Evaluation of feed restriction and abomasal infusion of resistant starch as models to induce intestinal barrier dysfunction in healthy lactating cows.

Intestinal hyperpermeability and subsequent immune activation alters nutrient partitioning and thus, decreases productivity. Developing experimental models of intestinal barrier dysfunction in heathy cows is a prerequisite in identifying nutritional strategies to mitigate it. Six cannulated Holstein cows (mean ± standard deviation, 37 ± 10 kg/d milk yield; 219 ± 97 d in milk; 691 ± 70 kg body weight) were used in a replicated 3 × 3 Latin square design experiment with 21-d periods (16-d wash-out and 5-d challenge) to evaluate either feed restriction or hindgut acidosis as potential models for inducing intestinal hyperpermeability. Cows were randomly assigned to treatment sequence within square and treatment sequences were balanced for carryover effects. Treatments during the challenge were (1) control (CTR; ad libitum feeding); (2) feed restriction (FR; total mixed ration fed at 50% of ad libitum feed intake); and (3) resistant starch (RS; 500 g of resistant starch infused in abomasum once a day as a pulse-dose 30 min before morning feeding). The RS (ActiStar RT 75330, Cargill Inc.) was tapioca starch that was expected to be resistant to enzymatic digestion in the small intestine and highly fermentable in the hindgut. Blood samples were collected 4 h after feeding on d 13 and 14 of the wash-out periods (baseline data used as covariate), and on d 1, 3, and 5 of the challenge periods. Fecal samples were collected 4 and 8 h after the morning feeding on d 14 of the wash-out periods and d 5 of the challenge periods. By design, FR decreased dry matter intake (48%) relative to CTR and RS, and this resulted in marked reductions in milk and 3.5% FCM yields over time, with the most pronounced decrease occurring on d 5 of the challenge (34 and 27%, respectively). Further, FR increased somatic cell count by 115% on d 5 of the challenge relative to CTR and RS. Overall, FR increased nonesterified fatty acids (159 vs. 79 mEq/L) and decreased BHB (8.5 vs. 11.2 mg/dL), but did not change circulating glucose relative to CTR. However, RS had no effect on production or metabolism metrics. Resistant starch decreased fecal pH 8 h after the morning feeding (6.26 vs. 6.81) relative to CTR and FR. Further, RS increased circulating lipopolysaccharide binding protein (4.26 vs. 2.74 µg/mL) compared with FR only on d 1 of the challenge. Resistant starch also increased Hp (1.52 vs. 0.48 µg/mL) compared with CTR, but only on d 5 of the challenge. However, neither RS or FR affected concentrations of serum amyloid A, IL1ß, or circulating endotoxin compared with CTR. The lack of consistent responses in inflammatory biomarkers suggests that FR and RS did not meaningfully affect intestinal barrier function. Thus, future research evaluating the effects of hindgut acidosis and FR using more intense insults and direct metrics of intestinal barrier function is warranted.

Effects of hindgut acidosis on metabolism, inflammation, and production in dairy cows consuming a standard lactation diet.

Postruminal intestinal barrier dysfunction caused by excessive hindgut fermentation may be a source of peripheral inflammation in dairy cattle. Therefore, the study objectives were to evaluate the effects of isolated hindgut acidosis on metabolism, inflammation, and production in lactating dairy cows. Five rumen-cannulated lactating Holstein cows (32.6 ± 7.2 kg/d of milk yield, 242 ± 108 d in milk; 642 ± 99 kg of body weight; 1.8 ± 1.0 parity) were enrolled in a study with 2 experimental periods (P). During P1 (4 d), cows were fed ad libitum a standard lactating cow diet (26% starch dry matter) and baseline data were collected. During P2 (7 d), all cows were fed the same diet ad libitum and abomasally infused with 4 kg/d of pure corn starch (1 kg of corn starch + 1.25 L of H2O/infusion at 0600, 1200, 1800, and 0000 h). Effects of time (hour relative to the first infusion or day) relative to P1 were evaluated using PROC MIXED in SAS (version 9.4; SAS Institute Inc.). Infusing starch markedly reduced fecal pH (5.84 vs. 6.76) and increased fecal starch (2.2 to 9.6% of dry matter) relative to baseline. During P2, milk yield, milk components, energy-corrected milk yield, and voluntary dry matter intake remained unchanged. At 14 h, plasma insulin and ß-hydroxybutyrate increased (2.4-fold and 53%, respectively), whereas circulating glucose concentrations remained unaltered. Furthermore, blood urea nitrogen increased at 2 h (23%) before promptly decreasing below baseline at 14 h (13%). Nonesterified fatty acids tended to decrease from 2 to 26 h (40%). Circulating white blood cells and neutrophils increased on d 4 (36 and 73%, respectively) and somatic cell count increased on d 5 (4.8-fold). However, circulating serum amyloid A and lipopolysaccharide-binding protein concentrations were unaffected by starch infusions. Despite minor changes in postabsorptive energetics and leukocyte dynamics, abomasal starch infusions and the subsequent hindgut acidosis had little or no meaningful effects on biomarkers of immune activation or production variables.

