Single nucleotide polymorphism (SNP) arrays for domestic cattle have catalyzed the identification of genetic markers associated with complex traits for inclusion in modern breeding and selection ...programs. Using actual and imputed Illumina 778K genotypes for 3887 U.S. beef cattle from 3 populations (Angus, Hereford, SimAngus), we performed genome-wide association analyses for feed efficiency and growth traits including average daily gain (ADG), dry matter intake (DMI), mid-test metabolic weight (MMWT), and residual feed intake (RFI), with marker-based heritability estimates produced for all traits and populations.
Moderate and/or large-effect QTL were detected for all traits in all populations, as jointly defined by the estimated proportion of variance explained (PVE) by marker effects (PVE ≥ 1.0%) and a nominal P-value threshold (P ≤ 5e-05). Lead SNPs with PVE ≥ 2.0% were considered putative evidence of large-effect QTL (n = 52), whereas those with PVE ≥ 1.0% but < 2.0% were considered putative evidence for moderate-effect QTL (n = 35). Identical or proximal lead SNPs associated with ADG, DMI, MMWT, and RFI collectively supported the potential for either pleiotropic QTL, or independent but proximal causal mutations for multiple traits within and between the analyzed populations. Marker-based heritability estimates for all investigated traits ranged from 0.18 to 0.60 using 778K genotypes, or from 0.17 to 0.57 using 50K genotypes (reduced from Illumina 778K HD to Illumina Bovine SNP50). An investigation to determine if QTL detected by 778K analysis could also be detected using 50K genotypes produced variable results, suggesting that 50K analyses were generally insufficient for QTL detection in these populations, and that relevant breeding or selection programs should be based on higher density analyses (imputed or directly ascertained).
Fourteen moderate to large-effect QTL regions which ranged from being physically proximal (lead SNPs ≤ 3Mb) to fully overlapping for RFI, DMI, ADG, and MMWT were detected within and between populations, and included evidence for pleiotropy, proximal but independent causal mutations, and multi-breed QTL. Bovine positional candidate genes for these traits were functionally conserved across vertebrate species.
In model organisms both the nutrition of the mother and the young offspring could induce long-lasting transcriptional changes in tissues. In livestock, such changes could have important roles in ...determining nutrient use and meat quality. The main objective was to evaluate if plane of maternal nutrition during late-gestation and weaning age alter the offspring's Longissimus muscle (LM) transcriptome, animal performance, and metabolic hormones. Whole-transcriptome microarray analysis was performed on LM samples of early (EW) and normal weaned (NW) Angus × Simmental calves born to grazing cows receiving no supplement low plane of nutrition (LPN) or 2.3 kg high-grain mix/day medium plane of nutrition (MPN) during the last 105 days of gestation. Biopsies of LM were harvested at 78 (EW), 187 (NW) and 354 (before slaughter) days of age. Despite greater feed intake in MPN offspring, blood insulin was greater in LPN offspring. Carcass intramuscular fat content was greater in EW offspring. Bioinformatics analysis of the transcriptome highlighted a modest overall response to maternal plane of nutrition, resulting in only 35 differentially expressed genes (DEG). However, weaning age and a high-grain diet (EW) strongly impacted the transcriptome (DEG = 167), especially causing a lipogenic program activation. In addition, between 78 and 187 days of age, EW steers had an activation of the innate immune system due presumably to macrophage infiltration of intramuscular fat. Between 187 and 354 days of age (the "finishing" phase), NW steers had an activation of the lipogenic transcriptome machinery, while EW steers had a clear inhibition through the epigenetic control of histone acetylases. Results underscored the need to conduct further studies to understand better the functional outcome of transcriptome changes induced in the offspring by pre- and post-natal nutrition. Additional knowledge on molecular and functional outcomes would help produce more efficient beef cattle.
