Intramuscular fat (IMF) content is related to insulin resistance, which is an important prediction factor for disorders, such as cardiovascular disease, obesity and type 2 diabetes in human. At the ...same time, it is an economically important trait, which influences the sensorial and nutritional value of meat. The deposition of IMF is influenced by many factors such as sex, age, nutrition, and genetics. In this study Nellore steers (Bos taurus indicus subspecies) were used to better understand the molecular mechanisms involved in IMF content. This was accomplished by identifying differentially expressed genes (DEG), biological pathways and putative regulatory factors. Animals included in this study had extreme genomic estimated breeding value (GEBV) for IMF. RNA-seq analysis, gene set enrichment analysis (GSEA) and co-expression network methods, such as partial correlation coefficient with information theory (PCIT), regulatory impact factor (RIF) and phenotypic impact factor (PIF) were utilized to better understand intramuscular adipogenesis. A total of 16,101 genes were analyzed in both groups (high (H) and low (L) GEBV) and 77 DEG (FDR 10%) were identified between the two groups. Pathway Studio software identified 13 significantly over-represented pathways, functional classes and small molecule signaling pathways within the DEG list. PCIT analyses identified genes with a difference in the number of gene-gene correlations between H and L group and detected putative regulatory factors involved in IMF content. Candidate genes identified by PCIT include: ANKRD26, HOXC5 and PPAPDC2. RIF and PIF analyses identified several candidate genes: GLI2 and IGF2 (RIF1), MPC1 and UBL5 (RIF2) and a host of small RNAs, including miR-1281 (PIF). These findings contribute to a better understanding of the molecular mechanisms that underlie fat content and energy balance in muscle and provide important information for the production of healthier beef for human consumption.
Efficiency of feed utilization is important for animal production because it can reduce greenhouse gas emissions and improve industry profitability. However, the genetic basis of feed utilization in ...livestock remains poorly understood. Recent developments in molecular genetics, such as platforms for genome-wide genotyping and sequencing, provide an opportunity to identify genes and pathways that influence production traits. It is known that transcriptional networks influence feed efficiency-related traits such as growth and energy balance. This study sought to identify differentially expressed genes in animals genetically divergent for Residual Feed Intake (RFI), using RNA sequencing methodology (RNA-seq) to obtain information from genome-wide expression profiles in the liver tissues of Nelore cattle.
Differential gene expression analysis between high Residual Feed Intake (HRFI, inefficient) and low Residual Feed Intake (LRFI, efficient) groups was performed to provide insights into the molecular mechanisms that underlie feed efficiency-related traits in beef cattle. A total of 112 annotated genes were identified as being differentially expressed between animals with divergent RFI phenotypes. These genes are involved in ion transport and metal ion binding; act as membrane or transmembrane proteins; and belong to gene clusters that are likely related to the transport and catalysis of molecules through the cell membrane and essential mechanisms of nutrient absorption. Genes with functions in cellular signaling, growth and proliferation, cell death and survival were also differentially expressed. Among the over-represented pathways were drug or xenobiotic metabolism, complement and coagulation cascades, NRF2-mediated oxidative stress, melatonin degradation and glutathione metabolism.
Our data provide new insights and perspectives on the genetic basis of feed efficiency in cattle. Some previously identified mechanisms were supported and new pathways controlling feed efficiency in Nelore cattle were discovered. We potentially identified genes and pathways that play key roles in hepatic metabolic adaptations to oxidative stress such as those involved in antioxidant mechanisms. These results improve our understanding of the metabolic mechanisms underlying feed efficiency in beef cattle and will help develop strategies for selection towards the desired phenotype.
