If you’ve ever wondered what affects residual feed intake (RFI) in beef cattle, Dr. Gordon Carstens of Texas A&M University will give you some helpful insights. In this article, he covers several important aspects related to RFI, including the effect of ruminal bacteria, sex, and alfalfa cubes. Read on to learn more. We also have a quiz to determine your RFI!
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Results of a study on residual feed intake in beef cattle
Results of a study on residual feed intake (RFI) in beef cattle are largely independent of growth performance. Using a variety of measures to determine the relationship between RFI and carcass traits, the researchers identified the factors influencing the efficiency of ruminant feeding. Although the differences in RFI between cattle were small, they were highly significant for both dry matter digestibility and the proportion of neutral detergent fiber in the rumen. Further, they identified genetic differences in rumen epithelial cells that may contribute to the efficiency of RFI.
RFI is related to differences in carcass marbling and leanness. Cattle with lower RFI have lower marbling, indicating lower carcass quality. Additionally, high RFI heifers may not cycle as early and have lower pregnancy rates than heifers with low RFI scores. But these negative effects can be offset by proper heifer management. Here are the main differences in residual feed intake among steers.
Effects of ruminal bacteria on RFI
The effects of ruminal bacteria on residual feed intake were investigated in a study in which the relative abundance of bacterial communities in the rumen was determined. Results showed that cattle in the most efficient RFI group had lower DMI and higher DMI/L compared to the least efficient animals. However, there were no significant differences in body weights among the RFI groups. It is therefore important to identify which factors influence RFI and which do not.
The researchers measured the rumen fluid by using the FLORA Ruminator probe on the farm. The sampled rumen fluid was obtained within 1.98+0.2 h after slaughter, after filtering the digesta. Samples were stored at -80degC in liquid nitrogen until analysis. In addition, tissue samples were extracted from the ventral sac and fixed in 10% neutral phosphate buffere formalin.
Effects of sexes on RFI
To date, little is known about the effects of gender on RFI. Previous studies have focused on RFI, and have also sought to determine the biological mechanisms responsible for this trait. This provides an alternative to direct dietary measurement, and advances genomic selection. Genetic studies of RFI have shown that RFI is associated with lipogenesis and the immune system, but so far, no specific genes are known to contribute to RFI.
Although there is a dearth of data on the role of gender in RFI, it is clear that genetics play an important role. While many factors contribute to RFI, breed and age of the animal all play a role. Breed and stage of development, dietary intake test period, and production management can all influence RFI. The study objective was to identify the genes involved in regulating RFI in beef cattle. Simmental heifers were reared under the same conditions as bulls.
Effects of alfalfa cubes on RFI
Alfalfa pasture management is a dynamic art. Many factors, including extreme weather, storms, and biting flies, interrupt regular grazing bouts. This can cause bloat outbreaks. To minimize the risk of bloat, producers should observe animals during high-risk periods, such as the day or evening, when bloat is more likely to occur.
One study, published in 2011, studied the effects of Alfalfa cubes on residual feed intake of beef cattle during the finishing period. Beef steers fed alfalfa-based and fescue-based forages gained from 0.60 to 2.08 pounds per day. Although the differences between fescue and alfalfa cube systems were not statistically significant, the higher alfalfa-fed cattle had higher dietary fat and lower leanness, as determined by a 1-to-5 scale.
Effects of gene expression on RFI
In a recent study, researchers determined the effects of various gene expressions on the residual feed intake (RFI) of beef cattle. This study examined the impact of several genes on RFI in steers and heifers. The most efficient cattle showed higher expression of HIF1A, SLC25A20, and COX8A, which are associated with energy production through oxidative phosphorylation. In addition, the highest RFI steers and heifers had higher expression of HIF1A and SLC9A, which are involved in the transport of VFA.
Although there is limited data available, the data show that approximately 20% of the variance in RFI in beef cattle can be attributed to differences in ruminal microbes. Highly efficient cattle have increased digestibility of dry matter, organic matter, and neutral detergent fiber, as well as higher protein and total digestible nutrients. These findings are important because divergent RFI in cows reveals differences between males and females in the epithelium tissue.
