Search

We present two flexible stochastic models for 2D and 3D ocean waves with potential to reproduce severe and non-homogeneous sea conditions. The first family consists of generalized Lagrange models for the movements of individual water particles. These models can generate crest-trough and front-back statistically asymmetric waves, with the same degree of asymmetry as measured ocean waves. They are still in the Gaussian family and it is possible to calculate different slope distributions exactly from a wave energy spectrum. The second model is a random field model that is generated by a system of nested stochastic partial differential equations. This model can be adapted to spatially non-homogeneous sea conditions and it can approximate standard wave spectra. One advantage with this model is that Hilbert space approximations can be used to obtain computationally efficient representations with Markov-type properties that facilitate the use of sparse matrix techniques in simulation and estimation.

We present two flexible stochastic models for 2D and 3D ocean waves with potential to reproduce severe and non-homogeneous sea conditions. The first family consists of generalized Lagrange models for the movements of individual water particles. These models can generate crest-trough and front-back statistically asymmetric waves, with the same degree of asymmetry as measured ocean waves. They are still in the Gaussian family and it is possible to calculate different slope distributions exactly from a wave energy spectrum. The second model is a random field model that is generated by a system of nested stochastic partial differential equations. This model can be adapted to spatially non-homogeneous sea conditions and it can approximate standard wave spectra. One advantage with this model is that Hilbert space approximations can be used to obtain computationally efficient representations with Markov-type properties that facilitate the use of sparse matrix techniques in simulation and estimation.

Abstract.: We present two flexible stochastic models for 2D and 3D ocean waves with potential to reproduce severe and non-homogeneous sea conditions. The first family consists of generalized Lagrange models for the movements of individual water particles. These models can generate crest-trough and front-back statistically asymmetric waves, with the same degree of asymmetry as measured ocean waves. They are still in the Gaussian family and it is possible to calculate different slope distributions exactly from a wave energy spectrum. The second model is a random field model that is generated by a system of nested stochastic partial differential equations. This model can be adapted to spatially non-homogeneous sea conditions and it can approximate standard wave spectra. One advantage with this model is that Hilbert space approximations can be used to obtain computationally efficient representations with Markov-type properties that facilitate the use of sparse matrix techniques in simulation and estimation.

Pulmonary fibrosis and interstitial lung disease are poorly understood in horses; the causes of such conditions are rarely identified. Equine herpesvirus 5 (EHV-5) is a γ-herpesvirus of horses that has not been associated with disease in horses. Pathologic and virologic findings from 24 horses with progressive nodular fibrotic lung disease associated with EHV-5 infection are described and compared with 23 age-matched control animals. Gross lesions consisted of multiple nodules of fibrosis throughout the lungs. Histologically, there was marked interstitial fibrosis, often with preservation of an “alveolar-like” architecture, lined by cuboidal epithelial cells. The airways contained primarily neutrophils and macrophages. Rare macrophages contained large eosinophilic intranuclear viral inclusion bodies; similar inclusion bodies were also found cytologically. The inclusions were identified as herpesviral-like particles by transmission electron microscopy in a single horse. In situ hybridization was used to detect EHV-5 nucleic acids within occasional macrophage nuclei. With polymerase chain reaction (PCR), the herpesviral DNA polymerase gene was detected in 19/24 (79.2%) of affected horses and 2/23 (8.7%) of the control horses. Virus genera–specific PCR was used to detect EHV-5 in all of the affected horses and none of the control horses. EHV-2 was detected in 8/24 (33.3%) of affected horses and 1/9 (11.1%) of the control horses. This disease has not been reported before, and the authors propose that based upon the characteristic gross and histologic findings, the disease be known as equine multinodular pulmonary fibrosis. Further, we propose that this newly described disease develops in association with infection by the equine γ-herpesvirus, EHV-5.

