Biomedical subjects

M D Stern

Publications and source records attributed to M D Stern.

At least 91 records · Page 5Linked to original sources

PubMed1991

Ruminal protein metabolism and intestinal amino acid utilization as affected by dietary protein and carbohydrate sources in sheep.

Eight wether lambs fitted with ruminal, duodenal, and ileal cannulas were used in a replicated 4 x 4 Latin square design to study the effects of carbohydrate and protein sources on ruminal protein metabolism and carbohydrate fermentation and intestinal amino acid (AA) absorption. Treatments were arranged as a 2 x 2 factorial. Carbohydrate sources were corn and barley; protein sources were soybean meal (SBM) and fish meal (FM). Diets contained 15.5% CP, of which 40% was supplied by SBM or FM. Corn or barley provided 39% of dietary DM that contained equal amounts of grass hay and wheat straw. Fish meal diets produced a lower (P less than .05) ruminal NH3 concentration and resulted in less CP degradation and bacterial protein flow to the duodenum than did SBM diets. Replacing SBM with FM increased (P less than .05) ruminal digestion of all fiber fractions. In addition, cellulose and hemicellulose digestibilities in the rumen tended to increase (P greater than .05) when barley replaced corn in the FM diets. Carbohydrate x protein interactions (P less than .05) were observed for OM digestion in the rumen and AA absorption in the small intestine (percentage of AA entering); these interactions were highest for the barley-FM diet. These results suggest that feeding FM with barley, which is high in both degradable carbohydrate and protein, might benefit ruminants more than feeding FM with corn, which is high in degradable carbohydrate but relatively low in degradable protein.

Amino Acids↗

PubMed1990

Sustained subthreshold-for-twitch depolarization in rat single ventricular myocytes causes sustained calcium channel activation and sarcoplasmic reticulum calcium release.

Single rat ventricular myocytes, voltage-clamped at -50 to -40 mV, were depolarized in small steps in order to define the mechanisms that govern the increase in cytosolic [Ca2+] (Cai) and contraction, measured as a reduction in myocyte length. Small (3-5 mV), sustained (seconds) depolarizations that caused a small inward or no detectable change in current were followed after a delay by small (less than 2% of the resting length), steady reductions in cell length measured via a photodiode array, and small, steady increases in Cai measured by changes in Indo-1 fluorescence. Larger (greater than -30 and less than -20 mV), sustained depolarizations produced phasic Ca2+ currents, Cai transients, and twitch contractions, followed by a steady current and a steady increase in Cai and contraction. Nitrendipine (or Cd, verapamil, or Ni) abolished the steady contraction and always produced an outward shift in steady current. The steady, nitrendipine-sensitive current and sustained increase in Cai and contraction exhibited a similar voltage dependence over the voltage range between -40 and -20 mV. 2 microM ryanodine in the presence of intact Ca2+ channel activity also abolished the steady increase in Cai and contraction over this voltage range. We conclude that when a sustained depolarization does not exceed about -20 mV, the resultant steady, graded contraction is due to SR Ca2+ release graded by a steady ("window") Ca2+ current. The existence of appreciable, sustained, graded Ca2+ release in response to Ca2+ current generated by arbitrarily small depolarizations is not compatible with any model of Ca2(+)-induced Ca2+ release in which the releasing effect of the Ca2+ channel current is mediated solely by Ca2+ entry into a common cytosolic pool. Our results therefore imply a distinction between the triggering and released Ca2+ pools.

Animals↗

PubMed1990

Simultaneous measurement of Ca2+, contraction, and potential in cardiac myocytes.

A system is described that can simultaneously record cytosolic Ca2+ concentration ([Ca2+]i), cell length, and either membrane potential or current in single cardiac myocytes loaded with the fluorescent Ca2+ indicator indo-1. Fluorescence is excited by epi-illumination with 3.8-microsecond flashes of 350 +/- 5 nm light from a xenon arc. Indo-1 fluoresence is measured simultaneously in spectral windows of 391-434 nm and 457-507 nm, and the ratio of indo-1 emission in the two bands is computed as a measure of [Ca2+]i for each flash. With cells loaded with the permeant acetoxymethyl ester of indo-1, quantitation of [Ca2+]i is not precise, owing to subcellular compartmentation of indo-1; however, the instrument would allow full quantitation if indo-1 free acid was introduced by microinjection. Simultaneously, cell length is measured on-line from the bright-field image of the cell. Because fluorescence collection is time gated during the brief flash, and red light (650-750 nm) is used for the bright-field image, cell length and [Ca2+]i measurements are obtained simultaneously without cross talk. Membrane potential or current can be recorded simultaneously with indo-1 fluorescence and cell length via standard patch-clamping techniques.

