This pilot study aimed to compare the growth performance, nutrient deposition efficiency and feeding behaviour of growing pigs fed on a standard two-phase feeding or a choice feeding regime. The experiment was performed with 12 Swiss Large White barrows between 23.2 and 108.0 kg body weight (BW). Six pigs assigned to the standard (ST) treatment were offered ad libitum access to a grower (ST-G) and finisher (ST-F) diet from 23.2 to 63.4 kg and from 63.4 to 108.0 kg, respectively. The ST-G and ST-F diets were formulated based on the Swiss feeding recommendation for swine for an average BW of 40 and 80 kg, respectively. The other six pigs assigned to the choice (CH) treatment had constant ad libitum access to both a grower (CH-G) and a finisher (CH-F) diet formulated for a reference BW of 20 and 100 kg. All diets were isocaloric and differed only in the crude protein and essential amino acid content according to the reference BW used for feed formulation. To determine the empty body nutrient deposition rate, pigs were scanned using dual-energy x-ray absorptiometry at 25.8 and 103.8 kg BW. Individual feed intake and feeding behaviour were monitored with automatic feeders. Changes in BW were determined weekly. Compared to ST pigs, CH pigs ingested more feed daily (P = 0.05) and grew faster (P = 0.02). Total crude protein consumption tended to be greater (P = 0.08) in CH than ST pigs due to a numerically greater intake of the protein-rich CH-G diet during the finisher period. A greater crude protein intake in CH than ST pigs was accompanied by a greater (P = 0.04) daily protein deposition rate but a similar protein efficiency. Regarding feeding behaviour, CH pigs went more often to the feeder, spent less time at the feeder, ate less feed per visit and had shorter intervals between two meals than ST pigs (P < 0.01 for each) in the grower but not in the finisher period. Considering the feeding behaviour traits, the CH pigs with a greater protein deposition potential preferred the protein-rich CH-G over the CH-F diet. In conclusion, these results show that, like the wild pigs, the domesticated modern pigs maintained the ability for an adequate nutrient self-supply according to their nutritional requirements.
