Carcass Traits In Beef Cattle Research Articles

Impact of rumen microbiome on cattle carcass traits

Rumen microbes are crucial in the anaerobic fermentation of plant polysaccharides to produce volatile fatty acids. However, limited information exists about the specific microbial species and strains in the rumen that affect carcass traits, and it is unclear whether there is a relationship between rumen metabolic functions and these traits. This study investigated the relationship between the rumen microbiome and carcass traits in beef cattle using 16S rRNA amplicon and shotgun sequencing. Metagenomic sequencing was used to compare the rumen microbiome between high-carcass weight (HW) and low-carcass weight (LW) cattle, and high-marbling (HM) and low-marbling (LM) cattle. Prokaryotic communities in the rumen of HW vs. LW and HM vs. LM were separated using 16S rRNA amplicon sequencing. Notably, shotgun metagenomic sequencing revealed that HW cattle had more methane-producing bacteria and ciliate protozoa, suggesting higher methane emissions. Additionally, variations were observed in the abundances of certain glycoside hydrolases and polysaccharide lyases involved in the ruminal degradation of plant polysaccharides between HW and LW. From our metagenome dataset, 807 non-redundant metagenome-assembled genomes (MAGs) of medium to high quality were obtained. Among these, 309 and 113 MAGs were associated with carcass weight and marbling, respectively.

The Impact of Liver Abscesses on Performance and Carcass Traits in Beef Cattle: A Meta-Analysis Study

The use of high-grain diets in feedlots is associated with the development of acidosis and ruminitis, which can lead to the occurrence of liver abscesses (LAs). However, the effect of LA on carcass traits is not well known. This study assessed the effects of LA on the performance and carcass traits of beef cattle. Nine peer-reviewed publications with forty-seven treatment means were included in the data set. The effects of the LA were evaluated by examining the weighted mean difference (WMD) between LA (animal with LA) and control treatment (animal without LA). Heterogeneity was explored by meta-regression, followed by a subgroup analysis of the scores and percentages of liver abscess and concentrate level in the feedlot diet. Animals affected by LA showed a reduction in dry matter intake (−1.03%) and feed efficiency (−1.82%). Animals with an LA score of “A” (one or two small abscesses) exhibited a decrease in carcass weight (WMD = 3.41 kg; p = 0.034) and ribeye area (WMD = −1.37 cm2; p = 0.019). When assessing the impact of LA on carcass traits, the most reliable finding indicates a 1.21% reduction in the ribeye area, with no adverse effects observed on subcutaneous fat thickness or the marbling score in the carcass.

Integrated analyses of genomic and transcriptomic data reveal candidate variants associated with carcass traits in Huaxi cattle 1

Cattle carcass traits are economically important in the beef industry. In the present study, we identified 184 significant genes and 822 alternative genes for 7 carcass traits using genome-wide association studies (GWASs) in 1566 Huaxi beef cattle. We then identified 5,860 unique cis-genes and 734 trans-genes in 227 longissimus dorsi muscle (LDM) samples to better understand the genetic regulation of gene expression. Our integration study of the GWAS and cis-eQTL analysis detected 13 variants regulating 12 identical genes, in which one variant was also detected in fine-mapping analysis. Moreover, using a transcriptome-wide association study (TWAS), we identified 4 genes (TTC30B, HMGA1, PRKD3 and FXN) that were significantly related to carcass chest depth (CCD), carcass length (CL), carcass weight (CW) and dressing percentage (DP). This study identified variants and genes that may be useful for understanding the molecular mechanism of carcass traits in beef cattle.

Does transport stress have any effect on carcass quality of Nellore cattle (Bos taurus indicus) in Brazil? - A case study.