Animals↗

PubMed1990

Evaluation of various nitrogen supplements in starter diets for growing Holstein steers and their effects on ruminal bacterial fermentation in continuous culture.

Concurrent in vivo and in vitro studies were conducted to evaluate urea (U), soybean meal (SBM), ground soybeans (RAW), extruded soybeans (ES) or extruded soybeans plus urea (ES + U) as primary supplemental N sources in starter diets for Holstein steers. Three groups of 48 Holstein steers each were fed five different starter diets to 181 kg BW in three experimental periods over 2 yr. Average daily gains were similar (P greater than .05) for steers fed ES + U (1.12 kg), ES (1.08 kg) and SBM (1.09 kg) but lower (P less than .05) for those fed U (1.00 kg) or RAW (.97 kg) diets. Feed/gain was similar (P greater than .05) for ES-fed steers vs those fed other diets except U. From 181 to 477 kg, all steers were fed the same diet. Steers fed the RAW starter diet had the lowest (P less than .05) ADG for the entire period. The starter diets were used as substrates for ruminal microbial metabolism in eight dual-flow continuous culture fermenters. True OM digestion was higher and NDF and ADF digestion was lower (P less than .05) for the ES + U diet than for the ES diet. Dietary protein degradation was lowest (P less than .05) for the ES diet (64.4%). Total bacterial N flow was higher (P less than .05) with the ES + U, SBM and U diets than with the ES diet. Lysine flow was higher (P less than .05) for the ES + U diet than for all other diets except ES. Results of these experiments indicate that ES as a protected ruminal escape N source with or without added urea did not improve steer performance above that obtained from SBM in starter diets.

Animal Feed↗

PubMed1990

Interlaboratory variation in a diaminopimelic acid assay: influence on estimated duodenal bacterial nitrogen flow.

Samples of ruminal bacteria and duodenal digesta were collected from two dairy cows fed a 65% forage diet. Samples were sent blind to four laboratories for diaminopimelic acid analysis. Analyzed values differed among laboratories within sample type, and concentrations ranked as follows: laboratory D greater than laboratory A greater than laboratory B greater than laboratory C. Consideration of differences in actual procedures used among laboratories resulted in several hypotheses to explain some of the interlaboratory variation. Using diaminopimelic acid values from each laboratory to estimate duodenal bacterial nitrogen flow showed that laboratory D estimated a 17% higher flow than the average for laboratories A, B, and C, which were similar.

Animals↗

PubMed1989

Laser backscatter studies of intracellular Ca2+ oscillations in isolated hearts.

We measured intensity fluctuations of 633 nm laser light backscattered from the epicardial surface of isolated, perfused rat and rabbit hearts. Scattered light intensity fluctuations (SLIF) were detected from verapamil-arrested rat hearts. The frequency of SLIF was increased by maneuvers that raise intracellular calcium. SLIF were abolished by removal of extracellular calcium with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and by blockade of sarcoplasmic reticulum calcium release by ryanodine. SLIF were not accompanied by any surface electro-cardiogram and were not abolished by 144 mM extracellular potassium. SLIF were absent in rabbit hearts under base-line conditions but could be provoked by calcium loading using zero potassium and ouabain. We conclude that backscatter SLIF monitor the microscopic motion caused by intracellular calcium oscillations in the intact heart. We measured SLIF from rat hearts during 60 min of global ischemia at 30 degrees C, followed by reflow. Ischemia reduced SLIF frequency to zero within 30 min. Reflow caused an overshoot of SLIF frequency to as much as five times control, suggesting that reflow causes major calcium overload of cells that are at least transiently viable.

Animals↗

PubMed1989

Evaluation of white lupines and triticale in calf starter diets.

