RESEARCH ▶▶▶


Night feeding increases fat deposition in pigs


Does time of feeding effect the metabolism of pigs? This was the main question in the study of Rik van Erp PhD student Wageningen University & Research. Van Erp presented his results at the symposium ‘Digestion Kinetics in Pigs’ on 3 October at Wageningen University.


T BY MARIEKE PLOEGMAKERS


ime of feed intake can be influence by several fac- tors, such as a high stocking density and heat stress. “Small pigs housed in high stocking density will be chased away by dominants pigs, forced to eat at dif-


ferent times. Also pigs experiencing heat stress will have dif- ferent feeding times,” according to Van Erp. The question of the study was if timing of feed intake matters, will it affect energy metabolism. During the study one group of pigs were fed at normal feeding times during the day and the other group was fed during the night.


Higher energy retention Results of the study showed that digestibility of dry matter, energy and nitrogen was similar in both groups (see figure 1). However, a metabolic difference was observed. Heat produc- tion of the day fed pigs was higher than of the night fed pigs. Resulting in a higher energy retention for the pigs fed at night. Van Erp: “We observed no difference in retention of protein, so all extra energy was stored as fat. The night fed group stored 7% more fat than the group fed at day time.” This extra storage of fat resulted in 1.7kg more final fat mass and 0.6 mm higher back-fat thickness. Per centage of meat decreased with 1.1% and carcass weight remained unchanged.


Heat production According to Van Erp the increase in fat deposition can be explained through the lower heat production of these pigs (see figure 2). “Heat production can be divided in heat pro- duction related to activity and heat production due to rest- ing metabolic rate (RMR). Looking at the two groups, 60% of the difference between heat production was related to RMR and 40% to activity


heat. Indicating that the difference in fat deposition is relat- ed to differences in metabolic processes, not only by activi- ty.” Activity heat production during the study in the night fed group could be explained by the activity of pigs during feed- ing times and because of lights in the morning. However, there was also an activity heat peak at 4pm in the afternoon that the researcher couldn’t explain. “There were no external circumstances at that time that could have an effect on the pigs. It is probably related to the circadian rhythm of ad lib fed pigs.”


Figure 1 - Effect of night feeding: grower-finishing phase (BW 30 kg – 115 kg) Inraporc.


Feed intake, g/d Growth, g/d


Protein deposition, g/d Fat deposition, g/d Feed-to-gain ratio, kg feed/kg gain


Day-fed 3019 1125


164 386 2.68


Night-fed 1145


412 2.64


3021 164


= + 7 %


Figure 2 - Both RMR and activity are reduced in night-fed pigs.


Difference


1000 1200 1400


200 400 600 800


0 Day Night ▶ ALL ABOUT FEED | Volume 27, No. 9, 2019 21


1269 213


–15 (40%) –39


1230 198


1056


–24 (60%)


RMR Activity heat


1035


kJ · kg BW–0.6·d–1


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