Strategic supplementation during late gestation has the potential to alter progeny performance. Mature fall-calving Simmental × Angus cows were used to evaluate the effects of late gestation ...supplementation of fatty acids to beef cows on cow performance, steer progeny growth performance during pre-weaning and backgrounding periods, and relative mRNA expression of genes associated with myogenesis and adipogenesis. Cows (n = 190; 4 pasture groups of cows/treatment) grazed endophyte-infected tall fescue and were supplemented during late gestation with calcium salts of either saturated fatty acid/monounsaturated fatty acid (SFA/MUFA), polyunsaturated fatty acid (PUFA), or an isocaloric and isonitrogenous control (CON). There were no differences (
≥ 0.11) in cow body weight (BW) or body condition scores from pre-supplementation to weaning or steer BW at birth, weaning, or at the end of the backgrounding period. Concentrations of C18:2n-6 in plasma were greater (
= 0.01) in SFA/MUFA and PUFA cows compared to CON cows during supplementation. For mRNA expression in the longissimus muscle of steer progeny from birth to weaning: PAX7 decreased to a greater (
< 0.01) extent for SFA/MUFA and PUFA steers; AGPAT1 and CPT1 increased to a greater (
≤ 0.02) extent for CON steers. The expression of MYH7 mRNA during the pre-weaning period was greater (
= 0.01) in PUFA. In conclusion, late gestation fatty acid supplementation modified plasma relative concentrations of fatty acids for dams and progeny and modified mRNA expression of genes related to myogenesis and adipogenesis but had limited effects on progeny growth performance during pre-weaning and backgrounding periods.
Abstract
The objective was to determine the effects of injectable vitamin E (VE) before or after transit on feedlot cattle receiving performance, health, and blood parameters. Angus × Simmental ...steers (n = 196; body weight BW = 163 ± 29 kg) were utilized in a randomized complete block design. Steers were blocked by BW and randomly assigned to 1 of 3 treatments: intramuscular injections of saline pre- and post-transit (CON), intramuscular injections of VE (2,000 mg d-α-tocopherol) pre-transit and saline post-transit (PRE), or intramuscular injections of saline pre-transit and VE (2,000 mg d-α-tocopherol) post-transit (POST). Pre-transit injections were administered on day 0, and steers were transported on day 7 for approximately 4 h (348 km). After arrival, steers were fed a common corn silage-based diet in GrowSafe bunks. Final BW tended to be greater (P = 0.08) for CON steers compared with POST steers while PRE steers were intermediate. From days 7 to 63, treatment affected average daily gain (ADG) with PRE and CON steers exhibiting (P = 0.04) greater ADG compared with POST steers. Dry matter intake (DMI), water intake, and gain to feed from days 7 to 63 were not affected (P ≥ 0.17) by treatment. Day 0 serum α-tocopherol concentrations were considered marginal (2.3 ± 0.2 mg/l). A treatment × day interaction (P < 0.01) was observed for serum α-tocopherol concentrations. Serum α-tocopherol concentrations were greatest for PRE steers on day 7 (prior to and post-transit), but greater for POST steers on dys 10 and 14. Plasma ferric-reducing antioxidant potential concentrations increased (P = 0.04) for POST steers compared with CON steers and PRE steers being intermediate. Plasma non-esterified fatty acids (NEFA) concentrations exhibited a treatment × day interaction (P = 0.04) with CON and POST steers being 16% and 14% greater than PRE steers on day 14, respectively. On day 21, NEFA concentrations were greatest for POST steers compared with PRE steers and CON steers being intermediate. There was no main effect (P ≥ 0.14) of treatment on the number of bovine respiratory disease morbidity treatments. Hair cortisol concentrations were decreased (P < 0.01) 14 days after transit for PRE and POST steers compared with CON steers. Overall, injectable VE administered before or after transit increased serum tocopherol concentrations while reducing stress, but did not improve the growth performance of beef steers during the receiving phase.
Transportation stressors can negatively impact lightweight calf performance and health. An injection of VE before or after the transit may reduce stress through improved antioxidant status during the receiving phase.
Lay Summary
Cattle are transported multiple times throughout their lifespan due to the geographic distribution of the United States beef industry. However, transportation can elicit a variety of stressors that jeopardize cattle growth performance and health. Lightweight feeder calves are at the greatest risk for stress-related morbidity and mortality during the feedlot receiving phase. This study evaluated the effects of injectable vitamin E (VE) before or after transit on feedlot receiving phase growth performance, health, and blood parameters of lightweight beef steers. Steers receiving an injection of VE before or after transit had increased serum α-tocopherol concentrations. However, treatment with VE did not improve growth performance and feed intake. Steers injected with VE before or after transit experienced a decrease in hair cortisol concentrations 14 d after transit while steers injected with VE after transit had improved antioxidant status 14 d after transit compared with control steers and those receiving VE before transit. These results indicate that an injection of VE around the time of transit had no effect on growth performance and intake but can improve antioxidant status during the receiving phase.
