April 2013 - AFMA

The way feed is presented will affect
energy and time required
to consume it. Poultry activity
or behaviour has not received
as much research attention as
other areas when considering performance.
In our modern production environments,
there has traditionally been little
perceived economic value in understanding
or monitoring bird behaviour.
Most of the focus in broiler production
has been on genetic progress, strain selection,
feeding programmes and management
systems rather than on how the bird
responds to such changes. However, bird activity
is responsible for the major energy loss
between consumed dietary metabolisable
energy and the amount of energy retained
as tissue, and so it merits consideration.
Using pellet quality to
improve broiler growth rate
and feed conversion
By Dr Chet Wiernusz, director of world feed milling and nutrition at Cobb-Vantress
Activity and energy consumption
Depending on the management system in
place, 20% of metabolisable energy intake
(MEI) is used for activity. In other words,
assuming that 14,287 Kcal ME must be
consumed to produce a 2,5kg broiler, approximately
2,858 Kcal ME is used for activity.
Therefore, reducing activity energy expenditure
by approximately 6% would save
a considerable amount of energy.
Pelleting poultry feeds has been long
recognised as a method to enhance bird
performance. Pelleting is known to increase
body weight, to reduce feed wastage and to
improve feed conversion.
Its exact mode of action, however, has
been speculative. Work reported by Jensen
et al. (1962) indicated that pelleting did indeed
elevate bird performance through
increased body-weight gain and improved
feed conversion. Additionally, Jensen et al.
(1962) noted that broilers fed pellets spent
less time eating and more time resting than
those fed mash.
Furthermore, the same study reported
that digestibility was not a factor in the improved
broiler performance. Consequently,
bird behaviour may well be a critical factor
for defining the mode of action for pelleting.
If true, then pelleting would also offer an avenue
to manipulate bird energy expenditure
for activity.
Observing behaviour
The importance of bird behaviour and feed
form were examined by Dr Robert Teeter at
Oklahoma State University in the following
two experiments.
Behavioural observations were conducted
by walking past each cage five times
spaced throughout the day and classifying
the broilers into one of nine behaviour categories.
These included eating, drinking,
standing, resting, pecking, preening, walking,
dust bathing and other activity. The five
observations for each bird were then put on
a percent-time basis to create results for data
analysis.
As described by McKinney and Teeter
(2004), bird body weight and feed conversion
values were transformed into effective
caloric value. The effective caloric value represents
the caloric density that would be
needed to achieve the same body weight
and feed conversion result under low stress
conditions. As such, effective caloric value
enables evaluation of calorie savings when
viewed as the difference between values
created by varying nutritional and/or nonnutritional
production scenarios.
In the first study, birds were offered two
feed forms – mash vs. pellets – with treatments
also including birds switched from
one feed form to the other. All birds were
offered the same ration composition, independent
of feed form, and allowed to consume
feed ad libitum.
Despite the fact that all birds were provided
a 3,050 Kcal ME/kg ration, the range
of an effective caloric value for individual
birds was from 2,450 Kcal when a bird spent
20% of its time resting to 3,550 Kcal when
a bird spent 85% of its time resting, creating
a spread of 1,100 Kcal of effective caloric
value/kg ration.
Encouraging quick consumption
The importance of bird activity as a source
of energy wastage is clear. Yet another factor
impacting bird behaviour appears to be
Processing
AFMA MATRIX ● APRIL 2013 35