thus, type traits could also provide useful insights into the morphological differences among animals underpinning phenotypic differences in these complex traits. The objective of the present study was to identify genomic regions associated with five subjectively scored skeletal linear traits, to determine if these associated regions are common in multiple beef and dairy breeds, and also to determine if these regions overlap with those proposed elsewhere to be associated with correlated performance traits. Analyses were carried out using linear mixed models on imputed whole genome sequence data separately in 1,444 Angus, 1,129 Hereford, 6,433 Charolais, 8,745 Limousin, 1,698 Simmental, and 4,494 Holstein-Friesian cattle, all scored for the linear type traits. There was, on average, 18 months difference in age at assessment of the beef versus the dairy animals. While the majority of the identified quantitative trait loci (QTL), and thus genes, were both trait-specific and breed-specific, a large-effect pleiotropic QTL on BTA6 containing the NCAPG and LCORL genes was associated with all skeletal traits in the Limousin population and with wither height in the Angus. Other than that, little overlap existed in detected QTLs for the skeletal type traits in the other breeds. Only two QTLs overlapped the beef and dairy breeds; both QTLs were located on BTA5 and were associated with height in both the Angus and the Holstein-Friesian, despite the difference in age at assessment. Several detected QTLs in the present study overlapped with QTLs documented elsewhere that are associated with carcass traits, feed intake, and calving difficulty. While most breeding programs select for the macro-traits like carcass weight, carcass conformation, and feed intake, the higher degree of granularity with selection on the individual linear type traits in a multi-trait index underpinning the macro-level goal traits, presents an opportunity to help resolve genetic antagonisms among morphological traits in the pursuit of the animal with optimum performance metrics.

Novel SNPs in HSPB8 gene and their association with heat tolerance traits in Sahiwal indigenous cattle.

Heat shock proteins (HSPs) are expressed in response to heat stress, and the polymorphism in HSP genes at single-nucleotide level has been reported to be associated with heat tolerance and production performance traits in cattle. HSPB8 gene has been mapped on Bos taurus autosome 17 (BTA-17) spanning nearly 13,252 bp and comprising three exons and two introns. The present study was conducted in Sahiwal cows (n = 108) reared in subtropical climate with the objectives to identify SNPs in all three exons and part of intron 1 of HSPB8 gene and to analyze their association with heat tolerance traits in Sahiwal cows. Respiration rate (RR) and rectal temperature (RT) were recorded once during probable extreme hours in different seasons or Temperature-Humidity Index (THI), i.e., winter, spring, and summer. Heat tolerance coefficient (HTC) was also calculated to check the adaptability of the animals during the period of heat stress. The comparative sequence analysis revealed a total two single-nucleotide polymorphisms (SNPs), i.e., g.507G>A in exon 1 and g.881T>C in intron 1 of HSPB8 gene. Out of these two identified SNPs, only one SNP, i.e., g.507G>A, was found to be significantly associated with heat tolerance indicator traits (RR, RT, and HTC) in Sahiwal cows. The perusal of results across different seasons showed the significant (P < 0.01) difference in RR, RT, and HTC between winter, spring, and summer seasons. RR, RT, and HTC were found to be significantly lower (P < 0.01) in GA as compared to GG genotype of g.507G>A SNP of HSPB8 gene. However, in case of another SNP, i.e., g.881T>C, located on intron 1, the RR, RT, and HTC were having non-significant association with the different genotypes, i.e., TT and TC. These findings may partly suggest that GA genotype of SNP g.507G>A of HSPB8 gene has a probable role in heat tolerance in Sahiwal cattle and can therefore be utilized as a marker in propagation of thermo-tolerance cattle in hot tropical and subtropical climate. Nevertheless, the involvement of other regulatory mechanisms cannot be overruled.

Novel SNPs in ATP1B2 Gene and their Association with Heat Tolerance Indicator Traits in Sahiwal Cattle

Heat Shock Proteins (HSPs) are expressed in response to heat stress and the polymorphism in HSP genes at single nucleotide level is reported to be associated with heat tolerance and production performance traits in cattle. ATP1B2 gene was mapped to Bos taurus autosome 19 (BTA 19) spanning nearly 4310bp, comprising 7 Exons and 6 Introns. The present study was conducted in Sahiwal cows (n=108) raised under sub-tropical climate with the objectives to identify SNPs in targeted regions (Intron 2,4 and Exon 3,5) of ATP1B2 gene and to analyze their association with heat tolerance traits in Sahiwal cows. Respiration rate (RR) and rectal temperature (RT) were recorded during probable extreme hours in winter, spring and summer seasons. Heat tolerance coefficient (HTC) was also calculated to check the adaptability of the animals during the period of heat stress. The comparative sequence analysis revealed a total of two SNPs in Intron 2 of ATP1B2 gene i.e. g.2243G&gt;A and g.2366T&gt;C. Out of these two identified SNPs, only one SNP i.e. g.2243G&gt;A was found to be significantly (PC, RR, RT and HTC were having non-significant association with the different genotypes i.e. TT and TC. These findings may partly suggest that AA and GA genotype of SNP g.2243G&gt;A of ATP1B2 gene can be utilized as potential marker for propagating thermo-tolerant cattle.

