WATT PoultryUSA - January 2012

Figure 5. Energy added to excreta over that anticipated by
dietary metabolizable energy value

Average Excreta Energy (Lcal/Day)

120 100 80 60 40 20

105

90 91

57

18 - 13 - 8

0 - 20

27 25 34 30 21 17 36 11

20 27 34 41 48 20 27 34 41 48 20 27 34 41 48 Age Lesion 0 1 2

environment inputs is well correlated with producer bene;t. Consequently, the energy value of nonnutritive components may be estimated as caloric density and capitalized.

Low lesion scores for coccidiosis have a pronounced impact upon ration energy loss with consequences becoming more pronounced late in the growth curve.

Figure 6. Effective caloric value for lesion scores
0, 1 and 2 throughout the growth curve to 3 kg.

Pred. ECV (Gross lessions model)

500

0

-500

1 2

-1000

-1500

-2000

-2500

600 1200 1800 2400 3000

Live Bird Mass (g)

Calories lost in the excreta averaged just 3.6% for control birds, while birds with full coccidiosis averaged over a 50 Kcal additional loss each day.

lated according to tables containing
nutrients in proportion to MEn (NRC,
1994). Though MEn values ignore bird
heat losses, the system has the advan-
tage of being easily determined, but
the disadvantage of not being strictly
quantitative. Failing to adequately
adjust for heat losses creates products
of varying lipid content and consumer
dissatisfaction. Too frequently, bird
performance varies independently
from MEn. Yet, for many produc-
ers, body weight, BWT, and FCR
responses to diet and environment are
predictable. This forms the basis of the
effective caloric value system. Figure
1 illustrates the relationships existing
between bird body weight, daily FCR
and dietary caloric density.

ECV applications

Historically, managerial, nutritional, environmental and health aspects of broiler production have been viewed as separate entities. However, these multifaceted components overlap, and the ;nal production outcome is contingent upon this interface. Fundamentally, energy metabolism is the ideal denominator among these seemingly disjointed factors. For example, facility and/or managerial improvements may decrease broiler energy expenditure associated with bird activity, and, consequently, additional energy becomes available to the bird for growth. Assuming the diet provides suf;cient indispensable nutrients for lean accretion, the additional calories would be shunted to lean growth. If insufficient nutrients are available, the added energy would be deposited as fat. Managerial and environmental factors potentially impacting bird energy expenditure in the production environment include: