Biomedical subjects

J H Harrison

Publications and source records attributed to J H Harrison.

At least 19 recordsLinked to original sources

PubMed2006

Prediction and evaluation of urine and urinary nitrogen and mineral excretion from dairy cattle.

Urine excretion is a substantial factor in the amount of manure that needs to be managed, and urinary N can contribute to ammonia volatilization. Development and validation of prediction equations focusing on dietary factors to decrease urine and urinary nutrient excretion will provide information for managing urine and feces separately or for other future technologies. The objective of this study was to develop equations for prediction of urine excretion and excretion of urinary N, Na, and K and to evaluate both new and previously published prediction equations for estimation of urine and urinary nutrient excretion from lactating dairy cows. Data sets from metabolism studies conducted at Washington State University were compiled and evaluated for excretion of minerals. Urine excretion averaged 24.1 kg/d and urinary nitrogen excretion ranged from 63 to 499 g/d in the calibration data set. Regression equations were developed to predict urine excretion, urinary N excretion, and urinary Na and K excretion. Predictors used in the regression equations included milk yield, body weight, dietary crude protein percentage, milk urea nitrogen, and nutrient intakes. Previously published prediction equations were evaluated using data sets from Washington State University and the University of Wisconsin. Mean and linear biases were evaluated by determining the regression of residuals on predicted values. Evaluation and validation of prediction equations are important to develop equations that will more accurately estimate urine and urinary nitrogen excretion from lactating dairy cows.

Animal Nutritional Physiological Phenomena↗

PubMed2005

Studies into using manure in a biorefinery concept.

Animal manure is an underutilized biomass resource containing a large amount of organic carbon that is often wasted with the existing manure disposal practices. A research project funded by the US Department of Energy explored the feasibility of using manure via the sugar platform in a biorefinery, converting the carbon from fiber to biochemicals. The results showed that (1) fiber was the major component of manure dry material making up approx 50%, 40%, and 36% of the dry dairy, swine, and poultry manure material, respectively; within dairy manure, more than 56% of the dry matter was in particles larger than 1.680 mm; (2) in addition to being a carbon source, manure could provide a variety of nutrient for fungi T. reesei and A. phoenicis to produce cellulase; (3) the hemicellulose component in the manure fiber could be readily converted to sugar through acid hydrolysis; while concentrated acid decrystallization treatment was most effective in manure cellulose hydrolysis; (4) purification and separation was necessary for further chemical conversion of the manure hydrolysate to polyols through hydrogenation; and (5) the manure utilization strategy studied in this work is currently not profitable.

Agriculture↗

PubMed2005

Effect of grain source and exogenous phytase on phosphorus digestibility in dairy cows.

Two experiments were conducted to determine P digestibility in lactating dairy cows fed corn or barley as grain sources. The first experiment utilized a replicated incomplete 5 x 4 Latin square design with 8 lactating Holstein cows fed diets containing either corn alone or corn in combination with one of 4 barley varieties that differed in chemical composition. Total tract digestibility of P ranged from 11 to 29% for diets containing the barley varieties and was approximately 35% for the corn diet. A second experiment compared P digestibility in cows fed diets containing corn or barley when exogenous phytase was added to the diets. Lactating Holstein cows (n = 16) were arranged in 4 replications of a Latin square with 2 grains (barley or corn), fed separately or with added exogenous phytase (427 phytase units/kg of total mixed ration and 4 periods of 21 d. Phytate P comprised about 50% of the total P (0.46% P) in the total mixed ration. The concentration of serum inorganic P was higher in cows fed diets with exogenous phytase (5.8 vs. 6.5 mg/dL in cows fed barley diets and 5.5 vs 6.0 mg/dL in cows fed corn diets). Using acid detergent lignin as an internal marker, hydrolysis of phytate P was increased by the exogenous phytase, and total P digestibility tended to be increased. In contrast to Experiment 1, in Experiment 2 there was no effect of grain source on P digestibility and total fecal P. Dry matter intake and efficiency of milk production were not affected by exogenous phytase or grain type. Although phytase activity occurs in the rumen, physical properties of the diet and ruminal passage rates may prevent total hydrolysis of phytate in the rumen of lactating cows. Thus, exogenous dietary phytase might improve P digestibility in dairy cows in some dietary situations.

6-Phytase↗

PubMed2005

Prediction of manure and nutrient excretion from dairy cattle.

Accurate estimates of manure excretion are needed for planning manure storage facilities and for nutrient management. Data sets from metabolism studies conducted at several universities were compiled and evaluated for excretion of total manure, N, P, and K. Animal groups included calves weighing up to 204 kg, heifers weighing between 274 and 613 kg, nonlactating cows, and lactating cows. Regression equations were developed to predict excretion of total manure, total dry matter, N, P, and K. Predictors used in the regression equations for lactating cows included milk yield, percentages of protein and fat in milk, dietary concentrations of crude protein and neutral detergent fiber, and intakes of nutrients. The regression equations provide improved predictions of excretion and enable more accurate planning of manure storage and nutrients to be managed at the farm level.

Animal Nutritional Physiological Phenomena↗

PubMed2003

Corn silage management: effects of hybrid, chop length, and mechanical processing on digestion and energy content.

Two experiments were conducted to evaluate the effects of chop length and mechanical processing of two hybrids of whole plant corn on digestion and energy content of the total mixed ration (TMR). The experimental designs in experiments 1 and 2 were 6 x 6 and 4 x 4 Latin squares, respectively. In the first experiment, Pioneer hybrid 3845 was harvested at three theoretical lengths of cut: 11.1, 27.8, and 39.7 mm. At each chop length, corn was harvested with and without mechanical processing using a John Deere 5830 harvester with an onboard kernel processor. In the second experiment, Pioneer hybrid Quanta was harvested at two theoretical lengths of cut: 27.8 and 39.7 mm, with and without mechanical processing. In both experiments, the increase in the theoretical length of cut of corn silage increased the average length of cut and tended to increase the percentage of particles greater than 19 mm and lower the percentage of particles between 8 and 19 mm. In experiment 1, apparent total tract dry matter, organic matter, and neutral detergent fiber (NDF) digestibilities were lower for cows fed diets containing corn silage harvested at a short chop length (11.1 mm) than for corn silage harvested at a long chop length (39.7 mm). The lower total tract digestibility of nutrients may have contributed to the lower TDN, metabolizable energy (percentage of digestible energy), and NEL concentration of diets containing the short chop length corn silage (experiment 1). In experiment 2, total tract starch digestibility was greater for cows fed medium chop (27.8 mm) corn silage diets, and total tract NDF digestibility was greater for cows fed long chop (39.7 mm) corn silage diets. The opposing effect of total tract starch and fiber digestibilities between chop lengths may have contributed to the lack of difference in energy content of the diets in experiment 2. The TDN and NEL concentrations of the processed corn silage diets were greater than the unprocessed corn silage diets in experiment 1. The increase in energy concentration for the processed corn silage diet was due to greater total tract digestibility of organic matter and ether extract. Total tract starch digestibility was greater, and total tract NDF digestibility was lower for cows fed processed corn silage diets than unprocessed corn silage diets in experiment 2. The opposing effect of total tract starch and fiber digestibilities between processed and unprocessed corn silage may have contributed to the lack of difference in energy content of the diets.

Animal Feed↗

PubMed2003

Corn silage management: effects of hybrid, maturity, inoculation, and mechanical processing on fermentation characteristics.