The effects of feeding mixed tocopherol oil on whole-blood respiratory burst and neutrophil immunometabolic-related gene expression in lactating dairy cows.

The 4 major tocopherol isoforms differ in their biochemical reactivity and cellular effects due to basic chemical structural differences. Alpha-tocopherol has been well studied regarding effects on bovine polymorphonuclear leukocyte (PMN) function and its involvement in respiratory burst. However, no studies to date have identified the effects of supplementing a mixed tocopherol oil (Tmix) particularly enriched in non-α tocopherol isoforms (i.e., γ- and δ-isoforms) on fundamental immunometabolic changes in dairy cows. Therefore, the objectives of this study were to determine whether short-term feeding of vegetable oil-derived Tmix alters specific biomarkers of metabolism, whole-blood leukocyte populations, respiratory burst, immunometabolic-related gene expression of PMN, or gene expression of isolated PMN when challenged with lipopolysaccharides (LPS). Clinically healthy multiparous lactating Holstein cows (n = 12; 179 ± 17 d in milk, 40.65 ± 3.68 kg of milk yield) were fed Tmix (620 g/d) for 7 consecutive days. Jugular blood (EDTA anticoagulant) was collected from all cows on d 0 before treatment initiation and again on d 7 after Tmix feeding. Total stimulated respiratory burst activity (RBA) and leukocyte populations were assessed in whole blood, and tocopherol isoform concentrations, metabolites, and hormones were measured in plasma. For gene expression analysis, isolated PMN from cows before and after Tmix feeding were incubated with LPS at a final concentration of either 0.0 or 1.5 µg/mL. Feeding of Tmix for 7 d increased the concentrations of α- and γ-tocopherol. The Tmix did not alter plasma insulin but decreased cholesterol. The Tmix did not alter whole-blood RBA or the leukocyte populations. The LPS challenge increased the expression of proinflammatory genes TNFA and IL6. However, Tmix treatment did not alter the patterns of LPS-affected expression of genes (e.g., TNFA, ITGB2, PPARA, and RXRA) associated with the immune or metabolic response. In conclusion, short-term feeding of Tmix may have no negative effect on animal health as Tmix increased α- and γ-tocopherol concentrations in blood and did not impair whole-blood RBA or alter leukocyte populations. The data provide further support that the α- and γ-tocopherol isoforms do not interfere with normal immune or metabolic function.

The effect of preexisting hypertension on early neurologic results of patients with an acute spinal cord injury.

