Prevalence of anemia among James Bay Cree infants of northern Quebec

BACKGROUND: Anemia is common among First Nation infants in Canada, often as a result of iron deficiency, which places them at risk for psychomotor impairment. Prevalence data are unavailable, and the risk factors are unknown. This study assessed the prevalence of anemia and associated risk factors among 9-month-old Cree infants in northern Quebec. METHODS: Between January 1995 and October 1998, 6 of 9 Cree villages in the James Bay region adopted a screening protocol for anemia in 9-month-old infants. Cross-sectional data were obtained from medical charts. The data for babies of very low birth weight and those with fever or infection were excluded. Among the 386 babies whose hemoglobin concentration was known, the type of milk consumed at the time of screening was known for 354. Associations between hemoglobin concentration and mean cell volume at 9 months, and milk type and weight gain since birth were analysed. RESULTS: The mean hemoglobin concentration of the 386 infants was 114.1 (standard deviation [SD] 10.6) g/L. The prevalence of anemia was 31.9% (95% confidence interval [CI] 27.2%-36.7%) with a hemoglobin cutoff value of 110 g/L, 17.6% 95% CI 13.9%-21.7%) with a cutoff value of 105 g/L, and 7.8% (95% CI 5.3%-10.9%) with a cutoff value of 100 g/L. Babies exclusively fed formula at 9 months had a higher mean hemoglobin concentration (118.5 [SD 9.9] g/L) than those exclusively fed breast milk (109.9 [SD 10.0] g/L), cow''s milk (112.5 [SD 10.1] g/L) or more than one type of milk (112.0 [SD 10.8] g/L) (p < 0.05). Compared with formula, the odds ratio (OR) for anemia was 7.9 (95% CI 3.4-18.2) for breast milk, 5.0 (95% CI 2.0-12.7) for cow''s milk and 5.2 (95% CI 1.9-14.6) for mixed milks. Infants fed formula and those fed cow''s milk had significantly greater weight gains since birth, by 724 g and 624 g respectively, than breast-fed infants (p < 0.05). When milk type was controlled for, weight gain since birth was significantly associated with the presence of microcytic erythrocytes (OR comparing highest tertile of weight gain to lowest tertile 2.9, 95% CI 1.2-6.6). INTERPRETATION: Iron-deficiency anemia is highly prevalent among James Bay Cree infants. Measures to increase iron intake are required.     

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.     

Relationship between locomotor play of dairy calves and their weight gains and energy intakes around weaning

Play behaviour has been proposed as a measure of good welfare in growing animals and locomotor play by calves is often reduced after weaning off milk. Adjusting weaning age according to individual calves’ abilities to eat solid feed maintains energy intake and weight gain during weaning. We investigated the effects of this method of weaning on locomotor play of calves and the relationship between locomotor play and energy intake and weight gains. We measured the running behaviour of 56 Holstein heifer calves before and after weaning. Calves were housed in groups of eight, fed milk, grain starter and hay from automated feeders. Weaning began when their voluntary intake of grain starter reached either 200 or 400 g/day, and weaning was completed when starter intake reached either 800 or 1600 g/day. Before weaning, older calves ran less than young ones; and the duration of running correlated with weight gains and digestible energy intake. Immediately after weaning, digestible energy intake and locomotor play decreased but no correlation was observed between these variables. One week after weaning, the duration of running was correlated with both energy intake and weight gain. Digestible energy intake increased but locomotor play continued to decrease. The amount of running a calf does after weaning partly reflects energy intake and weight gain, supporting suggestions that locomotor play is good indicator of welfare and fitness of growing animals. However, the decline in locomotor play following weaning is not solely due to decreased energy intake.     