Hepatoblastoma was diagnosed in 3 Thoroughbreds at the University of Kentucky Livestock Disease Diagnostic Center (LDDC) since 1997. Case #1 involved a fetus with a well-demarcated, multilobulated, solitary mass that extended from the left liver lobe. Case #2 was observed in a neonate with a primary hepatic mass and multiple metastases in the skin, brain, meninges, and stylohyoid bone. Case #3 was a solitary hepatic mass incidentally discovered in a neonate at necropsy. Microscopically, the masses were similarly composed of sheets and cords of fetal and embryonal epithelial cells that frequently formed sinusoid-like structures. Intermixed with the neoplastic epithelial cells were variable amounts of hemorrhage, necrosis, osteoid, and bone. Immunohistochemically, the epithelial cells stained variably positive for alpha- fetoprotein, frequently positive for vimentin, and occasionally positive for cytokeratin. All 3 cases were diagnosed as mixed hepatoblastoma with teratoid features.

Molecular features of ligand binding to MHC class II HLA-DR molecules have been elucidated through a combination of peptide structure−activity studies and structure-based drug design, resulting in analogues with nanomolar affinity in binding assays. Stabilization of lead compounds against cathepsin B cleavage by N-methylation of noncritical backbone NH groups or by dipeptide mimetic substitutions has generated analogues that compete effectively against protein antigens in cellular assays, resulting in inhibition of T-cell proliferation. Crystal structures of four ternary complexes of different peptide mimetics with the rheumatoid arthritis-linked MHC DRB1*0401 and the bacterial superantigen SEB have been obtained. Peptide−sugar hybrids have also been identified using a structure-based design approach in which the sugar residue replaces a dipeptide. These studies illustrate the complementary roles played by phage display library methods, peptide analogue SAR, peptide mimetics substitutions, and structure-based drug design in the discovery of inhibitors of antigen presentation by MHC class II HLA-DR molecules.

Lecithin-cholesterol acyltransferase (LCAT) catalyzes the formation of cholesterol esters on high density lipoproteins (HDL) and plays a critical role in reverse cholesterol transport. Sphingomyelin, an important constituent of HDL, may regulate the activity of LCAT at any of the key steps of the enzymatic reaction: binding of LCAT to the interface, activation by apo A-I, or inhibition at the catalytic site. In order to clarify the role of sphingomyelin in the regulation of the LCAT reaction and its effects on the structure of apolipoprotein A-I, we prepared reconstituted HDL (rHDL) containing egg phosphatidylcholine, cholesterol, apolipoprotein A-I, and up to 22 mol % sphingomyelin. Because the interfacial properties of substrate particles can dramatically affect LCAT binding and kinetics, we also prepared and analyzed proteoliposome substrates having the same components as the rHDL, except for a 4-fold higher ratio of phospholipid to apolipoprotein A-I. The reaction kinetics of LCAT with the rHDL particles revealed no significant change in the apparent Vmax but showed a concentration-dependent increase in slope of the reciprocal plots and in the apparent Km values with sphingomyelin content. The dissociation constant (Kd) for LCAT with these particles increased linearly with sphingomyelin content up to 22 mol %, changing in parallel with the apparent Km values. No structural changes of apolipoprotein A-I were detected in the particles with increasing content of sphingomyelin, but fluorescence results with lipophilic probes revealed that significant changes in the acyl chain, backbone, and head group regions of the lipid bilayer of the particles are introduced by the addition of sphingomyelin. On the other hand, the proteoliposome substrates also had increased Kdvalues for LCAT at high sphingomyelin contents but compared with the rHDL particles had a 6-10-fold lower affinity for LCAT binding and exhibited kinetics consistent with competitive inhibition by sphingomyelin at the active site. These results show conclusively that the dominant mechanism for the inhibition of LCAT activity with rHDL particles by sphingomyelin is the impaired binding of the enzyme to the interface. The results also underscore the significant differences in the enzyme reaction kinetics with different substrate particles.

