Feed efficiency in feedlot production

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Source: Ontario Ministry of Agriculture, Food and Rural Affairs

For feedlot producers, feed costs have historically represented between 50 – 70% of the cost of production and during periods of high corn prices these costs can increase to over 80%. Improving feed efficiency is one tool to help reduce the cost of production and improve profitability. Research by Beef Cattle Research Council suggests a feed efficiency improvement by 1% across the beef sector would save the feedlot sector as much as $11.1 million annually. Weaber (2011) showed that a 1% improvement in feed efficiency has the same effect as a 3% improvement in the rate of gain. Improving feed efficiency is vital for improving beef profitability through lower input costs. It also presents an opportunity to improve the environmental sustainability of beef production through reduced use of inputs leading to reduced greenhouse gas production.

Most beef farmers have a very good understanding of growth rate. Growth rate is a measure of how fast an animal grows or gains over a set period of time. It does not take into account the amount of feed required to put on this gain. Feed efficiency, correctly called feed conversion ratio (FCR), is the amount of feed (dry matter) required to gain one unit of gain. In beef cattle this runs between 4.5 and 7.5; a lower number is desirable. Compared with other livestock, ruminants have a poor FCR. Poultry have a FCR of less than 2:1 and swine are less than 3.5:1. The average FCR for Beef cattle is 6:1. This means, on average, it takes 6 lbs of feed (dry matter) for an animal to gain 1 lb of live weight.

The following example illustrates the effect of difference in feed conversion ratio.

Steer A
Steer B
Starting Weight (lbs)
900
900
Growth Rate (lbs/day)
3.5
3.5
Dry Matter Intake lbs/day
21
28
Feed Conversion Ratio
6:1
8:1
Ration Cost ($/lb DM)
0.085
0.085
Days on Feed
200
200
Cost per Day ($)
$1.79
$2.38
Total Feed Cost ($)
$357
$476

(BCRC: Optimizing Feedlot Feed Efficiency, 2016)

In this example two steers enter the feedlot at the same weight and grow at the same rate. Steer A consumes 21 lbs of dry matter but steer B consumes 28 lbs of dry matter to grow at the same rate. The feed conversion ratio shows that steer A is a more efficient animal as it takes less feed to grow at the same rate as steer B. If we assume a feed cost of $187 per ton (dry matter), it costs $0.59 per day more to feed steer B, the less efficient animal. If we assume both animals reach their finish weight in 200 days the less efficient steer B will have cost the producer $119 more than the more efficient steer A. As this example demonstrates, maximising feed efficiency is essential for feedlot profitability.

FCR has improved in poultry by 250% since 1957. Work by Loy on Iowa feedlots showed FCR improved by 0.047 lbs per year over the period 1978 to 1992. Further work by Loy showed on Midwestern feedlots showed FCR improved by 0.033 lbs per year over the thirty year period from 1985 to 2005. Compared to poultry and swine FCR improvements, ruminant FCR improvements have been modest. In the past 30 years, ruminant FCR has improved by about 30%. The majority of this improvement has come about through improvements in diet management. Forages have largely been replaced by processed grains in finishing rations. This development has significantly improved FCR in beef feedlots. The type and quality of grains in addition to having a balanced diet for vitamins and minerals all play a part in improving feed conversion ratio.

The use of growth promoters such as ionophores, implants and beta agonists in feedlot diets can significantly improve feed efficiency. A study by Faucitano et al. in 2008 showed that growth rates were 21% higher and feed efficiency 23% higher for feedlot animals given both an ionophore and an implant compared to those animals given no growth promoter.

Why are ruminants so feed inefficient? Unlike swine and poultry, ruminants consume diets that are much higher in fibre. Ruminants are dependent upon microorganisms, through rumen fermentation, for digestion. During rumen fermentation, bacteria produce byproducts that can the efficiency of digestion. Furthermore, ruminants have a high maintenance requirement compared to other livestock. Ruminants use greater than 50% of their feed intake for maintenance. There is also a lot of variability between the feed efficiencies of individual animals. European research has shown that there can be up to a 20% difference in FCR between the most efficient animal and the least efficient in a group. This can have significant cost implications for a feedlot owner. The biological mechanisms underlying variation in feed efficiency in animals with similar bodyweights and growth rates are not well understood.

