The studies reported on in this thesis addressed the development of suckingpatterns in preterm newborns. Preterm infants often have problems learningto suckle at the breast or to drink from a bottle. It is unclear whether this isdue to their preterm birth or whether it is the consequence of neurologicaldamage. From the literature, as well as from daily practice, we know thatthere is much variation in the time and in the way children start suckingnormally. Factors such as birth weight and gestational age may indeed berisk factors but they do not explain the differences in development. A smallspot-check proved that most hospitals in the Netherlands start infants onoral feeding by 34 weeks’ post-menstrual age (pma). By and large the policyis aimed at getting the infant to rely on oral feeding entirely as soon aspossible. The underlying rationale is to reduce the stay in hospital, and theidea that prolonged tube-feeding delays or even hampers the development ofsucking.
OBJECTIVE: Coordinating sucking, swallowing and breathing to achieve effective sucking is a complex process and even though sucking is essential for nutrition, little is known about sucking patterns after birth. Our objective was to study sucking patterns in healthy fullterm infants and to describe the age-specific variations.METHOD: We studied the sucking patterns of 30 healthy, fullterm infants longitudinally from 2 or 3 days after birth to 10 weeks of age. During this time we recorded five to seven feeding episodes that we assessed off-line with the Neonatal Oral-Motor Assessment Scale (NOMAS).RESULTS: We found a normal sucking pattern on the second or third day after birth in 27 out of 30 infants. During the following weeks we found abnormal sucking patterns in 23 out of 171 feeding episodes (14%) and normal patterns in 148 episodes (86%). Altogether, between 38 and 50 weeks' postmenstrual age (10 weeks after birth), 10 infants displayed a deviating, arrhythmical sucking pattern. Dysfunctional sucking patterns and problems of coordinating sucking, swallowing and breathing did not occur. Birth weight, gestational age, type of labour and gender did not influence sucking patterns. Arrhythmical sucking was seen more often in bottle-fed infants.CONCLUSION: Our study demonstrated that practically all healthy fullterm infants started off with a normal sucking pattern soon after birth. One-third of the infants displayed one or more deviating episodes up to the age of 10 weeks. Apart from bottle-feeding, no other factors were found that influenced sucking patterns.
The long spined sea urchin Diadema antillarum was an abundant grazer on Caribbean coral reefs, until 1983–1984, when densities were reduced by ∼98% during a region wide die-off. Since then, there has been very little natural recovery of the species and interest is growing in applying aquaculture as a tool for population enhancement. In this study we optimized a new shaker bottle cultivation method for D. antillarum. The method was tested in a series of experiments by culturing D. antillarum from egg to juvenile in the Netherlands as well as the USA. Larvae were cultured in standard 1-L glass reagent bottles, suspended by gentle constant movement on an orbital shaking table and fed with either the microalgae Rhodomonas lens or Rhodomonas salina. Effects on larval growth and survival were evaluated for different microalgal feeding concentrations, larval densities, and culture temperatures. Larval density and growth were measured twice a week over a period of up to 56 days. Larvae grew significantly faster on a higher feeding concentration up to 90,000 Rhodomonas sp. cells mL−1, twice weekly, compared to 30,000 and 60,000 cells mL−1. A density of 1 larvae mL−1 resulted in the highest body size and survival compared to densities of 2 or 4 larvae mL−1. Overall survival from larva to settled juvenile urchin increased from 8 to 10% settlement to 32–33% when the initial density was lowered further from 1.2 to 0.4 larvae mL−1. Growth, survival, competency and settlement did not differ between larval cultures kept at 25 °C or 28 °C. We believe that this novel method for culturing D. antillarum larvae, once scaled-up and validated to pilot scale, could provide juveniles for restocking of urchin-depleted reefs that suffer from algae overgrowth.
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