MyoD基因对肉牛胴体性状影响的分析

用PCR技术克隆到MyoD基因的第二内含子, 采用PCR-SSCP方法研究了3个黄牛品种(鲁西牛、晋喃牛、秦川牛)及4个杂交肉牛(夏洛莱×鲁西牛、安格斯×鲁西牛、利木赞×鲁西牛、西门塔尔×鲁西牛)群体MyoD基因的多态性, 并分析了基因位点多态性与肉牛肉质性状的相关性。实验结果,在国内首次扩增出肉牛MyoD基因的第二内含子的全部序列, 共261 bp。用SSCP方法检测到MyoD基因内含子2有A和B两个等位基因。测序结果表明该座位的多态性是由于内含子二39 bp处C-T的突变和112 bp处C→G的突变造成的。等位基因B在中国地方品种的分布频率高于引进品种的杂交牛群体。c2检验的结果表明, 在该位点的除夏洛莱和安格斯杂交牛外, 其余五个群体(晋南、鲁西、秦川、西门塔尔杂交牛和利木赞杂交牛)均处于Hardy-Weinberg不平衡状态(P>0.05)。实验群体不同基因型与肉牛的宰前活重、胴体重、净肉重、高档肉重、眼肌面积等性状的影响差异极显著或显著(P<0.01或P<0.05), 并且AA型个体均高于AB型个体。     

A novel 18-bp deletion mutation of the AMPD1 gene affects carcass traits in Qinchuan cattle

The objectives of the present study were focused on detecting deletion mutation in bovine AMPD1 gene, and analyzing its effect on body measurement and carcass traits in Qinchuan cattle by using DNA sequencing and agarose electrophoresis methods. The 198-bp PCR products of AMPD1 gene exhibited three genotypes and two alleles were revealed: A and B. The frequencies of genotype AA/AB/BB in Qinchuan populations was 0.7163, 0.2233 and 0.0605. The χ²-test analysis demonstrated that the breed was not in agreement with Hardy–Weinberg equilibrium (P < 0.05). The association of the 18-bp deletion mutation of AMPD1 gene with body measurement and carcass traits of Qinchuan cattle were analyzed. The cattle with AA genotype had slaughter weight and carcass weight than those with genotype AB (P < 0.01 or P < 0.05). These results suggest that the 18-bp deletion mutation may influence the carcass traits in Qinchuan cattle.     

Improved tenderness of beef from bulls supplemented with active dry yeast is related to matrix metalloproteinases and reduced oxidative stress

Supplementing diets with active dry yeast (ADY, Saccharomyces cerevisiae) improves the carcass quality grade of beef cattle and the tenderness of beef. The relevant mechanisms have not been fully elucidated, but may be related to the effect of ADY on oxidative stress and the activity of matrix metalloproteinases (MMPs). To provide further insight into these mechanisms, this study evaluated the influence of ADY supplementation on growth performance, carcass traits, meat quality, concentrations of MMPs in serum (MMP-2, MMP-9 and MMP-13), oxidative stress indices and antioxidant capacity indices in beef cattle. Forty-six crossbred Simmental × Yanbian bulls (～18 months of age, BW 436 ± 35 kg) participated in a 145-day finishing trial. ADY supplementation significantly improved marbling deposition, intramuscular fat content, and beef tenderness (P < 0.05); altered individual fatty acid proportions in the beef and increased saturated fatty acids while decreasing polyunsaturated fatty acids (P < 0.05); significantly decreased the abundance of reactive oxygen species in serum and meat; significantly increased the level of superoxide dismutase in meat (P < 0.05); tended to increase the level of catalase (P = 0.075) in serum and glutathione reductase (P = 0.066) in meat; and increased the secretion of MMPs. The improvement of beef tenderness following ADY supplementation of finishing bulls is related to the effects of ADY on the secretion of MMPs and the lowering of oxidative stress.     