One hundred fifty-two Holstein calves were used to evaluate white lupines (Lupinus albus cv. Ultra) and triticale in starter diets. The basal diet contained corn, oats, minerals, and vitamins. Starter components were 1) 14% soybean meal; 2) 10% soybean meal and 27% triticale; 3) 22% lupines; 4) 16% lupines and 24.5% triticale; 5) 11% lupines and 8% soybean meal; and 6) 7% lupines, 5% soybean meal, and 26.5% triticale. Dietary CP was approximately 16% of DM. Data collection began on d 4 after birth and continued through d 56. Calves were fed 3.6 kg of fermented colostrum from d 4 to 14 and 4.5 kg of fermented whole milk from d 15 to weaning at d 28. Starter diets and water were offered for ad libitum consumption from d 4 to 56. Dietary treatment had no effect on starter intake or weight gains. Average total gains during the experimental period were 25.6, 23.0, 23.3, 23.2, 25.0, and 21.6 kg for treatments 1, 2, 3, 4, 5, and 6, respectively. Calf health was excellent. Starter diets were examined in a dual flow continuous culture system to evaluate fermentation by rumen bacteria. Digestibilities of DM, organic matter, and total nonstructural carbohydrate did not differ among treatments. Ammonia N concentrations ranged from 11.9 to 13.8 mg/100 ml effluent. Chemical composition of bacteria, efficiency of bacterial protein synthesis, total VFA concentration in the effluent, and amino acid flow were similar for all treatments. The results indicate that lupines and triticale are satisfactory for use in calf starters when included in amounts equal to or less than those used in this experiment.

Animal Feed↗

PubMed1989

Influence of protein supplementation of alkaline hydrogen peroxide-treated wheat straw on ruminal microbial fermentation.

A dual flow continuous culture system was used to determine the effects of four protein sources (soybean meal, Ca-ligno-sulfonate treated-soybean meal, blood meal, and feather meal), supplied individually or in combination in diets composed predominantly of alkaline hydrogen peroxide-treated wheat straw, on ruminal microbial fermentation and amino acid flow. Diets containing blood meal had lower organic matter and fiber digestion, NH3 N and VFA concentrations, and CP degradation but higher non-NH3 N, dietary N, total amino acid, and essential amino acid flows. Feather meal fed alone or combined with other sources was not different from the blood meal diet in organic matter and fiber digestion. Combining treated soybean meal and blood meal resulted in similar organic matter and fiber digestibilities compared with the soybean meal diets. This combination was similar to the treated soybean meal diet in VFA concentration, non-NH3 N, and essential and total amino acid flows; however, amino acid profile was different with this combination, showing higher histidine and leucine flows. Results from this study suggest that amino acid profiles of digesta leaving the rumen may be manipulated by choice of protein supplement when diets containing a low protein, highly fermentable feedstuff such as alkaline hydrogen, peroxide-treated wheat straw are fed.

Animal Feed↗

PubMed1989

Effect of ruminal protein degradation of blood meal and feather meal on the intestinal amino acid supply to lactating cows.

Four lactating cows fitted with ruminal cannulae and T-type cannulae in the proximal duodenum and terminal ileum were utilized to measure protein degradation in the rumen and amino acid flow to and absorption from the small intestine. Soybean meal, blood meal, feather meal, and a 50-50 combination of blood meal and feather meal provided 50% of the protein in diets that contained 50% grain mix, 40% corn silage, and 10% alfalfa pellets on a DM basis. Ruminal degradation of dietary CP was 53, 43, 32, and 37% for diets containing soybean meal, blood meal, feather meal, and the combination of meals. Cows fed the latter two diets also had lower ruminal NH3 concentrations and efficiency of bacterial protein synthesis compared to those fed the soybean meal diet. Total tract N digestibility was lower for diets containing feather meal (63.4%) and a combination of meals (66.3%) than the soybean meal diet (78.5%). Total amino acid flow to the duodenum was 19.3 and 15.6% higher for cows fed the feather meal and combined meal diets, respectively, compared with the soybean meal diet. Total amino acid absorption from the small intestine was higher as well as absorption of individual amino acids for the combined meal diet compared with the soybean meal diet. Absorption of individual amino acids, expressed as a percentage entering the duodenum, was lowest for the feather meal diet. Results from this study show that feeding a combination of blood meal and feather meal instead of soybean meal can increase intestinal supply and absorption of amino acids in dairy cattle.

Amino Acids↗

PubMed1988

Spontaneous calcium release from the sarcoplasmic reticulum in myocardial cells: mechanisms and consequences.

