A total of 47 multiparous Large White sows in 10 successive replicates of 8 to 10 animals were used in the experiment. Two seasons were distinguished a posteriori from climatic measurements continuously recorded in the open-front farrowing room. The average ambient temperature and average daily relative humidity for the warm season were 23.6°C and 93.8%, respectively. The corresponding values for the hot season were 26.1°C and 93.7%. Within each group, the feeding behavior was measured on only 4 to 6 sows using electronic troughs. The dietary experimental treatments were a normal protein diet (NP; 17.3%), a low protein diet (LP; 14.1%), and a NP diet supplemented with an essential AA complement (NP+; 17.6%) and the sows were distributed according to backfat thickness, parity order, and BW after farrowing. Individual feeding behavior was recorded during the ad libitum period (between d 6 and 27), using an electronic trough connected to a load cell and a computer. Standing or sitting duration was recorded over the ad libitum period by using an infrared barrier located in the middle of the crate. Piglets were weighed at birth and at 14, 21, and 28 d of lactation. At weaning, sows were moved to a breeding facility and were presented to a mature boar twice daily to detect onset of standing estrus.
No interaction between season and diet composition was found for all criteria. Average daily feed intake was less (P<0.01) during the hot season (4.56±161 vs. 5.71±204 kg/d). Meal size was reduced during the hot season (542±37 vs. 757±47 g/meal; P<0.01). Daily ingestion time (45.5±3.2 vs. 55.8±4.0 min/d; P<0.05) was less in the hot season. In both seasons, daily feed intake, feed ingestion, and rate of feed intake were less (P<0.01) during the nocturnal period than during the diurnal period. The number of meals per day was not affected (P>0.10) by season or diet composition. Daily feed intake was greater for the sows fed the low protein diet when compared with normal protein treatments (P<0.05). Duration of standing was not affected by diet or season (P>0.05), and averaged 126±35 min/d. The reduced milk production was associated with a reduced litter growth rate (7.349 ± 261 vs. 8.348 ± 329 g/d and 2.102 ± 66 vs. 2.397 ± 84 g/d, respectively, for the hot and warm season; P=0.02).
In conclusion, this study confirms that feeding behaviour variables of the lactating sow are affected by seasonal variations of the tropical climate. Irrespective of season, the reduction of crude protein content improved feed consumption under tropical conditions.
BAN Silva, J Noblet, RFM Oliveira, JL Donzele, Y Primot, and D Renaudeau. 2009. Journal of Animal Science. 87:2104-2112