Effect of feeding programme on the metabolisable energy of feed for broilers: starvation-feeding-starvation vs ad libitum feeding

The determination of metabolisable energy (ME) in feed ingredients is essential for accurate diet formulation and growth management in broiler. However, the precision of ME determination may be influenced by the choice of feeding programme. This study tested the hypothesis that the starvation-feeding-starvation (SFS) programme would yield ME values that differ from those obtained with a continuous ad libitum feeding (ALF). A total of 120 male Arbor Acres Plus broilers (21 days old; BW = 1 087 ± 15 g) were randomly allocated to six treatments in a 2 × 3 factorial design. The treatments included a corn-soybean meal basal diet (CSMBD), a wheat diet, and a cottonseed meal diet, combined with either SFS or ALF. In the SFS programme, broilers were fasted for 17 h to empty the digestive tract, given access to the diet for 55 h, and then fasted again for 17 h. In the ALF programme, diet was available continuously for 72 h. BW was monitored using a balance sensor fixed in the cage and recorded by software. From 22 to 28 days of age, broilers in the SFS programme exhibited BW loss, whereas those in the ALF maintained BW gain. Consequently, final BW, average daily gain (ADG), average daily feed intake (ADFI) and excreta output were lower in SFS than ALF, regardless of diet (P < 0.01). Feeding programme did not affect the ME of any test diet or ingredient. A positive trend was observed between ADFI and apparent ME in the CSMBD and cottonseed meal diet (0.05 < P < 0.10), but no correlation was found between ADFI and nitrogen-corrected apparent ME in the CSMBD or cottonseed meal diet, or between ADFI and ME in the wheat diet, wheat or cottonseed meal. Linear regressions of ADG on ADFI or intake of ME and metabolisable CP (MCP) were significant under both feeding programme (P < 0.05). Moreover, the R² values for these regressions were higher in SFS than in ALF. These findings indicate that although the feeding programme does not alter ME values, the SFS programme provides more precise measurement of ADFI and intake of ME and MCP in relation to broiler growth than the ALF programme. Therefore, the SFS programme may be preferable when reduced variance is critical, whereas the ALF programme remains suitable when animal welfare considerations take precedence.