Assessment of Activity Profiles in Older Adults and Lower Limb Bone Parameters: Observations from the Hertfordshire Cohort Study.

As muscle strength and function decline with age the optimal high-impact physical activity (PA) required for bone remodelling is rarely achievable in older adults. This study aimed to explore the activity profiles of community-dwelling older men and women and to assess the relationship between individual PA profiles and lower limb bone parameters. Participants from the Hertfordshire Cohort Study wore triaxial accelerometers for 7 days and counts of low (0.5-1.0 g), medium (1.0-1.5 g), and high (> 1.5 g) vertical-impact activity were calculated. Two years later, participants underwent a pQCT scan of the tibia (4% and 38% sites) to obtain measures of bone mineral density and bone geometry. Linear regression was used to quantify associations between bone and PA loading profiles adjusting for age, sex, loading category, and BMI. Results are presented as ß [95% confidence interval]. Bone and PA data were available for 82 participants. The mean (SD) age at follow-up was 81.4(2.7) years, 41.5% (n = 34) were women. The median low-impact PA count was 5281 (Inter-quartile range (IQR) 2516-12,977), compared with a median of only 189 (IQR 54-593) in medium, and 39 (IQR 9-105) in high-impact counts. Positive associations between high-impact PA and cortical area (mm2), polar SSI (mm3), and total area (mm2) at the 38% slice (6.21 [0.88, 11.54]; 61.94 [25.73, 98.14]; 10.09 [3.18, 16.99], respectively). No significant associations were found at distal tibia. These data suggest that maintaining high (> 1.5 g)-impact activity is difficult for older adults to achieve; however, even small amounts of high-impact PA are positively associated with selected cortical bone parameters 2 years later.

Determining individual trajectories of joint space loss: improved statistical methods for monitoring knee osteoarthritis disease progression.

OBJECTIVES: Knee osteoarthritis (KOA) progression is frequently monitored by calculating the change in knee joint space width (JSW) measurements. Such differences are small and sensitive to measurement error. We aimed to assess the utility of two alternative statistical modelling methods for monitoring KOA. MATERIAL AND METHODS: We used JSW on radiographs from both the control arm of the Strontium Ranelate Efficacy in Knee Osteoarthritis trial (SEKOIA), a 3-year multicentre, double-blind, placebo-controlled phase three trial, and the Osteoarthritis Initiative (OAI), an open-access longitudinal dataset from the USA comprising participants followed over 8 years. Individual estimates of annualised change obtained from frequentist linear mixed effect (LME) and Bayesian hierarchical modelling, were compared with annualised crude change, and the association of these parameters with change in WOMAC pain was examined. RESULTS: Mean annualised JSW changes were comparable for all estimates, a reduction of around 0.14 mm/y in SEKOIA and 0.08 mm/y in OAI. The standard deviation (SD) of change estimates was lower with LME and Bayesian modelling than crude change (SEKOIA SD = 0.12, 0.12 and 0.21 respectively; OAI SD = 0.08, 0.08 and 0.11 respectively). Estimates from LME and Bayesian modelling were statistically significant predictors of change in pain in SEKOIA (LME P-value = 0.04, Bayes P-value = 0.04), while crude change did not predict change in pain (P-value = 0.10). CONCLUSIONS: Implementation of LME or Bayesian modelling in clinical trials and epidemiological studies, would reduce sample sizes by enabling all study participants to be included in analysis regardless of incomplete follow up, and precision of change estimates would improve. They provide increased power to detect associations with other measures.

Infant milk feeding and bone health in later life: findings from the Hertfordshire cohort study.

Using data from the Hertfordshire cohort study, this study examined the effect of breastfeeding and bottle feeding on adult lumbar spine and femoral neck bone mineral content (BMC) and bone mineral density (BMD). The type of infant milk feeding was significantly associated with lumbar spine BMD in males. INTRODUCTION: Using data from the Hertfordshire cohort study (HCS), this study aims to examine the effect of infant milk feeding on bone health in later life by comparing the effect of breastfeeding and bottle feeding on lumbar spine and femoral neck BMC and BMD. METHODS: Information about infant milk feeding, birth weight (kg) and weight at 1 (kg) was collected by health visitors between 1931 and 1939 in Hertfordshire. BMC and BMD measurements were taken by DXA scan between 1998 and 2004. Linear regression models adjusted for conditional weight at 1, age at DXA scan, sex, adult BMI, smoking behaviour, alcohol consumption, physical activity, dietary calcium, and prudent diet score. RESULTS: Infant milk feeding was significantly associated with lumbar spine BMD (b = - 0.028; 95% CI, - 0.055; - 0.000; p value, 0.047) in males. On average, males who consumed breastmilk alternatives in infancy had lower lumbar spine BMD measurements than those who were fed only breastmilk. These associations remained significant in fully adjusted models. There were no significant associations between infant milk feeding and bone health for females. CONCLUSIONS: Significant associations between infant milk feeding and lumbar spine BMD in males indicate that breastmilk may be protective for the bone health of male babies. The evidence presented here underscores the potential lifelong benefits of breastfeeding and may highlight the differences between osteoporotic risk factors for males and females.

