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Dual X-ray absorptiometry total body bone mineral content and bone mineral density in 18- to 22-year-old caucasian men.

Eighty-six healthy, young Caucasian 18-year-old men with no known disease or bone injury were recruited to this study at the United States Naval Academy. Change in bone mineral density (BMD) of the hip, lumbar spine, and distal tibia, and total body bone mineral content (TBMC) was measured by dual-energy X-ray absorptiometry (DXA). BMD and TBMC of these men were measured within 2 months (67 +/- 3 days) of entering the Academy, and, at the end of their first, second, and fourth years. Hip BMD was unchanged during the study period (p > 0.05). Lumbar spine BMD increased 3% (p < 0.001) and distal tibia BMD increased 5% (p < 0.001). TBMC showed a 7.5% increase over the study period. In this group of young men, gain in BMD and TBMC is greatest to age 21 years, with minimal further increase after age 21. The significance of this rise in bone mass during early adulthood on risk for osteoporotic fractures in later life or its impact on exercise-related bone injuries is unknown and warrants further examination.

Absorptiometry, Photon↗

Accuracy and precision of bone mineral density and bone mineral content in excised rat humeri using fan beam dual-energy X-ray absorptiometry.

The aim of this study was the evaluation of fan beam dual-energy X-ray absorptiometry (DXA) for measuring bone mineral density (BMD) and bone mineral content (BMC) of isolated rat humeri. Defleshed rat humeri from male Lewis rats were examined with a Hologic QDR 4500 A (Hologic, Inc., Bedford, MA) high-resolution densitometer both in water and 0.9% saline solution. The small animal scan protocol with the regional high-resolution mode was used. BMC measured by DXA was compared with bone dry weight, ash weight, and bone calcium content. Furthermore, DXA BMD and BMC precision were determined. We also evaluated the effect of salinity of the water bath in which the bones were measured. Correlations (r(2)) of BMC, as determined by DXA with dry weight, ash weight, and bone calcium content, were 0.978, 0.988, and 0.890, respectively. DXA overestimated ash weight by 5%-9%. Precision errors for BMC (BMD) were 0.90% (0.76%) without and 1.3 (0.86) with repositioning. Changes in the salinity of the water bath had a significant influence on the DXA results: At the 0.9% physiological level, BMC (-4.4%) and area (-4.1%), but not BMD, values were significantly lower (p < 0.005) compared with measurements in tap water. Fan beam DXA is a highly accurate and precise technique for measuring BMC and BMD in excised small animal bones. A physiological saline concentration in the water bath had a significant impact on BMC and area, but not on BMD, and should therefore be strictly controlled to avoid an underestimation of BMC.

Absorptiometry, Photon↗

Evidence for a major gene for bone mineral density/content in human pedigrees identified via probands with extreme bone mineral density.

Bone mineral content (BMC) and/or bone mineral density (BMD, i.e. BMC scaled by bone size) are major determinants for osteoporosis, which is a serious health problem. The major determinant of variation in BMD/BMC is genetic. The few studies now available are inconsistent in the identification and/or even in the existence of major gene(s) for BMD/BMC. In 51 human pedigrees with 941 individuals (526 measured for phenotypes) identified via probands with extreme BMD values, we performed complex segregation analyses to test the existence of a genetic locus with a major effect on BMD/BMC variation. We analyzed BMD and BMC at the spine, hip and wrist jointly by employing, as the study phenotype, factor scores (FS) of the principle component that explains approximately 75% of the total BMD/BMC variation at the three sites. The results indicate that a major gene exists with a codominant effect that is responsible for approximately 16% of the FS variation when adjusted for significant effects of sex, body weight and age. A significant genotype-x-sex-x-age interaction was found, which may explain approximately 14% of the FS variation after adjusting for body weight. Testing of various models did not provide support for shared familial environmental effects but suggested the existence of residual polygenic effects, which may explain approximately 50% of the FS variation when adjusting for sex, body weight and age. This study indicates a promising aspect of studies to identify a major gene for BMD/BMC variation in our pedigrees identified via extreme probands.

Bone Density↗

Bone mineral content and bone mineral density in adolescent girls with anorexia nervosa--a longitudinal study.

OBJECTIVE: Total body and lumbar spine bone mineral density (BMD-TB, BMD-L) and total body bone mineral content (BMC-TB) were measured to establish the course of bone demineralization in anorexia nervosa and the clinical factors influencing BMC-TB and BMD changes during treatment. METHOD: Forty-two girls with DSM III-R anorexia nervosa, age 14.7+/-2.4 years. BMC-TB, BMD-TB and BMD-L were measured in approximately 7-month intervals for 27.8+/-4.1 months using DXA. RESULTS: Despite nutritional improvement, there was an initial decrease of BMD-L, and no change in BMC-TB and BMD-TB. an increase in BMC-TB and BMD was observed after approx. 21 months from the beginning of the study. CONCLUSION: The improvement in BMC-TB and BMD was related to changes in nutritional status and was significantly marked in younger patients, with earlier anorexia onset and before menarche.

Adolescent↗

Positive effects of a chicken eggshell powder-enriched vitamin-mineral supplement on femoral neck bone mineral density in healthy late post-menopausal Dutch women.

Although bone metabolism is largely under genetic control, the role of nutrition is considerable. The present study evaluates the effects of chicken eggshell powder, a new source of dietary Ca, and purified CaCO3 on bone mineral density (BMD) of the lumbar spine and hip. Besides BMD we also looked at biochemical markers of bone and Ca metabolism. Both Ca sources were provided in combination with minerals and vitamins including Mg, cholecalciferol and phylloquinone. We designed a randomised, double-blind, placebo-controlled study to take place over 12 months. Healthy Caucasian women (n 85), selected by age (> or =50 and <70 years), from the databases of general practitioners were recruited by telephone calls. They had to be at least 5 years post-menopausal, with lumbar spine T-score being > - 2.5. At baseline, their mean habitual daily Ca intake was adequate. The women were randomly allocated to: eggshell powder-enriched (group A; n 24), purified CaCO3-enriched (group B; n 22), or a placebo product (group C; n 27). BMD was measured at baseline and then after 6 and 12 months of supplementation as were the biochemical markers bone-specific alkaline phosphatase, amino-terminal propeptide extension of type I collagen, deoxypyridinoline, calcitonin, intact parathyroid hormone, calcidiol, and urinary Ca. After 12 months of supplementation, only mean BMD of the femoral neck in group A was significantly increased (P=0.014) by 1.75% (95% CI 0.18, 3.32) compared with a decrease of -0.60% (95% CI -1.92, 0.72) in group C. This increase coincided with significant decreases in markers of bone resorption and formation. No significant changes were seen in BMD at other sites, including lumbar spine, nor in groups B and C. No differences were found between groups A and B, or B and C. The present study indicates that healthy late post-menopausal women with an adequate Ca intake at baseline may increase BMD of the hip within 12 months following supplementation with the chicken eggshell powder-enriched supplement.

Age Factors↗

Effect of weight loss on bone mineral content and bone mineral density in obese women.

Studies of body-composition changes during weight loss have had conflicting results with regard to changes in bone mineral content (BMC) and bone mineral density (BMD). We examined BMC and BMD for changes during weight loss. Fourteen women enrolled in a 15-wk weight loss program. Dual-energy X-ray absorptiometry (DXA) measures of the total body were made at baseline (T1), the midpoint of weight loss (T2), and at the end of weight loss (T3). Body weight changed significantly throughout the 15 wk, declining from a high of 89.7+/-3.6 to 74.1+/-3.2 kg. Fat-free mass declined initially (47.8+/-1.7 kg at T1, 45.7+/-1.4 kg at T2, and 46.0+/-1.5 kg at T3) and then stabilized. Fat mass changed significantly during the study (39.2 kg at T1, 32.4 kg at T2, and 29.3 kg at T3). No significant differences were observed in BMC or bone areal measurement during the study. However, BMD declined significantly from baseline (1.217 g/cm2 at T1, 1.197 g/cm2 at T2, and 1.200 g/cm2 at T3). The changes in BMC and BA were in opposite directions, resulting in a significant decline in BMD without a loss of BMC. These data suggest that changes in BMD observed with weight loss may be the result of a lack of instrument sensitivity when body weight and composition change and are simply an artifact and not a physiologic change in BMD. Further research is needed to determine the full effect of weight loss on BMC, bone area, and BMD.

