Household aggregation of Staphylococcus aureus by clonal complex and methicillin resistance profiles in Starr County, Texas.

Staphylococcus aureus is one of the most common causes of skin and soft tissue infections in health-care and community settings, but transmission of S. aureus in community-based populations is incompletely understood. S. aureus carriage phenotypes (persistent, intermittent, and non-carriers) were determined for households from Starr County, TX. Nasal swabs were collected from a cohort of 901 residents and screened for the presence of S. aureus. Isolated strains were spa-typed and assigned to clonal complexes. Of the 901 participants there were 134 pairs, 28 trios, 11 quartets, 3 quintets and 1 septet residing in the same household. There was a significant increase in "ever" carriers (persistent and intermittent carriers combined) in these households over that expected based on population frequencies (p = 0.029). There were 42 ever carrier pairs of individuals with 21 concordant for clonal complex type whereas only 4.7 were expected to be so (p = 6.9E-11). These results demonstrated clear aggregation of S. aureus carriage and concordance for strain types within households. As antibiotic-resistant S. aureus strains increase in community settings, it is important to better understand risk factors for colonization, mechanisms of transmission, clonal complexes present, and the role of household concordance/transmission.

Impact of genetic dynamics and single-cell heterogeneity on development of nonstandard personalized medicine strategies for cancer.

Cancers are heterogeneous and genetically unstable. Current practice of personalized medicine tailors therapy to heterogeneity between cancers of the same organ type. However, it does not yet systematically address heterogeneity at the single-cell level within a single individual's cancer or the dynamic nature of cancer due to genetic and epigenetic change as well as transient functional changes. We have developed a mathematical model of personalized cancer therapy incorporating genetic evolutionary dynamics and single-cell heterogeneity, and have examined simulated clinical outcomes. Analyses of an illustrative case and a virtual clinical trial of over 3 million evaluable "patients" demonstrate that augmented (and sometimes counterintuitive) nonstandard personalized medicine strategies may lead to superior patient outcomes compared with the current personalized medicine approach. Current personalized medicine matches therapy to a tumor molecular profile at diagnosis and at tumor relapse or progression, generally focusing on the average, static, and current properties of the sample. Nonstandard strategies also consider minor subclones, dynamics, and predicted future tumor states. Our methods allow systematic study and evaluation of nonstandard personalized medicine strategies. These findings may, in turn, suggest global adjustments and enhancements to translational oncology research paradigms.

First observation of edge localized modes mitigation with resonant and nonresonant magnetic perturbations in ASDEX Upgrade.

First experiments with nonaxisymmetric magnetic perturbations, toroidal mode number n=2, produced by newly installed in-vessel saddle coils in the ASDEX Upgrade tokamak show significant reduction of plasma energy loss and peak divertor power load associated with type-I edge localized modes (ELMs) in high-confinement mode plasmas. ELM mitigation is observed above an edge density threshold and is obtained both with magnetic perturbations that are resonant and not resonant with the edge safety factor profile. Compared with unperturbed type-I ELMy reference plasmas, plasmas with mitigated ELMs show similar confinement, similar plasma density, and lower tungsten impurity concentration.

Efficacy of mineral supplementation to growing cattle grazing winter-wheat pasture in northwestern Oklahoma.

