Selenium content of Spanish infant formulae and human milk: Influence of protein matrix, interactions with other trace elements and estimation of dietary intake by infants

The selenium content of infant formulae varies as a result of differences in the amount of intrinsic selenium compounds. Manufacturers have been gradually changing the protein profile of infant formulae to reflect human milk contents more closely. Because of these variations in infant formula composition and their potential impact on selenium content, this trace element was analysed with regard to the different protein sources.

The aims of this study were to determine the selenium content in infant formulae sold commercially in Spain, to estimate a daily dietary intake for infants fed on formulae and to compare with the selenium provided by Spanish breast milk samples used as a reference. We have also identified certain trace elements added to formulae which interact with selenium according to the type and protein matrix of the infant formulae.

Selenium concentration was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) with a hydride generator.

The selenium concentrations in human milk and infant formulae determined in this study are similar to those found by other researchers in different countries. The daily selenium intake from the formulae studied was estimated according to the recommended doses from the manufacturers. The theoretical selenium intake of nursed infants has been studied in relation to the Recommended Dietary Allowance (RDA: 10 μg Se/day) and the specific recommendations for infant formula nutrient contents (10–35 μg Se/L) set by the Expert Panel of Life Sciences Research Office (LSRO) of the American Society for Nutritional Sciences.

According to our results, on an overall view, infants fed on the studied infant formulae have an intake between basal and normative requirements. This might be considered as providing an adequate selenium supply. However, the intake of selenium provided by several formulae included in this research did not reach the RDA for the first month of neonate life.     

Donor milk intake and infant growth in a South African neonatal unit: a cohort study

Background

Implications of donor milk feedings on infant growth in resource limited settings remain uncertain. This knowledge gap includes the impact of donor milk availability on infant intake of mother’s own milk. Therefore, this investigation aimed to measure intake and growth in infants receiving donor milk when born to women from resource limited backgrounds with high rates of human immunodeficiency virus (HIV).

Methods

A retrospective cohort study enrolled eligible infants admitted to a South African combined neonatal intensive and secondary high care unit, within a one year admission period during 2015, with signed consent for donor milk feedings. A certified milk bank provided donor milk. Daily nutritional intake during the first month was recorded. Details included proportional intake of donor milk, mother’s own milk and infant formula. The primary outcome of infant growth velocity from day back to birth weight to discharge was calculated when length of stay was ≥14 days. Analyses primarily used T-tests; mixed effects models compared weekly calorie intake.

Results

One hundred five infants with donor milk consent were born at 30.9?±?3.6 weeks of gestation, weighing 1389?±?708 g. Forty percent of mothers had HIV. Infant growth velocity did not differ based on percent of feedings as donor milk (≥ 50%: 11.8?±?4.9 g/kg/d; <?50%: 13.5?±?5.3 g/kg/d; p?=?0.3). Percent of feedings from donor milk was similar based on maternal HIV status (positive: 31?±?25%; negative: 36?±?29%; p?=?0.4), as was percent of feedings as mother’s milk (positive: 53?±?35%; negative: 58?±?30%; p?=?0.4). Calorie intake increased markedly during the first two weeks and then plateaued (p?<?0.0001).

Conclusions

Donor milk feedings in higher proportions did not further impair growth of infants managed in a South African combined neonatal intensive and secondary high care unit with growth rates already below reference ranges. The provision of donor milk contributed to feedings being composed of primarily human milk during the first month. Increasing early calorie intake may improve infant growth in this center.

     

Protein Intake and Plasma Amino-acids of Infants of Low Birth Weight

The plasma amino-acid levels in infants of low birth weight fed on expressed human milk and on a proprietary breast-milk substitute, S26, with a protein intake of not more than 4·5 g/kg/day were compared with those in infants fed on an evaporated milk formula whose protein intake ranged from 6·15 to 12·3 g/kg/day, as well as with normal infants on normal feeds and protein intake. In general, there was little difference between the levels in infants of low birth weight and in normal infants on the same protein intake. The five infants of low birth weight on high protein intake had generally higher levels of plasma amino-acids compared with the group on the lower protein intake, and in particular the levels of tyrosine, phenylalanine, methionine, and cystathionine could be extremely high. Apart from methionine these high levels may be the result both of a reduction in activity of the enzymes involved in the metabolism of these amino-acids, due to the immaturity of the infant, and of the increased stress of a high protein intake. In view of a possible long-term effect of abnormally high plasma amino-acid levels it is suggested that the protein intake of infants of low birth weight should not exceed 6 g/kg/day.     