Absorptiometry, Photon↗

Total-body and regional bone mineral content and areal bone mineral density in children aged 8-18 y: the Fels Longitudinal Study.

BACKGROUND: Techniques for cross-calibration of bone mineral content (BMC) and bone mineral density (BMD) between manufacturers of dual-energy X-ray absorptiometry (DXA) instruments are currently inadequate for total body measurements. Therefore, manufacturer-specific data for BMC and BMD in children are needed. OBJECTIVE: We provided age- and sex-specific means and SDs for total-body and regional BMC and areal BMD in 8-18-y-old white children. DESIGN: BMC and BMD of the head, arms, legs, pelvis, spine, and total body were determined by DXA. Data include 465 annual measurements from 148 healthy children with body weights between 30 and 100 kg and statures <190 cm. RESULTS: There were significant sex differences in BMC at ages 15-18 y for the total body and legs, at ages 12 and 15-18 y for arms and pelvis, at ages 11-13 and 16-18 y for the spine, and at ages 10-11 y for the head. There were significant sex differences in BMD at ages 16-18 y for total body, arms, and legs; at ages 12-13 and 16-18 y for the pelvis; at ages 12-14 and 18 y for the spine; and at ages 13-18 y for the head. CONCLUSIONS: Data presented in this investigation can be used to compare the BMC and BMD of 8-18-y-old white children (with statures <190 cm and body weights between 30 and 100 kg) using DXA.

Absorptiometry, Photon↗

Influence of cognitive eating restraint on total-body measurements of bone mineral density and bone mineral content in premenopausal women aged 18-45 y: a cross-sectional study.

BACKGROUND: We examined the relation between cognitive eating restraint (CER) and total-body measurements of bone mineral density (BMD) and bone mineral content (BMC). OBJECTIVE: Our objective was to determine whether women with CER had lower total-body BMD and BMC than did other women. DESIGN: Premenopausal women, 90-150% of ideal weight, had measurements of their BMD and BMC made and completed questionnaires on physical activity, weight history, body size satisfaction, dieting history, eating behavior, and childbearing history. Bone measurements were examined for differences between groups with low and high CER scores by using analysis of covariance and quartiles of body weight to adjust for body size differences. CER was assessed by using the Three-Factor Eating Inventory and was defined as a score > or =9; normal eating restraint (NER) was defined by a score <9. Total-body BMC, BMD, and fat and lean masses were measured by dual-energy X-ray absorptiometry. RESULTS: Fifty-two percent of the women were classified as having CER. Women with CER were significantly more dissatisfied with their bodies. Analysis of covariance, with weight as the covariate, indicated a significant difference in BMC between women in preplanned pairs from the 5 lowest and 5 highest CER levels. No significant differences in BMD were observed between groups. Significantly lower BMC was found in women with high CER scores and body weights <71 kg than in those with high CER scores and weights > or =71 kg. CONCLUSIONS: BMC was significantly differently between women with low and high CER scores. BMC was significantly lower in women with body weights <71 kg and classified with CER. Lower BMC in women with high CER scores may indicate an increased risk of osteoporosis.

Adolescent↗

Vitamin B-12 status is associated with bone mineral content and bone mineral density in frail elderly women but not in men.