Two experiments were conducted to evaluate the efficacy of mineral supplementation to cattle grazing winter-wheat pasture. In experiment 1 (fall), 120 steers and heifers (body weight [BW] = 232 ± 11.4 kg) were assigned randomly to four blocks of replicated pastures during the second week of November in 2008 and 2009 and all herds (6 animals/pasture; 4.9 ha/pasture) were allowed to graze for 84 d. In experiment 2 (spring), 216 steers (BW = 248 ± 7.9 kg) were assigned randomly to five blocks of replicated pastures during the second week of February in 2009 and 2010 and all herds (12 or 6 animals/pasture; 4.9 ha/pasture) were allowed to graze for 84 d. Half the pastures in both experiments received a free-choice mineral mixture (Wheat Pasture Pro; Land O'Lakes Purina Feed, LLC; St. Paul, MN; Ca, 16% and P, 4%); mineral feeders were weighed weekly to determine mineral intake. All pastures were planted in early September of each year (67 kg of seed/ha) and fertilized with 50 kg of urea-N/ha. Standing herbage dry matter was determined midway between weigh dates by clipping wheat forage to the ground along 122 cm of drill rows at 10 locations/pasture. Data were analyzed by ANOVA, with treatment as the fixed effect and pasture, animal sex (experiment 1), and block as random effects. In experiment 1, cattle offered minerals had a 43% faster average daily gain (ADG; P = 0.02, 0.73 kg) than cattle not offered minerals (0.51 kg); hence, supplemented cattle weighed 6% more (P = 0.04; 286 kg) after 84 d than nonsupplemented cattle (271 kg). In experiment 2, cattle offered the mineral supplement had a faster ADG (20% increase; P = 0.04; 1.00 kg) than cattle not offered minerals (0.83 kg). Further, supplemented cattle weighed 4% more (P = 0.03; 326 kg) after 84 d than nonsupplemented cattle (312 kg). In both experiments, daily standing herbage dry matter averaged 1,381 kg/animal and never differed (P ≥ 0.47) between treatments. Mineral intakes averaged 135 (experiment 1) and 124 (experiment 2) g/d, resulting in a cost of supplement to kilogram of added BW gain of $0.53 and $0.64, respectively (assuming a mineral cost of $0.88/kg). Overall, supplementing an appropriate mineral mixture to cattle grazing winter-wheat pasture increased ADG in a cost-effective manner.

Sylvatic Transmission of Trypanosoma cruzi Among Domestic and Wildlife Reservoirs in Texas, USA: A Review of the Historical Literature.

Chagas disease (Trypanosoma cruzi infection) is one of the most important neglected tropical diseases affecting the Americas. The transmission dynamic of this parasite is a complicated process that involves three genera of Triatominae subfamily and over 100 known mammalian reservoirs composed of domestic, peridomestic and wildlife species. Understanding the complex relationship between vector species and mammalian hosts is important for preventing transmission to humans. We performed a historical literature review to assess the disease burden in the Texas wildlife and domestic animal population. Reports of sylvatic transmission in Texas date back to the 1940s. We found that up to 23 species can serve as reservoirs for T. cruzi in the state with wood rats, raccoons, and wild and domestic canine species most frequently reported as positive for the parasite. We finish with a discussion of the current research gaps, implications for high-risk populations and future directions for research.

Autochthonous Chagas disease in the southern United States: A case report of suspected residential and military exposures.

Chagas disease is a parasitic infection that can result in a progressive dilated cardiomyopathy. Here, we present the epidemiologic details of a suspected locally acquired transmission case originating from the southern United States. This is the first published report of Chagas disease in a young, healthy United States veteran with repeat triatomine exposures in Arizona. Military personnel and Arizona residents should be aware of their Chagas disease transmission risks.

Forage choice in pasturelands: Influence on cattle foraging behavior and performance.

We determined if combinations of adjacent pastures of 3 forage species led to complementary relationships that influenced animal behavior and performance over monocultures. Grazing bouts, behavioral levels of activity, blood urea N (BUN), chemical composition of feces, BW, and herbage biomass before and after grazing were monitored when beef calves strip-grazed 3 replications of 4 treatments from June 14 through August 23, 2013 (9 animals/treatment). Animals grazed monocultures of: 1) tall fescue (TF), 2) alfalfa (ALF), 3) sainfoin (SAN), or 4) a choice of strips of forages TF, ALF, and SAN (CHOICE). The lowest and greatest incidence of foraging bouts occurred for cattle in CHOICE and SAN, respectively (P < 0.01). Animals in CHOICE grazed SAN > ALF > TF (P < 0.01). Animals on TF and CHOICE took greater number of steps than animals grazing a monocultures of either legume (P = 0.01). Calves in TF had lower BUN (P < 0.01) and fecal CP concentration (P < 0.01) than calves grazing the remaining treatments, whereas animals in SAN showed the greatest concentrations of fecal CP (P < 0.01). Fecal NDF concentration was the greatest for animals grazing TF and the lowest for animals grazing SAN (P < 0.01), whereas fecal ADF concentration was greater for animals grazing TF and SAN than for animals grazing CHOICE and ALF (P = 0.02). Calcium, Mg, and Zn concentrations were the lowest in feces from calves grazing TF and the greatest for calves grazing a monoculture of either legume (P < 0.05). When averaging both periods, animals grazing SAN, ALF, or CHOICE gained more BW than animals grazing TF (P < 0.01). Thus, calves in CHOICE incorporated tall fescue into their diets, were more active, and displayed a lower number of grazing bouts than calves grazing monoculture of either legume. Herbage diversity may lead to levels of ADG comparable to legume monocultures with the potential benefit of maintaining plant species diversity in pasturelands.