Effect of dam factors on milk intake and performance of Belgian Blue suckling calves

Milk intake data were collected at 4-week intervals from Belgian Blue double-muscled (BBDM) suckling calves up to 16 weeks after birth. Dams were fed at 100%, 90%, 80% or 70% of their energy requirements during a 140-day indoor period from the beginning of December to the end of April (restriction period). Afterwards, cows were turned out on pasture (re-alimentation period). Mean calving date was 3 June, but parturitions were spread over the year. A total of 521 individual milk intake (IMI) and 120 average daily milk intake (AMI, mean of IMI) records were collected. IMI amounted to 7.0 ± 2.2 kg/day and was not affected by energy level during the indoor period. It was highest in May and June. Calves born out of multiparous cows consumed more milk than those born out of primiparous cows (7.4 v. 6.2 kg per day; P = 0.001), while intake tended to be higher in female than in male calves (7.2 v. 6.8 kg per day; P = 0.044). Dam age at calving, parity, post partum weight and body condition were only weakly correlated with AMI (r 0.4). AMI was correlated with pre-weaning live-weight gain (r = 0.807) and weaning weight (r = 0.783), with a slightly higher correlation for male than for female calves. Daily live-weight gain during the suckling period was increased by 79 g per extra kg daily milk intake on average, and by 86 and 74 g, respectively, for male and female calves. Calf solid feed intake was low, even when milk intake was low. In terms of net energy intake, milk was only substituted for solid feed by 29%. It can be concluded from the calf intake that milk production in BBDM cows is comparable with that of cows from other beef breeds, but its variation is considerable, complicating an accurate estimation.     

A physiological role of breast milk leptin in body weight control in developing infants

Objective: Leptin, a hormone that regulates food intake and energy metabolism, is present in breast milk. The aim of this study was to determine whether milk leptin concentration is correlated with maternal circulating leptin and BMI and with body weight gain of infants. Research Methods and Procedures: A group of 28 non‐obese women (BMI between 16.3 and 27.3 kg/m²) who breast‐fed their infants for at least 6 months and their infants were studied. Venous blood and milk samples were obtained from mothers at 1, 3, 6, and 9 months of lactation, and leptin concentration was determined. Infant body weight and height were followed until 2 years of age. Results: During the whole lactation period, milk leptin concentration correlated positively with maternal plasma leptin concentration and with maternal BMI. In addition, milk leptin concentration at 1 month of lactation was negatively correlated with infant BMI at 18 and 24 months of age. A better negative correlation was also found between log milk leptin concentration at 1 and at 3 months of lactation and infant BMI from 12 to 24 months of age. Discussion: We concluded that, in a group of non‐obese mothers, infant body weight during the first 2 years may be influenced by milk leptin concentration during the first stages of lactation. Thus, moderate milk‐borne maternal leptin appears to provide moderate protection to infants from an excess of weight gain. These results seem to point out that milk leptin is an important factor that could explain, at least partially, the major risk of obesity of formula‐fed infants with respect to breast‐fed infants.     

Milk intake in blue fox (Alopex lagopus) and silver fox (Vulpes vulpes) cubs in the early suckling period

Milk intake of fox cubs (2-16 days of age; body weight, 96-649 g) in ten blue fox litters and ten silver fox litters were measured by the water isotope dilution (WID) technique following a single intraperitoneal injection of tritiated water (3HHO). Litter size varied from four to 14 in blue foxes and from three to eight in silver foxes. Silver fox cubs had higher birth weights than blue foxes. Inter-species body weights and growth rates were apparently dependent on litter size and the dam's constitution. In both species growth rate increased with age and body weight (7-35 g per day). In the cubs, the biological half-life of body water turnover (BWT) rose from 1.5 days at 2-3 days of age to 2.5 days at 13-16 days of age, although a considerable scatter was seen. The mean daily milk intake of the cubs varied with body weight, from 31 to 193 g per day, whereas daily milk intake per unit of body mass remained stable at 30-35 g per 100 g body weight. The ratio of milk intake to body weight gain varied considerably among cubs, averaging 4.5 g/g during the 3-week experimental period. In suckling fox cubs, the calculated daily intake of metabolically energy (ME) corresponded fairly with the estimated energy requirements for growth and maintenance of the young. Finally, the applicability and the accuracy of the WID technique was evaluated in ten 3-week-old fox cubs, by tube-feeding with a milk replacer for 48 h, which documented that the daily rates of milk intake and water turnover can be accurately measured in suckling fox cubs by the WID technique following a single injection of 3HHO.     