STUDY DESIGN: Retrospective case-control. OBJECTIVES: To characterize changes in American Spinal Injury Association Motor Score (AMS) in patients treated with relative hypertension (HTN) (mean arterial pressure (MAP) > 85 mm Hg for 5 days) with and without preexisting HTN. SETTING: A regional spinal cord injury (SCI) center in Pennsylvania, United States. METHODS: All patients with an acute SCI who were treated with induced HTN (MAP goal above 85) in the intensive care unit (ICU) for at least 5 days were identified. Patients were stratified based on the presence of preexisting HTN, and the change in the AMS between admission and day 5 was determined. Predictors of outcome were identified using correlation analysis and multiple linear regression. RESULTS: Ninety-two patients met inclusion criteria of which 22 had a previous history of HTN. HTN was a predictor of poor early outcome. Patients with HTN had an average decline in their AMS of 7.6, compared with an average decrease of only 0.6 in the AMS of patients without HTN (P=0.04). HTN had no effect (P>0.05) on other in-hospital variables including length of stay, length of stay in the ICU, complications or mortality. Additionally, multiple linear regression analysis demonstrated that diabetes, coronary artery disease and pulmonary disease had no effect on the change in AMS. CONCLUSION: Chronic HTN is an independent risk factor for poor early neurologic recovery in patients treated with relative HTN for an acute SCI. This is independent of age and other comorbidities.

Gamma knife radiosurgery for high grade glial neoplasms: a Canadian experience.

OBJECT: To review our institutional experience with Gamma Knife (GK) stereotactic radiosurgery in treating focally recurrent high grade glial neoplasms of World Health Organization (WHO) grade III or IV. METHODS: We conducted a retrospective cohort review of all patients treated with GK for focally recurrent high grade gliomas at our institution between November 2003 and April 2013. Data on age, sex, tumor volume, location and maximal diameter, presenting clinical status, complications and clinical outcome was recorded. RESULTS: A total of 33 patients were identified. Four were lost to follow-up. Average post-GK and overall survival was 20.4 months (range: 3­72) and 63.3 months (range: 10­214) respectively. For WHO grade IV gliomas, the average post-GK and overall survival was 15.8 months (range: 3­77) and 40.1 months (range: 13­148) respectively. Similarily, for WHO grade III gliomas, the average post-GK and overall survival was 34.9 months (range: 6­72) and 136.4 months (range: 22­214) respectively. Twenty-two patients (75.9%) had post-GK edema, with 14 requiring dexamethasone and eight being asymptomatic. Four patients (13.8%) had imaging defined radiation necrosis. CONCLUSIONS: Gamma Knife SRS affords an extension of local tumor control, acceptable morbidity, and potentially prolonged survival, for highly selected patients with focally recurrent high grade glial neoplasms.Radiochirurgie par scalpel gamma pour les néoplasies gliales de haut grade de malignité : une expérience canadienne.

Gamma knife in the treatment of pituitary adenomas: results of a single center.

INTRODUCTION: Gamma Knife (GK) radiosurgery for pituitary adenomas can offer a means of tumor and biologic control with acceptable risk and low complication rates. METHODS: Retrospective review of all the patients treated at our center with GK for pituitary adenomas from Nov 2003 to June 2011. RESULTS: We treated a total of 86 patients. Ten were lost to follow-up. Mean follow was 32.8 months. There were 21 (24.4%) growth hormone secreting adenomas (GH), 8 (9.3%) prolactinomas (PRL), 8 (9.3%) adrenocorticotropic hormone secreting (ACTH) adenomas, 2 (2.3%) follicle stimulating hormone/luteinizing hormone secreting (FSH/LH) adenomas, and 47 (54.7%) null cell pituitary adenomas that were treated. Average maximum tumor diameter and volume was 2.21cm and 5.41cm³, respectively. The average dose to the 50% isodose line was 14.2 Gy and 23.6 Gy for secreting and non-secreting adenomas respectively. Mean maximal optic nerve dose was 8.87 Gy. Local control rate was 75 of 76 (98.7%), for those with followup. Thirty-three (43.4%) patients experienced arrest of tumor growth, while 42 (55.2%) patients experienced tumor regression. Of the 39 patients with secreting pituitary tumors, 6 were lost to follow-up. Improved endocrine status occurred in 16 (50.0%), while 14 (43.8%) demonstrated stability of hormone status on continued pre-operative medical management. Permanent complications included: panhypopituitarism (4), hypothyroidism (4), hypocortisolemia (1), diabetes insipidus (1), apoplexy (1), visual field defect (2), and diplopia (1). CONCLUSIONS: Gamma Knife radiosurgery is a safe and effective means of achieving tumor growth control and endocrine remission/stability in pituitary adenomas.