Subclinical vitamin B-12 deficiency is common in the elderly. Encouraged by early indications, we investigated the plasma vitamin B-12 status in association with bone mineral content (BMC) and bone mineral density (BMD) in frail elderly people. Data of 194 free-living Dutch frail elderly (143 women and 51 men) were available. BMC and BMD were measured by dual energy X-ray analysis. Biochemical analyses were performed on plasma or serum including vitamin B-12, methylmalonic acid, homocysteine, 25-hydroxy vitamin D and parathyroid hormone. Women had higher plasma vitamin B-12 (288 and 238 pmol/L, respectively) and lower plasma homocysteine levels (15.8 and 21.3 micro mol/L, respectively) than men. Of the total explained variance of BMC and BMD in women (46 and 22%, respectively), 1.3-3.1% was explained by plasma vitamin B-12, in addition to weight and height or energy intake. In men, the variance of BMC and BMD was explained by weight, smoking and/or height (total R(2) was 53 and 25%, respectively), but not by plasma vitamin B-12. Osteoporosis occurred more often among women whose vitamin B-12 status was considered marginal or deficient than in women with a normal status, i.e., the prevalence odds ratios (after adjustment for weight, age and calcium intake) (95% confidence intervals) were 4.5 (0.8;24.8) and 6.9 (1.2;39.4), respectively. These results suggest that vitamin B-12 status is associated with bone health in elderly women. Future studies on bone health should take into account a possible role of vitamin B-12 status in different populations.

Absorptiometry, Photon↗

Higher bone mineral density in Caucasian, hirsute patients of reproductive age. Positive correlation of testosterone levels with bone mineral density in hirsutism.

OBJECTIVE: The mechanisms leading to higher bone mineral density (BMD) in hirsute patients than in healthy controls have seldom been examined. We compared the metabolic, hormonal and bone metabolic parameters in hirsute patients and female controls and correlated BMD and bone metabolic parameters with testosterone, oestradiol and metabolic parameters. PATIENTS: Fifty-one Caucasian, reproductive-aged, hirsute patients referred to the outpatient clinic of an academic tertiary-care medical centre and 63 healthy, female Caucasian controls matched for season, weight and age. MEASUREMENTS: BMD (hip, neck, lumbar and total BMD), bone metabolic parameters (osteocalcin, alkaline phosphatase, PTH, ionized calcium, phosphate and 25-hydroxyvitamin D (25OHD)) and endocrine profiles (androgen status, oestradiol and insulin) were evaluated during follicular phase. Oestradiol measurement was repeated during cycle days 8-12. RESULTS: Lumbar and neck BMD levels were significantly higher in hirsute patients than in controls: (mean +/- SD): lumbar BMD 1.10 +/- 0.12 vs. 1.06 +/- 0.10 g/cm2 and neck BMD 0.91 +/- 0.11 vs. 0.87 +/- 0.12 g/cm2, P < 0.05. Fasting insulin and free testosterone levels were significantly higher in hirsute patients than in controls. Free testosterone correlated positively with neck and hip BMD levels in hirsute patients. During multiple regression analysis, testosterone, oestradiol and waist/hip ratio (WHR) were found to have positive effects on BMD levels independent of body mass index (BMI). 25OHD levels were significantly lower in hirsute patients [42 (13-131)] than in controls [72 (27-196)] nmol/l (geometric mean +/- 2SD), P < 0.001]. CONCLUSION: Hirsute patients demonstrated significantly higher bone mineral density levels than controls, which could be explained by hyperinsulinaemia and higher testosterone levels in hirsute patients compared with controls. The pathogenesis for significantly lower 25-hydroxyvitamin D levels in hirsute patients compared with controls needs to be evaluated in future studies.

Adult↗

Bone mineral density in patients with rheumatoid arthritis: relation between disease severity and low bone mineral density.