Detecting a deletion in the coding region of the bovine bone morphogenetic protein 15 gene (BMP15)

The aim of this study was to detect polymorphism in the bovine bone morphogenetic protein 15 (BMP 15) gene. On the basis of PCR-SSCP and DNA sequencing, a 4-bp deletion was identified in the coding region of the gene. Sequence analysis revealed that the deletion altered the reading frame and introduced a stop codon at position 264. Eight breeds (Luxi, Qinchuan, Nanyang, Jinnan, Bohai Black, Menggolian, Holstein, and Simmental) were genotyped by PCR-SSCP. No cows homozygous for this mutation were observed in these breeds. Heterozygous cows were detected in Luxi, Qinchuan, Nanyang, Jinnan and Bohai Black cattle. Fecundity was not increased in heterozygous individuals.     

Development of equations to predict carcass weight,empty body gain,and retained energy of Zebu beef cattle

The accurate supply of energy is essential to optimize livestock productivity and profitability. Furthermore, replacing empty BW gain (EBG) with carcass gain (CG) might be a suitable alternative to estimate the retained energy (RE) of beef cattle. Thus, this multi-analysis study was conducted aiming to estimate and validate new equations to predict carcass weight (CW), EBG, and RE of Zebu, beef crossbred, and dairy crossbred. A database composed by 1 112 animals encompassing bulls, steers, heifers of different genetic groups (Zebu, beef crossbred, and dairy crossbred), and two types of slaughter plants (commercial and experimental) was used for generating the new CW equation. For the development of the EBG and RE equations, a database of 636 observations composed of bulls, steers, and heifers of different genetic groups (Zebu, beef crossbred, and dairy crossbred) was assembled. The validation of new equations was performed using independent databases composed by 137 observations (80 for CW and 57 for EBG and RE). The new approaches for EBG and RE validation also included data from our research group studies (Inside) and independent data from literature publications (Outside). Furthermore, the new RE equation was compared to the current model devised by the nutritional requirements, diet formulation, and performance prediction of Zebu and crossbred cattle (BR-CORTE, 2016). Validation analyses were performed by using the Model Evaluation System (MES; 3.1.13, College Station, US). The CW was accurately estimated by the new equation when using both commercial and experimental data. Also, the equations developed in this study accurately estimated EBG and RE using both inside and outside data. In conclusion, equations proposed in this study accurately and precisely estimated CW, EBG, and RE of Zebu beef cattle that composed validation data set. Therefore, we suggest the following equations to estimate CW, EBG, and RE of Zebu cattle: CW, kg = − 11.0_±1.56 + P + ((0.609_±0.005 + G + B) × SBW); EBG (kg) = 0.044_±0.017 + 1.47_±0.026 × CG; RE (MJ/d) = 4.184 × (0.082_±0.002 × EQEBW^0.75 × CG^0.777±0.039), where P = slaughter plant effect, if commercial = − 10.98, if experimental = 0; G = gender effect, if steer = 0, if bull = 0.008169 and if heifer = − 0.00612; B = genotype effect, if Zebu = 0, if dairy crossbreds = − 0.03301 and if beef crossbreds = − 0.01595; SBW = shrunk BW; CG = carcass gain; EQEBW = equivalent empty BW.     

Haematobia irritans parasitism of F1 yak × beef cattle (Bos grunniens × Bos taurus) hybrids