Production and composition of Iberian sow's milk and use of milk nutrients by the suckling Iberian piglet

Sixteen purebred Iberian (IB) sows were used in two consecutive trials to determine the efficiency of conversion of sow's milk into piglet body weight (BW) gain and the relationship between milk protein and body protein retention and between milk energy yield and body energy retention in the nursing IB piglet. In each trial, four sows were selected in order to evaluate their milk production, litter growth and nutrient balance measurements, together with four additional sows for milk sampling. Litter size was equalized to six piglets. Daily milk yield (MY) was determined weekly by the weigh-suckle-weigh technique over a 34-day lactation period. Piglets were weighed individually at birth and then weekly from day 5 of lactation. Milk samples were collected on days 5, 12, 19, 26 and 34 post partum. The comparative slaughter procedure was used to determine piglet nutrient and energy retention. One piglet from each litter was slaughtered at birth and four on the morning of day 35. Total MY was on average 5.175 ± 0.157 kg/day. The average chemical composition (g/kg) of the milk was 179 ± 4 dry matter, 53.4 ± 1.0 CP, 58.5 ± 3.8 fat, 10.4 ± 0.3 ash and 56.9 ± 2.3 lactose. Milk gross energy (GE) was 4.626 ± 0.145 MJ/kg. Milk intake per piglet tended to increase in trial 2 (832 v. 893 g/day; P = 0.066). Piglet BW gain contained (g/kg) 172.1 ± 1.3 protein, 151.5 ± 3.5 fat, 41.4 ± 0.6 ash and 635 ± 3 water and 10.127 ± 0.126 MJ GE/kg. Throughout the 34-day nursing period, the piglets grew at an average rate of 168 ± 3 g/day. The ratio of daily piglet BW gain to daily MY was 0.195 ± 0.002 g/g and the gain per MJ milk GE intake was 41.9 ± 0.5 g/MJ. The overall efficiency of protein accretion (g CP gain/g CP milk intake) was low and declined in trial 2 (0.619 v. 0.571; P = 0.016). Nutrient and energy deposition between birth and weaning were 27.4 ± 0.5 g/day protein, 24.2 ± 0.8 g/day fat and 1615 ± 40 kJ/day energy. Piglet energy requirements for maintenance were 404 kJ metabolizable energy (ME)/kg BW0.75. ME was used for growth with a net efficiency of 0.584. These results suggest that poor efficiency in the use of sow's milk nutrients rather than a shortage in milk nutrient supply might explain the low growth rate of the suckling IB piglet.     

Longitudinal study of the dietary selenium intake of exclusively breast-fed infants during early lactation in Korea and Japan.

213 samples of human breast milk were collected from 51 healthy Korean women. Selenium content of the samples was determined by atomic absorption spectrometry with hydride generation. The selenium content of Korean milk decreased with increase of days after birth: The arithmetic mean of selenium content was higher in colostrum (< 4 days) 34 micrograms/kg (SD +/- 11, n = 44) than in transitional milk 21 micrograms/kg (SD +/- 8, n = 78) or in mature milk (> 10 days) 13 micrograms/kg (SD +/- 6, n = 91). The daily dietary selenium intake of 0-1 month aged Korean infants fed on breast milk is estimated to be around 10 micrograms per day (3 micrograms/kg body weight) regardless of days postpartum, resulting from the calculation of our selenium data and daily milk intake during early lactation. The same result on selenium intake for Japanese newborns, as well as Korean infants, is also estimated to be around 10 micrograms per day (3 micrograms/kg body weight) regardless of days postpartum.     

Gastrointestinal development of dairy calves fed low- or high-starch concentrate at two milk allowances