OBJECTIVE: To examine variables associated with bone mineral density (BMD) in patients with rheumatoid arthritis (RA). METHODS: We investigated 373 patients with low to moderately active RA. Patients with low disease activity were recruited from a cohort of patients in clinical remission. Patients with moderately active disease were included in a trial comparing the effects of long term high intensity exercise programme and conventional physical therapy. Demographic and clinical data were collected. Bone mineral density (BMD) was measured by means of dual x ray absorptiometry (DXA). Associations between demographic and clinical measurements on the one hand and BMD on the other were investigated in regression analyses. RESULTS: The patient group consisted of middle aged, mainly female, patients. The median (interquartile range) disease duration was 7 (4 to 13) years, the mean disease activity score (standard deviation) was 3.2 (1.4). Of the group, 66% was rheumatoid factor positive, and 83% (n = 304) had never used corticosteroids. The median Larsen score of hands and feet was 27 (5 to 61). Greater age and low body mass index were related to low BMD at the hip and spine. High Larsen score for hands and feet was significantly associated with low BMD at the hip. The use of corticosteroids was not independently associated with BMD. The results of the multiple regression analyses also applied to the subgroup of corticosteroid naive patients. CONCLUSION: BMD data of patients with low to moderately active RA demonstrated an association between high radiological RA damage and low BMD at the hip, which suggests an association between the severity of RA and the risk of generalised bone loss, which also occurred in corticosteroid naive patients.

Adrenal Cortex Hormones↗

Quantitative observations on mineralized and non-mineralized bone in the iliac crest.

The amounts of mineralized bone and osteoid in thin undecalcified sections of iliac crest have been measured in 68 control subjects at necropsy using a point-counting method. The effect of varying the site selected for quantitative study on the value obtained for total bone mass has been investigated in decalcified sections of iliac crest. The total bone mass shows individual variation within a fairly constant range with a mean of 22.7 +/- 0.5% up to the age of 50 years and then progressively falls to a mean of 15.5 +/- 1.1% for individuals aged > 50 years. Some of the lowest values in the range 5.5 to 16.4 (mean 8.9 +/- 1.9%) were observed in elderly women in the seventh to ninth decades. It is concluded that so-called senile osteoporosis is usually a manifestation of a normal aging process. In controls osteoid accounts for only about 0.1% of the area measured and for a maximum of 1.8% of bone with a mean mineralization of 99.5%. Osteoid is patchily distributed and the maximum number of birefringent lamellae in any seam is four. The results of quantitative histology carried out in different parts of the iliac crest indicate that there are variations with the distance of the site from the anterior superior spine and its depth below the crest surface. The importance of this in relation to the site and size of iliac crest biopsies used for quantitative histology is discussed. There is a significant correlation between the values for total bone mass when estimated by the point-counting technique in undecalcified sections and by a volumetric method using blocks of bone.

Adolescent↗

Specific causes of death in miners and ex-miners of the Rhondda Fach 1950-80.

The specific causes of death for miners and ex-miners of the Rhondda Fach have been examined in detail using the data base provided by the 30 year follow up. The main findings are the lower specific mortality for those with category A, compared with those with categories 0, 1, 2, and 3, for all circulatory diseases (particularly ischaemic heart disease) and the raised mortality for gastric cancer. These results are surprising because a high proportion of those with, especially, categories 2 and 3 developed category A during the 30 years but fail to show the specific death rates typical of those with category A. Possible reasons for this are discussed and an explanation put forward.

Cardiovascular Diseases↗

Bone mineral density in children and adolescents with juvenile diabetes: selective measurement of bone mineral density of trabecular and cortical bone using peripheral quantitative computed tomography.