To investigate the development of HLA-DR-associated autoimmune diseases, we generated transgenic (Tg) mice with HLA-DRA-IE alpha and HLA-DRB1*0401-IE beta chimeric genes. The transgene-encoded proteins consisted of antigen-binding domains from HLA-DRA and HLA-DRB1*0401 molecules and the remaining domains from the IE(d)-alpha and IE(d)-beta chains. The chimeric molecules showed the same antigen-binding specificity as HLA-DRB1*0401 molecules, and were functional in presenting antigens to T cells. The Tg mice were backcrossed to MHC class II-deficient (IA beta-, IE alpha-) mice to eliminate any effect of endogenous MHC class II genes on the development of autoimmune diseases. As expected, IA alpha beta or IE alpha beta molecules were not expressed in Tg mice. Moreover, cell-surface expression of endogenous IE beta associated with HLA-DRA-IE alpha was not detectable in several Tg mouse lines by flow cytometric analysis. The HLA-DRA-IE alpha/HLA-DRB1*0401-IE beta molecules rescued the development of CD4+ T cells in MHC class II-deficient mice, but T cells expressing V beta 5, V beta 11, and V beta 12 were specifically deleted. Tg mice were immunized with peptides, myelin basic protein (MBP) 87-106 and proteolipid protein (PLP) 175-192, that are considered to be immunodominant epitopes in HLA-DR4 individuals. PLP175-192 provoked a strong proliferative response of lymph node T cells from Tg mice, and caused inflammatory lesions in white matter of the CNS and symptoms of experimental allergic encephalomyelitis (EAE). Immunization with MBP87-106 elicited a very weak proliferative T cell response and caused mild EAE. Non-Tg mice immunized with either PLP175-192 or MBP87-106 did not develop EAE. These results demonstrated that a human MHC class II binding site alone can confer susceptibility to an experimentally induced murine autoimmune disease.

A basic nonapeptide P2 (antiflammin-2, HDMNKVLDL) which is identical to a portion of the amino acid sequence (residues 246–254) of lipocortin I, has been described to have antiinflammatory activity in a rat paw edema model (Nature 335: 726–730 [1988]). P2 (0.05 μM) was also reported to inhibit porcine pancreatic phospholipase A2 (PLA2). The effect of synthetic P2 (98% pure) on PLA2 was evaluated in two assay systems. Using porcine pancreatic PLA2 and phosphatidylcholine/deoxycholate mixed micellar substrate, P2 (0.005–50 μM) had no effect on PLA2 activity, even in the presence of 2-mercaptoethanol to prevent peptide oxidation. In another assay, using human synovial fluid PLA2 as the enzyme and [14C]-oleate-labelledE. coli substrate, P2 (0.005–50 μM) had no significant effect on PLA2 activity. A reported PLA2 inhibitor, manoalide, was a potent inhibitor of PLA2 in both assay systems. On the basis of these results, we conclude that P2 is devoid of PLA2 inhibitory activity.

Somatostatin is a 14-amino-acid peptide hormone that is proteolytically excised from its precursor, prosomatostatin, by the action of a paired-basic-specific protease. Yeast (Saccharomyces cerevisiae Mat alpha) synthesizes an analogous peptide hormone precursor, pro-alpha-factor, which is proteolytically processed by at least two separate proteases, the products of the KEX2 and STE13 genes, to generate the mature bioactive peptide. Expression in yeast of recombinant DNAs encoding hybrids between the proregion of alpha-factor and somatostatin results in proteolytic processing of the chimeric precursors and secretion of mature somatostatin. To determine if the chimeras were processed by the same enzymes that cleave endogenous pro-alpha-factor, the hybrid DNAs were introduced into kex2 and ste13 mutants, and the secreted proteins were analyzed. Expression of the pro-alpha-factor-somatostatin hybrids in kex2 mutant yeast resulted in secretion of a high molecular weight hyperglycosylated precursor. No mature somatostatin was secreted, and there was no proteolytic cleavage at the Lys-Arg processing site. Similarly, in ste13 yeast, only somatostatin molecules containing the (Glu-Ala)3 spacer peptide at the amino terminus were secreted. Our results demonstrate that in yeast processing mutants, the behavior of the chimeric precursors with respect to proteolytic processing was exactly as that of endogenous pro-alpha-factor. We conclude that the same enzymes that generate mature alpha-factor proteolytically process hybrid precursors. This suggests that structural domains of the proregion rather than the mature peptide are recognized by the processing proteases.