Nitrogen supply in cattle coupled with appropriate supply of utilisable crude protein at the duodenum,a precursor to metabolisable protein

The overall objective of this study was to calculate the amount of nitrogen (N) that cattle feed must contain in order to utilise the potential supply of utilisable crude protein at the duodenum provided by their energy intake without incurring a negative N balance, that is, without having to break down body protein. For this purpose, the literature was screened for measurements of net degradation and renal excretion of urea as well as N balances (N intake, faecal N and urinary N) in ruminants (cattle, sheep and goats) fed diets with varying N concentrations. Irreversible loss of N from the body urea pool increased with increasing N intake, but net degradation of urea as a proportion of irreversible loss decreased concurrently. Faecal N appeared not to be influenced by N intake and exceeded 11 g/kg dry matter intake (DMI) only in 7% of the data sets available. Urinary non-urea-N rarely exceeded 4 g/kg DMI and appeared independent of N intake. Urinary urea-N showed a clear dependence of N intake, and it is concluded that 1 g N/kg DMI is sufficient for compensating inevitable N losses in the form of urinary urea. In conclusion, ruminant rations should contain the following N concentrations (per kg DM) to account for obligatory losses: 11 g for compensating losses as faecal N, 4 g for compensating losses as urinary non-urea-N and 1 g for compensating inevitable losses as urinary urea-N. The derived recommendations should be helpful for limiting N excretion where this is desirable for ecological reasons.     

NTP-CERHR expert panel report on the developmental toxicity of soy infant formula

