Experiment 2 was designed to determine the AID and the
SID of CP and AA in chicken meal, poultry byproduct meal,
hydrolyzed porcine intestines, the spent hen–SBM mixture,
and SBM fed to weanling pigs. Twelve weanling barrows
(initial BW: 12.2 ± 1.5 kg) were equipped with a T-cannula
in the distal ileum according to procedures adapted from
Stein et al. (1998). Pigs were allotted to a replicated 6 ×
6 Latin square design with 6 periods and 6 diets in each
square. Pigs were housed individually in pens (1.2 by 1.5
m) in an environmentally controlled room. A feeder and a
nipple drinker were installed in each pen.
Six diets were prepared (Tables 3 and 4). One diet
contained SBM as the sole source of AA, and 4 diets
contained SBM and chicken meal, poultry byproduct
meal, hydrolyzed porcine intestines, or the spent hen–
SBM mixture. The last diet was a N-free diet, which
was used to estimate basal endogenous losses of CP and
AA. Chromic oxide (0.4%) was included in all diets
as an indigestible marker and vitamins and minerals
were included to meet or exceed estimated nutrient
requirements for weanling pigs (NRC, 1998).
Feeding and Sample Collection. Pigs were fed at
a daily level of 2.5 times the estimated maintenance
requirement for energy, and the daily allotment of feed
was provided at 0700 h each day. Water was available
at all times. The BW of each pig was recorded at the
beginning of each period and the amount of feed supplied
each day was recorded. Each experimental period lasted
7 d. The initial 5 d was an adaptation period to the diet
whereas ileal digesta were collected for 8 h on d 6 and 7.
A 225-mL plastic bag was attached to the cannula barrel
by a zip tie, and digesta that flowed into the bag were
collected. Bags were removed whenever they were filled
with digesta or at least once every 30 min, and digesta
were immediately stored at –20°C to prevent bacterial
degradation of AA in the digesta.