With the increasing concomitant demands for Brazilian beef and in particular high-quality beef, there is a need for observational studies of the effects of pre- and post-slaughter practices on beef carcass traits. We hypothesized in our case study that pre-slaughter transport of bovines over significant distances would induce stress in animals, and that this would reduce carcass quality because of higher pH resulting from long-distance transportation. To test this hypothesis, 30,230 Nellore carcasses from a private slaughterhouse were evaluated 24 h postmortem. Analysis showed correlations between animal maturity, ultimate pH, distance, and carcass weight. More precisely, there was a slight positive correlation between ultimate pH and weight (but not with transportation distance) and a slight positive correlation between maturity and weight. A linear regression model (R2 = 0.016) failed to show distance having a significant effect on ultimate pH (P = 0.63), while carcass weight significantly affected ultimate pH (P < 0.001) with a low coefficient of 0.0003. Maturity negatively affected ultimate pH also (P < 0.001) but with also a small effect (-0.0008). Results (from 95% confidence intervals of variance of the random effects and of the random errors) showed that the variability within farms was higher than between farms. The linear mixed model showed that maturity had a significant effect on carcass weight value (P < 0.001) with a large coefficient of 2.90. The R2 of the linear mixed model was 46.03%. In conclusion, while weight and maturity both affect ultimate pH, long distances did not significantly impact ultimate pH and therefore the beef quality from Nellore cattle. This could be because of low stress during transport, as well as the physical characteristics of the Nellore breed that favor greater resistance to tropical climatic conditions.

Integrated Comparative Transcriptome and circRNA-lncRNA-miRNA-mRNA ceRNA Regulatory Network Analyses Identify Molecular Mechanisms Associated with Intramuscular Fat Content in Beef Cattle.

Intramuscular fat content (IMF), one of the most important carcass traits in beef cattle, is controlled by complex regulatory factors. At present, molecular mechanisms involved in regulating IMF and fat metabolism in beef cattle are not well understood. Our objective was to integrate comparative transcriptomic and competing endogenous RNA (ceRNA) network analyses to identify candidate messenger RNAs (mRNAs) and regulatory RNAs involved in molecular regulation of longissimus dorsi muscle (LDM) tissue for IMF and fat metabolism of 5 beef cattle breeds (Angus, Chinese Simmental, Luxi, Nanyang, and Shandong Black). In total, 34 circRNAs, 57 lncRNAs, 15 miRNAs, and 374 mRNAs were identified by integrating gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Furthermore, 7 key subnets with 16 circRNAs, 43 lncRNAs, 7 miRNAs, and 237 mRNAs were detected through clustering analyses, whereas GO enrichment analysis of identified RNAs revealed 48, 13, and 28 significantly enriched GO terms related to IMF in biological process, molecular function, and cellular component categories, respectively. The main metabolic-signaling pathways associated with IMF and fat metabolism that were enriched included metabolic, calcium, cGMP-PKG, thyroid hormone, and oxytocin signaling pathways. Moreover, MCU, CYB5R1, and BAG3 genes were common among the 10 comparative groups defined as important candidate marker genes for fat metabolism in beef cattle. Contributions of transcriptome profiles from various beef breeds and a competing endogenous RNA (ceRNA) regulatory network underlying phenotypic differences in IMF provided novel insights into molecular mechanisms associated with meat quality.

Effects of increased dietary roughage during the late finishing period on beef cattle performance, carcass traits, and blood, ruminal, and faecal characteristics

Finishing cattle consume diets high in concentrates to efficiently deposit both muscle and adipose tissue while decreasing cost of gain during finishing. Concerns regarding liver abscesses and late finishing period morbidity and death loss have led to interest in increasing dietary roughage concentrations during late finishing. The objective of the current experiment was to evaluate the effects of increased roughage inclusion late in the finishing period on growth performance, carcass traits, blood, inflammation markers, ruminal, and fecal characteristics of feedlot steers. Crossbred beef steers (n = 60; initial body weight; BW = 289 ± 35.6 kg) were blocked by BW and assigned to experimental dietary treatments in a randomized complete block design during the final 58 d on feed. Experimental treatments included control (CON; 6% roughage DM), intermediate (INT; 12% roughage DM), and high (HGH; 18% roughage DM) roughage diets (CON = 5 pens and INT and HGH = 4 pens; 4 steers per pen). All experimental diets contained dry-rolled corn, prairie hay, Sweet Bran (Cargill, Inc., Blair, NE), dry supplement, urea, and a corn steep and molasses-based liquid supplement. The inclusion rate of roughage and dry-rolled corn were adjusted for each experimental treatment diet. Overall dry matter intake (DMI) tended to increase linearly (P = 0.02) with increasing roughage concentration. No differences in BW, overall average daily gain (ADG), or gain to feed (G:F) were observed (P ≥ 0.72). Rib eye area increased linearly with increasing roughage concentration (P = 0.02). Fat thickness, hot carcass weight (HCW), marbling, liver score, and kidney, pelvic, and heart fat (KPH) did not differ (P ≥ 0.29) among treatments. Steers consuming the HGH diet had a lower fecal pH at the end of the finishing period (P = 0.05) compared to CON and INT steers. Ruminal lactate was increased on d 14 for CON steers compared to other treatments (P &lt; 0.001). No differences were observed for ruminal pH (P ≥ 0.11) among treatments at any collection. Results from the current experiment suggest that increasing roughage late in the finishing period may not negatively impact growth performance or carcass characteristics but does alter feed intake and may alter fermentation and digestion.