Complete suppression of neoclassical tearing modes with current drive at the electron-cyclotron-resonance frequency in ASDEX upgrade tokamak

Noninductive current drive has been performed in the tokamak ASDEX upgrade by injection of radiofrequency waves at the second harmonic of the electron-cyclotron frequency in order to suppress unwanted disturbances of the magnetic-field configuration. The current has been driven parallel [co-electron cyclotron current drive (ECCD)] and antiparallel (counter-ECCD) to the plasma current to compare the effect of heating with direct current drive in the magnetic island. For the first time it has been shown experimentally that total stabilization of neoclassical tearing modes is possible with co-ECCD. The experiments verify the role of direct current drive as opposed to local heating.

Simultaneous attainment of high electron and ion temperatures in discharges with internal transport barriers in ASDEX upgrade

Internal transport barriers have been demonstrated to exist also under conditions with T(e) approximately T(i) approximately 10 keV and predominant electron heating of the tokamak core region. Central electron cyclotron heating was added to neutral beam injection-heated ASDEX Upgrade discharges with a preexisting internal transport barrier, established through programmed current ramping leading to shear reversal. Compared to a reference internal transport barrier discharge without electron cyclotron resonance heating, the electron heat conductivity in the barrier region was found not to increase, in spite of a fivefold increase in electron heat flux, and also angular momentum and ion energy transport did not deteriorate.

Atypical endogenous opioid systems in mice in relation to an auto-addiction opioid model of anorexia nervosa.

We have proposed that the atypical opioid system in the mouse may be representative of that in the anorexia nervosa patient and may account for a biological predisposition to the disorder. This is in the context of our auto-addiction model of anorexia nervosa in which endogenous opioids play a critical role in its etiology. Morphine activation of the endogenous opioid systems increases food intake and causes sedation in most species, including normal humans and rats. In contrast in BALB/C mice, morphine causes anorexia and hyperactivity, which we suggest may be true in the anorexia nervosa patient. A variety of atypical opioid systems have been demonstrated in different mouse strains, based on other responses. The present study examines these strains with reference to the responses relevant to our anorexia nervosa model. Three patterns are described--anorexia with hyperactivity (BALB/C and C57BL/6J mice), anorexia without hyperactivity (DBA/J mice), and a biphasic curve with hyperphagia at low doses and anorexia and hyperactivity at higher doses (CF-1 mice). Only female mice were used. These atypical opioid systems may reflect a spectrum of biological predispositions to the disorder. These strain differences may also provide useful correlations of the genetic determinants of various opiate responses and provide useful comparisons in characterizing the essential features responsible for the atypical responses.

Quantitation of acetaminophen and salicylic acid in plasma using capillary electrophoresis without sample pretreatment. Improvement of precision.

Capillary electrophoresis has become one of the most attractive techniques in the analysis of biological samples. Pharmaceuticals in human plasma can easily be determined on uncoated fused-silica capillaries without any sample pretreatment. Intra- and inter-day precision values of about 1-2% R.S.D. (n = 20) and 2-3% R.S.D. (n > 80) respectively are obtained using a sodium dodecyl sulfate-containing borate buffer, pH 10 and acetonitrile as a between-run rinsing reagent. This method is highly robust, no breakdowns of the current or capillary blockings were observed for several weeks. The general applicability is demonstrated for several model drugs. The effectiveness of other rinsing procedures including enzyme-containing solutions, different organic solvents and hydrofluoric acid is discussed.

Effects of arrival medication with tilmicosin phosphate on health and performance of newly received beef cattle.

