Effect of increasing levels of glycerin on growth rate, carcass traits and liver gluconeogenesis in young bulls

This study aimed to evaluate performance, carcass traits, glycerol kinase 1 (GK1) and cytoplasmatic phosphoenolpyruvate carboxykinase (PCK1) gene expression, and glycerol kinase activity in liver of young bulls receiving different levels of crude glycerin. Forty-four crossbred young bulls (initial body weight of 368 ± 4.2 kg) were used in a completely randomized design, with four treatments and 11 replicates. The experiment period lasted 84 days, preceded by an adaptation period of 28 days. The basal diet was composed of corn silage (300 g/kg) and concentrate (700 g/kg) containing corn and soybean. The experimental treatments were as follows: without glycerin or including 60, 120 or 180 g/kg of crude glycerin in the diet. Blood samples were collected on the last day of the experiment period to evaluate biochemical parameters. After slaughter, carcass traits were measured and liver samples were collected to analyze gene expression and glycerol kinase activity. There was no effect (P = 0.21) of glycerin on glucose blood concentrations. However, liver glycerol kinase activity was greater (P 0.17) performance and most of the carcass traits. However, there was a greater (P = 0.02) marbling score in the carcass of animals fed 120 and 180 g/kg of crude glycerin. In conclusion, the use of glycerin at a level of up to 180 g/kg is recommended in diets of feedlot beef cattle, and it increases liver glycerol kinase activity, feed efficiency and beef marbling

Nutrigenomics and Beef Quality: A Review about Lipogenesis

The objective of the present review is to discuss the results of published studies that show how nutrition affects the expression of genes involved in lipid metabolism and how diet manipulation might change marbling and composition of fat in beef. Several key points in the synthesis of fat in cattle take place at the molecular level, and the association of nutritional factors with the modulation of this metabolism is one of the recent targets of nutrigenomic research. Within this context, special attention has been paid to the study of nuclear receptors associated with fatty acid metabolism. Among the transcription factors involved in lipid metabolism, the peroxisome proliferator-activated receptors (PPARs) and sterol regulatory element-binding proteins (SREBPs) stand out. The mRNA synthesis of these transcription factors is regulated by nutrients, and their metabolic action might be potentiated by diet components and change lipogenesis in muscle. Among the options for dietary manipulation with the objective to modulate lipogenesis, the use of different sources of polyunsaturated fatty acids, starch concentrations, forage ratios and vitamins stand out. Therefore, special care must be exercised in feedlot feed management, mainly when the goal is to produce high marbling beef

Total nutrient digestibility and small intestine starch digestion in Nellore and Angus young bulls fed a whole shelled corn die

Eighteen Nellore and 18 Angus young bulls with BW of 381 ± 12 kg were randomly assigned into two feeding groups (whole shelled corn [WSC] or ground corn with silage [GC]) to evaluate the interaction of breed and diet on total nutrient digestibility, pancreatic α‐amylase, and maltase activity and SLC5A1expression in the small intestine. Experimental diets (DM basis) included (a) a diet containing 30% corn silage and 70% GC and soya bean meal‐based concentrate and (b) a diet containing 85% WSC and 15% of a soya bean meal‐ and mineral‐based pelleted supplement. The treatments were Nellore fed GC diet; Nellore fed WSC diet; Angus fed GC diet; and Angus fed WSC diet. Total faecal collection for the digestibility trial occurred from day 48 until day 50 of the experimental period. Feeding the WSC diet reduced DM and NDF intake (p 0.19). Angus had greater starch digestibility (p = 0.03) than Nellore. Cattle fed the WSC diet had greater DM, NDF and starch digestibility (p 0.05). In conclusion, Nellore had less capacity to digest starch. However, they did not have less pancreatic α‐amylase and duodenal maltase activity compared to Angus. The use of the WSC diet increases DM and total nutrient digestibility

Total nutrient digestibility and small intestine starch digestion in Nellore and Angus young bulls fed a whole shelled corn diet