Soy infant formula contains soy protein isolates and is fed to infants as a supplement to or replacement for human milk or cow milk. Soy protein isolates contains estrogenic isoflavones (phytoestrogens) that occur naturally in some legumes, especially soybeans. Phytoestrogens are nonsteroidal, estrogenic compounds. In plants, nearly all phytoestrogens are bound to sugar molecules and these phytoestrogen-sugar complexes are not generally considered hormonally active. Phytoestrogens are found in many food products in addition to soy infant formula, especially soy-based foods such as tofu, soy milk, and in some over-the-counter dietary supplements. Soy infant formula was selected for National Toxicology Program (NTP) evaluation because of (1) the availability of large number of developmental toxicity studies in laboratory animals exposed to the isoflavones found in soy infant formula (namely, genistein) or other soy products, as well as few studies on human infants fed soy infant formula, (2) the availability of information on exposures in infants fed soy infant formula, and (3) public concern for effects on infant or child development. On October 2, 2008 (73 FR 57360), the NTP Center for the Evaluation of Risks to Human Reproduction (CERHR) announced its intention to conduct an updated review of soy infant formula to complete a previous evaluation that was initiated in 2005. Both the current and previous evaluations relied on expert panels to assist the NTP in developing its conclusions on the potential developmental effects associated with the use of soy infant formula, presented in the NTP Brief on Soy Infant Formula. The initial expert panel met on March 15 to 17, 2006, to reach conclusions on the potential developmental and reproductive toxicities of soy infant formula and its predominant isoflavone constituent genistein. The expert panel reports were released for public comment on May 5, 2006 (71 FR 28368). On November 8, 2006 (71 FR 65537), CERHR staff released draft NTP Briefs on Genistein and Soy Formula that provided the NTP's interpretation of the potential for genistein and soy infant formula to cause adverse reproductive and/or developmental effects in exposed humans. However, CERHR did not complete these evaluations, finalize the briefs, or issue NTP Monographs on these substances based on this initial evaluation. Between 2006 and 2009, a substantial number of new publications related to human exposure or reproductive and/or developmental toxicity were published for these substances. Thus, CERHR determined that updated evaluations of genistein and soy infant formula were needed. However, the current evaluation focuses only on soy infant formula and the potential developmental toxicity of its major isoflavone components, e.g. genistein, daidzein (and estrogenic metabolite, equol), and glycitein. This updated evaluation does not include an assessment on the potential reproductive toxicity of genistein following exposures during adulthood as was carried out in the 2006 evaluation. CERHR narrowed the scope of the evaluation because the assessment of reproductive effects of genistein following exposure to adults was not considered relevant to the consideration of soy infant formula use in infants during the 2006 evaluation. To obtain updated information about soy infant formula for the CERHR evaluation, the PubMed (Medline) database was searched from February 2006 to August 2009 with genistein/genistin, daidzein/daidzin, glycitein/glycitin, equol, soy, and other relevant keywords. References were also identified from the bibliographies of published literature. The updated expert panel report represents the efforts of a 14-member panel of government and nongovernment scientists, and was prepared with assistance from NTP staff. The finalized report, released on January 15, 2010 (75 FR 2545), reflects consideration of public comments received on a draft report that was released on October 19, 2009, for public comment and discussions that occurred at a public meeting of the expert panel held December 16 to 18, 2009 (74 FR 53509). The finalized report presents conclusions on (1) the strength of scientific evidence that soy infant formula or its isoflavone constituents are developmental toxicants based on data from in vitro, animal, or human studies; (2) the extent of exposures in infants fed soy infant formula; (3) the assessment of the scientific evidence that adverse developmental health effects may be associated with such exposures; and (4) knowledge gaps that will help establish research and testing priorities to reduce uncertainties and increase confidence in future evaluations. The Expert Panel expressed minimal concern for adverse developmental effects in infants fed soy infant formula. This level of concern represents a "2" on the five-level scale of concern used by the NTP that ranges from negligible concern ("1") to serious concern ("5"). The Expert Panel Report on Soy Infant Formula was considered extensively by NTP staff in preparing the 2010 NTP Brief on Soy Infant Formula, which represents the NTP's opinion on the potential for exposure to soy infant formula to cause adverse developmental effects in humans. The NTP concurred with the expert panel that there is minimal concern for adverse effects on development in infants who consume soy infant formula. This conclusion was based on information about soy infant formula provided in the expert panel report, public comments received during the course of the expert panel evaluation, additional scientific information made available since the expert panel meeting, and peer reviewer critiques of the draft NTP Brief by the NTP Board of Scientific Counselors (BSC) on May 10, 2010 (Meeting materials are available at http://ntp.niehs.nih.gov/go/9741.). The BSC voted in favor of the minimal concern conclusion with 7 yes votes, 3 no votes, and 0 abstentions. One member thought that the conclusion should be negligible concern and two members thought that the level of concern should be higher than minimal concern. The NTP's response to the May 10, 2010 review ("peer-review report") is available on the NTP website at http://ntp.niehs.nih.gov/go/9741. The monograph includes the NTP Brief on Soy Infant Formula as well as the entire final Expert Panel Report on Soy Infant Formula. Public comments received as part of the NTP's evaluation of soy infant formula and other background materials are available at http://cerhr.niehs.nih.gov/evals/index.html.     

Molybdenum Content of Canadian and US Infant Formulas

Molybdenum is an essential trace nutrient in the human diet. Our purpose was to provide a comprehensive analysis of Mo content of various types of powdered infant formulas across Canada and the USA. All infant formulas, available on the day of sampling, were purchased from random supermarkets in Grand Forks, ND, USA; San Diego, CA, USA; Washington, DC, USA; and Winnipeg, MB, Canada. Reference powdered milk, human milk (HM), and formula samples were weighed and acid-digested prior to analysis by graphite furnace atomic absorption spectroscopy. Mo content in all formulas ranged from 15.4 to 80.3 μg/L (mean ± SE, 37.7 ± 1.7 μg/L). HM Mo concentration ranged from 1.5 to 9.5 μg/L (5.09 ± 0.81 μg/L). Formulas intended for full-term or for premature infants feeding contained, on average, more Mo than HM. Formulas intended for infants with special needs contained similar mean Mo levels to HM. No significant differences were detected between mean Mo values of formulas of a same type purchased from different brands and/or at different locations. High Mo intake may pose health risks, despite lower bioavailability of Mo from formula compared with HM.     

How much energy does the breast fed infant consume and expend?

Energy intake in breast fed infants is uncertain. The doubly labelled water method was used to measure, simultaneously and non-invasively, energy expenditure, energy intake, milk volume intake, energy deposition, and the energy content of breast milk in 12 "free living" breast fed babies at 5 and 11 weeks of age. The validity of this new approach was assessed in a parallel study in 12 formula fed infants. The babies who were exclusively breast fed expended 1.28 and 1.68 MJ/day at five and 11 weeks and had intakes of 1.81 and 2.22 MJ/day; these intakes were associated with normal growth but were well below those recommended previously. At five and 11 weeks the calculated energy content of breast milk was 0.24 and 0.25 MJ/100 ml, which is substantially lower than that commonly reported in milk obtained unphysiologically by expression of the breast. These data cast doubt on the widely used published standards for infant feeding.     

Effect of bacterial protein meal on protein and energy metabolism in growing chickens

Abstract

This experiment investigates the effect of increasing the dietary content of bacterial protein meal (BPM) on the protein and energy metabolism, and carcass chemical composition of growing chickens. Seventy-two Ross male chickens were allocated to four diets, each in three replicates with 0% (D0), 2% (D2), 4% (D4), and 6% BPM (D6), BPM providing up to 20% of total dietary N. Five balance experiments were conducted when the chickens were 3 – 7, 10 – 14, 17 – 21, 23 – 27, and 30 – 34 days old. During the same periods, 22-h respiration experiments (indirect calorimetry) were performed with groups of 6 chickens (period 1), 5 chickens (period 2), and one chicken (periods 3 – 5). After each balance period, one chicken in each cage was killed and the carcass weight was recorded. Chemical analyses were performed on the carcasses from periods 1, 3, and 5. Weight gain, feed intake, and feed conversion rate were found to be similar for all diets. Chickens on D0 retained 1.59 g N · kg^?0.75 · d^?1, significantly more than chickens on D2, D4, and D6, which retained 1.44 g, 1.52 g, and 1.50 g N · kg^?0.75 · d^?1, respectively. This was probably caused by the higher nitrogen content of D0. Neither the HE (p = 0.92) nor the retention of energy (p = 0.88) were affected by diet. Carcass composition was similar between diets, in line with the values for protein and energy retention found in the balance and respiration experiments. It was concluded that the overall protein and energy metabolism as well as carcass composition were not influenced by a dietary content of up to 6% BPM corresponding to 20% of dietary N.     

Effects of feeding high-quality hay with graded amounts of concentrate on feed intake,performance and blood metabolites of cows in early lactation

Dairy cows are commonly fed energy-dense diets with high proportions of concentrate feedstuffs to meet the increased energy needs of early lactation. However, feeding large amounts of concentrates may cause rumen acidosis and impact cow health. The hypothesis tested was that the energy supply and metabolic health of early-lactation Simmental cows can be maintained when high-quality hay rich in water-soluble carbohydrates (WSC) and crude protein (CP) is fed, despite the proportion of concentrates in the diet being reduced or even excluded. Twenty-four Simmental cows were allocated to one of four feeding groups beginning 10 d before the expected calving date, until 28 d thereafter. The feeding groups were 60CH (60% conventional fibre-rich hay plus 40% concentrate feed), 60HQH (60% high-quality hay plus 40% concentrate feed), 75HQH (75% high-quality hay plus 25% concentrate feed) and 100HQH (100% high-quality hay). The fibre-rich hay and high-quality hay differed in WSC content (110 g vs. 198 g of dry matter (DM)), neutral detergent fibre (646 g vs. 423 g of DM) and CP (65 g vs. 223 g of DM). Individual feed intake and milk production were monitored daily, and blood samples were collected weekly. Dry matter intake (DMI) and milk yield increased post partum, but 4 weeks post partum, the DMI of cows fed 100HQH only reached a daily mean DMI of 18.6 kg, whereas the DMI of the other groups averaged 21.9 kg (p < 0.046). The negative energy balance was less pronounced in cows fed 75HQH since they showed similar milk yields to the cows fed 60CH and 100HQH, but their energy intake was higher. Concentrations of milk components were similar across rations 60CH, 60HQH and 75HQH, as were most of blood parameters. Cows fed 100HQH responded to the energy deficit post partum with a higher ratio of non-esterified fatty acids to cholesterol and a higher concentration of ß-hydroxybutyrate (significant in comparison to cows fed 75HQH, p < 0.05). In conclusion, feeding high-quality hay with a WSC content of 20% in DM has the potential to decrease the proportion of concentrates in dairy cow feeding in early lactation, but cannot fully replace their supplementation due to a limited rumen capacity for forage intake.     