Two experiments were conducted to evaluate the effects of hybrid, maturity, mechanical processing, and inoculation of corn silage on fermentation characteristics. In experiment 1, Pioneer hybrid 3845 corn silage was harvested at three maturities (hard dough, one-third milkline, two-thirds milkline). In experiment 2, Pioneer hybrids 3845 and Quanta were harvested at three maturities (one-third milkline, two-thirds milkline, and blackline). In both experiments, corn silage was harvested at each maturity with and without mechanical processing and with and without inoculation. In experiments 1 and 2, corn silage was harvested at a theoretical length-of-cut of 6.4 and 12.7 mm, respectively. Maturity at harvest tended to have a greater impact on silage fermentation characteristics of corn silage than mechanical processing and inoculation. In experiments 1 and 2, corn silage harvested at the earliest maturity tended to have decreased dry matter content and increased water-soluble carbohydrate concentrations during the ensiling process than corn silage harvested at advanced maturities. In experiment 2, pH levels were lower for corn silage harvested at the early maturity (one-third milkline) compared with advanced maturities (two-thirds milkline and blackline) by 57 d after ensiling. The difference in pH can be explained by the greater concentration of water-soluble carbohydrates at the early maturity (one-third ML) soon after ensiling (2, 3, 6 and 10 d after ensiling) compared with advanced maturities (two-thirds ML and BL). The increased water-soluble carbohydrate concentrations in the less mature corn silage provided nutrients for bacteria to grow and produce primarily lactic acid (6, 10, and 57 d after ensiling) and some acetic acid (2, 3, 6, and 10 d after ensiling) which reduced the pH of corn silage more than at the advanced maturities. There was a slight change in silage fermentation characteristics when corn silage was inoculated with Pioneer 1132 inoculant in experiment 1. The inoculated corn silage had increased temperature, lactate and acetate concentrations, and lower water-soluble carbohydrate and pH levels compared with uninoculated corn silage. Dry matter recovery tended to be greater for processed corn silage in experiment 1, and greater for unprocessed corn silage in experiment 2. It appears that when fermentation was greater (increased temperature and lactate concentration 57 d after ensiling) the dry matter recovery was lower.

Acetic Acid↗

PubMed2003

Factors affecting application of milk allantoin as an estimator of microbial protein flow to the duodenum under commercial conditions.

Three experiments were conducted to determine the effect of diet change, milk sampling technique, and bovine somatotropin (bST) on allantoin output in milk and the use of allantoin as a practical, noninvasive method for estimating microbial protein flow in dairy cattle. In experiment 1, four lactating Holstein cows were used in a 2 x 2 Latin square design with two treatments (ratio of forage to concentrate) and two periods. In experiment 2, six Holstein cows were used in a completely randomized design, and milk was collected by 1) a strip sample collected immediately before milking, 2) a strip sample collected 3 min from start of milking, and 3) a composite sample taken with an autosampler. In experiment three, 10 cows were used in a randomized block design to determine the effect of bST on milk allantoin. Milk samples were taken daily for 21 d, 7 d before, and 14 d after bST administration. In experiment 1, allantoin output (mmol/d) was significantly greater for cows fed the higher ratio of concentrate to forage, and there was a significant change in the amount of allantoin in milk 12 h (first subsequent milking) after a diet change. There was no difference in milk yield or dry matter intake between treatments. In experiment 2, no difference was detected in milk allantoin concentration among the three sampling methods. In experiment 3, milk yield, allantoin concentration, and total allantoin output was significantly increased after bST administration even though dry matter intake (DMI) remained unchanged. During the first 14 d following bST administration, estimates of microbial protein production derived from milk allantoin may be inaccurate due to increased milk production without an increase in DMI.

Allantoin↗

PubMed2003

Corn silage management: effects of hybrid, maturity, chop length, and mechanical processing on rate and extent of digestion.