Genetic and phenotypic associations of mitochondrial DNA copy number, SNP, and haplogroups with growth and carcass traits in beef cattle

Mitochondrial DNA copy number (mtDNA CN) is heritable and easily obtained from low-pass sequencing (LPS). This study investigated the genetic correlation of mtDNA CN with growth and carcass traits in a multi-breed and crossbred beef cattle population. Blood, leucocyte, and semen samples were obtained from 2,371 animals and subjected to LPS that resulted in nuclear DNA (nuDNA) and mtDNA sequence reads. Mitochondrial DNA CN was estimated as the ratio of mtDNA to nuDNA coverages. Variant calling was performed from mtDNA, and 11 single nucleotide polymorphisms (SNP) were identified in the population. Samples were classified in taurine haplogroups. Haplogroup and mtDNA type were further classified based on the 11 segregating SNP. Growth and carcass traits were available for between 7,249 and 60,989 individuals. Associations of mtDNA CN, mtDNA haplogroups, mtDNA types, and mtDNA SNP with growth and carcass traits were estimated with univariate animal models, and genetic correlations were estimated with a bivariate animal model based on pedigree. Mitochondrial DNA CN tended (P-value ≤0.08) to be associated with birth weight and weaning weight. There was no association (P-value >0.10) between mtDNA SNP, haplogroups, or types with growth and carcass traits. Genetic correlation estimates of mtDNA CN were -0.30 ± 0.16 with birth weight, -0.31 ± 0.16 with weaning weight, -0.15 ± 0.14 with post-weaning gain, -0.11 ± 0.19 with average daily dry-matter intake, -0.04 ± 0.22 with average daily gain, -0.29 ± 0.13 with mature cow weight, -0.11 ± 0.13 with slaughter weight, -0.14 ± 0.13 with carcass weight, -0.07 ± 0.14 with carcass backfat, 0.14 ± 0.14 with carcass marbling, and -0.06 ± 0.14 with ribeye area. In conclusion, mtDNA CN was negatively correlated with most traits investigated, and the genetic correlation was stronger with growth traits than with carcass traits.

Effects of Feeding and Drinking Behavior on Performance and Carcass Traits in Beef Cattle.

Feed and water efficiency are important traits to improve beef cattle production’s economic and environmental sustainability. This study evaluated residual feed intake (RFI) and residual water intake (RWI) and their relationship with performance, ingestive behavior, and carcass traits in Caracu beef cattle. The data were analyzed using a generalized linear model with least squares means. The ingestive behavior, performance, and carcass traits were influenced by sex (p < 0.05). Males showed higher dry matter intake (DMI), average daily gain (ADG), mid-test metabolic weight (BW0.75), rib eye area, and rump fat thickness than females, besides spending more time drinking and eating. Low RFI animals exhibited higher DMI than high RFI animals. Low RWI animals ingested 3.89 L/d of water further than high RWI animals. The interaction between sex and RWI influenced the DMI, BW0.75, and backfat thickness. The ingestive behavior of low and high RFI animals was similar, although high RWI animals visited a smaller number of drinkers than low RWI animals. Water intake positively affects productive efficiency, and the combined use of RWI and RFI may help improve the selection of more efficient animals contributing to reducing the costs of beef cattle production and improving environmental sustainability.

The effects of weather on beef carcass and growth traits

To predict the impact of climate change on our beef animals and systems, we need a better understanding of how beef cattle traits are affected by varying weather and frequency of extreme events. We analysed the effect of minimum and maximum temperatures and average daily precipitation on a range of important carcass traits, including age at slaughter, cold carcass weight, carcass growth rate and conformation and fat score (N = >1.6 million), as well as calf 200-day live weight and growth rate (N = >270 000), using data from abattoirs across Britain (carcass traits) and calves in Scottish suckler beef herds (live weights and growth). Animals which experienced higher daily maximum and minimum temperatures had slower carcass and calf growth rates. Increased precipitation also led to poorer cold carcass weights, conformation scores, calf 200-day weights and calf growth. We also analysed the effect of frequency of extreme weather events, including heatwaves, cold waves, and dry and wet days. The frequency of heatwaves, dry and wet days were shown to have significant negative effects on almost all traits considered, for example, predicting that an increase in the frequency of heatwaves by 1 day per 100 days of life would reduce cold carcass weights by about 200 g and increase age at slaughter by about 3 days. Results show that varying weather and frequency of extreme weather, across the lifetime of a beef animal, influences traits which affect the potential profit for a beef farmer. These effects may be due to several factors, including direct effects on the animal, as well as feed availability and management decisions made by the farmer. However, there is potential to mitigate negative effects through a range of animal management strategies.

Genome-wide association and genotype by environment interactions for growth traits in U.S. Red Angus cattle

BackgroundGenotypic information produced from single nucleotide polymorphism (SNP) arrays has routinely been used to identify genomic regions associated with complex traits in beef and dairy cattle. Herein, we assembled a dataset consisting of 15,815 Red Angus beef cattle distributed across the continental U.S. and a union set of 836,118 imputed SNPs to conduct genome-wide association analyses (GWAA) for growth traits using univariate linear mixed models (LMM); including birth weight, weaning weight, and yearling weight. Genomic relationship matrix heritability estimates were produced for all growth traits, and genotype-by-environment (GxE) interactions were investigated.ResultsModerate to high heritabilities with small standard errors were estimated for birth weight (0.51 ± 0.01), weaning weight (0.25 ± 0.01), and yearling weight (0.42 ± 0.01). GWAA revealed 12 pleiotropic QTL (BTA6, BTA14, BTA20) influencing Red Angus birth weight, weaning weight, and yearling weight which met a nominal significance threshold (P ≤ 1e-05) for polygenic traits using 836K imputed SNPs. Moreover, positional candidate genes associated with Red Angus growth traits in this study (i.e., LCORL, LOC782905, NCAPG, HERC6, FAM184B, SLIT2, MMRN1, KCNIP4, CCSER1, GRID2, ARRDC3, PLAG1, IMPAD1, NSMAF, PENK, LOC112449660, MOS, SH3PXD2B, STC2, CPEB4) were also previously associated with feed efficiency, growth, and carcass traits in beef cattle. Collectively, 14 significant GxE interactions were also detected, but were less consistent among the investigated traits at a nominal significance threshold (P ≤ 1e-05); with one pleiotropic GxE interaction detected on BTA28 (24 Mb) for Red Angus weaning weight and yearling weight.ConclusionsSixteen well-supported QTL regions detected from the GWAA and GxE GWAA for growth traits (birth weight, weaning weight, yearling weight) in U.S. Red Angus cattle were found to be pleiotropic. Twelve of these pleiotropic QTL were also identified in previous studies focusing on feed efficiency and growth traits in multiple beef breeds and/or their composites. In agreement with other beef cattle GxE studies our results implicate the role of vasodilation, metabolism, and the nervous system in the genetic sensitivity to environmental stress.

Meta-analysis to evaluate the effect of yeast as a feed additive on beef cattle performance and carcass traits

Yeast (Saccharomyces cerevisiae) is a group of feed additives widely used in ruminant diets to improve rumen health and consequently animal performance. The present study evaluated the effect of yeast inclusion on beef cattle's performance and carcass traits by meta-analysis. We hypothesized that the variables experimental period, supply period, and statistical design affect beef cattle's performance and carcass traits supplemented with yeast. Thirty-one peer-reviewed publications with 106 treatment means were included in the data set. Yeast effect as an additive in beef cattle diets was evaluated by examining the weighted mean differences (WMD) between yeast treatment (diets with yeast inclusion as an additive) and control treatment (diet with no additive). Heterogeneity was explored by meta-regression and subgroup analysis using genetic group, experimental design, experimental period, yeast in diet (g/day), yeast type, feeding system, and concentrate in diet (g/kg of dry matter). The experimental period was the variable that most influenced the variability of responses with yeast in the diet. Yeast addition in the diets increased average daily gain (ADG; WMD= 0.03 kg/d; P = 0.001) and carcass weight (WMD=3.12 kg; P = 0.046). The experimental period and yeast supply for up to 90 days increased the animals’ final body weight. The effect of yeast inclusion in the diet on the variable final body weight was only affected by the inclusion period or yeast supply. For the other ADG, carcass weight, and dressing, the response's variation was dependent only on the level of yeast inclusion in the diet. The diet's inclusion levels between 10 and 15 g yeast/day increase average daily gain and carcass weight.