The lack of real progress in improvements in FCR for beef cattle is partially due to the preference for cow calf producers to select for animals that grow faster. Such selection produces larger framed animals that have a higher maintenance requirement and consequently a higher feed conversion ratio. Research by Teagasc at the Grange Animal & Grassland Research and Innovation Centre, Dunsany, Co. Meath, Ireland demonstrated that FCR is difficult to select for as the feed regime for the bulls under test is rarely replicated on commercial farms.

Consequently, the concept of residual feed intake (RFI, rather than FCR has become popular as a better method to measure feed efficiency. Residual Feed Intake is the difference between an animal’s actual feed intake and the animals expected intake based on its body weight and growth rate. This means that animals with a low RFI (desired) eat less than expected for their weight and growth rate.

Considerable variation in RFI exists within and across breeds. As the trait is about 40% heritable, this presents an opportunity to select for animals with low RFI. Dr. John Basarab et al. at Olds College, Alberta, used the GrowSafe System to measure intake by individual animals. They showed that animals with a low RFI had 10 – 12% lower feed requirement for the same body size and average daily gain compared with animals with high RFI. This is equivalent to having a 9-15% improvement in feed conversion ratio. Dr. Basarab showed that selecting animals for low RFI had no effect on carcase quality, provided RFI was adjusted for fatness, no effect on pregnancy rates, calving rates, weaning weights, age at puberty, pregnancy or calving pattern. Selecting for low RFI means a significant improvement in feed efficiency with no effect on carcase quality or other desirable productive traits.

Methane production from beef cattle in 2011 was 14% lower than 1981 levels. This reduction is primarily due to increased feed efficiency over this period. It is estimated that by selecting for low RFI, greenhouse gas emissions could be reduced by a further 15 – 20% due to reduced input requirements.

Dr. Danny Crews from Agriculture and Agri-Food Canada (AAFC) was the first to develop expected progeny differences (EPDs) for RFI. The first EPDs developed had an accuracy of 59%. It is expected this will increase as more bulls are tested. Dr. Crews developed a multi-trait index which includes RFI. The index will help producers select bulls based on how economically well their progeny perform under feedlot conditions. It is expected that bulls with low RFI will sire calves that will generate more net revenue for the feedlot industry. The increased revenue potential of these types of cattle should be reflected in higher prices for cow-calf producers who sire such cattle.

The use of feed conversion ratio and residual feed intake are very powerful tools to help drive improved feed efficiency and improved profitability for the beef industry. The production of more feed efficient cattle will help reduce the level of inputs required and can reduce greenhouse gas emissions.

References:

  1. Alberta Agriculture & Forestry. (2016) Residual Feed Intake (Net Feed Efficiency) in Beef Cattle
  2. Beauchemin, K. (2018) Reducing Methane Emissions for the Cow-Calf and Feedlot Sectors. AAFC Lethbridge Research & Development Centre, Saskatchewan Beef Industry Conference
  3. Beef Cattle Research Council. (2016) Optimizing Feedlot Feed Efficiency.
  4. Faucitano, L., Chouinard, P.Y., Fortin, J., Mandell, I.B., Lafrenière, C., Girard, C.L., and Berthiaume, R. (2008) Comparison of Alternative Beef Production Systems based on Forage Finishing or Grain-Forage diets with or without Growth Promotants. J.Anim. Sci. 86(7): 1678-89.
  5. McGee, M. (2014) Feed Efficiency in Beef Finishing Systems, Teagasc, Grange Animal & Grassland Research and Innovation Centre, Dunsany, Co. Meath, Ireland
  6. Shike, D.W. (2013) Beef Cattle Feed Efficiency. Driftless Region Beef Conference, University of Illinois at Urbana-Champaign
  7. Weaber, R. (2011) Kansas State University, National Program for the Genetic Improvement of Feed Efficiency in Beef Cattle

Author: James Byrne, Beef Cattle Specialist, OMAFRA

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