Effects of high ambient temperature and dietary protein level on feeding behavior of multiparous lactating sows

Abstract

Thirty-three multiparous Large White sows were used to determine the effect of high ambient temperature and level of dietary heat increment on their feeding behavior during lactation. Ambient temperature was maintained constant at 20 or 29°C over 28-d lactation. The experimental diets fed during lactation were a control diet (NP; 17.6% crude protein) and two low protein diets obtained by the reduction of the CP level (LP, 14.6% CP) or both the reduction of CP and addition of 4% fat (LPF, 15.2% CP). The sows were given feed ad libitum between the 7th and the 27th day of lactation. Feeding behavior parameters were not influenced by diet composition. Between d 7 and d 27, daily feed intake decreased at 29°C (P < 0.001; 4149 vs. 7444 g·-1 at 20 °C); this was achieved by a concomitant reduction in meal frequency (P < 0.001; 6.5 vs. 9.4 meals·d-1) and in meal size (P < 0.10; 687 vs. 834 g per meal). The ingestion rate was not influenced by temperature (126 g·min-1 on average), and consequently the reduction of daily feed intake resulted in a decreased ingestion and consumption time (-25 and 28 min·d-1, respectively). The proportion of small meals (i.e., < 250 g) was higher whereas that of medium sized meals (i.e., 250-1000 g) was lower at 29 °C. Diurnal feed and water intakes represented 84% and 79% of total consumption, respectively. Two peaks in feed were observed, the first one between 07.00 and 13.00 at both temperatures and the second one that was shorter at 29 °C (17.00 to 23.00 vs. 14.00 to 23.00 at 20 °C). Standing activity averaged 127 min·d-1 with no significant difference between temperatures. About 70% of standing time was dedicated to feed and water consumption. As determined by the calculation of correlation coefficients between post- or pre-prandial interval and meal size, this latter seems to be partly regulated by satiety mechanisms in most sows (67%).