Effects of enterally fed epidermal growth factor on the small and large intestine of the suckling rat

Epidermal growth factor (EGF) has been shown to be present in the milk of several species, including the rat, and to have gastrointestinal effects when given parenterally or orally in pharmacologic doses. We investigated the effect of enteral EGF in physiologic doses on the small intestine and colon of suckling rats. Serum thyroxine (T4) levels were also measured. Rats were gavage-fed by hand with an artificial formula with or without added EGF every 3 h from 11 to 14 days of age. Intake was adjusted to deliver 30 kcal/100 g b.wt./day of formula and 16 micrograms/kg/day of EGF approximating the daily caloric intake, and about twice the estimated daily EGF intake for suckling rats. Weight gain did not differ between groups (fed EGF: 3.8 + 0.2 g; not fed EGF: 3.7 + 0.1 g). The protein content of the whole colon of rats fed an EGF-containing formula was significantly lower and the DNA content significantly higher, than in rats fed formula without added EGF. The protein/DNA ratio was therefore markedly higher in the animals fed formula without added EGF; these effects were most evident in the distal colon. In contrast, there was no effect of EGF on small intestinal protein and DNA content; lactase, sucrase, and maltase activities were likewise unaffected, as was serum T4. These data suggest a physiologic role for breast milk EGF in the development of the suckling rat colon.     

Estimates of Water Ingestion in Formula by Infants and Children Based on USDA's 1994–1996 and 1998 Continuing Survey of Food Intakes by Individuals

Assessment of risk to infants and children resulting from the ingestion of contaminants in water is an important component of the analysis of possible environmental hazards. Children and infants represent a sensitive life stage because exposure to contaminants in early life can have developmental and long-lasting adverse effects. Children and infants tend to ingest relatively large amounts of water on a bodyweight-adjusted basis, especially those that are fed in early life with formula that is re-constituted or diluted with water. This article presents statistical estimates of the amounts of community water ingested by formula-fed infants based on nationwide sample survey data that support identification of respondents who consume formula and the amounts of water they ingest. Included are specific estimates of the amounts of community water ingested in formula. Estimates of total community water ingestion by children and infants who consume formula can be especially useful in exposure assessment since they represent a highly exposed population. For example, mean community water ingestion by infants 1 to 3 months of age who consume formula is 627 mL/day (136 mL/kg/day) and the 95th percentile is 1096 mL/day (290 mL/kg/day).     

Effects of feed intake level on efficiency of microbial protein synthesis and nitrogen balance in Boran steers consuming tropical poor-quality forage

This study aimed at evaluating the effects of feed intake level on the efficiency of rumen microbial protein synthesis (EMPS), nitrogen (N) excretion, and N balance in twelve 18-months old Boran (Bos indicus) steers with initial average liveweight of 183 kg (standard deviation (SD) 15.2). The experiment followed a 4 × 4 complete Latin Square design with four dietary treatments tested in four periods. Each period ran for 5 weeks with 3 weeks of adaptation and 2 weeks of sample collection; separated by 2 weeks of re-feeding. Steers were fed at 100%, 80%, 60%, and 40% of their metabolisable energy requirement for maintenance (MER, referred to as MER100, MER80, MER60, and MER40, respectively). Steers receiving MER80, MER60, and MER40 were only fed Rhodes grass hay. MER100 steers were offered Rhodes grass hay at 80% of their MER and cottonseed meal and sugarcane molasses at each 10% of MER. Mean daily dry matter intake differed between treatments (p < 0.001) and ranged between 2.1 kg/animal (SD 0.13) in MER40 and 4.5 kg/animal (SD 0.31) in MER100. Urinary N excretion and N balance did not differ between MER80, MER60, and MER40. According to contrast test, declining feed intake level from MER80 to MER40 reduced duodenal microbial crude protein flow (p < 0.001), but did not alter the EMPS (g microbial N/kg digestible organic matter intake). Yet, if scaled to N intake, EMPS increased (p < 0.049), whereas total N and faecal N excretions decreased linearly with declining intake level (p < 0.001 for both variables). At similar grass hay intake, duodenal microbial crude protein flow was 41% higher in MER100 than in MER80 steers (p < 0.001). In cattle offered poor-quality tropical forage below their MER, the very low EMPS and thus microbial protein supply aggravate the negative effects of low dietary nutrient and energy intakes in periods of feed shortage.     