Ro 25-1392 [Ac-Glu8,OCH3-Tyr10,Lys12,Nle17,Ala19,A sp25,Leu26,-Lys27,28-vasoactive intestinal peptide(cyclo 21-25)] is a cyclic peptide analog of vasoactive intestinal peptide (VIP) that potently exerts cellular effects typical of VIP. The selectivity of Ro 25-1392 for type I (VIPR1) and type II (VIPR2) VIP receptors was investigated first in competitive binding studies using Chinese hamster ovary cell transfectants stably expressing recombinant human VIPR1 and VIPR2. Nonradioactive Ro 25-1392 was as potent a competitive inhibitor as VIP for the binding of 125I-VIP to VIPR2 transfectants (Ki = 9.6 +/- 1.0 and 16 +/- 1.7 nM, respectively; mean +/- S.E.M., n = 4). In contrast, Ro 25-1392 had a very low affinity for VIPR1, compared with VIP, and attained a maximum of only 40% mean inhibition of binding of 125I-VIP at 1 microM. The affinity of VIP (Ki = 3.4 +/- 1.5 nM, mean +/- S.E.M., n = 4) for binding to VIPR1 was 1000-fold greater than that of Ro 25-1392. Ro 25-1392 evoked concurrent and concentration-dependent increases in intracellular levels of calcium and cyclic AMP (EC50 = 3.0 +/- 0.4 nM, mean +/- S.E.M., n = 4) in VIPR2 transfectants, but not in VIPR1 transfectants. The VIP receptor specificity of Ro 25-1392 was confirmed by preincubation of Chinese hamster ovary transfectants with 0.1 microM Ro 25-1392 for 18 hr at 37 degrees C, to down-regulate each type of VIP receptor. Pretreatment of VIPR2 transfectants with Ro 25-1392 decreased Bmax by a mean of 58% and VIP-induced increases in the intracellular concentration of cyclic AMP by a mean of 65%. In contrast, there was no significant change in VIPR1 transfectants after pretreatment with Ro 25-1392. Ro 25-1392 thus is selectively recognized by VIPR2, with consequent initiation of cyclic AMP and Ca+2 signals and down-regulation of VIPR2. This potent analog of VIP may prove useful for investigations of VIPR2-mediated physiological effects of VIP and exploration of the roles of VIPR2 in diseases.

T cell tolerance to self is achieved by deletion or inactivation of clones recognizing peptides of self proteins presented by major histocompatibility complex molecules. A considerable fraction of self proteins accessible to the immune system is contributed by the system itself, for example, the receptors used for antigen recognition (antibodies and T cell receptors [TCRs]). Thus far, it has remained unclear, whether antigen receptors are subject to self tolerance, or on contrary, engage into network interactions implying immunity rather than tolerance. In this study, we demonstrate self tolerance to synthetic peptides corresponding to the first hypervariable region of the V beta 8.1 and V beta 8.2 TCR proteins. We also show that the tolerogenic synthetic peptide corresponds to a fragment produced by processing of the V beta protein, and conversely, that a V beta peptide not produced by processing is also not subject to self tolerance. Thus, the rules of tolerance seem to apply to antigen receptors, at least to their germline-encoded portions, in a similar fashion as to other self proteins. This finding has important implications for studies of natural and artificially induced immune networks.

