Preliminary study: voluntary food intake in dogs during tryptophan supplementation.

Tryptophan, a precursor of important molecules such as serotonin, melatonin and niacin, is an essential amino acid for dogs. In pigs, tryptophan supplementation has been shown to induce a significant increase in food intake. The aim of the present study was to assess whether long-term tryptophan supplementation increases voluntary food intake in dogs and to observe whether this was accompanied by a change in serum ghrelin. In the present study, sixteen adult Beagle dogs were used, with four male and four female dogs fed diets supplemented with tryptophan (1 g/dog per d) during 81 d (Trp) and four male and four female dogs that were not supplemented (control). A voluntary food intake test was performed during 5 d following the supplementation period. The Trp group tended to show a higher food intake during the voluntary food intake test (58.0 (SE 5.37) v. 77.5 (SE 3.65) g/kg metabolic weight per d; P = 0.074). No significant differences were found for serum ghrelin concentrations.

Aggressive behavior in two different group-housing systems for pregnant sows.

The study housed 120 pregnant sows from Day 29 of pregnancy to 1 week before parturition either in groups of 10 with trickle feeding (TRICKLE) or in groups of 20 with an unprotected electronic sow feeding (FITMIX). The study recorded aggressive interaction on 11 nonconsecutive days. Frequency of aggressive interactions was higher in FITMIX (p < .05); yet, intense physical contact was unusual in both systems (3% of the total interactions). Conflicts in FITMIX centered largely on the feeder (83% vs. 23% for FITMIX and TRICKLE, respectively [p < .05]); in TRICKLE, they occurred mainly in the resting area (13% vs. 48% for FITMIX and TRICKLE, respectively [p < .05]). Forty-six percent of the FITMIX sows (mostly gilts and subordinates) needed assistance to adapt to the feeding system. Eventually, 8.3% of the FITMIX sows failed to adapt and had to be removed. In conclusion, although aggressive interactions were mainly of low intensity, sequential feeding appeared to make FITMIX a more competitive feeding system.

Feeder use patterns in group-housed pregnant sows fed with an unprotected electronic sow feeder (Fitmix).

Previous studies on feeder use in group-housed pregnant sows focused on dynamic groups and protected electronic sow feeders (ESF). This study observed 60 pregnant sows, 1st to 8th parity--housed from Day 29 of pregnancy to 1 week before parturition in stable groups of 20 animals, 1 Fitmix feeder per group. Data from 25 nonconsecutive 24-hr feeding cycles showed sows making several visits to the feeder. Literature on conventional ESF indicated shorter daily feeder occupation. Daily feeder occupation per sow decreased over time (p < .001). The study observed maximum feeder activity in the hours following the start of each feeding cycle. During the experiment, there was a relatively stable, quickly established, and maintained feeder order (W > 0.80, p < .001). This highly correlated with dominance rank (r(s) = 0.80, p < .001). High-ranking sows fed earlier and made as many--but longer--visits as low-ranking sows; thus, they occupied the feeder more time every day (p < .01). Although optimization of the feeder efficiency may take several weeks, Fitmix seems an efficient feeding system for medium-size, stable groups of sows.