Development of a diet for long-term raising of F344 rats--relationship between dietary digestible crude protein content and digestible energy content.

Mice and rats are frequently subjected to long-term raising in studies of aging. These animals are usually given growing or breeding diets from a young age. This raising method causes diseases such as chronic nephropathy with proteinuria due to nutritional excess. Consequently, a long-term raising study on male F344/DuCrj rats using nine sorts of diets differing in crude protein (CP; 12, 28, 44%) and digestible energy (DE; 2.8, 3.7, 4.5 kcal/g) contents was carried out. It was found that feed consumption was regulated by DE, not digestible crude protein (DCP) intake. Body weight was controlled within low energy areas, and was not influenced by feed or DCP intake. The liver and kidney weight at 105 weeks of age increased in response to an increase in the level of CP in the diet. Chronic nephropathy was severe in rats fed high protein diets and moderate levels of protein with moderate to high energy diets. Fatty liver and bile duct hyperplasia were found in rats fed a high protein and high energy diet. Few pathological findings of kidney and liver were found in the low protein and low energy diet group. The reduction of disorders attributable to excess energy or inappropriate diet suggests that low protein and low energy diets are most suitable for long-term raising in this strain of rat.     

Emergency preparedness for those who care for infants in developed country contexts

Emergency management organisations recognise the vulnerability of infants in emergencies, even in developed countries. However, thus far, those who care for infants have not been provided with detailed information on what emergency preparedness entails. Emergency management authorities should provide those who care for infants with accurate and detailed information on the supplies necessary to care for them in an emergency, distinguishing between the needs of breastfed infants and the needs of formula fed infants. Those who care for formula fed infants should be provided with detailed information on the supplies necessary for an emergency preparedness kit and with information on how to prepare formula feeds in an emergency. An emergency preparedness kit for exclusively breastfed infants should include 100 nappies and 200 nappy wipes. The contents of an emergency preparedness for formula fed infants will vary depending upon whether ready-to-use liquid infant formula or powdered infant formula is used. If ready-to-use liquid infant formula is used, an emergency kit should include: 56 serves of ready-to-use liquid infant formula, 84 L water, storage container, metal knife, small bowl, 56 feeding bottles and teats/cups, 56 zip-lock plastic bags, 220 paper towels, detergent, 120 antiseptic wipes, 100 nappies and 200 nappy wipes. If powdered infant formula is used, an emergency preparedness kit should include: two 900 g tins powdered infant formula, 170 L drinking water, storage container, large cooking pot with lid, kettle, gas stove, box of matches/lighter, 14 kg liquid petroleum gas, measuring container, metal knife, metal tongs, feeding cup, 300 large sheets paper towel, detergent, 100 nappies and 200 nappy wipes. Great care with regards hygiene should be taken in the preparation of formula feeds. Child protection organisations should ensure that foster carers responsible for infants have the resources necessary to formula feed in the event of an emergency. Exclusive and continued breastfeeding should be promoted as an emergency preparedness activity by emergency management organisations as well as health authorities. The greater the proportion of infants exclusively breastfed when an emergency occurs, the more resilient the community, and the easier it will be to provide effective aid to the caregivers of formula fed infants.     

Effects of various energy and protein levels during sequential feeding on feed preferences in meat-type chickens