Three trials were conducted to evaluate the use of tilmicosin phosphate (Micotil) as a prophylactic medication for newly received, stressed beef cattle. In Trial 1, 57 beef calves (average initial BW = 170 kg) were shipped to the research feedlot from Tennessee and either given no antibiotic at processing or treated with Micotil at 10 mg of tilmicosin phosphate/kg of BW. During a 28-d receiving period, treatment at processing with Micotil did not affect daily gain (P < .17) or DMI (P < .22) compared to control calves. Prophylactic treatment with Micotil decreased (P < .01) the percentage of calves treated for symptoms of bovine respiratory disease from 46.4 to 0%. In Trial 2, 117 calves (average initial BW = 191 kg) were shipped from Tennessee and allotted randomly to the same two treatments as in Trial 1. All calves grazed a 24-ha pasture of irrigated winter wheat during the 28-d receiving period. Treatment of calves with Micotil at the time of arrival processing did not affect (P > .50) daily gain during the trial; however, as in Trial 1, mass treatment with Micotil decreased (P < .01) the percentage of calves treated for respiratory disease from 32.8% to 12.1%. In Trial 3, two truckloads of beef calves (183 total; average initial BW = 232 kg) shipped from Tennessee were allotted randomly to the same two treatments used in Trials 1 and 2 or to a third treatment that consisted of administration of Micotil at arrival processing if the rectal temperature of the calf was > or = 39.7 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Forage intake by and site and extent of digestion in beef cattle grazing midgrass prairie rangeland or plains bluestem pasture throughout the summer.

Eight beef steers fitted with esophageal (four steers/pasture) and 12 beef calves fitted ruminal and duodenal (six calves/pasture; beginning BW = 267 +/- 6 kg) cannulas grazed either midgrass prairie rangeland (excellent range condition; MIDGRASS) or plains bluestem (Bothriochloa ischaemum var. Plains) pasture (BLUESTEM) during mid-May, late June, mid-August, and mid-October of 1990 and 1991 in order to compare nutrient intake and digestion. Forage OM intake (OMI) by cattle grazing MIDGRASS or BLUESTEM was similar (P > .05) in June and August. In May and October, cattle grazing MIDGRASS consumed more (P < .05) OM than cattle grazing BLUESTEM. The extent of true ruminal OM digestion was similar (P > .05) between forage types except in October 1991, when the extent of digestion for BLUESTEM was greater (P < .05) than for MIDGRASS. The N intake by cattle interacted by year and forage (P < .05). Nitrogen intake by cattle grazing MIDGRASS tended to be lower in June and August than in May and October. The N intake by cattle grazing BLUESTEM peaked (P < .05) in August during 1990; however, N intake was lowest (P < .05) in August during 1991. Duodenal non-ammonia N (NAN) flow was higher (P < .05) in cattle grazing BLUESTEM than in cattle grazing MIDGRASS from May through August; however, duodenal NAN flow in cattle grazing BLUESTEM was lower (P < .05) in October 1991. Duodenal microbial N synthesis (grams/day) responded quadratically (P < .05) to total ruminal OM digestion (kilograms/day). Extent of true ruminal N digestion of both forages decreased (P < .05) as forage became more mature and lower in total N. Midgrass prairie seemed superior to BLUESTEM in May and October because of higher energy intakes and BLUESTEM seemed to be a good alternative to MIDGRASS during June through August, suggesting that these forages would make excellent complements. Furthermore, these data suggest that, in cattle grazing either forage, duodenal NAN flow was disproportionately high relative to energy intake.

Effects of supplementary selenium source on the performance and blood measurements in beef cows and their calves.

On December 2, 1999, 120 pregnant cows were weighed, their body condition scored, and then sorted into six groups of 20 stratified by BCS, BW, breed, and age. Groups were assigned randomly to six, 5.1-ha dormant common bermudagrass (Cynodon dactylon [L.] Pers.) pastures for 2 yr to determine the effects of supplemental Se and its source on performance and blood measurements. During the winter, each group of cows had ad libitum access to bermudagrass/dallisgrass (Paspalum dilatatum Poir.) hay plus they were allowed limited access (1 to 4 d/wk) to a 2.4-ha winter-annual paddock planted in half the pasture. Treatments were assigned randomly to pastures (two pastures per treatment), and cows had ad libitum access to one of three free-choice minerals: 1) no supplemental Se, 2) 26 mg of supplemental Se from sodium selenite/kg, and 3) 26 mg of supplemental Se from seleno-yeast/kg (designed intake = 113 g/cow daily). Data were analyzed using a mixed model; year was the random effect and treatment was the fixed effect. Selenium supplementation or its source had no effect (P > or = 0.19) on cow BW, BCS, conception rate, postpartum interval, or hay DMI. Birth date, birth weight, BW, total BW gain, mortality, and ADG of calves were not affected (P > 0.20) by Se or its source. Whole blood Se concentrations and glutathione peroxidase (GSH-Px) activity at the beginning of the trial did not differ (P > or = 0.17) between cows receiving no Se and cows supplemented with Se or between Se sources. At the beginning of the calving and breeding seasons, cows supplemented with Se had greater (P < 0.01) whole blood Se concentrations and GSH-Px activities than cows receiving no supplemental Se; cows fed selenoyeast had greater (P < or = 0.05) whole blood Se concentrations than cows fed sodium selenite, but GSH-Px did not differ (P > or = 0.60) between the two sources. At birth and on May 24 (near peak lactation), calves from cows supplemented with Se had greater (P < or = 0.06) whole blood Se concentrations than calves from cows fed no Se. At birth, calves from cows fed seleno-yeast had greater (P < or = 0.05) whole blood Se concentrations and GSH-Px activities than calves from cows fed sodium selenite. Although no differences were noted in cow and calf performance, significant increases were noted in whole blood Se concentrations and GSH-Px activities in calves at birth as a result of feeding of seleno-yeast compared to no Se or sodium selenite.

