Agriculture Reference
In-Depth Information
Table 13.6. Optimum amounts of three feeds of fixed composition, for male and female broilers reared
separately.
Males
Females
R10/kg
R20/kg
R30/kg
R10/kg
R20/kg
R30/kg
Starter
945
945
421
632
632
632
Grower
1684
1580
474
2684
2684
2684
Finisher
1244
1329
3110
0
0
0
Revenue varied from R10 to R30/kg dressed weight (currency is South African Rand, R). The objective function maximized
was margin over food cost.
reflecting the lower amino acid require-
ments of the females compared with the
males. As the revenue per kilogramme in-
creased, the optimum amount of starter
and grower for females remained the same
throughout, but for males these decreased,
which is counterintuitive: most producers
would be inclined to feed less expensive
feeds when revenue decreases, thereby as-
suming that losses would be minimized.
However, these results suggest that when
revenue and hence margins are low, broil-
ers should be given the opportunity to
grow closer to their potential than when
profits are high. This is corroborated by
the evidence in Table 13.7 in which the
EFG broiler optimizer was used to deter-
mine the optimum lysine contents in the
three feeds for the three revenues used
above, but for fixed amounts of starter
(800 g), grower (1200 g) and finisher. This
was for a mixed flock of broilers. The ly-
sine content in the grower and finisher
was considerably increased at the lowest
revenue/kg, once again suggesting that
under such unprofitable circumstances the
best option is to grow the birds close to
their potential thereby minimizing the
loss in profitability.
The decision as to the optimum time to
switch from one feed to the next is depend-
ent on many variables, including the sex of
the broiler and the relationship between in-
gredient costs and revenue obtained. Where
a broiler producer purchases proprietary
feeds from a feed mill and has no say in the
composition of such feeds, it is possible to
alter the feeding programme as circum-
stances change thereby maximizing profit at
all times.
Table 13.7. Optimum lysine content (g/kg) in fixed
amounts of starter (800 g), grower (1200 g) and
finisher (remainder) to 35 days of age in a mixed
flock of broilers at three revenues (R10, R20 and
R30/kg dressed weight).
Revenue (R/kg)
10
20
30
Starter
13.77
13.77
13.77
Grower
11.53
10.09
10.01
Finisher
10.33
10.00
9.97
Currency used is South African Rand, R.
Conclusions
Until the advent of an accurate predictor of
food intake, and hence growth and carcass
composition of broilers, it was virtually im-
possible for poultry nutritionists to move
away from the comfort zone of using fixed
amino acid requirements when designing
feeds for commercial broilers. Once such a
facility became available the logical step
was to combine this with a feed formulation
program and an optimization routine, which
would enable the nutritionist to change the
feed composition and feeding programme
so as to maximize profitability for the enter-
prise. With account being taken of all inputs,
the cost of production may be accurately
calculated, and the revenue generated may
also be accurately predicted given the
diverse options available in the model for
selling the product and the accurate as-
sessment of what is to be sold. A wide
range of objective functions is available,
given that the aims of different broiler
producers may not be the same: hence,
 
 
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