Gamma knife radiosurgery for large vestibular schwannomas: a Canadian experience.

OBJECT: To review our institutional experience with Gamma Knife (GK) stereotactic radiosurgery in treating large vestibular schwannomas (VS) of 3 to 4 cm diameter. METHODS: We conducted a retrospective cohort review of all patients treated with GK for VS at our institution between November 2003 and March 2012. Data on age, sex, VS volume, location and maximal diameter, House-Brackmann (HB) facial nerve scores pre and post-GK, Gardner-Robertson (GR) hearing score pre and post-GK, GK treatment parameters, VS response time, complications and clinical outcome was recorded RESULTS: A total of 28 patients during the defined time period were identified. Three patients were lost to follow-up. Mean follow-up was 34.5 months. Tumor control occurred in 92%, and was maintained in 85.7% at two years. Facial nerve or hearing preservation occurred in all treated compared to pre-GK status, as per HB and GR grading. Transient complications occurred in 80%. Temporary vestibular dysfunction occurred in seven patients (28%). One patient (4%) had the permanent complication of worsening pre-GK hemifacial spasm. Four patients (16%) developed hydrocephalus post-GK. CONCLUSION: GK stereotactic radiosurgery as a primary treatment modality for large VS can provide acceptable tumor control rates with good facial nerve and hearing preservation, and low complication rates.

Gamma Knife radiosurgery of cavernous sinus meningiomas: an institutional review.

INTRODUCTION: Stereotactic radiosurgery offers a unique and effective means of controlling cavernous sinus meningiomas with a low rate of complications. METHODS: We retrospectively reviewed all cavernous sinus meningiomas treated with Gamma Knife (GK) radiosurgery between November 2003 and April 2011 at our institution. RESULTS: Thirty patients were treated, four were lost to follow- up. Presenting symptoms included: headache (9), trigeminal nerve dysesthesias/paresthesias (13), abducens nerve palsy (11), oculomotor nerve palsy (8), Horner's syndrome (2), blurred vision (9), and relative afferent pupillary defect (1). One patient was asymptomatic with documented tumor growth. Treatment planning consisted of MRI and CT in 17 of 30 patients (56.7%), the remainder were planned with MRI alone (44.3%). There were 8 males (26.7%) and 22 females (73.3%). Twelve patients had previous surgical debulking prior to radiosurgery. Average diameter and volume at time of radiosurgery was 3.4 cm and 7.9 cm3 respectively. Average dose at the 50% isodose line was 13.5 Gy. Follow-up was available in 26 patients. Average follow-up was 36.1 months. Mean age 55.1 years. Tumor size post GK decreased in 9 patients (34.6%), remained stable in 15 patients (57.7%), and continued to grow in 2 (7.7%). Minor transient complications occurred in 12 patients, all resolving. Serious permanent complications occurred in 5 patients: new onset trigeminal neuropathic pain (2), frame related occipital neuralgia (1), worsening of pre-GK seizures (1), and panhypopituitarism (1). CONCLUSION: GK offers an effective treatment method for halting meningioma progression in the cavernous sinus, with an acceptable permanent complication rate.

Extended adjuvant temozolomide with cis-retinoic acid for adult glioblastoma.

OBJECTIVE: To determine the toxicity and effectiveness of 24 months of adjuvant temozolomide (tmz) with cis-retinoic acid (cra) for patients with glioblastoma. METHODS: This retrospective population-based review considered the charts of all patients diagnosed with glioblastoma in Manitoba and referred to a provincial cancer centre during 2002-2008. Consecutive patients came from a population-based referral centre and provincial cancer registry. All patients were treated according to the local standard of care with surgical resection followed by concurrent radiotherapy and tmz 75 mg/m(2) daily, followed by tmz 150-200 mg/m(2) for days 1-5, repeated every 28 days for up to 24 cycles, and cra 50 mg/m(2) twice daily for days 1-21, repeated every 28 days. The main outcome measures were safety, tolerability, and effectiveness of long-term tmz and cra. RESULTS: Of 247 patients diagnosed with glioblastoma in Manitoba during the study period, 116 started concurrent chemoradiotherapy, and 80 received adjuvant tmz. Of the patients who started concurrent chemoradiotherapy, 80 began adjuvant chemotherapy. Patients completed a median of 5.5 cycles of tmz and 3 cycles of cra. Grade 3 or 4 hematologic toxicity was noted in 16% of patients. Median overall survival was 15.1 months, and 26.7% of patients remained alive at 2 years. CONCLUSIONS: Extended adjuvant tmz and cra is well tolerated. However, the population-based effectiveness of this regimen is similar to the clinical trial efficacy of 6 months of adjuvant tmz. Future studies in glioblastoma should incorporate duration of adjuvant chemotherapy into the study design.