Abstract
This study investigated the effects of injectable vitamin C (VC) at weaning and prior to transit on growth performance and immune function in early-weaned beef steers. On day 0, 91 Angus × ...Simmental steers (92 ± 4 kg) were weaned (65 ± 11 d of age), given vaccination boosters, blocked by age, and randomly assigned to weaning (WEAN) treatments: intramuscular injections (20 mL per steer) of VC (250-mg sodium ascorbate per mL; 5 g per steer) or saline (SAL). From days 0 to 48, steers were housed at the Dixon Springs Agricultural Center (Simpson, IL) in pens (six pens; N = 14 to 16 steers per pen) equipped with two to three Vytelle bunks to measure individual daily feed disappearance. On day 49, half of the steers in each WEAN treatment were randomly assigned to an additional injection treatment (20 mL per steer) of VC or SAL prior to transport (TRANS). After administering pretransit injections, all steers were loaded onto a commercial livestock trailer with equal representation of treatments across compartments. Steers were transported for 6 h (approximately 480 km) to the Illinois Beef and Sheep Field Laboratory (Urbana, IL). Upon arrival, steers were sorted into pens (six pens; N = 13 to 17 steers per pen) with 2 Vytelle bunks per pen. Steers were weighed on days 0, 1, 14, 48, 49, 64, 78, 106, and 107. Blood was collected (WEAN = 24 steers per treatment; TRANS = 12 steers per treatment) on days 0, 1, 2, 14, 49 (pre- and posttransit), 50, and 51. Data were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of age block, WEAN, TRANS, and WEAN × TRANS. Plasma ascorbate concentrations were greater (WEAN × time P < 0.01) on days 1 and 2 for steers that received VC at weaning. Similarly, for steers that received VC on day 49 pretransit, ascorbate concentrations were greater (TRANS × time P = 0.04) on days 49 posttransit, 50, and 51. Treatments did not affect (P ≥ 0.13) body weight, average daily gain, or gain to feed throughout the trial. Serum Bovine Viral Diarrhea Virus type 1 and 2 antibody titers on days 14 and 51 were not affected (P ≥ 0.32) by treatment. Injectable VC administered to early-weaned beef steers at the time of weaning or pretransit increased plasma ascorbate concentrations but did not improve growth performance or antibody response to vaccination booster.
Beef calves weaned at a younger age may encounter greater physiological or oxidative stress during weaning and transit. This research examined the ability of an injectable vitamin C to affect growth performance and immune function in early-weaned beef calves.
Lay Summary
Weaning and transit represent the primary stressors for beef calves in the United States and are responsible for increasing inflammation, suppressing the immune system, and decreasing antioxidant status. These adverse physiological responses to stressors may decrease growth and increase morbidity in beef calves. Vitamin C is the primary water-soluble antioxidant in plasma and when provided intramuscularly prior to the stress event, may be able to attenuate aspects of a stress response on growth and immune function. This study evaluated the effects of injectable vitamin C given to early-weaned beef calves prior to weaning on day 0 and a 6-h transit on day 49 after weaning. Basal levels of plasma ascorbate were lower than prior studies in older and larger animals. As expected, injectable vitamin C rapidly increased plasma ascorbate concentrations at 24 h, but concentrations also increased in control calves receiving a saline injection. Treatments did not affect overall growth performance or dry matter intake. Treatments also did not impact the immune response to a booster vaccination provided at weaning. While other research has indicated a positive effect of injectable vitamin C prior to transit, additional research is needed to refine the dosage and physiological need for exogenous antioxidants like vitamin C based on the severity and duration of a stress event in lightweight beef calves.