Systematic screening using FRAX® leads to increased use of, and adherence to, anti-osteoporosis medications: an analysis of the UK SCOOP trial.

In the large community-based SCOOP trial, systematic fracture risk screening using FRAX® led to greater use of AOM and greater adherence, in women at high fracture risk, compared with usual care. INTRODUCTION: In the SCreening of Older wOmen for Prevention of fracture (SCOOP) trial, we investigated the effect of the screening intervention on subsequent long-term self-reported adherence to anti-osteoporosis medications (AOM). METHODS: SCOOP was a primary care-based UK multicentre trial of screening for fracture risk. A total of 12,483 women (70-85 years) were randomised to either usual NHS care, or assessment using the FRAX® tool ± dual-energy X-ray absorptiometry (DXA), with medication recommended for those found to be at high risk of hip fracture. Self-reported AOM use was obtained by postal questionnaires at 6, 12, 24, 36, 48 and 60 months. Analysis was limited to those who initiated AOM during follow-up. Logistic regression was used to explore baseline determinants of adherence (good ≥ 80%; poor < 80%). RESULTS: The mean (SD) age of participants was 75.6 (4.2) years, with 6233 randomised to screening and 6250 to the control group. Of those participants identified at high fracture risk in the screening group, 38.2% of those on treatment at 6 months were still treated at 60 months, whereas the corresponding figure for the control group was 21.6%. Older age was associated with poorer adherence (OR per year increase in age 0.96 [95% CI 0.93, 0.99], p = 0.01), whereas history of parental hip fracture was associated with greater rate adherence (OR 1.67 [95% CI 1.23, 2.26], p < 0.01). CONCLUSIONS: Systematic fracture risk screening using FRAX® leads to greater use of AOM and greater adherence, in women at high fracture risk, compared with usual care.

Jumping Joints: The Complex Relationship Between Osteoarthritis and Jumping Mechanography.

We investigated the relationship between lower limb osteoarthritis (OA) and muscle strength and power (assessed by jumping mechanography) in UK community-dwelling older adults. We recruited 249 older adults (144 males, 105 females). OA was assessed clinically at the knee according to ACR criteria and radiographically, at the knee and hip, using Kellgren and Lawrence grading. Two-footed jumping tests were performed using a Leonardo Mechanography Ground Reaction Force Platform to assess maximum muscle force, power and Esslinger Fitness Index. Linear regression was used to assess the relationship between OA and jumping outcomes. Results are presented as ß (95% confidence interval). The mean age of participants was 75.2 years (SD 2.6). Males had a significantly higher maximum relative power during lift off (mean 25.7 W/kg vs. 19.9 W/kg) and maximum total force during lift off (mean 21.0 N/kg vs. 19.1 N/kg) than females. In adjusted models, we found significant associations in males between clinical knee OA and maximum relative power [- 6.00 (CI - 9.10, - 2.94)] and Esslinger Fitness Index [- 19.3 (- 29.0, - 9.7)]. In females, radiographic knee OA was associated with total maximum power [- 2.0 (- 3.9, - 0.1)] and Esslinger Fitness Index [- 8.2 (- 15.9, - 0.4)]. No significant associations were observed for maximum total force. We observed significant negative associations between maximum relative power and Esslinger Fitness Index and clinical knee OA in males and radiographic knee OA in females. We have used novel methodology to demonstrate relationships between muscle function and OA in older adults.

COVID-19 and associations with frailty and multimorbidity: a prospective analysis of UK Biobank participants.