Serious head injury in young children: birth trauma versus non-accidental head injury.

Birth injury of the skull and central nervous system can be a complication of a difficult delivery, especially following forceps or vacuum-assisted delivery. Birth trauma of the head can also mimic the appearance of a non-accidental head injury and is therefore an important differential diagnosis. We report on two young infants with serious head injuries. The difficult differential diagnosis birth trauma versus non-accidental head injury is discussed and the necessity for cooperation between clinicians, forensic doctors and specialized neuroradiologists is emphasized.

Vibrational spectra, structure and antioxidant activity of gossypol imine derivatives.

The structures and tautomeric equilibria of natural polyphenol gossypol and four its imine derivatives were studied by FT-IR-, NMR-spectroscopy and quantum chemistry methods. It was shown that gossypol Schiff bases exist in solution as enamine-enamine tautomer and hydrazones as imine-imine tautomer. Infrared absorption spectra of studied compounds were simulated using the PM3 method. The fundamental vibrational frequencies were evaluated using various scale factors which yield a good agreement between observed and calculated frequencies. Free radical scavenging activity of gossypol and its imine derivatives was evaluated using DPPH method. Antioxidant activity of studied compounds was characterized. Gossypol hydrazones were shown to be more efficient, while Schiff base to be less efficient as antioxidants in comparison with gossypol itself.

Gamma knife for cerebral arteriovenous malformations at a single centre.

BACKGROUND: We report the results of a consecutive series of patients treated with Gamma Knife (GK) Surgery for cerebral arteriovenous malformations (AVMs). METHODS: We retrospectively reviewed 69 patients treated with GK for cerebral AVMs between November 2003 and April 2009, recording clinical data, treatment parameters, and AVM obliteration rates in order to assess our effectiveness with GK in treating these lesions. RESULTS: Ten patients were lost to follow-up. Presentations included: seizure (24), hemorrhage (18), persistent headache (12), progressing neurological signs (10), and incidental (9). In 24 patients (34.8%) treatment planning consisted of digital subtraction angiography (DSA), magnetic resonance imaging (MRI), and computed tomogram (CT) angiography (CTA). Currently we rely predominantly on CTA and/or MRI scanning only. Fourty-one patients have been followed for a minimum of 3 years; average age 40.9 yr., 58.5% males. Average dose at the 50% isodose line was 20.3 Gy (range 16 to 26.4 Gy). Obliteration was observed in 87.8% by MRI, CT, or DSA. Not all obliteration was confirmed by DSA. Complications occurred in 12 of 59 (20.3%) patients, and in 11 of 41 (26.8%) with 3 year follow-up. Major (temporary) complications for the 59 included symptomatic cerebral edema (7), seizure (2), and hemorrhage (1). Major permanent complications occurred in one patient suffering a cranial nerve V deafferentation, and in two patients suffering a hemorrhage. CONCLUSION: GKS for cerebral AVM's offers an effective and safe method of treatment, with low permanent complication rate.

Synthesis, physicochemical properties and antimicrobial evaluation of new (E)-chalcones.

In a wide search program towards new and efficient antimicrobial agents, a series of 40 substituted chalcones have been synthesized and tested for their in vitro antibacterial and antifungal activities. The structures of these compounds have been investigated by nuclear magnetic resonance spectroscopy and mass spectrometry. Among the (E)-4-aminoalkylthiochalcones and (E)-4-aminoalkoxychalcones tested, compounds 7, 10, 11, 30 and 31 have exhibited good antibacterial property against Staphylococcus aureus, Enterococcus faecalis and Bacillus subtilis.

