Source: Olds College
In beef cattle production, feed costs constitute a substantial portion of expenses accounting for up to 70 per cent of the total operational costs. This can significantly impact a farmer’s bottom line. As feed costs fluctuate with grain prices, weather conditions and market demands, it affects the viability of individual farms and influences the industry’s overall sustainability. Consequently, improved feed efficiency has become a strategy for producers to optimize their operations.
Feed efficiency can be defined as the ability of cattle to convert feed into body weight gain. Improving feed efficiency can reduce feed costs while enhancing the profitability and sustainability of a farm operation. However, measuring and selecting for feed efficiency is not a simple task since different indicators and methods can be used to evaluate this complex trait.
One common indicator of feed efficiency has been feed conversion ratio (FCR), which is simply the ratio of feed intake to weight gain. However, FCR has some limitations as it does not account for the maintenance requirements of the animal, nor the differences in body composition and growth potential among animals. In fact, studies have shown that selecting animals using FCR results in larger mature weights over time.
A more accurate and comprehensive indicator of feed efficiency is residual feed intake (RFI), which is defined as the difference between actual feed intake and expected feed intake based on weight and growth rate. Animals with low (negative) RFI are more efficient as they consume less feed than expected for their level of production. RFI is independent of body size and growth rate, and can be used to select for feed efficiency without adversely affecting other production traits. Another indicator that combines RFI and residual average daily gain (RADG) is residual intake and body weight gain (RIG). RIG identifies cattle that consume less than expected and gain more weight than anticipated making it more suitable for beef selection. RFI and RIG calculations require feed intake monitoring and weight gain of individual animals over a period of time ranging from 49 to 91 day tests.
Selecting cattle based on RFI or RIG can have significant positive impacts on beef production systems. Studies have shown that selecting cattle for low RFI can reduce feed intake, improve feed efficiency (both RFI and FCR), reduce methane emissions and increase net income. Research assessing the relationship between RFI and carcass traits has been conflicting — some studies show reduced carcass fat and ribeye area in more efficient animals, but other studies show no significant effect. Similarly, results on reproductive performance associated with more efficient cattle are mixed; some studies found reduced pregnancy rates and others observed no differences between high and low RFI groups. Further research in these areas is needed to better understand the influence of selecting for improved feed efficiency.