Feed energy constitutes a major cost factor in laying hen production, yet current net energy ( NE ) evaluation ignores the impact of starch digestion kinetics. This study evaluated the effects of different starch digestion kinetics on productive performance and energy utilization in peak laying hens. A total of 360 Hy-Line Brown hens (35 weeks of age) were randomly assigned to four diets: rapid ( RAP ), medium ( MED ), slow ( SLO ) and resistant starch diet ( RES ). Productive performance was measured for 35 d in 280 hens, and respiratory calorimetry was conducted for 5 d in 48 hens selected from an additional group of 80 hens. The results indicated that the RAP diet showed the highest in vitro starch digestion rate constant k ( P 0.05), whereas the RAP diet showed the highest HI:GE ratio and the lowest NE:GE ratio ( P < 0.05). Quadratic regression revealed a significant relationship between the starch digestion rate constant k and the HI:GE ratio ( P = 0.030). Overall, an optimal range of glucose release rates may improve NE utilization in peak laying hens, supporting the potential value of incorporating starch digestion kinetics in NE evaluation.
Zhu et al. (Wed,) studied this question.