The objective was to study the effect of type of concentrate with varying starch and fibre content on growth and gastrointestinal development in preweaned dairy calves. Thirty-two newborn Danish Holstein male calves were allocated to four treatment groups in eight blocks of four calves. An experimental low-starch, high-molasses, high-fibre (EXP) concentrate or a traditional high-starch (TRA) concentrate were fed either at a high (HIGH; 2 × 3.2 kg/day) or a low (LOW; 2 × 1.6 kg/day) whole milk allowance in a 2 × 2 factorial design. TRA contained 350 and EXP 107 g starch/kg dry matter (DM), whereas the NDF content was 136 and 296 g/kg DM, respectively. Metabolizable energy (ME) was 11.2 and 12.2 MJ ME/kg DM in EXP and TRA, respectively. All calves had free access to artificially dried grass hay (9.8 MJ ME/kg DM). Four calves were culled during the experiment. The calves were euthanized either at 38 (12 calves) or 56 days (16 calves) of age. Evaluated across both slaughter ages, there was no difference between TRA and EXP in concentrate and hay intake, rumen weight and papillation. EXP resulted in increased villi number in duodenum and jejunum compared with TRA. Concentrate intake and reticulo-rumen weight was higher for LOW compared with HIGH milk allowance, whereas live weight gain was 20% lower. The results show that a low-starch, high-molasses, high-fibre concentrate with 8% lower ME content tended to reduce daily gain compared with a traditional calf starter concentrate, but resulted in similar ruminal development in preweaned calves both on a high and a low milk allowance fed along with grass hay. Furthermore, the results suggest that the experimental concentrate stimulated intestinal villi growth over that of the traditional concentrate.     

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.     

Infantile Overnutrition in the First Year of Life: A Field Study in Dudley,Worcestershire

A survey of feeding patterns and nutrient intake in relation to the growth of 300 normal infants up to 1 year of age in Dudley, Worcestershire, highlights a problem of overnutrition in the group; 50 (16·7%) were found to be suffering from infantile obesity and a further 83 (27·7%) were overweight.During the first three months of life the daily energy intakes of 136 cal/kg body weight for boys and 149 for girls were markedly greater than the level of 120/kg recommended by the Department of Health and Social Security. This coincided with the early addition of solid foods to a full milk intake. 119 babies (39·7%) were offered solids before they were 4 weeks old and 280 (93·3%) before 13 weeks of age. Some babies had solids from the first week after birth. Protein intake was persistently high throughout the first year, and the mean intake of 32·7 g/day was much greater than the intake of 20 g for infants aged up to 1 year recommended by the Department of Health. Standards for fat and carbohydrate intake are not available but in comparison with the levels reported in breast-fed babies intake of fat and carbohydrate was high in the first three months and came closer to the desired level for the former and remained slightly high for the latter in the subsequent age quarters.The relation of childhood and subsequent adult obesity to infant feeding patterns is not yet clear, but there is a high correlation between obese parents and obese and overweight babies; had these babies not been overfed the condition might have been prevented.     

Cord blood and breast-milk antibodies in neonatal rotavirus infection.

Studies were carried out during an outbreak of rotavirus type 2 infection in a neonatal nursery to determine the protective role of antibodies in cord blood and breast milk. The range, distribution, and geometric mean titres of rotavirus-specific antibody in the cord blood were similar among rotavirus-positive and rotavirus-negative neonates, and the amount of virus excreted did not correlate with antibody levels. Despite the protective effect of breast feeding, the pattern of rotavirus-specific IgA and IgG antibodies in the expressed breast milk of mothers of babies who were rotavirus excreters and non-excreters was similar. Nevertheless, a higher proportion of expressed breast milk samples contained rotavirus-specific IgA group 2 (92%) and type 2 (97%) specific antibodies than type I (67%) antibodies, and the geometric mean titres of group 2 and type 2 specific antibodies were tenfold higher than type I antibodies. Among breast-fed babies who excreted rotavirus there was no correlation between type 2 rotavirus-specific IgA antibodies in expressed breast milk and the amount of neonatal virus excretion. These studies suggest that factors other than the rotavirus antibodies in expressed breast milk are of importance in preventing rotavirus infection in newborn infants.     

A rearing system for colostrum-deprived neonatal piglets

A system for the artificial rearing of colostrum-deprived neonatal piglets is described. A total of 443 piglets in 6 batches was reared. Each piglet, immediately after birth was placed in a separate incubator which was ventilated with heated filtered air. Piglets were fed hourly by an automatic system and were offered a liquid milk substitute. The mean survival rate up to the time piglets were transferred out of the rearing unit at 2 weeks of age was 78 +/- 7%. The mean daily live weight gain up to 2 weeks of age was 148 +/- 16 g/day and the dry matter intake over the same period was 154 +/- 10 g/day per piglet.     

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.     

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.     