Integration of selection signatures and multi-trait GWAS reveals polygenic genetic architecture of carcass traits in beef cattle

Carcass merits are widely considered as economically important traits affecting beef production in the beef cattle industry. However, the genetic basis of carcass traits remains to be well understood. Here, we applied multiple methods, including the Composite of Likelihood Ratio (CLR) and Genome-wide Association Study (GWAS), to explore the selection signatures and candidate variants affecting carcass traits. We identified 11,600 selected regions overlapping with 2214 candidate genes, and most of those were enriched in binding and gene regulation. Notably, we identified 66 and 110 potential variants significantly associated with carcass traits using single-trait and multi-traits analyses, respectively. By integrating selection signatures with single and multi-traits associations, we identified 12 and 27 putative genes, respectively. Several highly conserved missense variants were identified in OR5M13D, NCAPG, and TEX2. Our study supported polygenic genetic architecture of carcass traits and provided novel insights into the genetic basis of complex traits in beef cattle.

Myostatin Gene as a Genetic Marker for Growth and Carcass Traits in Beef Cattle

&lt;p&gt;Growth and carcass traits are of economic importances in livestock breeding, because they affect the profitability of animal production. The phenotypic expression of these traits is controlled by multiple genes (polygenes), such as myostatin (MSTN) gene. This paper aims to discuss the expression, polymorphism and potential application of MSTN gene as a marker-assisted selection (MAS) for growth and carcass traits in beef cattle based on data from published studies. MSTN gene or known as growth and differentiation factor 8 (GDF8) is a member of the transforming growth factor-β (TGF-β) superfamily, which acts as a negative regulator of skeletal muscle mass deposition. Several published studies showed that mutations in the MSTN gene can inhibit the activation of myostatin, which leads to an increased muscle mass (hypertrophy). Several &lt;em&gt;MSTN&lt;/em&gt; gene polymorphisms were reported to be associated with growth and carcass traits in local cattle in several countries, including Indonesia, namely Bali cattle. Based on several assumptions: 1) there is MTSN gene polymorphisms in a population, 2) there is a significant association between MSTN gene polymorphisms and growth and carcass traits, as reported in several beef cattle populations and 3) those cattle with superior genotype have better growth performances, we expect that there will be improvement in growth performances in the future if those cattle are selected. Understanding MSTN gene polymorphisms would be useful to make strategies for the genetic improvement for growth and carcass traits of local cattle.&lt;/p&gt;

Methodology to identify candidate genes from beef carcass traits at weaning: A pilot study

The goal of the work reported herein was to investigate if a new methodology could provide gene expression profiles of brachiocephalicus muscle tissue from young steers and to compare this genetic expression with carcass traits determined at slaughter to identify potential candidate genes. Tissue samples were collected from steers using a fine needle biopsy from muscle in the neck region at weaning. Muscle tissue was removed using the Dunn Biopsy method, and RNA was extracted for sequencing and transcriptomic analysis. Animal groups for data analysis were designated using marbling score codes (MSC) established from carcass grade at slaughter, which identified DNER, PCBD1 and BGN genes associated with adipose; muscle genes included MAP7, PDE1B, and ADAMTS2; tenderness genes identified were FMO2 and ZKSCAN2; and marbling genes RPTN, DNER, and CACNA2D2. These results indicate muscle biopsies may yield complementary information associated with carcass traits to the current industry standards. Application of this technique may provide insight to the identification of candidate genes that could improve production decisions, increase accuracy of prediction from transcriptomic profiling, and ultimately speed genetic progress.

Genomic imprinting variances of beef carcass traits and physiochemical characteristics in Japanese Black cattle.

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

THI Modulation of Genetic and Non-genetic Variance Components for Carcass Traits in Hanwoo Cattle.