Effects of energy supply on leucine utilization by growing steers at two body weights.

The effects of energy supplementation on Leu utilization in growing steers were evaluated in 2 experiments by using 6 ruminally cannulated Holstein steers. In Exp. 1, steers (initial BW = 150 +/- 7 kg) were limit-fed (2.3 kg of DM/d) a diet based on soybean hulls and received a basal ruminal infusion of 100 g of acetate/d, 75 g of propionate/d, and 75 g of butyrate/d, as well as abomasal infusions of 200 g of glucose/d and a mixture (215 g/d) containing all essential AA except Leu. Treatments were arranged as a 3 x 2 factorial, with 3 amounts of Leu infused abomasally (0, 4, and 8 g/d) and supplementation of diets with 2 amounts of energy (0 and 1.9 Mcal/d of GE). Supplemental energy was supplied by ruminal infusion of 100 g of acetate/ d, 75 g of propionate/d, and 75 g of butyrate/d, as well as abomasal infusion of 200 g of glucose/d to provide energy to the animal without affecting the microbial protein supply. When no supplemental energy was provided, Leu supplementation increased N balance, with no difference between 4 and 8 g/d of Leu (24.5, 27.0, and 27.3 g/d for 0, 4, and 8 g/d of Leu), but when additional energy was supplied, N retention increased linearly in response to Leu (25.6, 28.5, and 31.6 g/d for 0, 4, and 8 g/d of Leu; Leu x energy interaction, P = 0.06). The changes in N balance were the result of changes in urinary N excretion. The greater Leu retentions in response to energy supplementation when Leu was the most limiting nutrient indicate that energy supplementation improved the true efficiency of Leu utilization. In addition, supplemental energy increased the gross efficiency of Leu utilization when the Leu supply was not limiting by increasing the maximal rates of protein deposition. Experiment 2 was similar to Exp. 1, but steers had an initial BW of 275 +/- 12 kg and were limit-fed at 3.6 kg of DM/d. Retention of N was not affected (P = 0.22) by Leu supplementation, indicating that Leu did not limit protein deposition. Energy supply increased N retention (P < 0.01) independently of Leu supplementation (33.0 vs. 27.8 g/d). Overall, energy supplementation improved Leu utilization by modestly increasing N retention when Leu was limiting and by increasing the ability of steers to respond to the greatest amount of supplemental Leu. We conclude from these results that the assumption of a constant efficiency of AA utilization is unlikely to be appropriate for growing steers.

Critical steps in fluoroquinolones and carbapenems prescriptions: results from a prospective clinical audit.

Antibiotic misuse is associated with emergence of resistance and high expenditures. Fluoroquinolones (FQ) and carbapenems (CP) are drugs with considerable potential of resistance development and its disseminated use is a concern. We undertook a prospective clinical audit to evaluate prescriptions of FQ and CP in a multistep process. Each prescription was unfolded in the following steps: indication for antimicrobial therapy; adequacy of initial prescription, dosage and route; previous cultures; and parenteral-oral transition. There was no antibiotics indication in 8.9% of FQ and 1.5% of CP group (p = 0.07). In CP 25.8% of initial schemes were inappropriate (21% in FQ). Lack of switch to oral therapy comprised 25% of monthly costs of FQ. Inadequacy in initial choice accounted for 13.6% of CP expenses. We concluded that, in spite of infection control restrictive policies, inappropriateness of antibiotic usage is worrisome. Clinical audit in a multistep approach may identify possible flaws in this process.

Silage chop length and hay supplementation on milk yield, chewing activity, and ruminal digestion by dairy cows.