Residual feed intake (RFI) describes an animal's feed efficiency independent of growth performance. The objective of this study was to determine differences in growth performance, carcass traits, ...major bacteria attached to ruminal solids-fraction, and ruminal epithelium gene expression between the most-efficient and the least-efficient beef cattle. One-hundred and forty-nine Red Angus cattle were allocated to three contemporary groups according to sex and herd origin. Animals were fed a finishing diet in confinement for 70 d to determine the RFI category for each. Within each group, the two most-efficient (
= 6; RFI coefficient = - 2.69 ± 0.58 kg dry matter intake (DMI)/d) and the two least-efficient animals (
= 6; RFI coefficient = 3.08 ± 0.55 kg DMI/d) were selected. Immediately after slaughter, ruminal solids-fraction and ruminal epithelium were collected for bacteria relative abundance and epithelial gene expression analyses, respectively, using real-time PCR.
The most-efficient animals consumed less feed (
= 0.01; 5.03 kg less DMI/d) compared with the least-efficient animals. No differences (
> 0.10) in initial body weight (BW), final BW, and average daily gain (ADG) were observed between the two RFI classes. There were no significant RFI × sex effects (
> 0.10) on growth performance. Compared with the least-efficient group, hot carcass weight (HCW), ribeye area (REA), and kidney, pelvic, and heart fat (KPH) were greater (
≤ 0.05) in the most-efficient cattle. No RFI × sex effect (
> 0.10) for carcass traits was detected between RFI groups. Of the 10 bacterial species evaluated, the most-efficient compared with least efficient cattle had greater (
≤ 0.05) relative abundance of
,
, and
, and lower (
≤ 0.05)
and total bacterial density. No RFI × sex effect on ruminal bacteria was detected between RFI groups. Of the 34 genes evaluated in ruminal epithelium, the most-efficient cattle had greater (
≤ 0.05) abundance of genes involved in VFA absorption, metabolism, ketogenesis, and immune/inflammation-response. The RFI × sex interactions indicated that responses in gene expression between RFI groups were due to differences in sex. Steers in the most-efficient compared with least-efficient group had greater (
≤ 0.05) expression of
,
, and
. The most-efficient compared with least-efficient heifers had greater (
≤ 0.05) mRNA expression of
and lower expression (
≤ 0.05) of
and
.
The present study revealed that greater feed efficiency in beef cattle is associated with differences in bacterial species and transcriptional adaptations in the ruminal epithelium that might enhance nutrient delivery and utilization by tissues. The lack of RFI × sex interaction for growth performance and carcass traits indicates that sex may not play a major role in improving these phenotypes in superior RFI beef cattle. However, it is important to note that this result should not be considered a solid biomarker of efficient beef cattle prior to further examination due to the limited number of heifers compared with steers used in the study.
Numerous studies have shown genetic variation at the
locus is strongly associated with growth traits in beef cattle. However, a causative molecular variant has yet to be identified. To define all ...possible candidate variants, 34 Charolais-sired calves were whole-genome sequenced, including 17 homozygous for a long-range haplotype associated with increased growth (
) and 17 homozygous for potential ancestral haplotypes for this region (
). The
haplotype was refined to an 814 kb region between chr6:37,199,897-38,014,080 and contained 218 variants not found in
individuals. These variants include an insertion in an intron of
, a previously documented mutation in
(rs109570900), two coding sequence mutations in
(rs109696064 and rs384548488), and 15 variants located within ATAC peaks that were predicted to affect transcription factor binding. Notably, rs384548488 is a frameshift variant likely resulting in loss of function for long isoforms of
. To test the association of the coding sequence variants of
with phenotype, 405 cattle from five populations were genotyped. The two variants were in complete linkage disequilibrium. Statistical analysis of the three populations that contained
animals revealed significant (
< 0.05) associations with genotype and birth weight, live weight, carcass weight, hip height, and average daily gain. These findings affirm the link between this locus and growth in beef cattle and describe DNA variants that define the haplotype. However, further studies will be required to define the true causative mutation.