The phenotype of carcass traits in beef cattle are affected by random genetic and non-genetic effects, which both can be modulated by an environmental variable such as Temperature-Humidity Index (THI), a key environmental factor in cattle production. In this study, a multivariate reaction norm model (MRNM) was used to assess if the random genetic and non-genetic (i.e., residual) effects of carcass weight (CW), back fat thickness (BFT), eye muscle area (EMA), and marbling score (MS) were modulated by THI, using 9,318 Hanwoo steers (N = 8,964) and cows (N = 354) that were genotyped on the Illumina Bovine SNP50 BeadChip (50K). THI was measured based on the period of 15–45 days before slaughter. Both the correlation and the interaction between THI and random genetic and non-genetic effects were accounted for in the model. In the analyses, it was shown that the genetic effects of EMA and the non-genetic effects of CW and MS were significantly modulated by THI. No significant THI modulation of such effects was found for BFT. These results highlight the relevance of THI changes for the genetic and non-genetic variation of CW, EMA, and MS in Hanwoo beef cattle. Importantly, heritability estimates for CW, EMA, and MS from additive models without considering THI interactions were underestimated. Moreover, the significance of interaction can be biased if not properly accounting for the correlation between THI and genetic and non-genetic effects. Thus, we argue that the estimation of genetic parameters should be based on appropriate models to avoid any potential bias of estimates. Our finding should serve as a basis for future studies aiming at revealing genotype by environment interaction in estimation and genomic prediction of breeding values.

95 Evaluation of variation attributable to lab and technician for measurements of beef carcass traits made using ultrasound

Abstract Carcass data that is collected using ultrasound contributes to national genetic evaluation of beef cattle. Cattle are scanned by many technicians and the resulting images are processed by three laboratories providing data to breed associations. The Ultrasound Guidelines Council certifies technicians and laboratories as being proficient. However, there has been no comprehensive evaluation of non-genetic sources of variation that affect the data. The objective of this study was to partition the variance of ultrasound carcass measurements to animal genetic effects, ultrasound scanning technician and image interpretation laboratory. Ultrasound carcass data for longissimus muscle area, percent intramuscular fat, and subcutaneous fat depth were provided by the American Angus Association (n=65,971), American Hereford Association (n=43,380), and American Simmental Association (n=48,298). For each breed variance components were estimated for additive genetic effects of each animal, technician, contemporary group nested within technician and residual. Genetic correlations were estimated treating measurements from the different interpretation laboratories as separate traits. Across all three breeds, additive genetic effects explained between 15 and 30%, 11 and 25%, and 6 and 13% of the phenotypic variance for IMF, SQF, and LMA, respectively. Similarly, technician explained 12-27%, 4-28%, and 4-26% of the phenotypic variance; contemporary groups within technician accounted for 25-45%, 20-54%, and 43-73% of phenotypic variance. Among the image interpretation laboratories, the ratio of greatest to least residual variance was 3.96, 1.62, and 1.50 for IMF, SQF, and LMA, respectively. Genetic correlations between labs ranged from 0.79 to 0.95 for IMF, 0.64 to 0.94 for SQF and 0.78 to 0.98 for LMA. These results suggest the potential for the residual variances to be heterogeneous, particularly for IMF, depending on the image interpretation laboratory.

Effects of parent-of-origin models with different pedigree information on beef carcass traits and fatty acid composition in Japanese Black cattle.

Genomic imprinting should be considered in animal breeding systems to avoid lead in bias in genetic parameter estimation. The objective of this study was to clarify the effects of pedigree information on imprinting variances for carcass traits and fatty acid composition in Japanese Black cattle. Carcass records [carcass weight, rib eye area, rib thickness (RT), subcutaneous fat thickness and beef marbling score (BMS)] and fatty acid composition were obtained for 11,855 Japanese Black feedlot cattle. To estimate and compare the imprinting variances for the traits, two imprinting models with different pedigree information [the sire-dam gametic relationship matrix (Model 1) and the sire-maternal grandsire (MGS) numerator relationship matrix (Model 2)] were fitted. The ratio of the imprinting variance to the total additive genetic variance for RT (6.33%) and BMS (19.00%) was significant in Model 1, but only that for BMS (21.09%) was significant in Model 2. This study revealed that fitting the sire-MGS model could be useful in estimating imprinting variance under certain conditions, such as when restricted pedigree information is available. Furthermore, the present result suggested that the maternal gametic effects on BMS should be included in breeding programmes for Japanese Black cattle to avoid selection bias caused by imprinting effects.

Partitioning variation in measurements of beef carcass traits using ultrasound.