Ro 25-1553, a cyclic peptide analog of vasoactive intestinal peptide (VIP), was designed to overcome many of the deficiencies inherent in this natural neuropeptide. On isolated guinea pig tracheal smooth muscle, Ro 25-1553 produces concentration-dependent relaxation of contractile responses to a number of different spasmogens. Depending on the contractile stimulus, Ro 25-1553 is 24 to 89 times more potent than VIP as a relaxant of guinea pig trachea. The high potency of Ro 25-1553 extends to studies on isolated, histamine-contracted, human bronchial smooth muscle, where Ro 25-1553 exhibits a 390-fold enhancement over native VIP and is more potent than other bronchodilating drugs, such as the beta 2-adrenoceptor agonists isoproterenol and salbutamol. Ro 25-1553 was shown to displace the radioligand 125I-VIP from rat forebrain membranes with an IC50 value of 4.98 nM, thereby demonstrating that it acts at a VIP receptor. In addition, when tested in a battery of 40 other binding assays (e.g., muscarinic, histamine, LTs, Ca++, TxA2, endothelin, alpha and beta adrenergic, platelet-activating factor, neurokinins, etc.) at concentrations as high as 10 microM, Ro 25-1553 was found to be inactive; thus it appears to be specific for VIP receptors. The potent smooth muscle relaxant activity exhibited in vitro by Ro 25-1553 is also evident after in vivo intratracheal administration or aerosolization of the compound. Pulmonary responses evoked by histamine, leukotriene D4, platelet-activating factor and acetylcholine are inhibited dose-dependently by intratracheally instilled Ro 25-1553 with nearly identical potency (ED50 values ranging from 0.07 micrograms to 0.26 micrograms).(ABSTRACT TRUNCATED AT 250 WORDS)

Studies were conducted to compare the effect of native vasoactive intestinal peptide (VIP), Ro 25-1553 (a cyclic peptide analog of VIP) and salbutamol (a beta2-adrenoceptor agonist) on antigen-induced pathophysiological effects in the guinea pig. Ro 25-1553 and salbutamol (0.01-1.0 microM) prevented antigen-induced contractions of the guinea pig trachea in vitro with IC50 values of 0.07 and 0.05 microM, respectively. VIP (0.01-1.0 microM) had no effect on antigen-induced tracheal contractions. Aerosolized Ro 25-1553 and salbutamol were equipotent in preventing antigen-induced increases in guinea pig lung resistance (IC50 value = 0.0001%), whereas aerosolized VIP (0.1%) was ineffective. Ro 25-1553 (0.1-100 micrograms), instilled intratracheally 2 min before the antigen challenge of buffer-perfused lungs from sensitized guinea pigs, produced a dose-dependent inhibition of bronchoconstrictor, vasoconstrictor and edemagenic responses, whereas intratracheal VIP (100 micrograms) had no effect. Intratracheal salbutamol (0.1-100 micrograms) inhibited antigen-induced responses in a manner comparable to Ro 25-1553. Lung inflammation was assessed as leukocyte accumulation in bronchoalveolar lavage fluid after the antigen provocation. Aerosolized antigen-induced bronchoalveolar lavage eosinophilia (13-fold increase over saline controls) at 6 hr after challenge was prevented in a concentration-dependent manner by pretreatment with nebulized Ro 25-1553 and salbutamol, but not by pretreatment with native VIP. These results indicate that Ro 25-1553 suppresses various pathophysiological features associated with pulmonary anaphylaxis and asthma, including airway reactivity, edema formation and granulocyte accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)

This report explores the potential side-chain functional groups required for interaction of the bronchodilator neuropeptide, vasoactive intestinal peptide (VIP), with its receptor. The binding affinity and biological activity of native VIP have been found to be sensitive to the removal of amino- and carboxyl-terminal residues. This data suggests that elements within the entire primary sequence of the VIP molecule appear to be necessary for recognition by VIP receptors. The introduction of alanine residues substituted into the VIP molecule is utilized to probe for side-chain functional groups that are crucial for eliciting high receptor binding affinity in vitro and high biological potency in vivo. The VIP pharmacophore appears to be identical in guinea pig lung and human lung and consists of multiple binding sites most likely involving positions Asp3, Phe6, Thr7, Tyr10, Tyr22, and Leu23. These findings could be exploited to enhance the biological potency of VIP by increasing the binding energy at these positions.