The horn fly Haematobia irritans (Diptera: Muscidae) is a blood obligate ectoparasite of bovids that causes annual losses to the U.S. beef cattle industry of over US$1.75 billion. Climate warming, the anthropogenic dispersion of bovids and the cross‐breeding of beef cattle with other bovid species may facilitate novel horn fly–host interactions. In particular, hybridizing yaks [Bos grunniens (Artiodactyla: Bovidae)] with beef cows (Bos taurus) for heterosis and carcass improvements may increase the exposure of yak × beef hybrids to horn flies. The present paper reports on the collection of digital images of commingled beef heifers (n = 12) and F1 yak × beef hybrid bovids (heifers, n = 7; steers, n = 5) near Laramie, Wyoming (～ 2200 m a.s.l.) in 2018. The total numbers of horn flies on beef heifers and F1 yak × beef heifers [mean ± standard error (SE): 88 ± 13 and 70 ± 17, respectively] did not differ significantly; however, F1 yak × beef steers had greater total horn fly abundance (mean ± SE: 159 ± 39) than female bovids. The present report of this experiment is the first such report in the literature and suggests that F1 yak × beef bovids are as susceptible as cattle to horn fly parasitism. Therefore, similar monitoring and treatment practices should be adopted by veterinarians, entomologists and producers.     

Three novel SNPs in the coding region of <Emphasis Type="Italic">PPARγ</Emphasis> gene and their associations with meat quality traits in cattle

The peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear hormone receptor that regulates adipogenesis and many other biological processes. In the present study, we carried out PCR–SSCP and DNA sequencing analyses to examine SNPs in coding region of the PPARγ gene. A total of 660 individuals from five Chinese cattle breeds were genotyped. We identified three SNPs and their associations with meat quality traits were analyzed in 108 Qinchuan cattle. Two missense mutations and one synonymous mutation were found: 200 A > G (genotypes AA, AB and BB) resulting in D7G change, the silent substitution 42895 C > T (genotypes JJ and JI) and 72472 G > T (genotypes CC, DC and DD) producing Q448H change, respectively. The frequencies of PPARγ-A allele were 0.86, 0.83, 0.80, 0.72 and 0.87 for Qinchuan, Nanyang, Jiaxian, Luxi and Xianan populations, respectively. The frequencies of PPARγ-J allele varied from 0.87 to 0.96 in the five populations. In the 72472 G > T locus, the frequencies of PPARγ-C allele were higher than PPARγ-D allele in the five populations, and ranged from 0.58 to 0.82. Least squares analysis revealed that in 42895 C > T locus, there was a significant effect on tenderness in 18-20 months Qinchuan cattle (P < 0.01), and in the 72472 G > T locus, animals with the genotype DC had lower mean values than these with genotype CC (P < 0.01) for back fat thickness in 18–20 months, and animals with the genotype DD had lower mean values than these with genotypes CC and DC (P < 0.01) for water holding capacity in 21–24 months (P < 0.01). The SNPs we have identified may contribute to establishing a more efficient selection program for improving of genetic characteristics in indigenous Chinese cattle     

Mutations of <Emphasis Type="Italic">MC4R</Emphasis> gene and its association with economic traits in Qinchuan cattle

MC4R belongs to a seven-transmembrane G-protein-coupled receptor which may regulate body composition and insulin action. Many mutations in the MC4R gene are associated with obesity, energy expenditure and serum triglyceride levels in human and animals. Six mutations in the MC4R gene were identified in our study (-293C>G, -193A>T, -192T>G, -129A>G, -84T>C and 1,069C>G). The -129A>G was significantly associated with live weight (LW) (P < 0.05), Cattle with the genotypes AG and GG had higher LW than genotype AA. The 1,069C>G was significantly associated with LW, carcass weight (CW), backfat thickness and marbling score (MS). Cattle with the genotype GG had higher LW, CW and MS than genotype CC; Cattle with the genotypes GG and CG had higher MS than CC. The results suggested that -129A>G and 1,069C>G SNP of the MC4R gene may be useful as a genetic marker for carcass and meat quality traits in Qinchuan cattle.     