Few studies have been published on the body growth of replacement dairy heifers from Jersey (JER) and Holstein × Gyr (H × G) breeds, as most of them have focused on Holstein (HOL) heifers. In ...addition, HOL genetics vary significantly across countries. Our goal was to study the body growth curves of 3 distinct genetic groups of heifers (HOL, H × G, and JER) using data from Brazilian commercial dairy herds. Heart girth to estimate body weight (BW), hip height (HH), and withers height (WH) were measured. Weights (heifers and cows) and heights (only heifers) were collected from animals in several herds for each genetic group to model and describe the growth rates, mature body weight (MBW), weights, and heights for the recommended age at first breeding (RAFB) and first calving (RAFC). The RAFB values for HOL, H × G, and JER cattle were 15, 18, and 13 mo, respectively. The RAFC values for HOL, H × G, and JER cattle were 24, 27, and 22 mo, respectively. Data were obtained from 18 dairy farms located in 4 Brazilian states and analyzed using nonlinear modeling. Data were collected from 2,266 animals: 878 HOL, 610 H × G, and 778 JER cattle. We observed different body growth patterns in each genetic group. Jersey cattle matured earlier than HOL and H × G, especially for BW and HH. Mature BW of the HOL, H × G, and JER cattle was 681, 607, and 440 kg, respectively. All genetic groups reached the recommended BW at RAFB. However, the genetic groups did not reach the recommended BW at RAFC. Average daily weight gain from weaning to RAFB was 0.84, 0.53, and 0.54 kg/d for HOL, H × G, and JER cattle, respectively. Average daily gain from RAFB to RAFC was 0.53, 0.42, and 0.48 kg/d for HOL, H × G, and JER cattle, respectively. The HH at RAFB and RAFC were 130 and 139 cm for HOL, 130 and 137 cm for H × G, and 114 and 124 cm for JER. Withers height at RAFB and RAFC were 125 and 134 cm, 125 and 134 cm, and 110 and 121 cm for HOL, H × G, and JER cattle, respectively. In general, the rearing practices were adequate to reach the recommended BW at RAFB but below the recommended BW at RAFC for all genetic groups. In addition, each genetic group demonstrated different body growth patterns, especially for BW.
The objectives of this study were to evaluate the effects of supplementing the diet of high-producing Holstein cows with 2-hydroxy-4-(methylthio)-butanoate (HMTBa) on their milk production and ...composition, milk fatty acid profile, blood metabolites, and body parameters. The study was conducted in a commercial dairy herd in Paraná State, Southern Brazil. One hundred and fifty-eight multiparous cows were used in a randomized block design during 42 experimental days. Cows were distributed into two treatments: the control treatment cows received 100 g/cow/day of corn meal, while the HMTBa-supplemented cows received 35 g of HMTBa + 65 g/cow/day of corn meal. HMTBa supplementation did not alter milk production but improved milk fat content. Cows receiving HMTBa supplementation showed an increase in the concentration of milk medium-chain fatty acids. Serum levels of blood urea and aspartate aminotransferase were lower in HMTBa-supplemented cows. Cows supplemented with HMTBa increased their body condition score. In summary, HMTB supplementation in high-producing Holstein cows improved productive performance, particularly increased milk fat content, altered milk fatty acid profile, and changed some blood metabolites. Our findings contribute to our understanding of using a methionine analogue as a dietary strategy for optimizing milk quality in high-producing Holstein cows.
Lipids are a class of molecules that play an important role in cellular structure and metabolism in all cell types. In the last few decades, it has been reported that long-chain fatty acids (FAs) are ...involved in several biological functions from transcriptional regulation to physiological processes. Several fatty acids have been both positively and negatively implicated in different biological processes in skeletal muscle and other tissues. To gain insight into biological processes associated with fatty acid content in skeletal muscle, the aim of the present study was to identify differentially expressed genes (DEGs) and functional pathways related to gene expression regulation associated with FA content in cattle.
Skeletal muscle transcriptome analysis of 164 Nellore steers revealed no differentially expressed genes (DEGs, FDR 10%) for samples with extreme values for linoleic acid (LA) or stearic acid (SA), and only a few DEGs for eicosapentaenoic acid (EPA, 5 DEGs), docosahexaenoic acid (DHA, 4 DEGs) and palmitic acid (PA, 123 DEGs), while large numbers of DEGs were associated with oleic acid (OA, 1134 DEGs) and conjugated linoleic acid cis9 trans11 (CLA-c9t11, 872 DEGs). Functional annotation and functional enrichment from OA DEGs identified important genes, canonical pathways and upstream regulators such as SCD, PLIN5, UCP3, CPT1, CPT1B, oxidative phosphorylation mitochondrial dysfunction, PPARGC1A, and FOXO1. Two important genes associated with lipid metabolism, gene expression and cancer were identified as DEGs between animals with high and low CLA-c9t11, specifically, epidermal growth factor receptor (EGFR) and RNPS.
Only two out of seven classes of molecules of FA studied were associated with large changes in the expression profile of skeletal muscle. OA and CLA-c9t11 content had significant effects on the expression level of genes related to important biological processes associated with oxidative phosphorylation, and cell growth, survival, and migration. These results contribute to our understanding of how some FAs modulate metabolism and may have protective health function.
