Eating behavior of lactating sows receiving growth hormone-releasing factor: effect of meal frequency and high-fiber gestation diets

Abstract

Forty-eight Yorkshire × Landrace gilts were used in an experiment with a factorial design (2 × 2 × 2). The treatments were control or bulky diet during gestation (4.1 vs. 15.3% crude fiber), the number of meals served daily in lactation (2 or 4) and three daily s.c. injections of saline or of 1 mg of a human growth hormone-releasing factor analog (GRF) from day 3 to day 29 of lactation. The animals were video-recorded for 30 s every 5 min over a 24-h period and observed continuously at feeding time at weeks 2 and 4 of lactation. Injections of GRF to lactating sows decreased the time spent eating after feed distribution (P = 0.007) but not eating frequency over 24 h. GRF-treated sows performed more oral non-feeding activities after feed distribution and over 24 h (P < 0.05). Sows fed four times a day spent less time eating and more time lying per feeding period than sows fed twice (P < 0.05) but the total eating time over the day was similar. Lying frequency did not decrease in GRF-treated sows fed at 23:15 h, contrary to saline-injected sows (P = 0.02). Feeding high-fiber diets during gestation had no effect on eating behavior during lactation. In conclusion, GRF injections during lactation modified the eating behavior of sows. However, using a bulky diet during gestation or increasing meal frequency during lactation did not counteract the decrease in eating time due to GRF. Key words: Meal frequency, fiber, growth hormone-releasing factor, eating behavior, sows