Eighteen Nellore and 18 Angus young bulls with BW of 381 ± 12 kg were randomly assigned into two feeding groups (whole shelled corn [WSC] or ground corn with silage [GC]) to evaluate the interaction of breed and diet on total nutrient digestibility, pancreatic α‐amylase, and maltase activity and SLC5A1expression in the small intestine. Experimental diets (DM basis) included (a) a diet containing 30% corn silage and 70% GC and soya bean meal‐based concentrate and (b) a diet containing 85% WSC and 15% of a soya bean meal‐ and mineral‐based pelleted supplement. The treatments were Nellore fed GC diet; Nellore fed WSC diet; Angus fed GC diet; and Angus fed WSC diet. Total faecal collection for the digestibility trial occurred from day 48 until day 50 of the experimental period. Feeding the WSC diet reduced DM and NDF intake (p 0.19). Angus had greater starch digestibility (p = 0.03) than Nellore. Cattle fed the WSC diet had greater DM, NDF and starch digestibility (p 0.05). In conclusion, Nellore had less capacity to digest starch. However, they did not have less pancreatic α‐amylase and duodenal maltase activity compared to Angus. The use of the WSC diet increases DM and total nutrient digestibility

Molecular Factors Underlying the Deposition of Intramuscular Fat and Collagen in Skeletal Muscle of Nellore and Angus Cattle

<div><p>Studies have shown that intramuscular adipogenesis and fibrogenesis may concomitantly occur in skeletal muscle of beef cattle. Thus, we hypothesized that the discrepancy of intramuscular fat content in beef from Nellore and Angus was associated with differences in intramuscular adipogenesis and fibrogenesis during the finishing phase. To test our hypothesis, longissimus muscle samples of Nellore (<i>n</i> = 6; BW = 372.5 ± 37.3 kg) and Angus (<i>n</i> = 6; BW = 382.8 ± 23.9 kg) cattle were collected for analysis of gene and protein expression, and quantification of intramuscular fat and collagen. Least-squares means were estimated for the effect of Breed and differences were considered at <i>P</i> ≤ 0.05. A greater intramuscular fat content was observed in skeletal muscle of Angus compared to Nellore cattle (<i>P</i>≤0.05). No differences were observed for mRNA expression of lipogenic and lipolytic markers <i>ACC</i>, <i>FAS</i>, <i>FABP4</i>, <i>SERBP–1</i>, <i>CPT–2</i>, <i>LPL</i>, and <i>ACOX</i> (<i>P</i> > 0.05) in skeletal muscle of Nellore and Angus cattle. Similarly, no differences were observed in mRNA expression of adipogenic markers <i>Zfp423</i>, <i>PPARγ</i>, <i>and C/EBPα</i> (<i>P</i>>0.05) However, a greater PPARγ protein content was observed in skeletal muscle of Angus compared to Nellore cattle (<i>P</i>≤0.05). A greater abundance of adipo/fibrogenic cells, evaluated by the PDGFRα content, was observed in skeletal muscle of Angus than Nellore cattle (<i>P</i>≤0.05). No differences in fibrogenesis were observed in skeletal muscle of Angus and Nellore cattle, which is in accordance with the lack of differences in intramuscular collagen content in beef from both breeds (<i>P</i>>0.05). These findings demonstrate that difference in intramuscular fat content is associated with a slightly enhanced adipogenesis in skeletal muscle of Angus compared to Nellore cattle, while no difference in fibrogenesis.</p></div

Performance and carcass traits of Angus and Nellore cattle.

<p>Performance and carcass traits of Angus and Nellore cattle.</p

Abundance of PDGFR_<i>α</i> in skeletal muscle of Angus and Nellore cattle.

<p>Quantification of PDGFR_<i>α</i> by western-blot using tubulin as a loading control as an indicator of the abundance of mesenchymal progenitor cells. Differences were considered at <i>P</i> ≤ 0.05 (*).</p

Ingredient proportion and chemical composition of experimental diet.

<p>¹Mineral mixture: Ca = 45.0 g/kg; Mg = 7.5 g/kg; P = 11.0 g/kg; Cu = 104 mg/kg; Zn = 344 mg/kg; Se = 0.83 mg/kg; Virginiamycin = 140.0 mg/kg; Monensin = 120.0 mg/kg</p><p>Ingredient proportion and chemical composition of experimental diet.</p

List of primers.

<p>List of primers.</p

Expression of lipid metabolism markers in skeletal muscle of Angus and Nellore cattle.

<p>A) mRNA expression of <i>acetyl-CoA carboxilase</i> (<i>ACC</i>), <i>fatty acid synthase</i> (<i>FAS)</i>, <i>Fatty acid binding protein 4</i> (FABP4) <i>sterol regulatory element-binding protein 1</i> (<i>SERBP</i>-1); B) mRNA expression of <i>carnitine palmitoyltransferase 2</i> (<i>CPT–2</i>), <i>lipoprotein lipase</i> (<i>LPL</i>) <i>acyl-CoA oxidase</i> (<i>ACOX</i>). mRNA expression did not differ (<i>P</i> ≥ 0.05).</p