BACKGROUND: Frailty and multimorbidity have been suggested as risk factors for severe COVID-19 disease. AIMS: We investigated, in the UK Biobank, whether frailty and multimorbidity were associated with risk of hospitalisation with COVID-19. METHODS: 502,640 participants aged 40-69 years at baseline (54-79 years at COVID-19 testing) were recruited across UK during 2006-10. A modified assessment of frailty using Fried's classification was generated from baseline data. COVID-19 test results (England) were available for 16/03/2020-01/06/2020, mostly taken in hospital settings. Logistic regression was used to discern associations between frailty, multimorbidity and COVID-19 diagnoses, after adjusting for sex, age, BMI, ethnicity, education, smoking and number of comorbidity groupings, comparing COVID-19 positive, COVID-19 negative and non-tested groups. RESULTS: 4510 participants were tested for COVID-19 (positive = 1326, negative = 3184). 497,996 participants were not tested. Compared to the non-tested group, after adjustment, COVID-19 positive participants were more likely to be frail (OR = 1.4 [95%CI = 1.1, 1.8]), report slow walking speed (OR = 1.3 [1.1, 1.6]), report two or more falls in the past year (OR = 1.3 [1.0, 1.5]) and be multimorbid (≥ 4 comorbidity groupings vs 0-1: OR = 1.9 [1.5, 2.3]). However, similar strength of associations were apparent when comparing COVID-19 negative and non-tested groups. However, frailty and multimorbidity were not associated with COVID-19 diagnoses, when comparing COVID-19 positive and COVID-19 negative participants. DISCUSSION AND CONCLUSIONS: Frailty and multimorbidity do not appear to aid risk stratification, in terms of positive versus negative results of COVID-19 testing. Investigation of the prognostic value of these markers for adverse clinical sequelae following COVID-19 disease is urgently needed.

Diet Quality and Bone Measurements Using HRpQCT and pQCT in Older Community-Dwelling Adults from the Hertfordshire Cohort Study.

There are few data describing associations between dietary patterns and bone microarchitecture. This study investigated the relationship between diet quality and HRpQCT and pQCT measures in older adults. Data were available for 184 men and 166 women. Dietary data were collected at baseline (1998-2003) using an administered food frequency questionnaire. A 'prudent' diet score (PDS) was identified using principal component analysis and used as an indicator of dietary quality. HRpQCT and pQCT images were acquired at follow-up in 2012, from the non-dominant distal radius and tibia using Scanco XtremeCT and Stratec XCT2000 instrument scanners, respectively. The mean (SD) PDS was - 0.24 (1.23) for men and 0.62 (1.14) for women. In women, a significant positive relationship was found between baseline dietary pattern and total and trabecular area at both the radius and the tibia, measured by HRpQCT. Similar trends were observed with pQCT parameters. Positive associations were observed for tibia total area (38% slice). At the radius, significant positive associations were found for total area (4% slice) and polar strength strain index (33% slice). All relationships remained robust to adjustment. For men, although patterns were similar, there were no significant associations for HRpQCT outcomes. Significant associations were observed for baseline PDS and polar strength strain and total area (66% slice) at the radius, measured by pQCT. Our data suggest that diets high in fruit, vegetables, oily fish and whole grain cereals in early old age are associated with greater bone size but not volumetric bone density or microarchitecture in later life in women.

Nutritional evaluation of canola meals produced from new varieties of canola seeds for poultry.

This study evaluated the nutritional value of 14 canola meals from new varieties of canola and compared them to conventional canola meal samples and soybean meals in chickens. Five experiments that included different sources of canola meals or soybean meals were conducted. For each experiment, a precision-fed rooster assay with conventional or cecectomized roosters was conducted to determine TMEn or amino acid digestibility. Analyzed nutritional composition of the canola meal samples indicated increases in crude protein and amino acids for all test canola meals (49.41 to 50.58% crude protein on a dry matter basis) compared to conventional canola meals (40.73 to 43.01%). All test canola meals also contained lower amounts of neutral detergent fiber and acid detergent fiber. Most test canola meals had significantly higher TMEn values than the conventional canola meals (P < 0.05), but all were lower than the soybean meal (P < 0.05). The test canola meals had higher amino acid digestibility coefficients than conventional canola meals in Experiments 1, 2, and 4 (P < 0.05), and higher concentrations of digestible amino acids in all 5 experiments. The results of this study indicated that nutritional value of the canola meal from new varieties of canola was greater than conventional canola meal for poultry.

Evaluation of the pepsin digestibility assay for predicting amino acid digestibility of meat and bone meals.

Sixteen meat and bone meal (MBM) samples were obtained and selected from various company plants to provide a wide range in pepsin nitrogen digestibility values. Pepsin digestibility was determined using either 0.02 or 0.002% pepsin. Amino acid (AA) digestibility of the 16 MBM samples was then determined using a precision-fed cecectomized rooster assay. The 0.02% pepsin digestibility values were numerically higher than the 0.002% pepsin values. The values varied from 77 to 93% for 0.02% pepsin and from 67 to 91% for 0.002% pepsin. The rooster AA digestibility results showed a wide range of values among MBM samples mostly due to the 4 samples having lowest and highest AA digestibility. A precision-fed broiler chick ileal AA digestibility assay confirmed that there were large differences in AA digestibility among the MBM samples having the lowest and highest rooster digestibility values. Correlation analyses between pepsin and AA digestibility values showed that the correlation values (r) were highly significant (P < 0.0001) for all AA when all 16 MBM samples were included in the analysis. However, when the MBM samples with the 2 lowest and the 2 highest rooster digestibility values were not included in the correlation analyses, the correlation coefficient values (r) were generally very low and not significant (P > 0.05). The results indicated that the pepsin nitrogen digestibility assay is only useful for detecting large differences in AA digestibility among MBM. There also was no advantage for using 0.02 versus 0.002% pepsin.

