Abstract
BackgroundThe selection of beef cattle for feed efficiency (FE) traits is very important not only for productive and economic efficiency but also for reduced environmental impact of livestock. Considering that FE is multifactorial and expensive to measure, the aim of this study was to identify biological functions and regulatory genes associated with this phenotype.ResultsEight genes were differentially expressed between high and low feed efficient animals (HFE and LFE, respectively). Co-expression analyses identified 34 gene modules of which 4 were strongly associated with FE traits. They were mainly enriched for inflammatory response or inflammation-related terms. We also identified 463 differentially co-expressed genes which were functionally enriched for immune response and lipid metabolism. A total of 8 key regulators of gene expression profiles affecting FE were found. The LFE animals had higher feed intake and increased subcutaneous and visceral fat deposition. In addition, LFE animals showed higher levels of serum cholesterol and liver injury biomarker GGT. Histopathology of the liver showed higher percentage of periportal inflammation with mononuclear infiltrate.ConclusionLiver transcriptomic network analysis coupled with other results demonstrated that LFE animals present altered lipid metabolism and increased hepatic periportal lesions associated with an inflammatory response composed mainly by mononuclear cells. We are now focusing to identify the causes of increased liver lesions in LFE animals.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2292-8) contains supplementary material, which is available to authorized users.
Highlights
The selection of beef cattle for feed efficiency (FE) traits is very important for productive and economic efficiency and for reduced environmental impact of livestock
Significant difference was observed for all FE traits (FCR, residual feed intake (RFI), residual body weight gain (RWG) and residual intake and body weight gain (RIG)) and for dry matter intake (DMI), which was higher in animals of LFE
There was a significant difference for final and gain of back fat thickness (BFT) and for final and gain of rump fat thickness (RFT) in the period (P ≤ 0.05), which were higher in LFE group
Summary
The selection of beef cattle for feed efficiency (FE) traits is very important for productive and economic efficiency and for reduced environmental impact of livestock. Feed efficiency (FE) in beef cattle is an important trait from productive and economic point of view because it identifies animals that present less feed intake to produce the same amount of beef and feed is considered the most expensive input in beef production [2]. There are several traits to estimate FE in beef cattle, for example by residual feed intake (RFI), a wellaccepted measure that is calculated by the difference between observed and predicted feed intake based on average daily gain (ADG) and metabolic weight [5]. The recently proposed residual intake and body weight gain (RIG) combines RFI and residual body weight gain to generate a measure that presents favorable correlations with both ADG and feed intake [6]
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