Net Feed
Efficiency Testing
Why
measure feed efficiency
The cost of feed is second only to fixed
costs in importance to the profitability of commercial beef operations and 70-75%
of the total dietary energy cost in beef production is used for maintenance,
including maintenance of the dam. In addition, a 5% improvement in feed
efficiency could have an economic impact four times greater than a 5%
improvement in average daily gain.
Defining
net feed efficiency
Net feed efficiency or net feed intake (NFI) is defined as the
difference between an animal's actual feed intake and its expected feed
requirements for maintenance and growth. Thus, it is the variation in feed
intake that remains after the requirements for maintenance and growth have been
removed. Like a golf score, a lower value is better and indicates an efficient
animal.
Take for example a British cross steer on a
finishing diet consisting of 22% barley silage, 73.3% steam rolled barley, 1.6%
molasses and 3.1% feedlot supplement. If this steer averaged 453.6 kg (1000 lb)
in body weight over the last 120 days on feed and its ADG was 1.76 kg/day, the
"Nutrient Requirements of Beef Cattle" (NRC 1996) would predict an
average feed intake of 14.5 kg/day over this same period. If the actual feed
intake for this steer was 10.2 kg/day, this would be 4.3 kg/day less feed than
expected, and its NFI would be minus 4.3 kg/day.
Considerable variation exists between
individual animals within breeds or genetic strains in NFI. This infers that
substantial progress can be made in NFI or feed efficiency since the
heritability of the trait is approximately 40%.
Key
Points
•Improving feed efficiency has an economic impact
four times greater than improving growth rate.
•Net Feed Intake (NFI) is a more useful measure
of feed efficiency than Feed Conversion
Ratio (FCR) and is moderately heritable.
•Benefits from selecting for NFI are improved
competitiveness, increased value of genetic seed-stock through the generation
of genetic merit values and potential reductions in methane emissions and
manure production by efficient cattle.
•NFI can be used to select cattle for lower
maintenance and feed consumption, without
affecting body size and growth rate, or adversely
affecting carcass characteristics,
composition of live weight gain or distribution
of fat depots.
•Preliminary results indicate that post-weaning NFI is highly related to mature cow efficiency and cow reproduction is unaffected.
•The GrowSafe® System in combination with
customized software is a robust and accurate system for non-invasively
monitoring individual animal feed intake under commercial conditions.
John
A. Basarab [1] , Mick A. Price 2 and Erasmus K. Okine 2