The number of animals required to represent the collective characteristics of a group remains a concern in animal movement monitoring with GPS. Monitoring a subset of animals from a group instead of ...all animals can reduce costs and labor; however, incomplete data may cause information losses and inaccuracy in subsequent data analyses. In cattle studies, little work has been conducted to determine the number of cattle within a group needed to be instrumented considering subsequent analyses. Two different groups of cattle (a mixed group of 24 beef cows and heifers, and another group of 8 beef cows) were monitored with GPS collars at 4 min intervals on intensively managed pastures and corn residue fields in 2011. The effects of subset group size on cattle movement characterization and spatial occupancy analysis were evaluated by comparing the results between subset groups and the entire group for a variety of summarization parameters. As expected, more animals yield better results for all parameters. Results show the average group travel speed and daily travel distances are overestimated as subset group size decreases, while the average group radius is underestimated. Accuracy of group centroid locations and group radii are improved linearly as subset group size increases. A kernel density estimation was performed to quantify the spatial occupancy by cattle via GPS location data. Results show animals among the group had high similarity of spatial occupancy. Decisions regarding choosing an appropriate subset group size for monitoring depend on the specific use of data for subsequent analysis: a small subset group may be adequate for identifying areas visited by cattle; larger subset group size (e.g. subset group containing more than 75% of animals) is recommended to achieve better accuracy of group movement characteristics and spatial occupancy for the use of correlating cattle locations with other environmental factors.
Background: The identification of genetic markers associated with complex traits that are expensive to record such as feed intake or feed efficiency would allow these traits to be included in ...selection programs. To identify large-effect QTL, we performed a series of genome-wide association studies and functional analyses using 50K and 770K SNP genotypes scored in 5,133 animals from 4 independent beef cattle populations with phenotypes for average daily gain (ADG), dry matter intake (DMI), metabolic mid-test body weight (MBW) and residual feed intake (RFI). Results: A total of 5, 5, 17 and 10 large-effect QTL (defined as 1-Mb genome windows explaining more than 1 % of the additive genetic variance) were identified for ADG, DMI, MBW and RFI, respectively. These QTL had little overlap across the 4 populations. The pleiotropic QTL on BTA 7 at 23 Mb identified in the Angus population harbours a promising candidate gene ACSL6 (acyl-CoA synthetase long-chain family member 6), and was the largest effect QTL associated with DMI and MBW explaining 10.39 % and 14.25 % of the additive genetic variance, respectively. Pleiotropic QTL associated with ADG and MBW were detected on BTA 6 at 38 Mb and BTA 7 at 93 Mb confirming previous reports. No QTL for RFI explained more than 2.5 % of the additive genetic variance in any population. Gene ontology (GO) analyses revealed that genes involved in the metabolism of nitrogen components, fatty acids and carbohydrates were significantly overrepresented in the QTL regions identified for RFI. GO analyses implicate the role of cytokines in the regulation of feed intake in beef cattle. Genes within the PI3K-Akt signaling pathway were enriched for their association with variation in both ADG and DMI. Conclusions: This GWAS study which is the largest performed for feed efficiency and its component traits in beef cattle to date, identified several large-effect QTL that cumulatively explained sufficient additive genetic variance to enable the implementation of genomic selection for feed efficiency. These results enhance our understanding of the biology of growth, feed intake and utilisation in beef cattle.
The objective was to investigate the effects of feeding late gestational beef cows supplements differing in fatty acid profile on steer progeny finishing phase growth performance, carcass ...characteristics, and relative mRNA expression of myogenic and adipogenic genes. Seventy Angus-cross steers (initial body weight BW 273 ± 34 kg) born from dams supplemented with either 155 g DM/d EnerGII (CON, rich in palmitic and oleic acids) or 80 g DM/d Strata + 80 g DM/d Prequel (PUFA, rich in linoleic acid, eicosapentaenoic acid, and docosahexaenoic acid) for the last 77 ± 6 d prepartum were used. Longissimus muscle and subcutaneous adipose biopsies were collected to evaluate relative mRNA expression of genes related to myogenesis and adipogenesis. Steers were slaughtered at 423 ± 6 d of age. No treatment × time interaction or treatment effect (p ≥ 0.21) was detected for steer finishing phase BW, while steers from PUFA supplemented dams tended (p = 0.06) to have a greater gain to feed ratio (G:F). Neither carcass characteristics nor relative mRNA expression was different (p ≥ 0.11). In conclusion, late gestation PUFA supplementation tended to increase steer progeny finishing phase G:F, but had no effects on finishing phase BW, carcass characteristics, or relative mRNA expression during the finishing phase.
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