Effects of feeding diets varying in energy and nutrient density to Hy-Line W-36 laying hens on production performance and economics.

The objectives of this study were to evaluate the effects of feeding 5 different energy and nutrient dense diets to Hy-Line W-36 hens on long-term performance and economics. A total of 480 19 wk old Hy-Line W-36 Single Comb White Leghorn hens were weighed and randomly allocated to 6 replicate groups of 16 hens each (2 adjacent cages containing 8 hens per cage, 60.9×58.4 cm) per dietary treatment in a randomized complete block design. The hens were fed 5 treatment diets formulated to contain 85, 90, 95, 100, and 105% of the energy and nutrient recommendations stated in the 2009 Hy-Line Variety W-36 Commercial Management Guide. Production performance was measured for 52 wk from 19 to 70 wk age. Over the course of the trial, a significant increasing linear response to increasing energy and nutrient density was seen for hen-day egg production, egg weight, egg mass, feed efficiency, energy intake, and body weight (BW). Feed intake showed no significant linear level response to increasing energy and nutrient density except during the early production cycle. No consistent responses were noted for egg quality, percent yolk, and percent egg solids throughout the study. Significant linear responses due to energy and nutrient density were seen for egg income, feed cost, and income minus feed cost. In general, as energy and nutrient density increased, egg income and feed cost per hen increased, but income minus feed cost decreased. Overall, these results indicate that feeding Hy-Line W-36 hens increasing energy and nutrient-dense diets will increase egg production, egg weight, egg mass, feed efficiency, energy intake, BW, egg income, and feed cost, but decrease egg income minus feed cost. However, these benefits do not take effect in early production and seem to be most effective in later stages of the production cycle, perhaps "priming" the birds for better egg-production persistency with age.

Short communication: Intestinal digestibility of amino acids in fluid- and particle-associated rumen bacteria determined using a precision-fed cecectomized rooster bioassay.

Microbial protein represents the majority of metabolizable protein absorbed by ruminant animals. Enhanced understanding of the AA digestibility of rumen microbes will improve estimates of metabolizable protein. The objective of this experiment was to determine the digestibility of AA in fluid- (FAB) and particle-associated bacteria (PAB) using the precision-fed cecectomized rooster bioassay. Bacteria were isolated from 4 ruminally cannulated lactating Holstein cows by differential centrifugation, including particle suspension in 0.1% Tween-80 for increased removal of PAB from ruminal digesta. Samples of FAB and PAB were fed to 9 cecectomized roosters to determine standardized digestibility of AA. Total AA digestibility was 76.8 and 75.5% for FAB and PAB, respectively, but did not differ. Differences existed in AA digestibilities within bacterial type when compared with the mean essential AA digestibility value. Compared with previous literature estimates of AA digestibility in microbes (mean = 76%; range = 57-87%) and relative to National Research Council estimates of total AA from rumen bacteria (80%), the precision-fed cecectomized rooster assay is an acceptable in vivo model to determine AA digestibility of rumen bacteria.

Effect of day-old chick weight on the response of broilers to high doses of exogenous phytase.