Five experiments were conducted to evaluate the effects of hybrid, chop length, maturity, and mechanical processing of corn silage on dry matter and nutrient disappearance in the rumen. Corn silage that had not been dried or ground was incubated in macro in situ bags (30 x 35 cm) for 8, 16, 24,48, and 96 h. Experiments la and 2 evaluated the effects of maturity and mechanical processing for two corn silage hybrids harvested at two theoretical lengths-of-cut. Experiments 3 through 5 evaluated the effects of chop length and mechanical processing for two corn silage hybrids harvested at two-thirds milkline. The hybrid with low neutral fiber (NDF) concentrations had greater dry matter and starch disappearance than the hybrid with high NDF concentrations. The effect of chop length on nutrient disappearance was variable across experiments 3 through 5. Processing improved dry matter disappearance in experiments la, 2 (two-thirds milkline and blackline), 3, 4, and 5 at the majority of ruminal incubation timepoints. Starch disappearance was greater for unprocessed corn silage in experiment la (hard dough and two-thirds milkline) and was greater for processed corn silage in experiments 2 and 5. However, there was no consistent trend in starch disappearance between processed and unprocessed corn silage in experiments 3 and 4. This can be partially explained by the high disappearance of starch (experiment 3, > or = 98% and experiment 4, > or = 94%) by 24 h of ruminal incubation. Minimal differences were detected in NDF disappearance between processed and unprocessed corn silage across maturities. In experiments 2 and 5, crude protein disappearance was improved due to processing at some incubation timepoints. Rate of dry matter, starch (one-third milkline and two-thirds milkline), and NDF disappearance tended to increase when corn silage was mechanically processed in experiment 2. Dry matter, starch, and crude protein disappearance tended to be greater for corn silage harvested at the early maturity (one-third milkline) in experiment 2 compared with advanced maturities (two-thirds milkline and blackline). Disappearance of NDF was greater at early maturities compared with advanced maturities in experiments 1a and 2. Rate of dry matter (hybrid 3845), starch, and NDF (hybrid 3845) disappearance tended to decrease as maturity advanced from one-third milkline to blackline in experiment 2. These results suggest that the macro in situ method can be used to evaluate nutrient disappearance in the rumen.

Animals↗

PubMed2002

Corn silage management: effects of maturity, inoculation, and mechanical processing on pack density and aerobic stability.

Three experiments were conducted to evaluate the effects of inoculation, maturity, and mechanical processing of corn silage on aerobic stability and pack density. Corn silage was stored in 20-L mini silos for the three aerobic stability experiments. Corn silage was stored in 80-L mini silos for the three pack-density experiments. The wet pack density of corn silage tended to decrease as maturity advanced in all of the pack-density experiments, and processed corn silage had a greater wet pack density compared with unprocessed corn silage in two of the three 20-L mini silo experiments. Aerobic stability, measured as the number of hours to reach 1.7 degrees C above ambient, was greater for processed corn silage in two of the three 20-L mini silo experiments, and was greater for inoculated corn silage across the three 20-L mini silo experiments. Inoculation of corn silage with lactic acid producing bacteria tended to improve aerobic stability of corn silage more than maturity and mechanical processing.

Aerobiosis↗

PubMed2002

Corn silage management I: effects of hybrid, maturity, and mechanical processing on chemical and physical characteristics.

Two experiments were conducted to evaluate the effects of hybrid, maturity, and mechanical processing of whole plant corn on chemical and physical characteristics, particle size, pack density, and dry matter recovery. In the first experiment, hybrid 3845 whole plant corn was harvested at hard dough, one-third milkline, and two-thirds milkline with a theoretical length-of-cut of 6.4 mm. In the second experiment, hybrids 3845 and Quanta were harvested at one-third milkline, two-thirds milkline, and blackline stages of maturity with a theoretical length-of-cut of 12.7 mm. At each stage of maturity, corn was harvested with and without mechanical processing by using a John Deere 5830 harvester with an onboard kernel processor. The percentage of intact corn kernels present in unprocessed corn silage explained 62% of variation in total tract starch digestibility. As the amount of intact kernels increased, total tract starch digestibility decreased. Post-ensiled vitreousness of corn kernels within the corn silage explained 31 and 48% of the variation of total tract starch digestibility for processed and unprocessed treatments, respectively. For a given amount of vitreous starch in corn kernels, total tract starch digestibility was lower for cows fed unprocessed corn silage compared with processed corn silage. This suggests that processing corn silage disrupts the dense protein matrix within the corn kernel where starch is embedded, therefore making the starch more available for digestion. Particle size of corn silage and orts that contained corn silage was reduced when it was processed. Wet pack density was greater for processed compared with unprocessed corn silage.

Animal Feed↗

PubMed2002

Corn silage management II: effects of hybrid, maturity, and mechanical processing on digestion and energy content.

