Factors influencing the immunogenicity of the haptenic drug chlorhexidine in mice--Part I. Molecular requirements for the induction of IgE and IgG anti-hapten antibodies.

The immunogenicity of a novel hapten, the anti-microbial agent, chlorhexidine (1,1'-hexamethylene bis [5-(p-chlorophenyl)biguanide]) was assessed in mice, using alum as adjuvant. The i.p. injection of electrostatically-linked chlorhexidine + keyhole limpet haemocyanin (KLH) mixtures induced low level primary IgG anti-chlorhexidine antibody synthesis. In contrast, covalently-linked chlorhexidine-KLH complexes induced both IgE and IgG anti-chlorhexidine antibody synthesis. Covalent binding was facilitated by the N-chlorination of secondary amide groups on the biguanide moeities of the chlorhexidine molecule. The immunogenicity of such complexes was related to the degree of conjugation of chlorhexidine to KLH; which, in turn, was related to the molarity of chlorine used to effect N-chlorination. Immune responses to covalently-linked complexes could be enhanced by carrier priming. The induction of low levels of IgG anti-hapten antibodies by electrostatically-linked complexes may reflect T cell-independent specific B cell activation, either by chlorhexidine itself or by a "pseudo-plurivalent" chlorhexidine + KLH antigen.

Benign familial polycythaemia.

An English family suffering from thalassaemia minor is described. Three generations are affected, and all the affected members had a considerably raised red cell count in the presence of slight or moderate anaemia, obviously abnormal peripheral films, and only slightly reduced M.C.H.C. values; and each had a moderately raised haemoglobin A(2) level, though foetal haemoglobin levels were normal. The presentation of a family with erythrocytosis recalls the condition described in the older literature as benign familial polycythaemia which was, in some cases at least, thalassaemia minor. It is suggested that the presence of a raised red cell count is a more reliable distinguishing feature than the presence of target cells, or the serum iron level, in thalassaemia minor.

Studies on the dinitrophenylated lymphocytes in guinea pig painted with DNCB.

The number of DNP group-bearing lymphocytes in the regional lymph node, thoracic duct and peripheral blood was determined at various time intervals after painting normal guinea pigs with DNCB by the immunofluorescent method using anti-DNP antibody. The incidence of such cells in the regional node was maximal at 12 hours whereas in the thoracic duct and peripheral blood the maximum incidence was found at 0.1-2 hours after painting. Unreacted DNCB was demonstrated in both the thoracic lymph duct and the blood at least for 12 or 24 hours respectively following exposure to DNCB. The authors therefore suggest that DNCB reacts directly in vivo with the lymphocyte cell membrane of guinea pig following epicutaneous application of the chemical.

Nitrogen metabolism of growing lambs fed coastal bermudagrass as influenced by formaldehyde treatment and glucose.

Six abomasally-cannulated wethers (average initial weight 18 kg) were used in a split 3 X 3 Latin square design experiment with a crossover to determine effects of glucose (G) administered orally (O) or infused (I) into the abomasum on nitrogen metabolism and forage fiber digestion. Basal diets were Coastal bermudagrass (CBG) or CBG treated with 1% formaldehyde (F-CBG). Individual treatments were: (1) CBG, (3) CBG + G(O), (3) CBG + G(I), (4) F-CBG, (5) F-CBG + G(O) and (6) F-CBG + G(I). Nitrogen balance was 3.67, 4.86, 4.80, 5.04, 5.73 and 6.04 g/day and urinary N was 6.50, 4.10, 4.42, 5.25, 3.26 and 3.00 g/day for treatments 1,2,3,4,5 and 6, respectively. Nitrogen balance was increased and urinary nitrogen decreased (P < .005) by formaldehyde treatment and addition of G. Crude protein digested was decreased (P < .005) by G but was unaffected by formaldehyde (P > .05). Concentration of essential amino acids in plasma was decreased by addition of G (P < .005). Digestion of cellulose and hemicellulose was decreased by G (P < .005) administered orally but was unaffected by G infusion or formaldehyde treatment. Addition of G thus increased the overall efficiency of nitrogen and energy utilization.

Effects of dietary fiber and feeding frequency on ruminal fermentation, digesta water-holding capacity, and fractional turnover of contents.

To determine the effects of different sources of fiber and feeding frequency on digesta water-holding capacity (WHC; g H2O/g DM) and ruminal liquid contents, four ruminally fistulated Jersey steers were fed a 60:40 roughage-concentrate diet at 1.5 times NEm. Diets contained either sorghum silage (SS) or a 67:33 mixture of SS and soyhulls (SH) as roughage and were fed either once or 12 times daily, in a 2 x 2 factorial experiment with 15-d periods. Ruminal fluid was sampled at 2, 4, 6, 8, 10, 12, 16, 20, and 24 h after a dose of Co-EDTA on d 10 and analyzed for Co, VFA, ammonia, buffering capacity, and osmolality. Ruminal WHC, NDF, ADF, lignin, and starch were measured in samples obtained by ruminal evacuation at 3, 6, 12, and 24 h after feeding on d 11, 12, 14, and 15, respectively. Substitution of SH for SS decreased ruminal pH .32 units and dilution rate by 26.8% but increased total VFA by 10.9%, osmolality by 13.6%, and the fractional turnover rate (FTR) of ADF by 22.5% (P less than .05). Frequent feeding resulted in 4.7, 21.9, and 74.4% increases in total VFA and FTR of ruminal DM and starch (P less than .05), respectively. Interactions (P less than .05) were observed between dietary fiber source and feeding frequency for ruminal fluid molar percentage acetate to propionate ratio (A/P), liquid volume (evacuated), and WHC (kilograms). Substituting SH for SS decreased ruminal WHC (kilograms), liquid volume, and A/P only in steers fed once daily. Ruminal WHC (kilograms) was correlated positively with ruminal liquid volume but negatively with DM FTR. The dynamics of digesta WHC (kilograms) associated with dietary fiber source and feeding frequency suggest that it may influence the contribution of water and salivary secretions to ruminal liquid contents.