Utilization of milk energy by suckling mink kits

A total of 36 mink dams and their litters of 3, 6 or 9 kits were used for determination of milk intake of the suckling young by means of deuterium dilution technique, and chemical composition of milk and of kit bodies. Measurements were performed during lactation weeks 1-4, each week with 3 dams with each litter size. Milk intake was determined over a 48 h measurement period, and by the end of this milk samples were collected and 2 kits (litters of 6 and 9) or 1 kit per litter (litters of 3) were killed for body chemical composition. Based on the results, different models were applied for calculation of the energetic efficiency of milk. Dam milk yield increased steadily from week 1 until week 3 but only slightly from week 3 to 4. The increase declined with increasing litter size, and for dams suckling 9 kits the increment from week 3 to week 4 was only 2 g. The dry matter content of milk increased significantly as lactation progressed, being reflected in crude protein increasing from 6.9% in lactation week 1 to 8.1% in week 4. Milk fat increased concomitantly from 5.6% to 8.0%. In kit bodies, crude protein content increased from 9.4% in week 1 to about 12% in weeks 3 and 4. Body fat content increased from week 1 (4.1%) to week 3 (8.4%) and then declined in week 4 (7.1%). Animals suckled in litters of 3 kits had the highest milk intake and live weight and kits suckled in litters of 9 had the lowest milk intake, live weight and daily gain. In terms of milk intake per g gain kits in litters of 6 were the most efficient, with 4.1 g milk per g body gain. The metabolizable energy requirement for maintenance (MEm) was estimated to 448 kJ/kg(0.75 and the efficiency of utilization of ME for body gain (kg) to 0.67, the estimates being higher (MEm) or in good agreement with previous findings (kg) in suckling mink kits.     

Influence of maternal diet during lactation and use of formula feeds on development of atopic eczema in high risk infants.

OBJECTIVE--To examine the effects of maternal diet during lactation and the use of formula feeds on the development of atopic eczema in infants at risk. DESIGN--Mothers who planned to breast feed exclusively were randomly allocated to either a restricted diet (avoiding milk and other dairy products, eggs, fish, peanuts, and soybeans) or a diet without restrictions. Mothers who did not plan to breast feed were randomly allocated to using one of three formula feeds. SETTING--Child health centre in Canada. SUBJECTS--97 Mothers who chose to breast feed and 124 mothers who did not. INTERVENTIONS--Restricted diet for 49 mothers who breast fed. Casein hydrolysate formula, soy milk formula, or cows'' milk formula for infants not breast fed. MAIN OUTCOME MEASURE--Development of eczema in babies. RESULTS--Infants were followed up over 18 months and examined for eczema. Eczema was less common and milder in babies who were breast fed and whose mothers were on a restricted diet (11/49 (22%) v 21/48 (48%)). In infants fed casein hydrolysate, soy milk, or cows'' milk 9/43 (21%), 26/41 (63%), and 28/40 (70%), respectively, developed atopic eczema. CONCLUSIONS--In families with a history of atopic disease [corrected] mothers who breast feed should avoid common allergenic foods during lactation. If they choose not to breast feed a hydrolysate formula should be used.     

Ausscheidungen der Aminosäuren mit dem Harn und Kot von kolostomierten und nicht operierten Hennen — Beitrag zur Methode der Aminosäurenresorbierbarkeit

Veal calves aged 8 weeks were fed iso‐energetic amounts of milk replacers with either a low (7.1g of calcium/kg of air‐dry diet) or a high concentration of calcium (11.6g of calcium/kg of air‐dry diet) for a period of 10 weeks. The extra calcium was added in the form of calcium formiate. Final body weight of the two dietary groups was similar. Faeces were collected during the final week of the trial. The high calcium diet raised faecal dry matter output by 87% and faecal energy by 70%. The extra output of faecal dry matter was composed of 36% and 37% of crude fat and ash, respectively. The extra faecal energy output was for 75% in the form of crude fat. The high versus low calcium intake not only depressed apparent digestibility of total lipids but also that of crude protein, carbohydrates and ash. It is concluded that a high calcium intake by veal calves reduced energy availability without affecting body weight gain.     

How important is milk for near-weaned red kangaroos (<Emphasis Type="Italic">Macropus rufus</Emphasis>) fed different forages?