Two experiments were conducted to evaluate the effects of maturity and mechanical processing of two hybrids of whole plant corn on starch, fiber, and ether extract digestibilities and energy content of the total mixed ration fed to lactating Holstein cows. In the first experiment, Pioneer hybrid 3845 whole plant corn was harvested at hard dough, one-third milkline, and two-thirds milkline with a theoretical length of cut of 6.4 mm. At each stage of maturity, corn was harvested with and without mechanical processing. In the second experiment, Pioneer hybrids 3845 and Quanta were harvested at one-third milkline, two-thirds milkline, and blackline stages of maturity with and without mechanical processing. The theoretical length of cut was 12.7 mm. The measured TDN and NEL concentrations were lower for diets containing processed corn silage in experiment 1 and greater for diets containing processed corn silage in experiment 2, compared with diets containing unprocessed corn silage. The lower energy content for diets containing processed corn silage in experiment 1 can be explained by the lower total tract NDF, ether extract, and CP digestibilities. The greater energy content for diets containing processed corn silage in experiment 2 can be attributed to greater total tract starch and NDF digestibilities for cows fed processed corn silage diets. In experiment 2, diets containing processed corn silage (1.59 Mcal/kg) had approximately 2.6% more energy available per kilogram of DM consumed compared with diets containing unprocessed corn silage (1.55 Mcal/kg). For hybrid Quanta in experiment 2, the TDN and NEL concentrations of diets containing corn silage harvested at two-thirds ML were greater than at other maturities.

Animal Nutritional Physiological Phenomena↗

PubMed2002

Corn silage management III: effects of hybrid, maturity, and processing on nitrogen metabolism and ruminal fermentation.

Two experiments were conducted to evaluate the effects of maturity and mechanical processing of two hybrids of whole plant corn silage on DM and OM digestibility, nitrogen metabolism, ruminal fermentation, and milk production and composition in lactating Holstein cows. In the first experiment, Pioneer hybrid 3845 whole plant corn was harvested at hard dough, one-third milkline, and two-thirds milkline with a theoretical length-of-cut of 6.4 mm. At each stage of maturity, corn was harvested with (1-mm roll clearance) and without (15.9-mm roll clearance) mechanical processing using a John Deere 5830 harvester with an on-board kernel processor. In the second experiment, Pioneer hybrids 3845 and Quanta were harvested at one-third milkline, two-thirds milkline, and blackline stages of maturity with and without mechanical processing. The theoretical length-of-cut was 12.7 mm. Total tract DM and OM digestibilities were lower for cows fed diets containing processed corn silage in experiment 1, and tended to be lower for cows fed diets containing unprocessed corn silage in experiment 2. Ruminal acetate concentrations were greater and ruminal propionate concentrations were lower 2 and 6 h after feeding for cows fed diets containing corn silage harvested at physiological maturity in experiment 2. This was due to decreased digestion of starch at advanced maturities in experiment 2. Ruminal pH tended to decline rapidly after feeding for cows fed hybrid Quanta (2 h) compared to hybrid 3845 (5 h) corn silage based diets. Ruminal acetate concentrations decreased and ruminal propionate concentrations increased 2 and 6 h after feeding for cows fed diets containing hybrid Quanta corn silage compared to hybrid 3845 corn silage. This was related to a greater starch concentration in the corn silage, greater starch intake, and increased rate of starch digestion for cows fed hybrid Quanta corn silage-based diets. Microbial nitrogen flow was lower and feed nitrogen flow was greater for cows fed diets containing hybrid Quanta corn silage. The lower microbial nitrogen flow was due to lower microbial nitrogen concentration and nonammonia nitrogen flow to the duodenum. Milk fat and protein concentrations had a strong quadratic relationship with forage NDF intake as a percentage of body weight. When forage NDF intake as a percentage of body weight dropped below 0.70%, there was a rapid decline in milk fat and protein concentrations.

Animals↗

PubMed2001

Effect of hybrid, maturity, and mechanical processing of corn silage on intake and digestibility by beef cattle.