Polymorphism of chicken myocyte-specific enhancer-binding factor 2A gene and its association with chicken carcass traits

Myocyte-specific enhancer-binding factor 2A (MEF2A) gene is a member of the myocyte-specific enhancer-binding factor 2 (MEF2) protein family which involved in vertebrate skeletal muscle development and differentiation. The aim of the current study is to investigate the potential associations between MEF2A gene SNPs (single nucleotide polymorphisms) and the carcass traits in 471 chicken samples from four populations. Three new SNPs (T46023C, A72626G, and T89232G) were detected in the chicken MEF2A gene. The T46023C genotypes were associated with live body weight (BW), carcass weight (CW), eviscerated weight, semi-eviscerated weight (SEW), and leg muscle weight (LMW) (P < 0.05); the A72626G genotypes were associated with BW, CW, LMW (P < 0.01) and breast muscle weight (BMW), leg muscle percentage (LMP) (P < 0.05); whereas the T89232G genotypes were associated with carcass percentage (CP) and semi-eviscerated percentage (SEP) (P < 0.05). The haplotypes constructed on the three SNPs were associated with BW, CW, LMW (P < 0.01), SEW, BMW, CP (P < 0.05). Significantly and suggestive dominant effects of diplotype H1H2 were observed for BW, CW, SEW, BMW and CP, whereas diplotype H5H5 had a negative effect on BW, CW, SEW, BMW and LMW. Our results suggest that the MEF2A gene may be a potential marker affecting the muscle trait of chickens.     

Genetic Structure and Differentiation of Three Chinese Indigenous Cattle Populations

Levels of genetic differentiation, gene flow, and genetic structure of three indigenous cattle populations (Luxi, Bohai, and Minnan) and two reference cattle populations (Chinese Holstein and Qinhai yak) in China were estimated using the information from 12 microsatellites, and 141 microsatellite alleles were identified. The mean number of alleles per locus ranged from 2.9005 in yak to 4.9722 in Holstein. The observed heterozygosity ranged from 0.5325 (yak) to 0.7719 (Holstein); 29 private alleles were detected. The global heterozygote deficit across all populations amounted to 58.5% (p < 0.001). The overall significant (p < 0.001) deficit of heterozygotes because of inbreeding within breeds amounted to 43.2%. The five cattle populations were highly differentiated (F _st = 26.9%, p < 0.001) at all loci. The heterozygote deficit within the population was highest in Luxi cattle and lowest in yak. The average number of effective migrants exchanged per generation was highest (1.149) between Luxi and Holstein, and lowest (0.509) between Luxi and yak. With the application of prior population information, cluster analysis achieved posterior probabilities from 91% to 98% of correctly assigning individuals to populations. Combining the information of cluster analysis, gene flow, and Structure analysis, the five cattle populations belong to three genetic clusters, a taurine (Luxi and Chinese Holstein), a zebu (Bohai and Minnan), and a yak cluster. This indicates that Bohai black is closer to Bos indicus than Luxi cattle. The evolution and development of three indigenous cattle populations are discussed.     

Hypoxia-induced Activation of Epidermal Growth Factor Receptor (EGFR) Kinase in the Cerebral Cortex of Newborn Piglets: The Role of Nitric Oxide

The present study aims to investigate the mechanism of EGFR kinase activation during hypoxia and tests the hypothesis that hypoxia-induced increased activation of EGFR kinase in the cerebral cortical membrane fraction of newborn piglets is mediated by nitric oxide (NO) derived from neuronal nitric oxide synthase (nNOS). Fifteen newborn piglets were divided into normoxic (Nx, n = 5), hypoxic (Hx, n = 5) and hypoxic-treated with nNOS inhibitor (Hx-nNOSi, n = 5). Hypoxia was induced by an FiO2 of 0.07 for 60 min. nNOS inhibitor I (selectivity >2,500 vs. endothelial NOS, eNOS, and >500 vs. inducible NOS, iNOS) was administered (0.4 mg/kg, i. v.) 30 min prior to hypoxia. EGFR kinase tyrosine phosphorylation at Tyr1173, an index of activation of EGFR kinase, was determined by Western blot analysis using an anti-phospho (pTyr¹¹⁷³)-EGFR kinase antibody. Protein bands were analyzed by imaging densitometry and expressed as absorbance (OD × mm²). EGFR kinase activity was determined radiochemically using immunopurified enzyme. EGFR kinase activity was expressed as pmols/mg protein/hr. Density of phosphor (pTyr¹¹⁷³)-EGFR kinase (OD × mm²) was 60.2 ± 9.8 in Nx, 177.0 ± 26.9 in Hx (P < 0.05 vs. Nx) and 79.9 ± 15.7 in Hx-nNOSi (P < 0.05 vs. Hx, P = NS vs. Nx). Activity of EGFR kinase (pmoles/mg protein/hr) was 4,603 ± 155 in Nx, 8,493 ± 427 in Hx (P < 0.05 vs. Nx) and 4,516 ± 104 in Hx-nNOSi (P < 0.05 vs. Hx, P = NS vs. Nx). Pretreatment with nNOS inhibitor prevented the hypoxia-induced increased phosphorylation and increased activity of EGFR kinase. We conclude that the mechanism of hypoxia-induced increased activation of EGFR kinase is mediated by nNOS-derived NO.     