We have previously identified four anchor positions in HLA-DRB1*0101-binding peptides, and three anchors involved in peptide binding to DRB1*0401 and DRB1*1101 molecules, by screening of an M13 peptide display library (approximately 20 million independent nonapeptides) for DR-binding activity. In this study, high stringency screening of the M13 library for DRB1*0401 binding has resulted in identification of three further anchor positions. Taken together, a peptide-binding motif has been obtained, in which six of seven positions show enrichment of certain residues. We have demonstrated an additive effect of anchors in two different ways: (i) the addition of more anchors is shown to compensate for progressive truncation of designer peptides; (ii) the incorporation of an increasing number of anchors into 6- or 7-residue-long designer peptides is shown to result in a gradual increase of binding affinity to the level of 13-residue-long high-affinity epitopes. The anchor at relative position 1 seems to be obligatory, in that its substitution abrogates binding completely, whereas the elimination of other anchors results only in partial loss of binding affinity. The spacing between anchors is critical, since their effect is lost by shifting them one position toward the N or C terminus. The information born out of this study has been successfully used to identify DR-binding sequences from natural proteins.

Ruminal digestion relative to the digestion in the remainder of the gastro-intestinal tract accounts for about 70 to 85% of the total digestion of dry matter (Annison, 1956). Phillipson (1958) showed that losses of digestible materials via absorption between the mouth and the duodenum were approximately 70% of that total. The interpretation of rumen composition and digestion data is complicated by several factors, such as dilution with materials remaining from previous feedings, inflow of saliva, variations in flow rate of the different nutrients and the time of sampling af ter feeding, (Yadava et al., 1964; Yadava and Bartley, 1964; Gray, Pilgrim and Weller, 1958a,b).The objectives of these experiments were to: 1. Determine the effects of the type of feed and the time of sampling after feeding on the concentration of selected nutrient fractions in the rumen; 2. Calculate the total digestion of the feed as determined by lignin vs.chromic oxide feed/feces ratios and; 3. Estimate the extent of total dry matter digestion accounted for by ruminal fermentation and absorption.

Data are presented from a four-year study on the seasonal variation in the blood phosphorus level of range ewes. Blood samples were collected from a group of about 40 Columbia ewes at 3 to 7 different times during the year.Seasonal trends in blood phosphorus level were fairly definite and-variations between seasons were highly significant. Highest blood phosphorus levels were found on the winter and spring ranges, while lowest levels were found at lambing time, in the late summer and fall, and on the winter feed lot. Supplemental feeding of cottonseed cake or oats on the winter range or feed lot increased the phosphorus content of the blood.Blood phosphorus was lower for ewes that had lambed than for ewes that had not yet lambed. Dry ewes had higher blood phosphorus than ewes which were pregnant or were suckling lambs. Ewes with one lamb had higher blood phosphorus than ewes with two lambs.A relationship was found between gain or loss in body weight and blood phosphorus. Ewes which were losing weight tended to have higher blood phosphorus.Blood phosphorus tended to decrease with age.No definite evidence of phosphorus deficiency was found except low blood phosphorus levels. The percentage of ewes having blood phosphorus values of 3.50 mg. or below for the various seasons were 5.30 for the fall range, 2.50 for the feed lot, 20.0 at lambing, 2.7 for the spring range and 10.0 for the summer range.

Experiments to determine the phosphorus requirement for fattening lambs have been carried out employing 675 western lambs in a series of five experiments. Lambs fed on rations containing 0.07 to 0.12 per cent phosphorus or an intake of 1.20 to 1.67 grams of phosphorus per 100 pounds live weight showed abnormally slow gains, high feed requirements, and specific symptoms of aphosphorosis such as depraved appetite, unthrifty appearance and low blood phosphorus. A level of 0.14 per cent phosphorus in the diet indicated a borderline phosphorus deficiency, which proved to be inadequate for normal growth and feed utilization. Lambs receiving rations with a phosphorus content ranging from 0.15 to 0.23 per cent were adequately supplied with phosphorus as indicated by good rate of gain, efficient feed utilization and normal blood phosphorus levels. On the basis of phosphorus intake per unit live weight, lambs receiving from 2.17 to 3.38 grams daily per 100 pounds of live weight will meet their phosphorus requirement.Although a somewhat lower phosphorus level may be adequate, due to the different conditions under which lambs are fattened, it is suggested that the optimum feed phosphorus requirement for fattening lambs be set at 2.40 grams per 100 pounds of live weight or the ration should contain on a dry basis 0.17 per cent or more phosphorus.These results indicate that a phosphorus deficiency in lambs exerts a more depressing effect on the utilization of the feed than on the appetitie.