Under certain conditions of Ca2+ loading, cardiac myocytes, both isolated and in intact tissue, exhibit spontaneous, oscillatory Ca2+ transients due to Ca2+ release from the sarcoplasmic reticulum. These transients are not triggered by depolarization of the sarcolemma, though they themselves can generate depolarizing currents which can reach threshold to trigger an action potential. Spontaneous Ca2+ release occurs locally in a subcellular region and, once initiated, can propagate through the cell with a velocity of roughly 100 microns/s. Locally, the cytosolic Ca2+ concentration during spontaneous release is probably comparable to that during an electrically excited twitch. The mechanisms of initiation and propagation of spontaneous Ca2+ release are uncertain, but are probably closely related to the Ca2+-induced Ca2+ release which plays a role in normal excitation-contraction coupling. Spontaneous and triggered Ca2+ release appear to compete for a common pool of releasable sarcoplasmic reticulum Ca2+, with the result that spontaneous Ca2+ release imposes a beat-rate-dependent limit on the inotropic effect of interventions which increase intracellular Ca2+. Mathematical modeling of this effect shows that it can also explain increased diastolic tone, the development of aftercontractions and oscillatory restitution of contractility in states of 'Ca2+ overload'. Spontaneous Ca2+ release is a cause of arrhythmias, and may well play a role in some cases of systolic and diastolic myocardial dysfunction.

Animals↗

PubMed1988

Anoxic contractile failure in rat heart myocytes is caused by failure of intracellular calcium release due to alteration of the action potential.

Anoxia of the heart causes failure of contraction before any irreversible injury occurs; the mechanism by which anoxia blocks cardiac excitation-contraction coupling is unknown. Studies in whole muscle are confounded by heterogeneity; however, achieving the low oxygen tensions required to study anoxia in a single myocyte during electrophysiological recording has been a barrier in experimental design. Guided by calculations of oxygen transport, we developed a system to insulate myocytes in an open dish from oxygen by a laminar counterflowing argon column, permitting free access to the cell by microelectrodes while maintaining a PO2 less than 0.02 torr (1 torr = 133 Pa). In the absence of glucose, the amplitude of stimulated contraction of anoxic ventricular myocytes fell to zero over 2 min after a lag period attributable to the consumption of endogenous glycogen. The cytosolic calcium concentration transient, measured by indo-1 fluorescence, fell to zero simultaneously with contraction. After the twitch had failed, microinjection of caffeine around the cell still caused a large calcium release and contraction, indicating that sarcoplasmic reticular calcium stores were not depleted. Twitch failure was accompanied by shortening and then failure of the action potential; under voltage clamp, large outward currents, reversing at the resting potential, developed during contractile failure. After failure of action potential-mediated contraction, voltage-clamp depolarization, with a large command voltage to compensate for the series-resistance error due to outward currents, restored normal twitch contraction. We conclude that anoxic contractile failure in the rat myocyte is due to alteration of the action potential and the distal pathways of excitation-contraction coupling remain essentially intact.

Action Potentials↗

PubMed1988

Spontaneous Ca2+ release from the sarcoplasmic reticulum limits Ca2+-dependent twitch potentiation in individual cardiac myocytes. A mechanism for maximum inotropy in the myocardium.

We hypothesized that the occurrence of spontaneous Ca2+ release from the sarcoplasmic reticulum (SR), in diastole, might be a mechanism for the saturation of twitch potentiation common to a variety of inotropic perturbations that increase the total cell Ca. We used a videomicroscopic technique in single cardiac myocytes to quantify the amplitude of electrically stimulated twitches and to monitor the occurrence of the mechanical manifestation of spontaneous SR Ca2+ release, i.e., the spontaneous contractile wave. In rat myocytes exposed to increasing bathing [Ca2+] (Cao) from 0.25 to 10 mM, the Cao at which the peak twitch amplitude occurred in a given cell was not unique but varied with the rate of stimulation or the presence of drugs: in cells stimulated at 0.2 Hz in the absence of drugs, the maximum twitch amplitude occurred in 2 mM Cao; a brief exposure to 50 nM ryanodine before stimulation at 0.2 Hz shifted the Cao of the maximum twitch amplitude to 7 mM. In cells stimulated at 1 Hz in the absence of drugs, the maximum twitch amplitude occurred in 4 mM Cao; 1 microM isoproterenol shifted the Cao of the maximum twitch amplitude to 3 mM. Regardless of the drug or the stimulation frequency, the Cao at which the twitch amplitude saturated varied linearly with the Cao at which spontaneous Ca2+ release first occurred, and this relationship conformed to a line of identity (r = 0.90, p = less than 0.001, n = 25). The average peak twitch amplitude did not differ among these groups of cells. In other experiments, (a) the extent of rest potentiation of the twitch amplitude in rat myocytes was also limited by the occurrence of spontaneous Ca2+ release, and (b) in both rat and rabbit myocytes continuously stimulated in a given Cao, the twitch amplitude after the addition of ouabain saturated when spontaneous contractile waves first appeared between stimulated twitches. A mathematical model that incorporates this interaction between action potential-mediated SR Ca2+ release and the occurrence of spontaneous Ca2+ release in individual cells predicted the shape of the Cao-twitch relationship observed in other studies in intact muscle. Thus, the occurrence of spontaneous SR Ca2+ release is a plausible mechanism for the saturation of the inotropic response to Ca2+ in the intact myocardium.