Red kangaroos (Macropus rufus) are large (>20 kg) herbivorous marsupials common to the arid and semi-arid regions of inland Australia, where drought is frequent. Young-at-foot (YAF) red kangaroos are the age/size class usually most affected by drought. Kangaroos at this YAF stage are making the transition from a milk-based diet to one of herbivory and an inability to adequately digest high-fibre feeds may contribute to their high mortalities during drought. We examined the role of milk in the nutrition of YAF red kangaroos fed forages of different fibre content and evaluated it as an extra energy and/or nitrogen source. Milk intake had little impact on the digestion of herbage by YAF red kangaroos fed low-fibre chopped lucerne (alfalfa) hay. Organic matter (OM) intake was 210+/-20 g day(-1) and 228+/-22 g day(-1), respectively, by YAF fed lucerne and lucerne with milk. Apparent digestibility of lucerne OM was ca. 55%, regardless of milk intake. Fed lucerne, with and without milk, YAF sustained growth rates of ca. 45 g day(-1). Conversely, even with a milk supplement, YAF red kangaroos ingested only 90+/-11 g day(-1) of high-fibre chopped oaten hay, of which they digested only ca. 36%. Despite milk intake, YAF fed chopped oaten hay lost between 0 and 75 g body mass day(-1) and were in negative nitrogen balance (-0.40+/-0.11 g N day(-1)). On all diets nitrogen loss was primarily as endogenous nitrogen (urinary and faecal) rather than as dietary nitrogen. Endogenous nitrogen losses were elevated in YAF fed chopped oaten hay, primarily as non-dietary faecal nitrogen. Overall, when high-quality feed was available, YAF were not markedly dependent on milk. However, YAF fed poor-quality chopped oaten hay would require up to 540 ml day(-1) of late-stage kangaroo milk to attain intakes of energy and nitrogen, and hence growth rates, comparable with those YAF fed lucerne.     

Evaluation of nutrition models to estimate performance of young dairy calves: a meta-analytical study under tropical conditions

Mathematical models are important tools to estimate nutritional requirements and animal growth. Very few calf models generated from other countries with different feeding programs, environment and production systems have been evaluated. The objective of this paper is to evaluate two calf models: (i) the National Research Council (NRC) in 2001 and (ii) the updates published by Van Amburgh and Drackley in 2005 and inputted into Agricultural Modeling and Training Systems (AMTS, version 3.5.8). Data from 16 previous studies involving 51 diets for dairy calves under tropical conditions (n=485 calves, initial BW 37.5±4.35 kg and weaning weight of 62.0±10.16 kg) were used. The calves were fed with whole milk, milk replacer or fermented colostrum, plus starter (20.9±1.78% of CP). The accuracy of the average daily gain (ADG) prediction was evaluated by mean bias, mean square prediction error (MSPE), concordance correlation coefficient, bias correction factor (Cb), and regression between the observed and predicted values. The ADG observed from birth to weaning was 0.452±0.121 kg/day. Calves fed with whole milk had greater ADG compared with calves fed milk replacer (0.477 v. 0.379 kg/day) during the milk-feeding period. When all data were pooled (n=51 diets), predictions had a mean bias of −0.019 and 0.068 kg/day for energy-allowable gain using NRC and AMTS models, respectively. The regression equation between observed and predicted values obtained from energy of diets showed an intercept different from zero (P<0.0001) and slope that differed from unity (P<0.0001). In a second evaluation, when calves were fed only milk replacer, the energy-allowable gain from AMTS showed the lowest mean bias (0.008 kg/day) and 82.1% of the MSPE value originated from random errors. The lowest MSPE, the higher Cb value and no significant slope bias (P>0.05) indicate that the AMTS growth model resulted in accurate predictions for calves fed with milk replacer. However, within these latter two approaches, the goodness of fit (R²) was low, representing low precision. The weight gain estimated by the energy available from the diet was overestimated by 19 g/day when calculated by the NRC and underestimated by 68 g/day when calculated by AMTS. The reasons for this discrepancy need to be understood, for only then new models could be developed and parameterized to estimate animal performance in tropical conditions more accurately and precisely.