Research on association between variants and haplotypes of TRPV1 and TRPA1 genes with growth traits in three cattle breeds

The objective of this study was to examine the association of transient receptor potential vanilloid 1 (TRPV1) and transient receptor potential ankyrin 1 (TRPA1) genes polymorphisms with growth traits in three Chinese cattle breeds (Jiaxian red cattle, Qinchuan cattle and Luxi cattle). Through experiments we identified three single nucleotide polymorphisms (SNPs) in these three cattle breeds TRPV1 and TRPA1 genes using PCR-SSCP, (forced) PCR-RFLP methods. Three of these polymorphisms are all synonymous mutation which includes (NW_003104493.1: 30327 C?>?T), (NW_003104493.1: 33394 A?>?G) and (NW_003104493.1: 38471?G?>?A) are in exons. The other three polymorphisms are located at 3'UTR. Furthermore, we evaluated the haplotype frequency and the statistical analyses indicated that these SNPs of TRPV1 and TRPA1 genes were associated with bovine body height, body length, waist angle width, hucklebone width, cross ministry height, chest qingwidth (p?<?0.05) and recommendation height, cannon circumference (p?<?0.01) of Qingchuan cattle; body length, waist angle width (p?<?0.05) of Jiaxian red cattle; body weight, Body length, cannon circumference, chest circumference (p?<?0.05) and body height (p?<?0.01) of Luxi cattle. Our result confirms the polymorphisms in the TRPV1 and TRPA1 genes are associated with growth traits that may be used for marker-assisted selection (MAS) in three beef breeds programs.     

The effect of body weight on some welfare indicators in feedlot cattle in a hot environment

Heat stress has important effects on the welfare of livestock. The effects of heat stress in cattle include changes in biological functions and behaviors. The aim of this study was to investigate the behavioral differences between light and heavy feedlot cattle reared in a hot environment. Sixteen male Holstein feedlot cattle were allocated to light (353.8 ± 15.5 kg, n = 8) and heavy (737.1 ± 15.8 kg, n = 8) groups according to their live weight and were kept in a semi-open feedlot barn. The individual behavioral response variables measured were standing, lying, feeding, drinking, ruminating, locomotor activity and elimination (urinating and defecating). The effects of group, day, observation time, replicate and all interactions were included in an explanatory statistical (GLM) model. The data were analyzed using the PROC GLM procedure of SAS. Overall, the heavy cattle spent more time standing (P < 0.001), lying (P < 0.001), and eliminating (P < 0.05) compared to the light group. In contrast, the light group spent more time eating, drinking and ruminating (P < 0.001). Locomotor activity did not differ significantly between groups (P > 0.05). During the day, heavy cattle spent more time standing (at 1600 hours) and less time eating in comparison with the light cattle (P < 0.001) (at 1300 and 1600 hours). Light and heavy feedlot cattle behaved differently in a hot environment. The findings of the study indicate that the welfare of the heavy Holstein feedlot cattle was impacted negatively when the ambient temperature was high (at 1300 hours).     