Animals↗

PubMed1988

Influence of methionine derivatives on effluent flow of methionine from continuous culture of ruminal bacteria.

Two separate studies were conducted using a continuous culture fermenter system to determine effects of supplementing D,L-methionine and various methionine derivatives on degradation of methionine by ruminal bacteria. A basal diet containing 20% alfalfa hay, 20% corn silage and 60% grain mix (DM basis) was provided at a rate of 75 g DM/d per fermenter and served as an unsupplemented control in both experiments. In Exp. 1, methionine sources included D,L-methionine, D,L-methionine hydantoic acid, D,L-methionine hydantoin, N-acetyl-D,L-methionine, methylthio-isobutyric acid, methylthio-propionic acid and D,L-methionine sulfoxide. These sources were added directly to fermenters twice daily and supplied an equivalent of 98 mg/d D,L-methionine (.13% of diet DM) and 21 mg/d S. Effluent methionine flow from fermenters was higher (P less than .05) with diets supplemented with D,L-methionine hydantoic acid (245 mg/d), D,L-methionine hydantoin (245 mg/d) and N-acetyl-D,L-methionine (270 mg/d) than with control (211 mg/d) or D,L-methionine (211 mg/d) treatments, indicating a lower ruminal bacterial degradation of these methionine derivatives. There were no major effects on bacterial fermentation due to methionine supplementation or source. In Exp. 2, methionine sources included D,L-methionine, methionine hydroxy analog and N-hydroxymethyl-D,L-methionine; these were mixed with the basal diet to provide an equivalent of 250 mg/d D,L-methionine (.33% of diet DM). Sodium sulfate was added to the control diet to attain equal S (54 mg/d) levels across treatments. Flow of methionine was not affected (P greater than .05) by methionine supplementation, indicating extensive degradation of all three methionine sources by ruminal bacteria.

Animals↗

PubMed1988

Effects of forage source on ruminal microbial nitrogen metabolism and carbohydrate digestion in continuous culture.

Eight single-flow, continuous culture fermentors were used in Exp. 1 to study the effects of forage source on ruminal bacterial N metabolism and carbohydrate digestion. Forages included alfalfa, cicer milkvetch, birdsfoot trefoil and sainfoin with respective CP concentrations of 26.0, 28.7, 26.3 and 20.0%. Each forage provided 100% of the substrate for microbial metabolism and supplied 2.6 g N/d. Ammonia-N, protein degradation and efficiency of ruminal bacterial protein synthesis were lowest (P less than .05) for sainfoin. Protein degradation and efficiency of bacterial protein synthesis were higher (P less than .05) for birdsfoot trefoil than for alfalfa. Effluent flow of amino acids was highest (P less than .05) for sainfoin. Total nonstructural carbohydrate digestion tended to be highest for sainfoin and birdsfoot trefoil, whereas structural carbohydrate digestion was highest (P less than .05) for alfalfa and cicer milkvetch. In Exp. 2, mixed diets were supplied to dual-flow, continuous culture fermentors with alfalfa, cicer milkvetch, birdsfoot trefoil and sainfoin contributing 85% of the total dietary CP. Each diet contained approximately 12.9% CP. Ammonia-N concentration in the effluent and CP degradation tended to be lowest with the sainfoin diet and highest with the birdsfoot trefoil diet. Effluent flow of amino acids tended to be highest with the cicer milkvetch diet and lowest with the alfalfa and birdsfoot trefoil diet. Total structural and nonstructural carbohydrate digestion was not different (P greater than .05) among forages. Results from these experiments indicate that bacterial degradation of protein was lower for sainfoin than for alfalfa. Birdsfoot trefoil and cicer milkvetch appear to be comparable to alfalfa with regard to metabolism of N and carbohydrates by ruminal bacteria.

Animal Feed↗

PubMed1988

Evaluation of calcium lignosulfonate-treated soybean meal as a source of rumen protected protein for dairy cattle.