A total of 360 Ross 708 male broiler chicks were used in an 8 treatment and 9 replicate cage study to explore the influence of day-old chick weight on the efficacy of exogenous phytase. Treatments were arranged as a 2 × 4 factorial with the factors being diet (a positive (PC) and negative control (NC) varying in nutrient density fed without or with 2 concentrations of exogenous phytase) and chick weight (light; <38.5 g or heavy; >42 g). Chicks were sourced from the same breeder flock, with light and heavy chicks being selected from the naturally occurring heterogeneity in the population. The diets were corn-soybean meal based and the PC was formulated to meet the nutrient requirements of male broiler chicks. The NC was formulated to contain 120 kcal/kg, 0.5, 0.18, and 0.18% less apparent metabolizable energy (AME), crude protein (CP), calcium (Ca), and phosphorus (P), respectively, than the PC. Amino acid (AA) density in the NC was also reduced in line with the reduction in CP and the manufacturers' recommendations for the effect of phytase on amino acid digestibility. Phytase at either 1,000 FYT/kg or 3,000 FYT/kg was added only to the NC to create a total of 4 diets. Water and mash feed were available ad libitum and were offered to 8 replicate cages, each containing 5 chicks. The experiment was conducted over a period of 3 wk and diets were offered in 2 phases (starter from d 1 to 10 and grower from d 11 to 21). Growth performance was monitored at the end of each diet phase and on d 21 ileal digesta were collected for estimation of apparent digestibility of energy (DE), nitrogen (N), Ca, P, dry matter (DM), and AA. There were no statistically significant interactions between diet and day-old chick weight for any of the measured parameters. Light chicks had significantly lower weight gain (approx. 5%) at both d 10 and d 21 compared with heavy chicks. This effect was principally associated with reduced feed intake and there was no significant effect of chick weight on feed conversion ratio (FCR). Chick weight had no effect on ileal nutrient digestibility. The reduction in nutrient density from the PC to the NC generated a significant reduction in weight gain (around 12%) and a significant increase in FCR (1.68 vs. 1.83). This effect was associated with a significant reduction in ileal DE (approximately 150 kcal/kg) and in the digestibility of several AA. Exogenous phytase significantly increased weight gain, reduced FCR and generated a significant increase in the ileal digestibility of energy, N, P, and several AA. Although chick weight and diet did not interact statistically, heavy chicks benefited more than light chicks from high doses of exogenous phytase across almost all measured end points which was confirmed by regression analysis. In conclusion, light chicks have inferior performance outcomes than heavy chicks principally because of reduced feed intake, but putatively not in digestive capacity per se. Exogenous phytase is effective in improving performance and nutrient digestibility in nutrient deficient diets. The effect of chick weight per se, and also breeder flock age, on the utility of supra-nutritional inclusion concentrations of exogenous phytase warrants further study.

Ileal phosphorus digestibility of soybean meal for broiler chickens remains consistent across institutions in a collaborative study regardless of non-phytate phosphorus concentration in the pre-experimental starter diet.

The same experimental protocol was used in 4 institutions to evaluate the impact of non-phytate phosphorus (nPP) concentration in the starter diet on regression method-derived ileal P digestibility of soybean meal (SBM) during the subsequent grower phase. A total of 1,536 Ross 308 male broiler chickens on d 0 post hatching were allotted to 2 pre-experimental starter diets that contained 3.5 or 4.5 g nPP/kg (96 replicate cages per diet, 8 birds per cage) for 18 d. Subsequently, 576 birds from each starter diet were selected and allocated to 3 experimental semi-purified grower diets containing 400, 510, or 620 g SBM/kg (32 replicate cages per diet, 6 birds per cage) for 3 d until collection of ileal digesta. Statistical analysis was conducted as a randomized complete block design with the starter period as whole plot and the grower period as split-plot. The only significant 2-way interaction was between grower diet and experimental institution (P < 0.05) on BW gain and gain to feed ratio. The main effect of institution and grower diet impacted (P < 0.05) feed intake, the digestibility of DM, P, and calcium, and disappearance of inositol hexakisphosphate (InsP6) in the grower diets. Birds fed the 3.5 g nPP/kg starter diet had lower (P < 0.05) BW gain and feed intake during the grower period, but presented higher (P < 0.05) digestibility of P and disappearance of InsP6 compared with the birds that were fed the 4.5 g nPP/kg starter diet. Regression method-derived ileal P digestibility of SBM was determined to be 46 or 42% for the respective 3.5 or 4.5 g nPP/kg pre-experimental starter diet and was not affected by the nPP concentration or by the institution. In conclusion, the experimental protocol used in the current study resulted in similar estimates across multiple institutions and is thus endorsed for future application in studies that aim to expand the database of digestible P content in plant source feed ingredients.

Dietary guanidino acetic acid is an efficacious replacement for arginine for young chicks.