Results from a factorial experiment involving 72 Columbia-type lambs on two different protein supplements and four levels of stilbestrol are presented. Soybean oil meal was a significantly better protein supplement than urea when urea (42% N) was fed at the rate of three % of the concentrate mixture with poor quality non-legume hay (urea furnished 41% of the nitrogen in the ration). Feeding stilbestrol produced significantly greater gains on both types of nitrogen. There were no significant differences in carcass grades or yields as a result of stilbestrol treatment. No death loss nor observable deleterious effects were attributable to the stilbestrol.

A chromatographic method for the determination of cobalt in feeds is described. The ashed sample is dissolved with HCl, filtered, and the filtrate evaporated to dryness. Perchloric acid is added and the contents evaporated to white fumes. With the addition of distilled water and nitroso R salt, the cobalt complex color is developed in the usual manner. The entire solution is passed through a perchloric acid-washed alumina column. The cobalt complex is adsorbed on the column. The excess reagent is eluted from the column with dilute HNO3. The cobalt complex is then eluted with dilute H2SO4, and determined colorimetrically.Advantages over previous methods are that copper and iron do not interfere with the cobalt determination, and larger initial samples may be ashed to give a greater concentration of cobalt in the final solution for a colorimetric determination.As determined by this method, the cobalt content of hays range from 0.047 to 0.468 p.p.m., cereal grains from 0.014 to 0.091 p.p.m., and plant protein concentrates (sunflower, cottonseed, and linseed meal) from 0.190 to 0.500 p.p.m.

Two experiments designed to study the protein requirements of pregnant ewes are reported. Six lots of twenty ewes each were included in each experiment. In the first experiment rations which contained approximately 7, 10, and 13 percent total crude protein were compared and in the second rations containing 5, 8, and 11 percent protein.No statistically significant differences were found between the various rations in fleece weight, birth weight of lambs, or weight of lambs at thirty days of age. Some trends were noted, however, in that the ewes fed the lowest levels of nitrogen tended to shear lighter fleeces and their twin lambs weighed slightly less at thirty days.The death loss of ewes was somewhat higher on the low-protein rations. The low nitrogen intake may have been a predisposing factor in a number of these deaths.Nitrogen balance experiments showed no significant differences in nitrogen retention between the three levels of nitrogen intake during early and mid gestation. In late pregnancy the ewes fed the higher levels of nitrogen retained significantly larger amounts.A highly significant correlation (r=0.69) was found to exist between nitrogen retention and digestible dry matter intake. Covariance analysis showed that, at the levels fed in these investigations, the amount of nitrogen stored was influenced more by the amount of dry matter digested than by the amount of nitrogen fed.The results obtained indicate that present recommendations with respect to amounts of crude protein for pregnant ewes may be decreased when the rations fed are adequate in other nutrients.

A rapid, simple and accurate method has been presented for the determination of the wool fiber diameter. This method makes use of the audio oscillator and a vibrascope constructed from a “2” inch permanent magnet speaker. With this apparatus, the frequency is obtained at the maximum vibration of the wool fiber. The diameter of a vibrating wool fiber then can be calculated from the following equation:Where D is the diameter of the wool fiber in microns, T is the tension in grams: d is the density of the fiber; L is the length in cm. and V is the frequency in cycles per second.This method has been found useful for evaluating the quality of individual fleeces in a selection program, designed to reduce variability in fiber diameter.