Effects of supplemental zinc concentration and source on performance, carcass characteristics, and serum values in finishing beef steers.

Three studies were conducted to examine the effects of zinc concentration or source in diets of finishing beef steers. In Exp. 1, 108 (British x Continental) beef steers were supplemented with concentrations of added zinc (as ZnSO4) at 20, 100, or 200 mg/kg of dietary DM. No differences (P > 0.10) were noted among treatments for ADG or gain:feed for the 112-d finishing period. However, a linear (P < 0.10) decrease was noted in daily DMI with increasing zinc concentrations for the overall finishing period. No differences (P > 0.10) were noted in hot carcass weight; dressing percentage; longissimus muscle area; percentage of kidney, pelvic, and heart fat; or marbling score. There were, however, quadratic increases in s.c. fat thickness (P < 0.05) and yield grade (P < 0.01) with added zinc. In Exp. 2, 12 beef steers were used to examine effects of added dietary zinc on serum concentrations of cholesterol and fatty acid profiles. No differences (P > 0.10) were observed in cholesterol or fatty acids among the supplemental zinc levels. In Exp. 3, 84 Brangus- and Angus-sired steers were fed a steam-flaked corn-based diet containing 30 mg of supplemental zinc per kilogram of dietary DM from one of the following sources: 1) ZnSO4, 2) Zn amino acid complex, or 3) a zinc polysaccharide complex. No differences (P > 0.10) were noted for the overall 126-d trial for ADG, DMI, or gain:feed ratio. Percentage kidney, pelvic, and heart fat was increased (P < 0.10) in steers supplemented with ZnSO4 vs the average of Zn amino acid and Zn polysaccharide complexes. However, s.c. fat thickness was greater (P < 0.10) in steers supplemented with Zn amino acid and Zn polysaccharide complexes vs ZnSO4. Serum zinc concentration did not differ (P > 0.10) among zinc sources. Supplemental zinc concentration in finishing diets did not seem to influence feedlot performance and had a minimal impact on carcass quality. Either the organic or inorganic source can be included in finishing diets without affecting feedlot performance.

Diet quality and ruminal digestion in beef cattle grazing midgrass prairie rangeland or plains bluestem pasture throughout the summer.

Beef cattle fitted with esophageal (four steers/pasture) or ruminal and duodenal (six calves/pasture; beginning BW +/- SE = 267 +/- 6 kg) cannulas grazed midgrass prairie rangeland (excellent range condition; MIDGRASS) or plains bluestem (Bothriochloa ischaemum var. Plains) pasture (BLUESTEM) in mid-May, late-June, mid-August, and mid-October of 1990 and 1991. Nitrogen in masticate samples collected from MIDGRASS was lowest (P < .05) in June and August across both years. The N in BLUESTEM masticate peaked (P < .05) in August 1990, but N was lowest (P < .05) in August 1991. The detergent fiber content of masticate from both forages increased (P < .05) as the grazing season advanced from May through August; fall regrowth in October occasionally resulted in a small decrease (P < .05) in fiber content. In vitro OM disappearance (IVOMD) followed a pattern similar to N content. The IVOMD of BLUESTEM masticate was greater (P < .05) than that of MIDGRASS masticate. The ruminal ammonia N concentration (milligrams/deciliter) in cattle grazing BLUESTEM (4.5) usually was greater (P < .05) than in cattle grazing MIDGRASS (3.3). In situ OM and N disappearance was greater (P < .05) from BLUESTEM masticate than from MIDGRASS masticate in May, June, and August. The ruminally degraded N:ruminally degraded OM ratio (grams/kilograms) estimated from in situ digestion suggested that cattle grazing MIDGRASS during the mid-summer of both years and BLUESTEM in August 1991 may have been marginally deficient in ruminally degraded N. Plains bluestem pasture would complement MIDGRASS by providing better quality grazing during the mid-summer.

