POULTRY NUTRITION & HEALTH
How management, intestinal health
influence poultry caloric efficiency
Broiler growing conditions, and especially the resulting intestinal health of ;ocks, are
critical to ef;cient energy metabolism. BY R.G. TEETER AND A. BEKER
2. 32. 17 2.01 .86 1.70 1. 54 1. 39 1.233250 3067 2883 Dietary energy, MEn/kg 1967 2700 FCR Figure 1. Body weight, FCR and dietary caloric density relationship.
Broiler performance has improved
over the years with feed conversion
ratios for 2. 5 kg birds reared in “good
growing conditions” falling from 1.91
to 1.61 from 1994 to 2011. Though
dietary values for nitrogen-corrected
metabolizable energy, MEn, are relatively unchanged, the ef;ciency of
MEn use for tissue accretion under
these conditions has improved over
19%. The theoretical limit for converting dietary substrates to tissue has
been estimated at 76%. At this level
of energetic ef;ciency, the feed conversion ratio for creating a 2. 5 kg bird
would be 1.01 as opposed to 1.61. The
difference between birds reared under
near-ideal conditions and the theoretical FCR possibility of 1.01 is the cost
of the production environment.
The range of performance is further
magni;ed when contrasted to com-
❯❯
Body weight, 9
1233
Producer-observed BWT and FCR values allow for the estimation of the dietary MEn required to
mimic bird performance under reference standard conditions.
2700
500
environments limit broiler performance and add considerable cost.
Indeed, the production environment
is critical as it either takes away or
adds to the ef;ciency of MEn utiliza-
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mercial birds under varying conditions
around the world. Though it is not
reasonable to expect that production
ef;ciencies will ever reach theoretical
limits, it is apparent that production
tion. The purpose of Effective Caloric
Value is to enable energy assignment
to production environment compo-
nents related to husbandry, health and
nutritional technologies.
Energy partitioning
Many factors impact energy utilization. Classical descriptors found in most
nutrition texts range from gross energy
(GE, total energy) to net energy (NE,
energy for function). The energy form
most commonly utilized by the poultry
industry is MEn, which fails to account
for heat loss. Bird heat production is
in;uenced by myriad factors including
ambient temperature (Weirnusz and
Teeter, 1993), ration composition, tissue
type synthesized and activity (Mckinney
and Teeter, 2004). Failure to account for
variations in heat production, regardless
of source, eventually has the net result of
R.G. Teeter and A. Beker, Department of Animal Science, Oklahoma State University, Stillwater, OK 74074; Email teeterbob1@hotmail.com;
Phone (405) 880-1170