Abstract
This study determined the energy requirement for maintenance of purebred Nellore cattle and its crossbreds using data from a comparative slaughter trial in which animals were raised under ...the same plane of nutrition from birth through slaughter and born from a single commercial Nellore cowherd. A total of 79 castrated steers (361 ± 54 kg initial body weight BW) were used in a completely randomized design by age (22 mo ± 23 d of age) with four genetic groups (GG): Nellore (NL), ½ Angus × ½ Nellore (AN), ½ Canchim × ½ Nellore (CN), and ½ Simmental × ½ Nellore (SN). The experimental design provided ranges in metabolizable energy (ME) intake (MEI), BW, and average daily gain needed to develop regression equations to predict net energy for maintenance (NEm) requirements. Four steers of each GG were slaughtered to determine the initial body composition. The remaining 63 steers were assigned to different nutritional treatments (NT) by GG; ad libitum or limit-fed treatments (receiving 70% of the daily feed of the ad libitum treatment of the same GG). Full BW was recorded at birth, weaning, 12, 18, and 22 mo. In the feedlot, steers were fed for 101 d a diet containing (DM basis) 60% corn silage and 40% concentrate. No difference in age at weaning (P = 0.534) and slaughter (P = 0.179 and P = 0.896, for GG and NT, respectively) were observed. AN steers were heavier at weaning weight, yearling weight and had higher empty BW (EBW; P = 0.007, P = 0.014, and P < 0.001, respectively) in comparison to NL, CN, and SN. There were no interactions (P > 0.05) between GG and NT for any variable evaluated. When fed ad libitum, AN steers had higher daily MEI (Mcal/d; P < 0.001) in comparison to NL, CN, and SN. On a constant age basis, differences were observed on body composition (P < 0.05) between GG. The slope (P = 0.600) and intercept (P = 0.702) of the regression of log heat production on MEI were similar among GG. Evaluating at the same age and the same frame size, there were no differences in NEm requirement between Nellore and AN (P = 0.528), CN (P = 0.671), and SN (P = 0.706). The combined data indicated a NEm requirement of 86.8 kcal/d/kg0.75 EBW and a ME required for maintenance requirement had a common value of 137.53 kcal/d/kg0.75 EBW. The efficiency of energy utilization for maintenance and the efficiency of energy utilization for growth values were similar among GG (P > 0.05 and P > 0.05, respectively) and were on average 63.2% and 26.0%, respectively. However, although not statistically different, the NEm values from NL showed a decrease in NEm of 5.76% compared with AN steers.
Lay Summary
Although several studies have shown that the maintenance energy expenditures vary with breeds, there has been no available data comparing the energy requirements of different genetic groups of beef cattle determined during the finishing phase when raised under the same plane of nutrition from birth through slaughter born from a single cowherd. This study evaluated the influence of purebred Nellore and its crosses with Simmental, Angus, and Canchim slaughtered at the same age and body composition on their net energy requirement for maintenance (NEm). Animals were reared in tropical conditions, receiving only free-choice minerals from birth through the beginning of the feedlot phase, potentially altering the intake, carcass composition, mature weight, and consequently, affecting the energy requirement for maintenance during the finishing period. The pooled data analysis for Nellore and its crosses resulted in common NEm requirement of 86.9 kcal/d/kg0.75 of empty body weight (EBW). However, although not statistically different, the NEm values from Nellore (NL) and Angus × Nellore (AN) were 85.5 and 90.8 kcal/d/kg0.75 EBW, respectively, showing a decrease in NEm of 5.76% for NL in comparison with AN steers.
The knowledge and understanding of the maintenance energy requirements among beef cattle breeds is key to the success of diet formulation in feedlot cattle, aiming for optimal production and sustainable profit. Studies evaluating the energy requirement of purebred Nellore cattle and its crossbreds reared in the same experimental conditions from birth to slaughter will give valuable information for nutritionists and consultants working in the beef production system under tropical conditions.
This study was conducted to test the effect of dietary tannin on the fatty acid profile and sensory attributes of meat from Nellore steers. Thirty‐two Nellore bull male were distributed in a ...completely randomized design and fed diets with condensed tannin extract as follows: 0, 10, 30, and 50 g/kg total DM basis. The physicochemical composition of the meat, lipid oxidation, fatty acid profile, flavor, tenderness, and overall acceptance were evaluated. There was a linear decrease (P ≤ 0.05) on lipid content, tenderness, cooking weight loss, myristic, palmitic, and oleic acids in meat as tannin increased in the diets. The total saturated and monounsaturated fatty acids, the atherogenicity index decreased. However, a linear increase (P ≤ 0.05) was observed for linoleic, linolenic, arachidonic, eicosapentaenoic, and docosapentaenoic acids. The physicochemical characteristic of the meat, such as moisture, ash, and protein contents, water retention capacity, final pH, Warner‐Bratzler shear force, collagen, and color indexes (lightness, redness, yellowness, and chrome) did not change with dietary tannin. Also, CLA, n‐6:n‐3 ratio, Δ9‐desaturase, and elongase activity were not different among diets. In conclusion, condensed tannin linearly increases unsaturated fatty acids and decreases the atherogenicity index of meat; thus, it can be recommended at the highest level (50 g/kg DM) in the diet of Nellore steers.
Practical Application
Agriculture byproducts plays an important part in the diet of ruminant animals and consequently on food chain and has implications for the composition and quality of the livestock products (milk, meat, and eggs) that people consume. Feeding tannin to steers increases the amount of unsaturated fatty acids and meat tenderness, with a concomitant reduction on saturated fatty acids and the atherogenicity index in meat. Thus, we recommend adding tannin to steer diets to reduce the risk factors for cardiovascular diseases in red meat for human consumption.
This study aimed to evaluate the effect of including soybean molasses (SM) on performance, blood parameters, carcass traits, meat quality, fatty acid and muscle (longissimus thoracis) transcriptomic ...profiles of castrated lambs. Twenty Dorper × Santa Inês lambs (20.06 ± 0.76 kg BW) were assigned to a randomized block design, stratified by BW, with the following treatments: CON - 0 g/kg of SM and SM20 - 200 g/kg of SM on DM basis, allocated in individual pens. The diet consisted of 840 g/kg concentrate and 160 g/kg corn silage for 76 days, with the first 12 days as an adaptation period and the remaining 64 days on the finishing diet. The SM20 diet increased blood urea concentration (P = 0.03) while reduced glucose concentration (P = 0.04). Lambs fed SM showed higher subcutaneous fat deposition (P = 0.04) and higher subcutaneous adipocyte diameter (P < 0.01), in addition to reduced meat lipid oxidation (P < 0.01). Soybean molasses reduced the quantity of branched-chain fatty acids in longissimus thoracis (P = 0.05) and increased the quantity of saturated fatty acids (P = 0.01). In the transcriptomic analysis, 294 genes were identified as differentially expressed, which belong to pathways such as oxidative phosphorylation, citric acid cycle, and monosaccharide metabolic process. In conclusion, diet with SM increased carcass fat deposition, reduced lipid oxidation, and changed the energy metabolism, supporting its use in ruminant nutrition.
This study evaluated the effects of the duration of ZH supplementation and days on feed (DOF) on performance, carcass characteristics, and saleable meat yield of Nellore young bulls. The fixed ...effects included the duration (0, 20, 30, or 40 d before slaughter plus a 3 d ZH withdrawal period—8.33 mg of ZH/kg of DM) and DOF (90 and 117 d). Feed efficiency (G:F) linearly increased when the duration of ZH supplementation increased (p < 0.01). Nellore bulls fed ZH had greater HCW (p < 0.01), dressing percentage (p < 0.01) and Longissimus muscle area (LMA) (p < 0.01), but less 12th-rib fat (p = 0.04) than the control group. The hot carcass weight (HCW) (p < 0.01), and dressing percentage increased linearly (p < 0.01) with the increase of duration of ZH supplementation. The HCW, ossification, and 12th-rib fat increased with DOF (p < 0.01). The ZH supplemented group had most of the individual cuts of hindquarters and total saleable meat increased compared with the control. Zilpaterol hydrochloride was effective in improving hot carcass weight, hindquarter, and saleable meat yields of Nellore bulls when fed for at least 20 d before slaughter, independently of days on feed.
•Crossbred young bulls versus steers were feedlot finished for 180 days.•Castration affects the expression of genes related to lipid metabolism.•Steers had more intramuscular fat than bulls (5.59 vs. ...2.07%).•Steers had a higher proportion of monounsaturated fatty acids (FA) in meat.•Bulls trend to shown higher levels of polyunsaturated FA in meat.
This study investigated the effects of castration on skeletal muscle gene expression and beef quality. Six-hundred and forty F1 Angus–Nellore steers and bulls (initial body weight of 299 and 297 ± 4.1 kg, respectively) feedlot finished were used. Gene expression revealed that steers showed up-regulation (P<0.05) of acetyl-CoA carboxylase alpha, fatty acid-binding protein, fatty acid synthase, peroxisome proliferator activated receptor (PPAR)-gamma and stearoyl-coa desaturase, while bulls shown higher expression of PPAR-alpha and sterol regulatory element-binding protein 1. Consequently, steers had greater (P<0.01) intramuscular fat (IMF) in longissimus muscle compared to bulls (5.59 vs. 2.07%). Greater concentration of monounsaturated fatty acids was observed in beef loins of steers (P<0.01), while bulls trend to shown higher (P = 0.08) polyunsaturated fatty acids and higher elongase activity (P<0.05). Thus, differences in gene expression were associated with differences in IMF deposition (marbling). Even after 180 days on feed, crossbred young bulls does not produce meat with adequate IMF and better fatty acid profile than steers.
PDF