Ultrasound technology provides cattle breeders with a quick, noninvasive, and inexpensive way to measure carcass data on live animals. Ultrasound data are used as indicator traits in cattle genetic evaluations for economically relevant carcass traits. Ultrasound cattle genetic evaluations assume homogeneous additive genetic and residual variance. Thus, the objective was to partition phenotypic variance in ultrasound carcass measurements into components for additive genetic effects, technicians, contemporary groups within technicians, and residual and to examine the homogeneity of these variances among image interpretation laboratories. Records of longissimus muscle area (LMA), percentage of intramuscular fat (IMF), and subcutaneous fat depth (SFD), measured using ultrasound, were provided by the American Angus Association (n = 65,967), American Hereford Association (n = 43,182), and American Simmental Association (n = 48,298). The data also included contemporary group, technician, imaging lab, and a three-generation pedigree for each animal. Variance components for ultrasound carcass measurements were first estimated with univariate animal models for each breed and imaging laboratory using derivative-free restricted maximum likelihood. Then, treating data from each imaging laboratory as separate traits, genetic correlations between laboratories for LMA, percentage of IMF, and subcutaneous fat were estimated with trivariate animal models. The technician explained 12–27%, 5–23%, and 4–26% of the variance for IMF, SFD, and LMA, respectively, across all three breeds. Variance due to technician was often greater than variance due to additive genetic effects but almost always less than that explained by the contemporary group. Within breeds, estimates of additive genetic variance for LMA, SFD, and IMF differed (range divided by mean) among laboratories by 4.5%, 21.5%, and 39.4 % (Angus); 31.6%, 15.0%, and 49.1% (Hereford); and 19.9%, 46.6%, and 55.3% (Simmental), respectively. Likewise, estimates of residual variance for LMA, SFD, and IMF differed among laboratories by 43.4%, 22.9%, and 43.3% (Angus); 24.9%, 15.2%, and 79.2% (Hereford); and 26.4%, 32.5%, and 46.2% (Simmental), respectively. Genetic correlations between labs across breeds ranged from 0.79 to 0.95 for IMF, 0.26 to 0.94 for SFD, and 0.78 to 0.98 for LMA. The impact of the observed heterogeneity of variance between labs on genetic evaluation requires further study.

Effects of utilizing cotton byproducts in a finishing diet on beef cattle performance, carcass traits, fecal characteristics, and plasma metabolites.

Increased cotton production in the Southwestern United States has increased the availability of cotton byproducts for use in cattle diets. The objective of this experiment was to evaluate the inclusion of cotton byproducts in feedlot finishing diets on the performance, carcass traits, fecal characteristics, and plasma metabolites of steers. Crossbred beef steers (n = 64; BW = 318 ± 12.3 kg) were assigned to 1 of 2 experimental treatments in a randomized complete block design (8 pens per treatment; 4 steers per pen). Treatments included a control (CON) diet, which included prairie hay, Sweet Bran, rolled corn, and a corn steep and molasses-based liquid fat supplement, and a cotton byproduct (CTN) diet, which included cotton gin trash, whole cottonseed, rolled corn, and water. Both diets contained urea and dry supplement. Over the entire feeding period, DMI (P = 0.04) was greater for CTN steers than CON steers with no difference in the gain to feed ratio (P = 0.86) between treatments. The CTN steers tended to have heavier final BW (P = 0.09) and greater overall average daily gain (P = 0.08). The CTN steers had heavier hot carcass weight (P = 0.02) and greater fat thickness (P = 0.03) than CON steers, but marbling score and rib eye area were not different between treatments (P ≥ 0.64). Steers fed the CON diet tended to have a lower yield grade (P = 0.07), less kidney, pelvic and heart fat (P = 0.09), and decreased dressing percentage (P = 0.10) than CTN steers. Liver scores did not differ (P ≥ 0.17) between treatments. Fecal consistency scores were decreased for CTN steers on day 56 (P = 0.03) and fecal pH tended to be greater for the CTN steers on day 28 (P = 0.09) compared with CON steers, but neither differed during other periods (P ≥ 0.18). A treatment × day interaction (P = 0.04) was detected for plasma urea nitrogen (PUN) concentrations, where PUN concentrations differed between treatments only on days 28 and 56. On both days 28 and 56, CTN steers had lower PUN concentrations (P = 0.03, P = 0.002, respectively). No treatment × day interaction was detected for plasma glucose or lactate concentrations. A day effect was observed for both metabolites (P < 0.01). Results from this experiment suggest that cotton byproducts can be effectively used as a source of fiber, fat, and protein in feedlot rations without adverse effects on performance or carcass characteristics.