The effects of whole-plant corn silage (CS) particle size and long unprocessed grass hay (LH) supplementation on milk yield, chewing activity, and ruminal digestion in dairy cows were evaluated in 2 experiments. In Experiment 1, corn silage harvested at fine (6 mm; FCS) or coarse (23 mm; CCS) theoretical cut length were fed to 22 lactating Holstein cows. Treatments were 2 total mixed rations containing 58% of dry matter (DM) as FCS or CCS. Diet DM intake tended to be higher in cows fed FCS than those fed CCS (23.4 vs. 22.1 kg/d). However, milk yield and composition, body condition score, and plasma metabolite concentrations were not affected by the dietary treatments. In the second experiment, 5 cannulated Holstein cows were used in a 5 x 5 Latin square design to evaluate the effects of the addition of LH to the diets evaluated in Experiment 1 on chewing activity and ruminal digestion. Treatments were 5 total mixed rations: FCS-based diet plus the addition of 0, 5, or 10% LH (DM basis) and CCS-based diet plus 0 or 5% LH. Long hay addition linearly decreased DM intake in cows fed FCS-based diets (25.0 to 21.7 kg/d), but increased DM intake in those fed CCS-based diets (22.7 to 27.1 kg/d). The intake of neutral detergent fiber (NDF) increased with LH addition in CCS-based diets (7.6 vs. 9.4 kg/d). Rumination time increased (16.8 to 21.0 min/kg of DM intake) when LH was added to FCS-based diets, but it decreased when included in CCS-based diets (18.8 vs. 12.9 min/kg of DM intake). Ruminal pH was higher (5.9 vs. 5.7) and lag-time for in situ NDF disappearance was shorter (3.5 vs. 8.7 h) for cows fed CCS compared with cows fed FCS. The rate of NDF disappearance tended to be higher for the CCS-based diet with 5% LH than for the diet with 0% LH (2.0 vs. 4.4 %/h), but solids passage rate was not affected by the treatments. These results suggest that addition of LH to FCS-based diets does not affect ruminal environment or digestion, but depressed DM intake. In contrast, addition of LH to CCS-based diets may improve ruminal NDF digestion, increasing DM intake by reducing filling effect and time needed for rumination.

Excess amino acid supply improves methionine and leucine utilization by growing steers.

In 2 experiments, 6 ruminally cannulated Holstein steers (205 +/- 23 and 161 +/- 14 kg initial BW in Exp. 1 and 2, respectively) housed in metabolism crates were used in 6 x 6 Latin squares to study the effects of excess AA supply on Met (Exp. 1) and Leu (Exp. 2) use. All steers received a diet based on soybean hulls (DMI = 2.66 and 2.45 kg/d in Exp. 1 and 2, respectively); ruminal infusions of 200 g of acetate/d, 200 g of propionate/d, and 50 g of butyrate/d, as well as abomasal infusion of 300 g of glucose/d to provide energy without increasing the microbial protein supply; and abomasal infusions of a mixture of all essential AA except Met (Exp. 1) or Leu (Exp. 2). Periods were 6 d, with 2-d adaptations and 4 d to collect N balance data. All treatments were abomasally infused. In Exp. 1, treatments were arranged as a 2 x 3 factorial, with 2 amounts of l-Met (0 or 4 g/d) and 3 AA supplements (no additional AA, control; 100 g/d of nonessential AA + 100 g/d of essential AA, NEAA + EAA; and 200 g/d of essential AA, EAA). Supplemental Met increased (P < 0.01) retained N and decreased (P < 0.01) urinary N and urinary urea N. Retained N increased (P < 0.01) with NEAA + EAA only when 4 g/d of Met was provided, but it increased (P < 0.01) with EAA with or without supplemental Met. Both AA treatments increased (P < 0.01) plasma urea and serum insulin. Plasma glucose decreased (P = 0.03) with supplemental Met. In Exp. 2, treatments were arranged as a 2 x 3 factorial with 2 amounts of L-Leu (0 or 4 g/d) and 3 AA supplements (control, NEAA + EAA, and EAA). Supplemental Leu increased (P < 0.01) retained N and decreased (P < 0.01) urinary N and urinary urea N. Both AA treatments increased (P < 0.01) retained N, and they also increased (P < 0.01) urinary N, urinary urea N, and plasma urea. Serum insulin increased (P = 0.06) with supplemental Leu and tended (P = 0.10) to increase with both AA treatments. Supplementation with excess AA improved Met and Leu use for protein deposition by growing cattle.