The role of BBS2 in regulating adipogenesis and the association of its sequence variants with meat quality in Qinchuan cattle

The BBS2 gene plays a vital role in human obesity and fat deposition. However, little is known about it in beef cattle. Therefore, this study investigates the function of BBS2 in the fat deposition of beef cattle and screens the effective SNPs marker for meat quality traits in cattle breeding. The expression of BBS2 is negatively correlated with marbling ratios of beef cattle. Moreover, the knockdown of BBS2 promoted adipogenesis and lipid accumulation of bovine preadipocytes by stimulating PPARγ, FABP4, and FASN expression (P < 0.01). Four novel SNPs in the exons of BBS2 in Chinese Qinchuan cattle were identified and of which the g.24226239C > T (Q527), g.24223562G > A (V441I), and g.24227851A > G (Q627R) were significantly associated with the meat quality of Qinchuan cattle (P < 0.01, P < 0.05). The findings suggested that BBS2 could be used as a candidate gene for meat quality improvement in Qinchuan cattle. Furthermore, these genotypes can be exploited as molecular markers in future beef breeding projects.     

Association of bovine carcass phenotypes with genes in an adaptive thermogenesis pathway

Associations of carcass phenotypes with genes regulating fat and energy metabolism involved in adaptive thermogenesis were examined in beef cattle. Carcass weight (CW) was found to be associated with MAP2K6 and UCP2 genes; back fat thickness (BFT) was found to be associated with PPARGC1A, MAP2K6, and UCP2 genes; marbling score (MS) was found to be associated with PPARGC1A and MAP2K6 genes; and eye-muscle area (EMA) was found to be associated only with UCP2 gene (P < 0.05). Further analyses found significant associations of interactions between PPARGC1A and MAP2K6 genes with CW and MS. Especially, interactive genetic associations were identified between c.424 and 222 G>A in PPARGC1A and c.17-10118 T>G in MAP2K6 and between c.228+28619 A>G in PPARGC1A and c.17-10118 T>G in MAP2K6, and they were both detected for CW and MS at a significant level (P < 0.05). The current study suggested that the individual and interactive associations of PPARGC1A, MAP2K6, and UCP2 genes with carcass phenotypes might be resulted from the pathway with fat and energy metabolism through the adaptive thermogenesis.     

Chromium Supplementation Can Alleviate the Negative Effects of Heat Stress on Growth Performance,Carcass Traits,and Meat Lipid Oxidation of Broiler Chicks without Any Adverse Impacts on Blood Constituents

This study was conducted to determine the effects of dietary supplementation with Cr nicotinate and Cr chloride and their optimum inclusion rate on performance, carcass traits, meat oxidative stability, serum metabolites, hematological parameters, and liver chromium concentration in heat-stressed broilers. A total number of 420, 1-day-old male broiler chicks were randomly assigned to seven treatments with four replicates of 15 chicks. The dietary treatments consisted of the basal diet supplemented with 0 (control), 500, 1,000, and 1,500 μg/kg Cr in the form of Cr nicotinate and Cr chloride. Chicks were raised for 6 weeks in heat stress condition (33 ± 2°C). Supplements of organic and inorganic Cr particularly at 1,500 μg/kg incorporation increased feed consumption (P < 0.05) and body mass gain of broilers (P < 0.01). Cr supplementation increased carcass yield and decreased abdominal fat (P < 0.01). Supplementation of 1,500 μg/kg Cr nicotinate (P < 0.05) enhanced liver Cr concentration. Storage time increased lipid oxidation of meat (P < 0.01). Cr decreased lipid oxidation of breast and thigh muscles over 2 (P < 0.01) or 6 (P < 0.05) days of storage time. Birds fed 1,500 μg/kg Cr nicotinate, had lower concentration of serum glucose and triglyceride at 21 days (P < 0.05). Hematological parameters tested at 21 and 42 days, were not influenced. The results suggested that dietary Cr supplementation regardless of its source have a positive effect on productive, and carcass traits, also enhances oxidative stability of refrigerated meat in broilers reared under heat stress conditions.     

