We previously showed in rats that pre- and postnatal deficiencies in iron and omega-3 (n-3) fatty acids can impair bone development, with additive and potentially irreversible effects when combined. This study aimed to investigate, in female rats consuming a combined iron and n-3 fatty acid deficient (ID + n-3 FAD) diet preconception, whether supplementation with iron and docosahexaenoic/eicosapentaenoic acid (DHA/EPA), alone and in combination, can prevent bone impairments in offspring. Using a 2 × 2 factorial design, female Wistar rats consuming an ID + n-3 FAD diet preconception were randomised to receive an: 1) iron supplemented (Fe + n-3 FAD), 2) DHA/EPA supplemented (ID + DHA/EPA), 3) Fe + DHA/EPA, or 4) ID + n-3 FAD diet from gestational day 10 throughout pregnancy and lactation. Post-weaning, offspring (n = 24/group; male:female = 1:1) remained on the respective experimental diets for three weeks until postnatal day 42–45. Offspring born to female rats consuming a control diet preconception and an Fe+DHA/EPA diet throughout pregnancy and lactation served as non-deficient reference group (Control+Fe+DHA/EPA). Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry and bone strength using three-point bending tests. Only offspring in the Fe+DHA/EPA group had significantly higher spine and femur BMD, and higher femur stiffness than offspring in the ID + n-3 FAD group, and had similar spine BMD and femur stiffness as the Control + Fe + DHA/EPA group. Offspring in the Fe + DHA/EPA group further had significantly higher femur strength (ultimate load) than the other experimental groups, and a similar femur strength as the Control + Fe + DHA/EPA group. This study shows that only combined iron and DHA/EPA supplementation can prevent bone impairments in offspring of female rats consuming an iron and n-3 FA deficient diet preconception.

Fertile eggs from Cobb 500 broiler breeder hens were incubated to provide low starting egg shell temperatures (EST; 36.9°C to 37.3°C) which were gradually increased to 37.8°C during the first 7 to 15 days of incubation compared with eggs incubated with a constant EST of 37.8°C (standard conditions) over the first 18 days of incubation. Time of individual chick hatching (measured at 6 h intervals from 468 h of incubation), chick weight, chick length and yolk weight were measured at take-off and BW was measured at 7, 14, 28, 34 and 42 days of age. Male birds at 34 and 42 days of age were assessed for their ability to remain standing in a latency-to-lie test. At 34 and 42 days, male birds were examined for leg symmetry, foot pad dermatitis, hock bruising and scored (scale 0 to 4, where 0=no lesion and 4=lesions extending completely across the tibial growth plate) for tibial dyschondroplasia (TD) lesions. The lower EST profiles caused chicks to hatch later than those incubated under the standard EST profile. Chicks which hatched at ⩽498 h incubation grew faster over the first 7 days than those that hatched later. There were significantly more birds (only males were studied) that hatched from the lower EST profiles with TD scores of 0 and 1 and fewer with score 4 at 34 days than those hatched under the standard profile. Male birds at 34 days with TD lesions ⩾3 stood for significantly shorter times than males with TD scores ⩽2. Moreover, male birds at 34 and 42 days with TD lesion scores of ⩾3 hatched significantly earlier and grew significantly faster over the first 2 weeks of age than did male birds with TD scores ⩽2. It appears possible to decrease the severity and prevalence of TD in the Cobb 500 broiler by ensuring that the birds do not hatch before 498 h of incubation.