Guanidino acetic acid (GAA) is synthesized in the liver and kidney from Arg and Gly and subsequently methylated by S-adenosylmethionine to form creatine. Four bioassays were carried out to determine the capacity of GAA to serve as a dietary replacement for Arg for growing chicks. Broiler chicks were fed Arg-deficient dextrose-casein (0.88% Arg) or corn-corn coproduct-soybean meal (1.0% Arg) basal diets during 9-d battery feeding trials involving 5 pens of 4 chicks per treatment. The dextrose-casein diet was shown to be markedly deficient in Arg as both weight gain and G:F increased (P < 0.01) due to addition of Arg, GAA, or creatine. The optimal level of added GAA was 0.12% of the diet, but this level of GAA or 1.0% creatine-H(2)O did not improve growth performance when added to an Arg-adequate diet. A second assay confirmed this level of optimal Arg in a 2 × 2 factorial arrangement of l-Arg and GAA supplementation. Using a practical-type diet based on corn, corn gluten meal, distillers dried grains with solubles, and soybean meal, similar improvements (P < 0.05) in G:F resulted from addition of 0.25% Arg, 0.12% GAA, or 0.15% creatine·H(2)O. These results demonstrate that 0.12% supplemental GAA, like creatine, produces consistent growth responses in young chicks fed Arg-deficient diets. To provide further evidence of the capacity for GAA to serve as a dietary Arg replacement, the dextrose-casein diet was supplemented with 7 graded doses of Arg in the absence or presence of 0.12% GAA (14 total diets). Quadratic (P < 0.01) responses in weight gain and G:F responses to supplemental Arg were observed. Similar supplemental Arg requirements were estimated in the absence and presence of 0.12% GAA, but GAA elicited a greater improvement (P < 0.05) in G:F when added to Arg-deficient, compared with Arg-adequate, diets. Collectively, these data indicate that GAA can be used as an efficacious replacement for dietary Arg for young chicks.

Effects of adaptation diet and exogenous enzymes on true metabolizable energy and cecal microbial ecology, short-chain fatty acid profile, and enzyme activity in roosters fed barley and rye diets.

Three experiments evaluated effects of adaptation diet and exogenous ß-glucanase and xylanase on TMEn of barley and rye. Single Comb White Leghorn roosters were fed adaptation diets based on corn/soybean meal (SBM), barley/SBM with and without ß-glucanase, or rye/corn/SBM with and without xylanase for 4 wk. In Experiments 1 and 2, after the adaptation period, TMEn was determined using a 48 h precision-fed rooster assay for 100% barley or 100% rye diets with or without ß-glucanase or xylanase, respectively. Experiment 3 consisted only of feeding adaptation diets for 4 wk. Cecal samples were collected at the end of experiments for microbial ecology, short-chain fatty acid (SCFA) profiles, and enzyme activity analyses. In Experiments 1 and 2, ß-glucanase increased (P < 0.05) TMEn of barley, and there was no significant effect of adaptation diet on TMEn values. Total cecal Eubacteria and Ruminococcaceae were decreased (P < 0.05) and Escherichia coli were increased (P < 0.05) at the end of the TMEn assay compared with the end of the adaptation period (with no TMEn assay). There was a large decrease (P < 0.05) for most cecal SCFA at the end of the TMEn assay compared with the end of the adaptation period. Both cecal ß-glucanase and xylanase activity were increased for birds fed adaptation diets containing the respective enzyme. In Experiment 3, there were no consistent effects of adaptation diet on cecal microbial profiles or SCFA but cecal ß-glucanase activity was increased (P < 0.05) by exogenous ß-glucanase for barley and cecal xylanase activity was increased (P < 0.05) by exogenous xylanase for rye. Overall, the results indicated that TMEn of barley was increased by exogenous ß-glucanase, adaptation diet did not significantly influence the TMEn response to the dietary enzymes, and cecal fermentation (based on cecal SCFA) was greatly reduced by the TMEn assay. Cecal ß-glucanase and xylanase activity, however, were often increased by feeding high barley and high rye diets containing exogenous enzymes.

Nutritional evaluation of soybean meals varying in particle size.

The objective of this study was to evaluate the effect of varying soybean meal (SBM) particle sizes on nutritional value of the SBM. Seven samples of dehulled solvent-extracted SBM from the same batch were ground to varying mean particles of <386, 466, 809, 1,174, 1,577, 2,026, and 2,321 µm. Two precision-fed rooster assays (crop intubation with 25 g of SBM followed by 48 h total excreta collection) were performed to determine TMEn and standardized amino acid (AA) digestibility. There were no significant differences for TMEn among SBM samples, and there was also no consistent significant effect of particle size on standardized AA digestibility. In addition to the 2 precision-fed rooster assays, a 21 d broiler chick trial was conducted using corn-SBM based diets using 4 diets that differed only in the mean particle size of SBM (466, 809, 1,174, or 1,577 µm), being fed from 2 to 23 d of age. Chicks fed diets containing 809 or 1,174 µm SBM had increased (P < 0.05) weight gain compared with chicks fed the diet containing 466 µm SBM, and chicks fed diets containing 1,174 or 1,577 µm SBM had increased (P < 0.05) feed efficiency compared with chicks fed the diet containing 466 µm SBM. The diet containing 466 µm SBM yielded the highest (P < 0.05) AMEn and total tract P retention. Ileal P digestibility and standardized AA digestibilities did not differ among treatments. Relative gizzard weight (percent of body weight) was increased (P < 0.05) by the 2 largest SBM particle sizes. The results from these 3 experiments showed that increasing SBM particle size may be beneficial to broiler growth performance and may increase gizzard size but had no consistent significant effect on ME, AA digestibility, or P digestibility/retention.