Short-term feed preferences were studied in individually caged chickens fed sequentially in order to understand a previously described imbalance in the intake of diets offered. Sequential feeding (SF) was carried out for four 48 h cycles in male broiler chickens. The diets varied in energy (2800 (E−) and 3200 kcal/kg (E+)) and protein (230 (P+) and 150 g/kg (P−)) contents. SF was compared to standard feeding (C) (3000 kcal/kg ME and CP = 190 g/kg). In experiment 1, three treatments were used: C, S_E (E− followed by E+) and S_E′ (E+ followed by E−). Four treatments were used in experiment 2: C, S_P (P+ followed by P−), S_E and S_EP (P+E− followed by P−E+). Total feed intake was measured during the SF period. After this, short-term preferences were evaluated with a choice test on chickens previously fed with the same feeds during the SF period (experienced birds) and in C chickens (naïve birds). In both experiments, total feed intake was similar among treatments and the percentage of each feed consumed was not significantly different from controls (50%). In experiment 1, S_E and S_E′ chickens over-consumed E+ and under-consumed E− diets only during the first 15 min of the fourth cycle. The choice test indicated that experienced chickens preferred E+, while naïve chickens preferred E−. Similarly, in experiment 2, chickens over-consumed E+ and E+P− during the first 15 min of the fourth cycle, but the intake of diets varying in protein content was not different from controls. During the choice test, as in experiment 1, experienced chickens preferred E+, while naïve chickens preferred E−. There was a slight preference for the protein-poor diet in naïve birds and there was no preference in the diet varying in both protein and energy contents. Experience modified choice between feeds varying in energy content but not in protein. When feeds were known, preference for energy affected the feed intake immediately after switching from one diet to the other, although lower with the diet also varying in protein, it did not influence the total intake of each diet. Interactions between the nutritional properties and sensorial cues of feed could explain these results.     

Effect of a moderate variation in dietary energy intake on the retention and excretion of zinc,calcium, and magnesium

Mineral balance was studied by metabolic balance techniques in 13 healthy college females aged 21–23 yr. They were fed diet containing 1780 kcal, 2580 kcal, and 25 g protein in a 20-d experiment period. Both diets contained approximately 5.28 mg zinc, 216.85 mg calcium, and 364.3 mg magnesium. The diet consisted of habitually consumed foods. Blood, urine and fecal samples were collected for mineral analysis using atomic absorption spectrophotometry. Plasma mineral levels were not affected by the change in dietary energy intake. Fecal calcium and magnesium were significantly higher when subjects were fed the low calorie (1780 kcal) diet, whereas there was no significant difference in fecal zinc for the two levels of dietary energy. Urinary calcium and magnesium were also significantly higher when the diet provided 1780 kcal though, on the other hand, urinary zinc was significantly higher when the diet provided 2680 kcal (P<0.05). Urinary calcium and magnesium correlated negatively, whereas urinary zinc correlated positively, with the dietary energy intake (P ^o<0.05). Dietary energy intake has a significant effect on the mineral balance of the subjects.     

Interactive effects of protein and energy intake on nutrient partitioning and growth in Nile tilapia

Studies of fish growth response to changes in dietary protein and energy content are often conducted with fish fed to apparent satiation or at fixed percentages of their body mass. Such designs result in simultaneous changes in protein and non-protein energy intake, thereby failing to distinguish their separate effects on nutrient partitioning and growth. The present study was designed to address this limitation and test the existence of distinct protein- and non-protein energy-dependent growth phases in Nile tilapia (Oreochromis niloticus). All-male Nile tilapia (63 g, SD = 1.3) were subjected to an 8 × 2 factorial design consisting of eight levels of digestible protein (DP) intake (0.44–1.25 g/day) and two levels of non-protein digestible energy (NPDE) intake (16.0 and 22.4 kJ/day). Fish (n = 960) were housed in 60-litre tanks with two replicates per treatment and hand-fed twice a day for 42 days. Nutrient balances were calculated from changes in body mass, analysed body composition and digestible nutrient intake. Linear regression models were compared to linear-plateau regression models to determine whether protein gain followed distinct protein- and non-protein energy-dependent phases or not. Body mass gain increased linearly with increasing DP intake and was significantly higher (2.6 vs 2.3 g/d, P < 0.05) in fish receiving a high NPDE intake. This increase mainly reflected a higher mean fat gain (0.29 vs 0.20 g/d) rather than a higher protein gain (0.42 vs 0.39 g/d) in fish fed a high vs low level of NPDE intake. The comparison of linear and linear-plateau models did not give clear support for the presence of distinct protein and non-protein energy-dependent phases in protein gain. These results indicate that non-protein energy intake has a modest protein-sparing potential, and that protein gain is simultaneously limited by protein and energy intake in Nile tilapia.     