Genetic relationships between carcass cut weights predicted from video image analysis and other performance traits in cattle

The objective of this study was to quantify the genetic associations between a range of carcass-related traits including wholesale cut weights predicted from video image analysis (VIA) technology, and a range of pre-slaughter performance traits in commercial Irish cattle. Predicted carcass cut weights comprised of cut weights based on retail value: lower value cuts (LVC), medium value cuts (MVC), high value cuts (HVC) and very high value cuts (VHVC), as well as total meat, fat and bone weights. Four main sources of data were used in the genetic analyses: price data of live animals collected from livestock auctions, live-weight data and linear type collected from both commercial and pedigree farms as well as from livestock auctions and weanling quality recorded on-farm. Heritability of carcass cut weights ranged from 0.21 to 0.39. Genetic correlations between the cut traits and the other performance traits were estimated using a series of bivariate sire linear mixed models where carcass cut weights were phenotypically adjusted to a constant carcass weight. Strongest positive genetic correlations were obtained between predicted carcass cut weights and carcass value (min rg(MVC) = 0.35; max rg(VHVC) = 0.69), and animal price at both weaning (min rg(MVC) = 0.37; max rg(VHVC) = 0.66) and post weaning (min rg(MVC) = 0.50; max rg(VHVC) = 0.67). Moderate genetic correlations were obtained between carcass cut weights and calf price (min rg(HVC) = 0.34; max rg(LVC) = 0.45), weanling quality (min rg(MVC) = 0.12; max rg(VHVC) = 0.49), linear scores for muscularity at both weaning (hindquarter development: min rg(MVC) = −0.06; max rg(VHVC) = 0.46), post weaning (hindquarter development: min rg(MVC) = 0.23; max rg(VHVC) = 0.44). The genetic correlations between total meat weight were consistent with those observed with the predicted wholesale cut weights. Total fat and total bone weights were generally negatively correlated with carcass value, auction prices and weanling quality. Total bone weight was, however, positively correlated with skeletal scores at weaning and post weaning. These results indicate that some traits collected early in life are moderate-to-strongly correlated with carcass cut weights predicted from VIA technology. This information can be used to improve the accuracy of selection for carcass cut weights in national genetic evaluations.

Relationship between the insertion/deletion polymorphism within the promoter and the intron 1 sequence of the PRNP gene and milk performance traits in cattle

Current studies on the prion protein (PRNP) gene polymorphism focus primarily on the causative mutations that influence BSE susceptibility in cattle. The specific genetic structure determined by the insertion/deletion (indel) polymorphism within the 23 bp promoter sequence and the 12 bp intron 1 sequence of the PRNP gene, and its genomic location suggest that this polymorphism can be a potential QTL marker. The objective of the present study was to determine whether the indel polymorphism within the promoter sequence (23 bp) and the intron 1 sequence (12 bp) of the PRNP gene can be used as a factor differentiating the values of milk performance traits. The experimental materials comprised 285 primiparous Polish Holstein-Friesian cows, daughters of two dihybrid (23ins-12ins/23del-12del) sires (progeny of sire 1 &amp;ndash; 149 cows, progeny of sire 2 &amp;ndash; 136 cows). The following milk performance traits were analysed: milk yield, milk fat yield, milk protein yield, fat and protein contents of milk during the first 305-day lactation. The polymorphism in the promoter region (23 bp) was found to have a significant (P = 0.040) effect on protein yield and a highly significant (P = 0.007) effect on the protein content of milk. The highest values of these traits were noted in 23 ins/del heterozygotes and the lowest in 23 del/del homozygotes. There was an interrelation between diplotype variants and the concentrations of milk components. The protein content of milk was highly significantly (P = 0.007) higher in 23ins-12ins/23del-12del heterozygotes and significantly (P = 0.028) higher in 23ins-12ins/23ins-12ins homozygotes, compared to 23del-12ins/23del-12del cows. 23ins-12ins/23del-12del heterozygotes were also characterized by a significantly (P = 0.046) higher fat content of milk, in comparison with 23del-12del/23del-12del homozygotes.