Winter-annual pasture as a supplement for beef cows.

In each of two experiments, 120 pregnant beef cows were stratified by body condition score, BW, breed, and age, randomly divided into six groups of 20, and assigned to one of six 5.1-ha bermudagrass (Cynodon dactylon [L.] Pers.) pastures (two replicates/ treatment) in early January to evaluate the use of winter-annual pasture as a supplement. All cows in Exp. 1 and 2 had ad libitum access to bermudagrass/dallisgrass (Paspalum dilatatum Poir.) hay plus three treatments: 1) a concentrate-based supplement fed 3 d/wk, 2) limit grazing on winter-annual pasture 2 d/wk (7 hr/ d; 0.04 ha x cow(-1) x grazing d(-1)), or 3) limit grazing on winter-annual pasture 3 d/wk (7 hr/d; 0.04 ha x cow(-1) x grazing d(-1)) sod-seeded into a portion of the pasture until mid-May. The seeded portion of pastures in Exp. 1 was planted with a mixture of wheat (Triticum aestivum L.) and rye (Secale cereale L.), but annual ryegrass (Lolium multiflorum Lam.) was added to the seed mixture in Exp. 2. In mid-May, cows were blocked by treatment and the previous sorting factors, randomly assigned to six new groups of 20, and placed on the six perennial pastures until calves were weaned. Groups of cows were exposed to a bull for 60 d beginning in mid-May. In Exp. 1 and 2, limit-grazing winter-annual pasture compared to the concentrate-based supplement or limit grazing 2 vs 3 d/wk did not affect (P > 0.15) cow BW. In Exp. 1, cows limit grazed on winter-annual pasture had a lower (P = 0.05) body condition score than cows fed the concentrate-based supplement in the early spring. However, in Exp. 2, cows limit grazed on winter-annual pasture had higher (P < or = 0.07) body condition score than cows fed the concentrate-based supplement. The conception rate of cows in Exp. 1 and 2 did not differ (P > 0.22) between cows fed concentrate-based supplements and cows limit grazed on winter-annual pasture. In Exp. 2, cows limit grazed 2 d/wk tended to have a greater (P = 0.10) conception rate than cows limit grazed 3 d/wk. In Exp. 1 and 2, birth weight, total gain, BW, and ADG of calves were not affected (P > 0.15) by treatment. We conclude that wheat and rye pasture is a marginal supplement for lactating beef cows. However, cows limit grazed 2 d/wk on winter-annual pasture of wheat, rye, and annual ryegrass as a supplement maintained BW and body condition score as well as cows fed the concentrate-based supplement. But, grazing pasture 3 vs 2 d/wk did not seem to affect performance of cows.

Influence of branched-chain fatty acid supplementation on voluntary intake, site and extent of digestion, ruminal fermentation, digesta kinetics and microbial protein synthesis in beef heifers consuming grass hay.

Four heifers (British x British; average BW 372 kg) cannulated at the rumen and duodenum and consuming a grass hay (fescue-orchardgrass) diet were used in a 4 x 4 Latin square and supplemented with four levels (0, 20, 40, and 60 g.head-1.d-1) of supplemental four- and five-carbon VFA (BCFA). Forage OM, ADF, NDF and N intakes and digestibilities were not affected (P greater than .10) by BCFA supplementation. Likewise, duodenal N (microbial, feed and ammonia) flows and microbial efficiency were not altered (P greater than .10) by BCFA supplementation. Neither particulate and fluid passage rate nor in situ rate of NDF digestion was affected (P greater than .10) by treatment. Ruminal pH, ammonia concentrations and total VFA concentrations were similar (P greater than .10) among treatments. Ruminal proportions of acetate and propionate were not affected (P greater than .10) by treatment; however, butyrate responded in a cubic (P less than .05) fashion to BCFA, with the lowest proportion of butyrate at the 40 g BCFA feeding level. A time x treatment interaction (P less than .05) was noted for isobutyrate, isovalerate and valerate proportions; they were increased as a function of BCFA dosage at 2 to 8 h postdosing. Supplemental four- and five-carbon VFA had no effect on digestion and fermentation of grass hay. Supplementation of low-quality roughages with BCFA is not justified.