A study involving a 2 x 2 x 2 factorial arrangement of treatments was conducted to evaluate effects of hybrid (Pioneer 3335 and 3489), maturity (half milkline and blacklayer), and mechanical processing (field chopper with and without on-board rollers engaged) on intake and digestibility of corn silage. Forty Angus steers (322 +/- 5.2 kg BW) were assigned to the eight silage treatments (five steers per treatment) and individually fed using electronic gates. Diets consisted of 60% corn silage and 40% chopped alfalfa hay (DM basis). Following a 5-d adaptation period, intake was measured for 7 d and subsequently fecal samples were collected for 5 d. Chromic oxide (5 g/d) was fed beginning 7 d before fecal sample collection and digestibility was determined by the ratio of Cr in the feed and feces. Steers were reallocated to treatments and these procedures were repeated, providing 10 observations per treatment. In addition, all silages were ruminally incubated in six mature cows for 0, 8, 16, 24, 48, and 96 h to determine extent and rate of DM, starch, NDF, and ADF disappearance. Processing increased DMI of hybrid 3489 but did not affect DMI of hybrid 3335 (hybrid x processing; P < 0.06). Total tract digestibility of DM, starch, NDF, and ADF decreased (P < 0.01) as plant maturity increased. Maturity tended to decrease starch digestibility more for hybrid 3489 than for hybrid 3335 (hybrid x maturity; P < 0.10). Processing increased (P < 0.01) starch digestibility but decreased (P < 0.01) NDF and ADF digestibility, resulting in no processing effect on DM digestibility. There was a numerical trend for processing to increase starch digestibility more for latethan for early-maturity corn silage (maturity x processing; P = 0.11). Processing increased in situ rates of DM and starch disappearance and maturity decreased in situ disappearance rates of starch and fiber. These data indicate that hybrid, maturity, and processing all affect corn silage digestibility. Mechanical processing of corn silage increased starch digestibility, which may have been associated with the observed decreased fiber digestibility.

Adaptation, Physiological↗

PubMed2000

The effects in humans of rapid loss of body mass on a boxing-related task.

The physiological effects of strategies for a rapid loss of body mass immediately before weighing-in for competition in weight-governed sports are unclear. This study examined the effects of a 3%-4% loss in body mass on a boxing-related task. Seven novice amateur boxers completed three 3 min rounds of simulated boxing on a prototype boxing ergometer in an euhydrated state (E-trial) and after exercise-induced thermal dehydration (D-trial). All subjects lost body mass following dehydration-mean body mass fell 3.8 (SD +/- 0.3)% [77.3 (SD +/- 11.3) to 74.4 (SD +/- 10.7) kg, P<0.001] - but changes in plasma volume (PV) were inconsistent. Four subjects suffered reductions in PV between 15% and 30%, one subject maintained his E-trial value and two recorded an increase. The D-trial mean PV value was 8.0 (SD +/- 17.2)% lower but this fall was not statistically significant (P>0.05). Analysis of D-trial boxing performance showed one subject maintained his performance over the two trials and a second improved 17.8%. A two-way ANOVA (condition x time) with repeated measures on both factors showed no significant main effect differences for condition (F1,6 = 3.93 P>0.05), time (F1.83,48 = 1.12, P>0.05) or interaction between them (F1.93,48, P>0.05). Furthermore, neither heart rate nor blood lactate responses in the boxing task differed between trials. These data were affected by the small sample. Power and effect size analysis using eta(2) procedure and removing the outlier data produced a mean fall in boxing performance of 26.8%. However, some subjects appeared able to resist the deleterious effects of a rapid loss of body mass prior to competition and further research is needed to explain the mechanisms under-pinning this ability.

Adult↗

PubMed2000

Estimation of the flow of microbial nitrogen to the duodenum using milk uric acid or allantoin.

Data were collected from 10 experiments with duodenally cannulated Holstein dairy cows (271 combinations of cow and period) to evaluate the relationship between milk purine metabolites and microbial nitrogen flow. Experiments evaluated the effects of dietary factors on microbial N production and included: 1) supplemental sources of ruminally protected amino acids; 2) grass silage treated with fibrolytic enzymes; 3) bacterial inoculation of corn silage; 4) a comparison of corn and barley grain; 5) ruminal starch availability as affected by corn silages of varying maturity; and, 6) ruminal starch availability as affected by corn silages harvested at varying chop length and with or without mechanical processing. The coefficient of determination for individual experiments for the relationship between microbial nitrogen flow and allantoin or uric acid excretion in milk ranged from -0.01 to 0.77 and -0.06 to 0.22 respectively. Across all experiments, the coefficients of determination between microbial nitrogen flow and allantoin or uric acid excretion in milk were r2 = 0.09 and 0.01 respectively. Milk allantoin output was used to develop a prediction equation estimating microbial nitrogen flow to the duodenum. The greatest predictive value (r2 = 0.25) relationship was observed across non-bST experiments and included the factors of allantoin excretion, milk yield, dry matter intake, and days in milk. When milk yield was included in the model, the predictive value improved (r2 = 0.44). Based on these data, milk uric acid excretion alone cannot be used to predict microbial N production accurately [corrected].