Exposure to isoflavones (ISO), abundant in soy protein infant formula, for the first 5 days of life results in higher bone mineral density (BMD), greater trabecular connectivity and higher peak load of lumbar vertebrae (LV) at adulthood. The effect of lengthening the duration of exposure to ISO on bone development has not been studied. This study determined if providing ISO for the first 21 days of life, which more closely mimics the duration that infants are fed soy protein formula, results in higher BMD, improved bone structure and greater strength in femurs and LV than a 5-day protocol. Female CD-1 mice were randomized to subcutaneous injections of ISO (7 mg/kg body weight/day) or corn oil from postnatal day 1 to 21. BMD, structure and strength were measured at the femur and LV at 4 months of age, representing young adulthood. At the LV, exposure to ISO resulted in higher (P < 0.05) BMD, trabecular connectivity and peak load compared with control (CON). Exposure to ISO also resulted in higher (P < 0.05) whole femur BMD, higher (P < 0.05) bone volume/total volume and lower (P < 0.05) trabecular separation at the femur neck, as well as greater (P < 0.05) peak load at femur midpoint and femur neck compared with the CON group. Exposure to ISO throughout suckling has favorable effects on LV outcomes, and, unlike previous studies using 5-day exposure to ISO, femur outcomes are also improved. Duration of exposure should be considered when using the CD-1 mouse to model the effect of early life exposure of infants to ISO.

This study examined concurrent stresses of nematode infection and pregnancy using pregnant and non-pregnant CD1 mice infected 3 times with 0, 50 or 100 Heligmosomoides bakeri larvae. Physiological, energetic, immunological and skeletal responses were measured in maternal and foetal compartments. Resting metabolic rate (RMR) was elevated by pregnancy, but not by the trickle infection. Energy demands during pregnancy were met through increased food intake and fat utilization whereas mice lowered their body temperature during infection. Both infection and pregnancy increased visceral organ mass and both altered regional bone area and mineralization. During pregnancy, lumbar mineralization was lower but femur area and mineralization were higher. On the other hand, infection lowered maternal femur bone area and this was associated with higher IFN-γ in maternal serum of heavily infected pregnant mice. Infection also reduced foetal crown-rump length which was associated with higher amniotic fluid IL-1β.

Two experiments were conducted to determine the available P requirements of grower and grower/finisher pigs and to define the conditions for conducting a growth assay for P availability. In the first experiment, diets with four levels of calculated available P (1–4 g/kg) and four Ca: available P ratios (1·7–2·9) were used to determine the available P requirements of grower pigs. The diets were formulated by substituting the required amounts of limestone and sodium tripolyphosphate for sugar in a soya-bean meal and sugar-based diet. In addition to measuring growth responses, a range of bones were examined to determine the most suitable criteria for assessing the response to available P. There was a small quadratic response of feed intake and growth rate of the pigs to level of available P, with maximum responses occurring to approximately 3 g available P/kg (P < 0·05). There were linear depressing effects of increasing Ca:available P ratios on carcass gain and feed conversion ratio (P < 0·01) but most of these effects occurred when the ratio exceeded 2·5:1. All bone variables examined increased linearly (P < 0·05) or curvilinearly (P < 0·01) with increasing available P concentration. In general, these variables were not affected by the Ca: available P ratio. The results of the growth responses and bone development indicate that the grower pig requires approximately 3 g available P/kg. However, for availability assays, where linearity of response is needed, the dietary concentration of available P should be a maximum of approximately 2 g/kg. In the second experiment four levels of calculated available P (1–4 g/kg) with a Ca: available P ratio of 2·5:1 were used to determine the available P requirements of grower/finisher pigs from 20 to 90 kg live weight. At 50 kg live weight the dietary available P concentration for half the pigs fed at 2, 3 and 4 g available P/kg was reduced to 1, 2 and 3 g/kg respectively. The pigs were fed ad lib. and growth performance, bone characteristics, P retention and ash concentration in the empty body were taken as response criteria to assess P adequacy. Among the variables tested, the ash concentration in the radius/ulna bone and P and ash concentrations in the empty body appeared to be more responsive than other variables to the changes in dietary P levels. Based on these variables, the P requirements for growth and bone development of growing pigs from 20 to 50 kg live weight was 3 g/kg and reduced to 2 g/kg for finisher pigs from 50 to 90 kg live weight.