The effect of stiffness and hole size on nipple compression in infant suckling

During infant feeding, the nipple is an important source of sensory information that affects motor outputs, including ones dealing with compression of the nipple, suction, milk bolus movement, and swallowing. Despite known differences in behavior across commercially available nipples, little is known about the in vivo effects of nipple property variation. Here we quantify the effect of differences in nipple stiffness and hole size on an easily measured metric representing infant feeding behavior: nipple compression. We bottle‐fed 7‐day old infant pigs (n = 6) on four custom fabricated silicone nipples. We recorded live X‐ray fluoroscopic imaging data of feeding on nipples of two levels of hardness/stiffness and two hole sizes. We tested for differences in nipple compression at the nipple's maximum compression across different nipple types using a mixed model analysis of variance. Stiffer nipples and those with smaller holes were compressed less than compliant nipples and nipples with larger holes (p