To overcome negative energy balance during the peripartal period of sows, an ad libitum
feeding strategy (ADLIB) as alternative for commonly used restricted feeding (STANDARD,
on average 3 kg feed/day) was evaluated. Plasma metabolites and thyroid hormones, change
of back fat thickness (BF), reproductive traits, and piglet performance were monitored.
Voluntary feed intake of ADLIB sows declined at farrowing but was still more than twice
the amount of what was offered to STANDARD sows. Consequently, ADLIB sows lost less
BF than STANDARD sows (P = 0.041). Additionally, BF change was affected by body condition.
LEAN sows (BF < 18 mm on d 105 of gestation) lost less BF than MODERATE sows
(18 mm ≤ BF ≤ 22 mm) which lost less BF than FAT sows (BF > 22 mm) (P < 0.001). Except for
a decreased percentage of stillborn piglets for MODERATE sows (P = 0.044), reproduction
results were not affected. Piglet weaning weight of ADLIB-FAT and STANDARD-MODERATE
sows was reduced in comparison with that of ADLIB-LEAN sows (P = 0.005). Regardless of
body condition, all metabolites and thyroid hormones measured showed a time dependent
profile (P < 0.001). On d 112 of gestation increased concentrations of creatinine (P = 0.004),
non-esterified fatty acids (P = 0.039), and serum crosslaps (P = 0.016) for STANDARD sows
were observed. Triglycerides were increased for FAT sows (P < 0.001), and decreased faster
over time for ADLIB (P = 0.013) and for FAT (P = 0.012). Although ad libitum feeding during
the peripartal period only resulted in less mobilization of muscle, fat, and bone reserves on
d 112 of gestation, results of BF change and piglet weaning weight indicated that ad libitum
feeding is beneficial for sow performance provided that BF is below 22 mm.