Exploring the interaction of viscosity and nipple design on feeding performance in an infant pig model.

Infant feeding behaviors are modulated via sensorimotor feedback, such that sensory perturbations can significantly impact performance. Properties of the nipple and milk (e.g., nipple hole size and viscosity) are critical sources of sensory information. However, the direct effects of varying milk and nipple properties on infant motor output and the subsequent changes in feeding performance are poorly understood. In this study, we use an infant pig model to explore the interaction between nipple hole size and milk viscosity. Using high-speed videofluoroscopy and electromyography, we measured key performance metrics including sucks per swallow and suck duration, then synchronized these data with the onset and offset of activity of jaw opening and closing muscles. The combination of a small nipple hole and thick milk resulted in negative effects on both suck and swallow performance, with reduced feeding efficiency compared to the other treatments. It also appears that this combination of viscosity and hole size disrupts the coordination between correlates of tongue and jaw movements. We did not see a difference in feeding efficiency between viscosities when infants fed on the large-hole nipple, which may be the result of non-Newtonian fluid mechanics. Our results emphasize the importance of considering both fluid and nipple properties when considering alterations to an infant's feeding system.

Identification, migration, and childhood exposure of methylsiloxanes in silicone infant bottle nipples marketed in China.

The analysis, migration, and childhood exposure of methylsiloxanes (MSs) in 32 silicone infant bottle nipples marketed in China were studied. Thirty types of MSs in two families, which included 11 linear MSs (LMSs, L4-L14) and 19 cyclic MSs (CMSs, D4-D22), were identified using gas chromatography-mass spectrometry (GC-MS) associated with standards, retention index, and carbon number rule. In 32 nipples, MSs with molecular weight < 1000 Da and CMSs were predominant. Considering the actual daily use of bottle nipples, the migration tests of MSs from nipples to artificial saliva and reconstituted powdered formula were performed. In particular, the orthogonal test design-QuEChERS-GC/MS was employed to detect MSs in formula. The median migration level of ΣMSs (MW < 1000 Da) in formula was 950.9 ng/mL, which was much higher than that in artificial saliva (98.1 ng/mL). If formula is fed to children aged 3-36 months using bottle nipples according to product instructions, the daily oral exposure to ΣMSs (MW < 1000) for children ranged from 52 to 146 µg/kg bw-day, which were two to five orders of magnitude higher than those of other exposure pathways. In sum, oral intake (especially through formula) may be the predominant pathway of exposure of MSs in children. This research enhances our understanding of the oral exposure risks of MSs and provides useful information that could aid the development of risk management strategies.