A reversal of wool pigmentation from white to black and vice versa has occurred in Hampshire sheep fed rations low in vitamins A and D.Vitamin A treatments to depleted sheep of Hampshire origin brought no response in pigmentation pattern.A reversion to original wool pigmentation was noted when vitamin D was administered to lambs previously treated with vitamin A.Sheep of Delaine-Merino × Rambouillet ancestry or Columbia-type sheep that were heterozygous for black showed no pigmentation reversal pattern.There was a difference between Hampshire lambs in their response to rations deficient in vitamins A and D.

The results of three double reversal, nitrogen balance experiments conducted with mature ewes are presented. These experiments were designed to determine the effect of methionine supplementation upon the utilization of various amounts and sources of protein.When the results of the three experiments, in which five different rations were studied, are considered the addition of DL-methionine significantly increased nitrogen retention. The supplemental methionine had considerably greater effect when added to certain rations than when added to others. Possible reasons for these differences are discussed.L-methionine intake and excretion values were determined microbiologically in two of the experiments. The results of these analyses indicated that the supplemental methionine was either completely utilized or destroyed.When fed at approximately the same level of protein intake dehydrated alfalfa had a significantly higher biological value than field peas. The data presented suggest that some factors other than the level of protein intake or amino acid make-up influenced the utilization of protein in these experiments.

The results of four experiments are presented. There were no consistent differences in lamb production from ewes fed rations approximately equal in total digestible nutrients but which varied from 6.8 to 11.0 percent total protein. There were no apparent differences in production between ewes fed linseed meal or dried skimmilk as a protein supplement to a grass hay, shelled corn ration.Pregnant Shropshire ewes averaging 135 pounds in body weight remained in positive nitrogen balance, made satisfactory gains and gave birth to thrifty lambs when fed an average of 0.10 pound digestible protein per ewe daily. No improvement in utilization of protein or production was noted from the addition of 0.10 percent DL methionine.Further work is needed relative to the protein requirements of pregnant ewes.

A total of 992 blood samples of pregnant ewes fed various kinds and amounts of protein were analyzed for oxyhemoglobin, total serum proteins, serum albumins and serum globulins. Considerable variation was found in these constituents between individual sheep and between bi-weekly samples from the same ewe.Ewes fed rations low in protein had lower serum albumins than those fed a liberal or adequate amount of protein. Low protein rations also caused a reduction in oxyhemoglobin. Serum globulins were not affected by the rations fed.When fed at an equal level of protein there were no differences in blood proteins between ewes fed linseed meal and those fed dried skim milk as the protein supplement.Ewes with high oxyhemoglobin levels tended to have high serum albumins and low serum globulins. In these experiments serum globulins predominated over serum albumins. The oxyhemoglobin, total serum protein and serum globulin levels of individual ewes were highly correlated between years.

Six wethers were fed 1500 gm./day of pelleted alfalfa. The rate of passage of Cr2O3incorporated as a component of paper and as a powder in rations was determined. Chromic oxide “powder” was excreted significantly faster than “paper”.The wethers were put on a 10-day digestion trial, and coefficients obtained by the conventional method agreed with those obtained by the ratio technique using Cr2O3“paper”. Low recovery of the “powder” was noticed in all runs. The levels of Cr2O3paper and crude fiber in the feces were correlated significantly.Following the digestibility trial the wethers were slaughtered 10 to 12 hours after the last feeding and the alimentary tract contents removed in 13 sections. The digesta from each section was analyzed for dry matter, ash, Cr2O3, calcium, phosphorus, protein, crude fiber and lignin. Indigestibilities of these feed constituents were calculated using Cr2O3“paper”, Cr2O3“powder”, and lignin techniques. Chromic oxide apparently was passed out of the rumen faster than lignin or the bulk of the dry matter. The rate of flow of calcium and Cr2O3appeared to be very similar. Indigestibilities and levels of lignin and crude fiber showed a high degree of association of these constitutents in their rate of flow through the tract. The concentrations of phosphorus did not follow those of calcium.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.