Bone mineral density (BMD) was studied in 21 children and adolescents with type I diabetes and in age- and sex-matched healthy controls. BMD was selectively measured in trabecular and total bone using peripheral quantitative computed tomography (pQCT). Cortical bone density was calculated. There was a decrease of trabecular bone density (-18.9%, p < 0.01), total bone density (-9.0%, NS) and cortical bone density (-5.1%, NS) in diabetes. Trabecular bone density was inversely correlated with the duration of diabetes and the concentration of glycosylated hemoglobin (HbA1) (r = -0.48, p = 0.027 and r = -0.63, p = 0.002, respectively). Total BMD correlated inversely with HbA1 (r = -0.52, p = 0.017). pQCT allows the selective measurement of metabolically active trabecular bone where changes of mineralization first occur. We conclude that pQCT is a useful method for investigating BMD in diabetes.

Adolescent↗

Increased cortical bone mineral content but unchanged trabecular bone mineral density in female ERbeta(-/-) mice.

Ovariectomy in young, growing rodents results in decreased trabecular bone mineral density (BMD) and increased radial growth of the cortical bone. Both of these effects are reversed by treatment with estrogen. The aim of the present study was to determine the physiological role of estrogen receptor-beta (ERbeta) on bone structure and bone mineral content (BMC). The BMC was increased in adult (11 weeks old), but not prepubertal (4 weeks old), female ERbeta(-/-) mice compared with wild-type (WT) mice. This increase in BMC in females was not due to increased trabecular BMD, but to an increased cross-sectional cortical bone area associated with a radial bone growth. Male ERbeta(-/-) mice displayed no bone abnormalities compared with WT mice. Ovariectomy decreased the trabecular BMD to the same extent in adult female ERbeta(-/-) mice as in WT mice. The expression levels of osteoblast-associated genes - alpha1(I) collagen, alkaline phosphatase, and osteocalcin mRNAs - were elevated in bone from adult ERbeta(-/-) females compared with WT mice. These observations provide a possible explanation for the increased radial bone growth seen in female mutants, suggesting a repressive function for ERbeta in the regulation of bone growth during female adolescence. In summary, ERbeta is essential for the pubertal feminization of the cortical bone in female mice but is not required for the protective effect of estrogens on trabecular BMD.

Aging↗

Mandibular bone mineral density measured using dual-energy X-ray absorptiometry: relationship to hip bone mineral density and quantitative ultrasound at calcaneus and hand phalanges.

The main aim of this cross-sectional study was the estimation of relationships between mandibular bone mineral density (m-BMD), hip bone mineral densities (BMDs) and quantitative ultrasound at calcaneus and hand phalanges. Correlations between m-BMD and age, years since menopause (YSM) and body size were also evaluated. 42 edentulous persons (36 females and 6 males aged 60.5 +/- 6.9 years) were evaluated. In the group studied no factors affecting bone metabolism (either medical conditions or medications) were noted. Bone status was assessed by dual-energy X-ray absorptiometry (mandible, hip--Lunar DPX-L), and quantitative ultrasound (calcaneus--Lunar Achilles which measures speed of sound (SOS, m s-1) and broadband ultrasound attenuation (BUA, dB MHz-1); and phalanges of the hand--DBM Sonic 1200 which measures amplitude-dependent speed of sound (AD-SOS, m s-1)). CV% for mandibular measurements was 2.06%. m-BMD correlated significantly with the following measurements: femoral neck r = 0.39, p < 0.01; Ward's r = 0.39, p < 0.01; calcaneal BUA r = 0.39, p < 0.01; and phalangeal AD-SOS r = 0.4, p < 0.01. Negative correlation consistent with a significant decrease with age was observed in m-BMD (r = -0.36, p < 0.05) and AD-SOS (r = -0.4, p < 0.01). BMD in the mandible also decreased with YSM (r = -0.47, p < 0.01). m-BMD was correlated with age, YSM, height and weight in stepwise, multiple, linear regression analysis. The following equation was obtained: m-BMD = -2.21 + 0.018 x height (cm) -0.02 x YSM (years) + 0.13 x age (years). It may be concluded that mandibular BMD may be an appropriate measurement site for the evaluation of skeletal status in osteoporosis.