Four Holstein cows fitted with ruminal, duodenal, and ileal cannulae were used in a 4 x 4 Latin square design to measure ruminal protein degradation and small intestinal digestion of diets containing untreated soybean meal or soybean meal treated with heat and either water, xylose, or calcium lignosulfonate. Diets consisting of 40% corn silage, 10% alfalfa cubes, and 50% grain mix, and averaging 16.8% crude protein (DM basis) were fed four times daily. Approximately 50% of the total dietary protein was supplied by the respective soybean meal source. Ruminal protein degradation was 70.6, 69.6, 55.8, and 53.7% for diets containing untreated soybean meal, water-soybean meal, xylose-soybean meal, and calcium lignosulfonate-soybean meal, respectively. Duodenal non-NH3 N flow (g/d) and absorption of non-NH3 N (g/d) in the small intestine were generally not affected by treatment. Duodenal bacterial N flow (g/d) was lower with xylose-soybean meal and lignosulfonate-soybean meal than with untreated soybean meal. Treatment of soybean meal with xylose or calcium lignosulfonate was successful in decreasing ruminal protein degradation. However, it may be necessary to include a source of readily fermentable N in diets that contain protected proteins in order to supply adequate NH3 N for microbial protein synthesis.

Animal Feed↗

PubMed1987

Influence of supplemental nitrogen source on digestion of nitrogen, dry matter and organic matter and on in vivo rate of ruminal protein degradation.

Seven Holstein steers (340 kg) fitted with ruminal, duodenal and ileal cannulae were used to measure the influence of supplemental N source on digestion of dietary crude protein (CP) and on ruminal rates of protein degradation. Diets used were corn-based (isonitrogenous, 12% CP on a dry matter basis, and isocaloric, 80% total digestible nutrients) with urea, soybean meal (SBM), linseed meal (LSM) or corn gluten meal (CGM) as supplemental N. Ruminal ammonia N concentrations were higher (P less than .05) in steers fed LSM than in those fed CGM, but did not differ from those in steers fed urea or SBM (11.7, 6.7, 9.1 and 9.2 mg/100 ml, respectively). Due to the high degradability of urea, ruminal digestion of dietary CP was greater (P less than .05) in steers fed urea than in those fed CGM, but intermediate in steers fed SBM and LSM (58.4, 48.8, 53.1 and 53.9%, respectively). Flow of bacterial nonammonia N to the duodenum was highest (P less than .05) in steers fed SBM or LSM, intermediate (P less than .05) for urea and lowest (P less than .05) for CGM (86.8, 86.1, 76.3 and 65.9 g/d, respectively). Efficiency of bacterial protein synthesis was lowest in steers fed CGM and differed (P less than .05) from SBM (15.6 vs 21.8 g N/kg organic matter truly digested, respectively). Rate of ruminal digestion for SBM-CP differed (P less than .05) from that of CGM-CP but not from that of LSM-CP (17.70, 5.20 and 10.13%/h, respectively). The slow rate of ruminal degradability of CGM resulted in increased amounts of dietary protein reaching the intestinal tract but lower amounts of bacterial protein, thus intestinal protein supply was not appreciably altered.

Animal Nutritional Physiological Phenomena↗

PubMed1987

Comparison of sweet white lupin seeds with soybean meal as a protein supplement for lactating dairy cows.

Data were from 45 Holstein cows (23 multiparous, 22 primiparous) assigned by calving date and parity within groups to one of two isonitrogenous (16% crude protein) diets. The diets were 50% forages (corn silage, alfalfa silage) and 50% concentrate, dry basis. In diet A, soybean meal supplied 34.2% of total crude protein; in diet B, ground sweet white lupin seeds provided 37.9% of total crude protein. Cows were fed once daily during the experimental period (d 4 to 116 postpartum). Cows fed lupins consumed significantly less dry matter, produced 1.8 kg/d less milk (but not significantly different), and had lower milk protein percent. Milk fat and total solids percents were similar. Reasons for reduced intake of cows fed lupins were not evident. Traces of alkaloids (.005% dry basis) were present in diet B. Combined results of in vitro continuous culture fermentation and in situ degradation measurements indicated that crude protein from lupins was more degradable than that of soybean meal. Poor performances of cows fed lupins could be partly due to a reduced true protein supply to the small intestine.

Animal Feed↗

PubMed1986

A new capsulotomy scissors.

A new scissors has been designed to perform the square-window anterior capsulotomy. Several design features make it an improvement over the previously modified Vannas scissors.

Cataract Extraction↗