Standardized amino acid digestibility and true metabolizable energy for several increased protein ethanol co-products produced using back-end fractionation systems.

Precision-fed rooster trials were conducted to evaluate standardized AA digestibility and TMEn of the increased protein ethanol co-products corn fermented protein (CFP), high protein-distillers dried grains with solubles (HP-DDGS), and reduced fiber high protein-DDGS (RFHP-DDGS) produced using post-fermentation back-end fractionation systems. The TMEn was determined using conventional adult Leghorn roosters, while cecectomized roosters were used to determine standardized AA digestibility. Three to 6 roosters were fasted per treatment for 26 h prior to crop intubation with 27 g of sample and excreta were collected for 48 h post-feeding. Statistical analyses were conducted using a one-way ANOVA for a completely randomized design. Eight samples of CFP were found to contain a mean of 56% CP (DM basis) compared with a mean of 32% for conventional DDGS. The mean TMEn of CFP (3,556 kcal/kg) was greater (P < 0.05) than conventional DDGS1 and 2 (2,767 kcal/kg DM); mean standardized AA digestibility for CFP was similar to conventional DDGS and ranged from 88 to 94%. The mean digestible Lys, Met+Cys, and Thr concentrations for conventional DDGS were 0.79, 1.12, and 0.94%, respectively, whereas those for CFP were 1.74, 2.06, and 1.88%, respectively (DM basis). Two samples of HP-DDGS contained a mean of 51% CP (DM basis), a mean TMEn of 3,325 kcal/kg DM, a mean standardized AA digestibility of 90%, and mean concentrations of digestible Lys, Met+Cys, and Thr, which were 1.53, 1.77, and 1.60%, respectively (DM basis). The mean CP content of 2 RFHP-DDGS was 48% and the mean TMEn was 3,711 kcal/kg DM, which was greater (P < 0.05) than conventional DDGS3 and 4 (2,920 kcal/kg DM). Mean standardized AA digestibility of RFHP-DDGS was 90% and mean digestible Lys, Met+Cys, and Thr concentrations increased from 0.82, 1.01, and 0.95% for conventional DDGS, respectively, to 1.00, 1.59, and 1.44% for RFHP-DDGS, respectively (DM basis). Results indicate these high protein corn ethanol co-products have increased nutritional value for poultry compared with conventional DDGS.

Research Note: Evaluation of a precision-fed rooster assay for determination of phytic acid disappearance in feedstuffs.

The objective of this study was to evaluate a precision-fed rooster assay that is suitable for determination of phytic acid (myo-inositol 1,2,3,4,5,6-hexakis; InsP6) disappearance in plant-based feed ingredients. A 48-h precision-fed rooster assay was used to measure InsP6 disappearance using conventional White Leghorn roosters. A minimum of 4 individually-caged roosters per treatment were fasted for 26 h prior to crop intubation with 15 to 30 g of sample, and excreta were quantitatively collected for 48 h. Soybean meal, soybean hulls, canola meal, conventional distillers dried grains with solubles (DDGS), palm kernel meal (PKM), and wheat bran were evaluated in Experiment 1, whereas wheat middlings (WM) and rice bran (RB) were evaluated without and with 1,000 and 1,800 U/kg phytase in Experiment 2. Data from Experiment 1 were subjected to a one-way ANOVA for a completely randomized design, while data from Experiment 2 were subjected to two-way ANOVA for a 2 × 3 factorial arrangement of treatments. In Experiment 1, InsP6 disappearance ranged from 3 to 95% among all ingredients. The InsP6 disappearance for conventional DDGS (95%) was the highest (P < 0.05), wheat bran and soybean hulls were intermediate (47-48%), PKM was low (24%), and soybean meal and canola meal were very low (3-5%). In Experiment 2, there was a significant ingredient × phytase interaction (P < 0.05). Phytase inclusion at both 1,000 and 1,800 U/kg resulted in a significant improvement (P < 0.05) in InsP6 disappearance for RB; however, only the addition of 1,800 U/kg resulted in an increase in InsP6 disappearance for WM. The addition of 1,800 U/kg phytase increased the InsP6 disappearance from 58 to 74% for WM and from 26 to 53% for RB. These results suggest the precision-fed rooster assay can be used to evaluate phytic acid disappearance in plant-based feed ingredients and the assay was able to detect a significant effect of 1,800 U/kg of exogenous phytase on phytic acid disappearance for WM and RB.