Absorptiometry, Photon↗

Dietary pharmacological or excess zinc and phytase effects on tissue mineral concentrations, metallothionein, and apparent mineral retention in the newly weaned pig.

Feeding pharmacological zinc (Zn) to weaned pigs improves growth, and dietary phytase improves P and Zn availability. Metallothionein (MT) increases in the duodenum, kidney, and liver of pigs fed 1000 mg Zn/kg with phytase or 2000 mg Zn/kg with or without phytase when fed for 14 d postweaning. The goal of this study was to determine the effects of feeding pharmacological Zn and phytase on tissue minerals, MT, mineral excretion, and apparent retention. Twenty-four newly weaned pigs (20 d; 7.2 kg) were individually fed twice daily, a basal diet supplemented with 0, 1000, or 4000 mg Zn/kg as Zn oxide, without or with phytase (500 phytase units [FTU]/kg) for 14 d, followed by a basal diet (100 mg Zn/kg) without phytase for 7 d. Pigs fed 4000 mg Zn/kg without phytase had higher (p=0.01) plasma, hepatic, renal Zn, renal Cu, and hepatic, renal, and jejunal MT than pigs fed the basal diet or 1000 mg Zn/kg. Duodenal MT was higher (p=0.0001) in pigs fed 1000 and 4000 mg Zn/kg than in pigs fed the basal diet. In pigs fed 1000 and 4000 mg Zn/kg, Zn loading occurred during the first 11 d of supplementation; by d 14, excess Zn was being excreted in the feces.

6-Phytase↗

Effects of a long-acting, trace mineral, reticulorumen bolus on range cow productivity and trace mineral profiles.

The objectives were to determine if strategic supplementation of range cows with a long-acting (6 mo), trace mineral, reticulorumen bolus containing Cu, Se, and Co would: (1) increase cow BCS and BW, and calf birth, weaning, and postweaning weights, or weight per day of age (WDA); (2) increase liver concentrations of Cu or Zn in cows, or blood Se, Cu, or Zn concentrations in cows and calves; and (3) vary by cow breed for any of these response variables. There were 192 control and 144 bolused Composite cows (C; 25% Hereford, Angus, Gelbevieh, and Senepol or Barzona); 236 control and 158 bolused Hereford (H) cows; and 208 control and 149 bolused Brahman cross (B) cows used in a 3-yr experiment. Cows were weighed and scored for body condition in January, May, and September, and all bolused cows received boluses in January. Each year, from among the 3 breed groups a subset of 15 control and 15 bolused cows (n = 90) had samples obtained in January and May for liver Cu and Zn, blood Se, and serum Cu and Zn. As for cows, blood and serum from the calves of these cows were sampled each year in May and September for Cu, Se, and Zn. There was a significant breed x year x treatment interaction (P = 0.001) for cow weight loss from January to May. Calf WDA, weaning, and postweaning weights did not differ (P > 0.40) between bolused and control cows, but there was a significant (P = 0.022) breed x year x treatment interaction for birth weight. Liver Cu was deficient (< 75 ppm; P < 0.001) in control cows and adequate (< 75 to 90 ppm) for bolused cows. Liver Cu differed by year (P < 0.001). Blood Se was adequate (< 0.1 ppm) for all cows except in January 2001 and 2002. There was no difference (P > 0.50) in blood Se between treatment groups in January, but bolused cows had greater (P < 0.01) blood Se in May. Breed differences for blood Se concentrations existed for bolused cows, with B having greater (P < 0.05) blood Se than either C or H cows. Breed differences also existed for control cows, with H having less blood Se (P < 0.04) than B or C cows. Calves from bolused cows had greater blood Se than calves from control cows (P = 0.01). Supplementation via a long-acting trace mineral bolus was successful in increasing liver Cu in cows and blood Se in cows and calves, but the responses varied by year. Bolus administration had variable effects on BW change in early lactation, depending on breed and year, which may indicate the need for breed- and year-specific supplementation programs.

Animal Husbandry↗