Associations between newly discovered polymorphisms in the Bos taurusgrowth hormone receptor gene and performance traits in Holstein-Friesian dairy cattle

Variations in the growth hormone receptor (GHR) gene sequence are associated with performance traits in cattle. For example, the single nucleotide polymorphism (SNP) F279Y in transmembrane exon 8 has a strong association with milk yield. In this study, 32 previously unreported, putative novel SNPs (31 in the 5' non-coding region) were identified by resequencing ∼19 kb of the GHR gene in genomic DNA from 22 cattle of multiple breeds. A population of 848 Holstein-Friesian AI sires was subsequently genotyped for the 32 putative novel SNPs and seven published SNPs (including F279Y, one in exon 1A promoter and five in exon 10). Associations between each segregating SNP and genetic merit for performance were quantified in the 848 Holstein-Friesians using weighted animal linear mixed models. Six of the published SNPs and seven of the novel SNPs were associated with at least one of the traits--milk yield, fat yield, protein yield, fat percentage, protein percentage, somatic cell score, calving interval, survival and growth and size traits. Even when the allelic substitution effect (P < 0.001) of F279Y was accounted for, the allelic substitution effect of one of the novel SNPs (GHR4.2) in the 5' non-coding region of GHR was associated with a lactation milk yield of 37.46 kg (P < 0.001). GHR4.2 and F279Y were not in linkage disequilibrium (r(2) = 0.00, D' = 0.04) in the 848 Holstein-Friesians, indicating that their association with milk yield was independent.

Estimating myostatin gene effect on milk performance traits using estimated gene content for a large number of non-genotyped cows

The objective of this study was to estimate the myostatin (mh) gene’s effect on milk, protein and fat yield in a large heterogeneous cow population, of which only a small portion was genotyped. For this purpose, a total of 13 992 889 test-day records derived from 799 778 cows were available. The mh gene effect was estimated via BLUP using a multi-lactation, multi-trait random regression test-day model with an additional fixed regression on mh gene content. As only 1416 animals, (of which 1183 cows had test-day records) were genotyped, more animals of additional breeds with assumed known genotype were added to estimate the genotype (gene content) of the remaining cows more reliably. This was carried out using the conventional pedigree information between genotyped animals and their non-genotyped relatives. Applying this rule, mean estimated gene content over all cows with test-day records was 0.104, showing that most cows were homozygous +/+. In contrast, when gene content estimation was only based on genotyped animals, mean estimated gene content over all cows with test-day records was with 1.349 overestimated. Therefore, the applied method for gene content estimation in large populations needs additional genotype assumptions about additional animals representing genetic diversity when the breed composition in the complete population is heterogeneous and only a few animals from predominantly one breed are genotyped. Concerning allele substitution effects for one copy of the ‘mh’ gene variant, significant decreases of −76.1 kg milk, −3.6 kg fat and −2.8 kg protein/lactation were obtained on average when gene content estimation was additionally based on animals with assumed known genotype. Based on this result, knowledge of the mh genotypes and their effects has the potential to improve milk performance traits in cattle.

Single nucleotide polymorphisms at the imprinted bovine insulin-like growth factor 2 (IGF2) locus are associated with dairy performance in Irish Holstein-Friesian cattle

The imprinted insulin-like growth factor 2 gene (IGF2) encodes a fetal mitogenic hormone protein (IGF-II) and has previously been shown to be associated with performance in dairy cattle. In this study we assessed genotype-phenotype associations between four single nucleotide polymorphisms (SNPs) located within the bovine IGF2 locus on chromosome 29 and a range of performance traits related to milk production, animal growth and body size, fertility and progeny survival in 848 progeny-tested Irish Holstein-Friesian sires. Two of the four SNPs (rs42196909 and IGF2.g-3815A>G), which were in strong linkage disequilibrium (r2 = 0·995), were associated with milk yield (P ≤ 0·01) and milk protein yield (P ≤ 0·05); the rs42196901 SNP was also associated (P ≤ 0·05) with milk fat yield. Associations (P ≤ 0·05) with milk fat percentage and milk protein percentage were observed at the rs42196901 and IGF2.g-3815A>G SNPs, respectively. The rs42196909 and IGF2.g-3815A>G SNPs were also associated with progeny carcass conformation (P ≤ 0·05), while an association (P ≤ 0·01) with progeny carcass weight was observed at the rs42194733 SNP locus. None of the four SNPs were associated with body size, fertility and progeny survival. These findings support previous work which suggests that the IGF2 locus is an important biological regulator of milk production in dairy cattle and add to an accumulating body of research showing that imprinted genes influence many complex performance traits in cattle.

Whole-plant corn, forage sorghum, and grain sorghum silages for growing cattle (1993)

Agronomic and cattle performance traits were measured for eight silages produced in 1991. The silages were: irrigated Pioneer 3377 corn; dryland (early-planted) DeKalb 535 corn; irrigated and dryland DeKalb DK 42Y grain sorghum; and dryland forage sorghums Cargill 200F, Pioneer 947, Northrup King (NK) 300, and Funk's 102F. The irrigated corn and NK 300 and Funk's 102F forage sorghums had the highest whole-plant dry matter (DM) yields per acre; early-planted corn had the lowest yield. The dryland grain sorghum had the highest grain yield and the early-planted corn, the lowest. Average daily gains (ADG) were excellent for steers fed each of the eight silage rations and reflected the relatively high grain contents of the silages and the high DM intakes (2.37 to 2.81% of body wt). As expected, the irrigated corn silage produced the fastest and most efficient gain; the late-maturing, Funk's 102F forage sorghum produced the slowest and least efficient gain.