Effects of dietary cholesterol on adipose tissue lipoprotein lipase in the baboon

The effects of infant diet (breast milk or formula containing 2, 30 or 60 mg/dl cholesterol) and subsequent dietary cholesterol (0.02, 1.0 or 1.7 mg/kcal) and fat (saturated or unsaturated) on heparin-releasable lipolytic activity from omental adipose tissue was estimated from 99 baboons of 5-8 years of age. This lipase activity was characterized as lipoprotein lipase based on salt inhibition and apolipoprotein C-II activation. Lipoprotein lipase activity released from adipose tissue by heparin was significantly (P less than 0.002) lower in high cholesterol-fed baboons than in those fed low cholesterol. Most of this difference was due to impaired long-term heparin release of lipoprotein lipase. Adipose tissue lipoprotein lipase increased with increasing fat cell size regardless of diet, but there was no effect of diet on adipocyte size. There were no significant effects of infant cholesterol intake nor adult saturated or unsaturated fat on lipoprotein lipase activity. Adult baboons breast fed as infants had lower adipose tissue lipoprotein lipase activity (P less than 0.07) than adults fed formula as infants.     

Estimating daily intakes of manganese due to breast milk,infant formulas,or young child nutritional beverages in the United States and France: Comparison to sufficiency and toxicity thresholds

BackgroundAlthough manganese (Mn) is an essential nutrient, recent research has revealed that excess Mn in early childhood may have adverse effects on neurodevelopment.MethodsWe estimated daily total Mn intake due to breast milk at average body weights by reviewing reported concentrations of breast milk Mn and measurements of body weight and breast milk intake at 3 weeks, 4.25 months, 7 months, and 18 months. We compared these figures to the Mn content measured in 44 infant, follow-up, and toddler formulas purchased in the United States and France. We calculated Mn content of formula products made with ultra-trace elemental analysis grade water (0 μg Mn/L) and with water containing 250 μg Mn/L, a concentration which is relatively high but less than the World Health Organization Health-based value of 400 μg Mn/L or the United States Environmental Protection Agency Health Advisory of 350 μg Mn/L.ResultsEstimated mean daily Mn intake from breast milk ranged from 1.2 μg Mn/kg/day (3 weeks) to 0.16 μg Mn/kg/day (18 months), with the highest intakes at the youngest age stage we considered, 3 weeks. Estimated daily Mn intake from formula products reconstituted with 0 μg Mn/L water ranged from 130 μg Mn/kg/day (3 weeks) to 4.8 μg Mn/kg/day (18 months) with the highest intakes at 3 weeks. Formula products provided 28–520 times greater than the mean daily intake of Mn from breast milk for the 4 age stages that we considered. Estimated daily Mn intake from formula products reconstituted with water containing 250 μg Mn/L ranged from 12 μg Mn/kg/day to 170 μg Mn/kg/day, which exceeds the United States Environmental Protection Agency Reference Dose of 140 μg Mn/kg/day for adults.ConclusionsMn deficiency is highly unlikely with exclusive breast milk or infant formula feeding, but established tolerable daily intake levels for Mn may be surpassed by some of these products when following labeled instructions.     

Effect of the energy density of non-purified diets on reproduction, obesity, alopecia and aging in mice.

Four diets with graded levels of energy at 24% crude protein were fed to C57BL/6J mice for approximately 3 years to develop pelleted non-purified diets. The nitrogen-corrected metabolizable energy (MEn) of the diets ranged from 2.86 to 3.73 kcal per g of dry matter (DM). Fifteen males and 30 females were assigned to each diet. The mice were housed together for 1 week at 7 week intervals, experiencing 5 matings. After the reproduction stage, they were allowed to complete their life span. Moribund mice after 60 weeks of age were subjected to histopathological examination. The highest energy diet showed the following results in comparison with the lowest energy diet: (1) weaning weight of pups increased by 31.6%; (2) males showed slight obesity even during the reproduction stage, but females did not; (3) both sexes developed remarkable obesity after 50 weeks of age with 41.2% (males) and 49.6% (females) increasing in maximum body weight; (4) although daily feed intake decreased by approximately 18%, the MEn was slightly over consumed; (5) females showed higher incidence of alopecia with age; (6) the survival rate after 50 weeks of age decreased earlier and life span was shortened; (7) histopathological changes associated with aging developed earlier. On the other hand, the early death rate of dams at parturition increased with a decrease in dietary energy. It was concluded that at least 2 types of diets are needed throughout the life span of C57BL/6J mice; a high energy diet with an MEn value of 3.73 kcal/g DM for maximum reproduction and a low energy diet with an MEn value of 2.86 kcal/g DM for the long term stage after reproduction to retard obesity and aging most effectively.