Determination of TMEn, standardized amino acid digestibility, phosphorus digestibility, and phosphorus bioavailability in conventional and reduced phosphorus distillers dried grains with solubles.

The TMEn, amino acid (AA) digestibility, and P availability in 2 conventional corn distillers dried grains with solubles (C-DDGS1 and 2; 0.86 to 1.14% P, DM basis) and reduced phosphorus DDGS (RP-DDGS; 0.39% P) were evaluated. The TMEn of C-DDGS1 and 2 and RP-DDGS were determined in Experiment 1 using conventional adult Leghorn roosters, while standardized AA digestibility was determined in Experiment 2 using cecectomized roosters. Apparent ileal digestibility (AID) of P at different Ca levels was determined using precision-fed (crop intubation) broiler chickens in Experiments 3 and 4. The AID and total tract retention of P in C-DDGS2 were evaluated in Experiment 5 using ad libitum-fed broilers. Phosphorus bioavailability in C-DDGS2 relative to KH2PO4 based on bone ash was determined in Experiment 6. Experiments contained 4 to 5 replicates per treatment. In Experiment 1, the TMEn of C-DDGS1 and RP-DDGS was 3,428 and 2,840 kcal/kg, respectively (DM basis). In Experiment 2, there were no differences (P > 0.05) in rooster AA digestibility values between C-DDGS1 and RP-DDGS. In Experiment 3 with precision-fed chicks, AID of P in C-DDGS1 and RP-DDGS was 81 and 59%, respectively; there was no effect (P > 0.05) of increasing dietary Ca level from 0.04 to 1.0% for C-DDGS1 or reducing Ca from 1.5 to 1.0% for RP-DDGS. The AID of P in precision-fed chicks for C-DDGS2 in Experiment 4 was 48 and 80% at 1.3 and 0.3 Ca:total P ratios, respectively (P < 0.05). In Experiment 5, AID of P in C-DDGS2 at Ca:total P ratios of 1.3 and 2.5 was 63 and 42%, respectively, in precision-fed chicks. Regression of bone ash content (mg/tibia) on supplemental P intake in Experiment 6 yielded a P bioavailability of 61% relative to KH2PO4 for C-DDGS2. In conclusion, total and digestible P content in RP-DDGS was greatly reduced compared with C-DDGS, and the digestibility and bioavailability of the P in C-DDGS was affected by type of experimental assay and dietary Ca level.

Quantification of secretory IgA and mucin excretion and their contributions to total endogenous amino acid losses in roosters that were fasted or precision-fed a nitrogen-free diet or various highly digestible protein sources.

The objective of this study was to quantify total secretory IgA (sIgA) and mucin excretion via excreta in roosters fed diets containing highly digestible protein sources and to determine their proportional contributions to total endogenous amino acid (AA) losses. Precision-fed rooster assays with 24 h excreta collections were conducted using conventional White Leghorn roosters (4-8 roosters per treatment). In Experiment 1, roosters were fasted or precision-fed 30 g (crop intubation) of a nitrogen-free (NF) or semi-purified diet containing 10% casein. Roosters in Experiment 2 received a NF or semi-purified diet containing either 10% casein, 17% whole egg, 10% egg white, 9.8% soy protein isolate, 10.2% chicken breast meat, 11.2% spray-dried animal plasma (SDAP), or an AA mixture containing the same AA as casein. A Latin square design was used in Experiment 3, where roosters received NF or semi-purified diets containing either 10% casein, 17% whole egg, or 9.6% of a crystalline AA mixture to evaluate both diet and individual bird effects. In Experiment 1, mucin excretion did not differ (P > 0.05) among treatments; however, total sIgA excretion was lower for fasted birds, intermediate for the NF diet, and highest for casein (P < 0.05). Total endogenous AA losses (proportion of the total) from sIgA were higher for roosters fed casein, whereas mucin contributions were higher for fasted roosters (P < 0.05). In Experiment 2, sIgA excretion did not differ (P > 0.05) among treatments; however, mucin excretion was reduced for NF, whole egg, egg white, and chicken breast compared with casein and SDAP. In Experiment 3, sIgA and mucin excretion did not differ (P > 0.05) among treatments; however, sIgA excretion differed among individual roosters (7-27 mg/24 h; P < 0.05). Overall, fasting reduced sIgA excretion and sIgA and mucin excretion were affected by dietary protein source. Further, roosters excreted a substantial amount of sIgA, and sIgA and mucin were considerable contributors to total endogenous AA losses.