Abstract
The inclusion of agro-industry by-products originated from corn ethanol production has increased in animal nutrition in Brazil, reducing formulation costs. In the literature, there is no consensus on how the high inclusion of de-oiled wet distillers grains can affect beef quality and the expression of lipogenic genes in Longissimus muscle. The aim of this study was to evaluate the effects of WDG in the diet of F1 Angus-Nellore cattle on meat quality characteristics, chemical composition and expression of genes involved in lipid metabolism. A hundred F1 Angus-Nellore bulls, with average initial body weight (BW) of 369.5 ± 49 kg were used. The experiment was carried out in a randomized block design, and the animals were divided into two blocks (light and heavy) according to the initial body weight. The animals were fed diets containing levels of 0 (control), 15, 30 and 45% of WDG replacing dry corn and soybean meal. After 129 days of feedlot, the animals were slaughtered and samples of the longissimus thoracis (LT) muscle were collected for quality analyzes such as shear force (3, 10 and 17 aging days), color (luminosity, red, Chroma and Hue), cooking losses, pH and chemical composition (moisture, protein, lipids and ash contents). In addition, the expression of the PPARα, PPARγ, SREBP-1c, SCD1, LPL, FABP4, FASN, ACOX, CPT2, GPX1 and ACACA genes was investigated in the LT muscle by real-time reverse transcription polymerase chain reaction (RT-PCR). Data were analyzed using polynomial contrasts (linear, quadratic and control vs. WDG). There was no interaction (P > 0.05) between aging times and the inclusion of WDG in the diets on the meat quality (pH, cooking losses, coloration and tenderness). However, diets with increasing levels of WDG caused a linear reduction (P = 0.01) in the intramuscular fat of LT. The lipogenic genes SCD1, PPARγ, FASN and CPT2 were less expressed (P < 0.05) in response to the inclusion of WDG. These results suggest that the inclusion of WDG reduced the expression of lipogenic genes and consequently the marbling of LT muscle without affecting tenderness (shear force) and meat color traits.
Highlights
The production of corn ethanol in Brazil has increased along with the availability of by-products originated from this process in feedlot cattle diets
About 50–75% of the acetyl units used in intramuscular lipogenesis are derived from glucose, which might increase marbling in the meat (Smith & Crouse, 1984) when animals are fed diets rich in starch
The de-oiled-Wet distillers grains (WDG) used in the United States have about 9.2% fat (Jolly-Breithaupt et al, 2018), while industries in Brazil have generated this ingredient with fat content of less than 5%, which may justify the differences when compared to the results reported in the literature
Summary
The production of corn ethanol in Brazil has increased along with the availability of by-products originated from this process in feedlot cattle diets. In countries such as the USA, distillers grains have been used in animal nutrition since the 1980s due to the high production of corn ethanol (Firkins, Berger & Fahey, 1985). About 50–75% of the acetyl units used in intramuscular lipogenesis are derived from glucose, which might increase marbling in the meat (Smith & Crouse, 1984) when animals are fed diets rich in starch It may explain the reduction in marbling score of the meat in animals fed WDG (Schoonmaker, Trenkle & Beitz, 2009)
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