Expression analysis, single nucleotide polymorphisms and combined genotypes in candidate genes and their associations with growth and carcass traits in Qinchuan cattle

The apolipoprotein E (ApoE) gene is an important component of plasma lipoprotein, and Fas apoptosis inhibitory molecule (FAIM) is a novel anti-apoptotic gene. In this study, we researched and discussed seven genes in eight different tissues in Qinchuan cattle by quantitative Real-time PCR. The result of analysis showed that ApoE and FAIM ₂ genes had a correlation with muscle and fat. PCR–RFLP was applied to analyze the genetic variations of the ApoE and FAIM ₂ genes and verify the effect on growth and carcass traits in a total of 365 Qinchuan cattles. The result of haplotype analysis showed that nine different haplotypes were identified among the four SNPs in ApoE and FAIM ₂ genes. The statistical analyses indicated that the four SNPs were significant association with growth and carcass traits (P < 0.05, N = 365); and the four SNPs were significant association between nine combined genotypes of candidate genes and growth and carcass traits. Taken together, our results provide the evidence that polymorphisms in candidate genes are associated with growth and carcass traits in Qinchuan cattle, and may be used as a possible candidate for marker-assisted selection and management in beef cattle breeding program.     

Effects of canola oil and antioxidants on performance,serum parameters,carcass traits,and rumen fermentation patterns of Nellore cattle

Several nutritional strategies have been used in beef cattle production in order to increase animal performance and profitability. However, in the past two decades, the increase of consumer preference for functional foods has driven the investigation for improving food via adding functional substances to animal diets. We evaluated the effect of canola oil supplementation associated with vitamin E and selenium on performance, rumen metabolism, carcass traits, meat tenderness, and serum, liver, and meat status of antioxidants in finishing Nellore males. Animals were fed for 106 days in a feedlot and were randomly distributed in a 2 × 2 factorial arrangement: two levels of oil in the diet (no inclusion and 3% canola oil, defined as diet without oil inclusion (NO) and effect of oil (OIL), respectively) and two levels of antioxidants in the diet (no inclusion and 2.5 mg of Se/kg of DM + 500 UI of vitamin E/kg of DM, defined as diet without antioxidant inclusion (NA) and effect of the antioxidants (ANT), respectively). DM intake (kg/day) was evaluated daily; performance and serum were analysed at the beginning of the feedlot and every 28 days. Animals were slaughtered and hot carcass weight (kg) was recorded; ruminal fluid and liver samples were collected. At 24 h postmortem, carcass pH was recorded and the Longissimus thoracis was sampled. There was no significant effect of the OIL*ANT interaction (P > 0.05) for any trait evaluated. Bulls fed OIL presented greater final BW (P < 0.01), average daily gain (kg/day; P < 0.01), feed efficiency (P < 0.01), rump fat thickness (P8RF; P < 0.05), and greater tenderness; the ANT diet increased P8RF (P < 0.05). The levels of selenium and vitamin E in serum, liver, and meat were increased (P < 0.01) with the inclusion of ANT. ANT did not change triiodothyronine (T3, ng/mL) and thyroxine (T4, µg/gL) serum concentrations but decreased serum glucose levels. The treatments did not affect (P > 0.05) ruminal parameters or the protozoa population. Our results showed that the inclusion of 3% canola oil in the diet DM increased performance, feed efficiency, carcass fat deposition, and tenderness, with no effect on rumen fermentation and protozoa population of Nellore cattle in a feedlot system. The inclusion of ANT in the cattle diet did not affect performance or rumen parameters. However, the levels of ANT were increased in the serum, liver, and meat, enriching the final product with these compounds.