Effects of energy level on methionine utilization by growing steers.

We evaluated the effect of energy supplementation on Met use in growing steers. Six ruminally cannulated Holstein steers (228 +/- 8 kg of BW) were used in a 6 x 6 Latin square and fed 2.8 kg of DM/d of a diet based on soybean hulls. Treatments were abomasal infusion of 2 amounts of Met (0 or 3 g/d) and supplementation with 3 amounts of energy (0, 1.3, or 2.6 Mcal of GE/d) in a 2 x 3 factorial arrangement. The 1.3 Mcal/d treatment was supplied through ruminal infusion of 90 g/d of acetate, 90 g/d of propionate, and 30 g/d of butyrate, and abomasal infusion of 30 g/d of glucose and 30 g/d of fat. The 2.6 Mcal/d treatment supplied twice these amounts. All steers received basal infusions of 400 g/d of acetate into the rumen and a mixture (125 g/d) containing all essential AA except Met into the abomasum. No interactions between Met and energy levels were observed. Nitrogen balance was increased (P < 0.05) by Met supplementation from 23.6 to 27.8 g/d, indicating that protein deposition was limited by Met. Nitrogen retention increased linearly (P < 0.05) from 23.6 to 27.7 g/d with increased energy supply. Increased energy supply also linearly reduced (P < 0.05) urinary N excretion from 44.6 to 39.7 g/d and reduced plasma urea concentrations from 2.8 to 2.1 mM. Total tract apparent OM and NDF digestibilities were reduced linearly (P < 0.05) by energy supplementation, from 78.2 and 78.7% to 74.3 and 74.5%, respectively. Whole-body protein synthesis and degradation were not affected significantly by energy supplementation. Energy supplementation linearly increased (P < 0.05) serum IGF-I from 694 to 818 ng/mL and quadratically increased (P < 0.05) serum insulin (0.38, 0.47, and 0.42 ng/mL for 0, 1.3, and 2.6 Mcal/d, respectively). In growing steers, N retention was improved by energy supplementation, even when Met limited protein deposition, suggesting that energy supplementation affects the efficiency of AA use.

Effects of energy source on methionine utilization by growing steers.

We evaluated the effects of different supplemental energy sources on Met use in growing steers. Ruminally cannulated Holstein steers were used in two 6 x 6 Latin squares, and data were pooled for analyses. In Exp. 1, steers (148 kg) were fed 2.3 kg of DM/d of a diet based on soybean hulls. Treatments (2 x 3 factorial) were abomasal infusion of 0 or 3 g of l-Met/d, and supplementation with no energy or with glucose (360 g/d) or fat (150 g/d) continuously infused into the abomasum. In Exp. 2, steers (190 kg) received 2.6 kg of dietary DM/d and were provided (2 x 3 factorial) with 0 or 3 g of l-Met/d, and with no supplemental energy or with acetate (385 g/d) or propionate (270 g/ d) continuously infused into the rumen. In both experiments, the energy sources supplied 1.3 Mcal of GE/d, and all steers received basal infusions of 400 g of acetate/d into the rumen and a mixture (125 g/d) of all essential AA except Met into the abomasum. Nitrogen balance (18.8 vs. 23.5 g/d; P < 0.01) and whole-body protein synthesis (2.1 vs. 2.3 kg/d; P < 0.07) were increased by Met supplementation, indicating that protein deposition was limited by Met. Supplemental energy reduced (P < 0.01) urinary N excretion and increased (P < 0.01) N retention without differences among energy sources. Increases in N retention in response to Met were numerically greater when energy was supplemented. Efficiency of supplemental Met use was 11% when no energy was supplemented but averaged 21% when 1.3 Mcal of GE/d was provided. Whole-body protein synthesis and degradation were not affected by energy supplementation. Serum insulin concentrations were increased by glucose and propionate supplementation. Serum IGF-I concentrations were increased by supplementation with Met or glucogenic sources of energy. In growing steers, N retention was increased by energy supplementation even though protein deposition was limited by Met, suggesting that energy supplementation improves the efficiency of AA use. These responses were independent of the source of energy.