Allantoin↗

PubMed1999

Bone density and antiepileptic drugs: a case-controlled study.

This case-controlled study explored the relationship between bone mineral density (BMD) and long-term treatment with antiepileptic drugs (AEDs) in older adults with epilepsy. Seventy-eight patients (47 post-menopausal females, 31 males, aged 47-76 years) with epilepsy participated in the study. Each had only ever received treatment with either enzyme-inducing (n = 52) or non-inducing (n = 26) AEDs. Individuals were matched for age, sex, height and weight with a drug-naive control. All patients underwent bone densitometry at the lumbar spine and femoral neck and had blood sampling and urine collected for a range of bone markers. Male patients had lower BMD than controls at the lumbar spine (P < 0.01) and neck of the femur (P < 0.005). Female patients had significantly reduced bone density at the femoral neck (P < 0.05) only. AED usage was independently associated with an overall reduction in bone density at femoral sites and contributed to just over 5% of the variance at the femoral neck. Duration of treatment and type of AED were not independent factors for reduction in BMD. This case-controlled study supports the hypothesis that long-term AED therapy is an independent risk factor for reduced BMD in epileptic patients. Adults receiving treatment for epilepsy are at higher risk of osteoporosis and should be offered bone densitometry.

Adult↗

PubMed1999

Nutritive value of corn silage as affected by maturity and mechanical processing: a contemporary review.

Stage of maturity at harvest and mechanical processing affect the nutritive value of corn silage. The change in nutritive value of corn silage as maturity advances can be measured by animal digestion and macro in situ degradation studies among other methods. Predictive equations using climatic data, vitreousness of corn grain in corn silage, starch reactivity, gelatinization enthalpy, dry matter (DM) of corn grain in corn silage, and DM of corn silage can be used to estimate starch digestibility of corn silage. Whole plant corn silage can be mechanically processed either pre- or postensiling with a kernel processor mounted on a forage harvester, a recutter screen on a forage harvester, or a stationary roller mill. Mechanical processing of corn silage can improve ensiling characteristics, reduce DM losses during ensiling, and improve starch and fiber digestion as a result of fracturing the corn kernels and crushing and shearing the stover and cobs. Improvements in milk production have ranged from 0.2 to 2.0 kg/d when cows were fed mechanically processed corn silage. A consistent improvement in milk protein yield has also been observed when mechanically processed corn silage has been fed. With the advent of mechanical processors, alternative strategies are evident for corn silage management, such as a longer harvest window.

Animals↗

PubMed1999

A dairy herd model for use in whole farm simulations.

A dairy herd submodel was created for integration with other farm submodels to form DAFOSYM, a dairy farm simulation model. The herd submodel determines the best mix of available feeds to meet the fiber, energy, and protein requirements for each of six animal groups. The groups are early-, mid-, late-, and nonlactating cows, heifers over 1 yr old, and younger heifers. Feed intake, milk production, and manure dry matter and nutrient (N, P, and K) excretions are functions of the nutrient content of the diets. Required feed characteristics include crude protein, rumen degradable protein, acid detergent insoluble protein, net energy of lactation, neutral detergent fiber, total digestible nutrients, P, and K concentrations. Feed intake is predicted with fill and roughage units. These units are functions of feed neutral detergent fiber adjusted for particle size distribution and the relative rate of ruminal digestibility or physical effectiveness of the fiber. The herd submodel predicted feed intakes, nutrient requirements, diets, and manure excretions similar to those recommended or measured for dairy animals. When integrated with other farm components in DAFOSYM, the comprehensive model provides a useful tool for evaluating the long-term performance and economics of alternative dairy farm systems.

Animal Feed↗