Thirty or sixty percent milk replacer reduction for calves: effects on alfalfa hay intake and digestibility, digestive kinetics and ruminal fermentation.

Twelve artificially reared, male Holstein calves, ruminally cannulated at 53 d of age, were used in a split-plot design to study the effects of no milk replacer reduction (CON), or reduction by 30% (30R) or 60% (60R) of this value on alfalfa hay intake and digestibility, ruminal fermentation and digestive kinetics. Milk replacer reduction began at 53 d of age and continued until 135 d of age, after which no milk replacer was fed. All calves had ad libitum access to long-stemmed alfalfa hay from birth. Five collection periods were conducted at average calf ages of 72, 87, 108, 129 and 151 d. Reducing the amount of milk replacer fed resulted in a linear increase (P less than .05) in forage OM intake; however, total OM intake (forage + milk) was not different (P greater than .10) among milk reduction groups. Size of particles in feces exhibited quadratic effects in response to milk replacer reduction (P less than .05) but only in the small (less than 150 microns) size groupings. Ruminal pH and ammonia and individual VFA concentrations (except isobutyrate) were not altered by milk reduction (P greater than .10) but increased (P less than .01) with calf age. Milk replacer reduction had a quadratic effect (P less than .05) on fluid outflow rate from the rumen, increasing as milk replacer was reduced. Other fluid and particulate kinetic data, as well as NDF digestion rate and DM digestion showed no effects (P greater than .10) from milk replacer reduction but changed with calf age. Milk replacer reduction increased forage intake but had minimal effects on digestive variables evaluated, suggesting that intake of milk replacer by calves can be reduced by up to 60% without disturbing forage fermentation and passage.

Forage intake and digestion by cattle grazing midgrass prairie rangeland or sideoats grama/sweetclover pasture.

In mid-May, beef cattle fitted with esophageal (four steers/pasture) or ruminal and duodenal cannulas (six heifers/pasture; 274 +/- 6 kg BW +/- SE) grazed midgrass prairie (excellent range condition; PRAIRIE) or a seeded mixture of sideoats grama (48% of pasture DM) and sweetclover (6% of pasture DM; Bouteloua curtipendula [Michx.] Torr./Melilotus officinalis [L.] Lam.; PASTURE). Masticate NDF, ADF, and in vitro OM disappearance did not differ (P > .11) between forage types (average = 66.6, 36.1, and 58.8% of OM). Only N differed (P = .02) between PRAIRIE (2.1) and PASTURE (2.4% of OM). Extents of in situ OM and N disappearance were greater (P < .05) and rate of N disappearance between 12 and 36 h was slower (P < .10) from PRAIRIE than from PASTURE masticate. Based on in situ data, the ruminally degraded N: ruminally degraded OM (grams/kilogram) ratio differed (P < .05) between PRAIRIE (22) and PASTURE (25). Ruminal ammonia N concentration (milligrams/deciliter) was less (P = .02) for PRAIRIE (2.8) than for PASTURE (3.8). Forage OM intake and fecal OM output did not differ (P > .72; average = 8,207 and 3,380 g/d), but duodenal OM flow tended (P = .13) to be greater (PRAIRIE = 4,892, PASTURE = 5,170 g/d) in cattle grazing PASTURE. Apparent and true ruminal OM digestion did not differ between forage types (P > .18; average = 38.3 and 48.5%). Nitrogen intake, nonammonia N, and forage N flow at the duodenum were greater (P < .04) for PASTURE (198 vs 171, 242 vs 210, and 162 vs 135 g/d) than for PRAIRIE. Microbial N flow (average = 78 g/d) and microbial efficiency (average = 20 g of microbial N/kg of OM truly fermented) did not differ (P > .25) between forage types. Apparent and true ruminal N digestion did not differ (P > .65; average = -26.6 and 19.3%) between forage types. Flow of nonammonia N was in excess relative to digestible OM intake; hence, digestible OM intake seemed to be first-limiting for performance by cattle grazing either forage type.