The effect of microbial phytase in a pearl millet-soybean meal diet on apparent digestibility and retention of nutrients, serum mineral concentration, and bone mineral density of nursery pigs.

Eighteen gilts (initial BW of 10.9 kg; age 4 wk) were used in a 35-d experiment to study the effects of adding microbial phytase to a pearl millet-soybean meal-based diet on growth, apparent digestibility and retention of nutrients, and bone mineral status. The dietary treatments were arranged in a 2 x 3 factorial with two levels of P (.58%, low-P or .95%, adequate-P) and three levels of microbial phytase (0, 700, or 1,000 units/kg of diet). Phosphorus, Ca, and N balance were determined from d 32 to 35. Blood samples were collected on d 0 and 35 for serum mineral analysis. Global bone mineral content (GBMC) and global bone mineral density (GBMD) were determined on d 0 and 35 using dual-energy x-ray absorptiometry (DXA). A microbial phytase level x P level interaction was observed for final BW, ADG, gain:feed (P < .001), and serum P concentration (P < .003). Phytase supplementation of the low-P diets increased final BW, ADG, gain: feed, and serum inorganic P concentration but did not improve growth or serum inorganic P concentration in pigs fed the adequate-P diets. The addition of microbial phytase to the low-P and adequate-P diets reduced fecal P (P < .01), fecal N (P < .05), increased P absorption and retention (P < .01), and increased N absorption (P < .05). Pigs fed the adequate-P diets absorbed more P (P < .01) but excreted more P (P < .01) in the feces. Phytase tended to increase Ca (P < .07) and N (P < .10) retention, apparent threonine digestibility (P < .06), and serum Zn concentration (P < .09). Phytase increased GBMC and GBMD (P < .04). Phosphorus also increased GBMC and GBMD (P < .007 and P < .002, respectively). These results show that supplemental microbial phytase in pearl millet-soybean meal diets increased P availability, decreased the amount of P excreted in feces, and increased bone mineralization in nursery pigs.

Effects of supplemental protein source on ruminal fermentation, protein degradation, and amino acid absorption in steers and on growth and feed efficiency in steers and heifers.

In Exp. 1, four Holstein steers with cannulas in the rumen, abomasum and terminal ileum were used to determine the effects of 1) soybean meal (SBM), 2) heated SBM (HSBM), 3) corn gluten meal (CGM), or 4) a combination of HSBM and CGM (COMBO) as protein supplements on ruminal and total tract nutrient digestibilities and intestinal amino acid flows and absorption. In Exp. 2, 24 Holstein steers and 16 Holstein heifers were used in a 56-d growth trial to study the effects of these protein supplements on growth, feed efficiency, and apparent digestibility of DM, OM, CP, and fiber components. Increasing undegradable intake protein (UIP) in diets with HSBM, CGM, and COMBO decreased ruminal fluid ammonia N concentrations (P < .05) and ruminal DM and OM digestion (P < .05) and increased flow to the abomasum and absorption from the small intestine of CP (P < .05), total amino acids (P < .05), and total essential amino acids (P < .01). Increasing UIP increased bacterial and nonbacterial CP and amino acids flowing to the abomasum (P < .05). However, UIP supplementation did not affect DMI, ADG, or feed efficiency in steers or heifers (P < .05).

Nitrogen balance, abomasal crude protein and amino acids in wethers fed formaldehyde-treated coastal bermudagrass and infused with methionine, glucose or monensin.

A 5 X 5 Latin square design was used to study the effects on nitrogen balance, wool growth and plasma amino acids of infusing methionine and (or) glucose into the abomasum of growing wethers fed formaldehyde-treated Coastal bermudagrass (F-CBG) or untreated Coastal bermudagrass hay. Daily treatments were: (1) CBG; (2) F-CBG + 3 g methionine (met); (4) F-CBG + 96 g glucose and (5) F-CBG + 3 met + 96 g glucose. Glucose infusion decreased (P < .005) moles/100 g of total essential amino acids in plasma; moles/100 g of lysine, valine, leucine and isoleucine were also reduced (P < .005). Moles/100 g of methionine in plasma were increased significantly by methionine infusion, but nitrogen retention was not affected (P > .10). The grams digestible protein to megacalorie digestible energy (DE) ratio was 36.6, 35.9 and 32.4 for CBG, F-CBG and F-CBG + glucose, respectively. The decrease (36.6 to 32.4) resulted in increased nitrogen retained (P < .05), increased percentage nitrogen intake retained (P < .05) and increased percentage digested nitrogen retained (P < .01). Urinary nitrogen excretion was lower (P < .01) in wethers receiving the F-CBG + glucose treatment than in those receiving the F-CBG treatment (3.60 vs 5.09 g/day). Effects of formaldehyde treatment of CBG and rumen infusion of monensin on quantities of various crude protein (CP) components reaching the abomasum were also determined in a 4 X 4 Latin square design experiment. Total CP reaching the abomasum increased (P < .01) with formaldehyde treatment and resulted in increased quantities of amino acids reaching the abomasum (P < .05). Monensin had no effect on these two parameters, and no interaction between monensin and formaldehyde was observed. Dietary CP reaching the abomasum increased with formaldehyde treatment (P < .005) and with infusion of monensin (P < .025). Total microbial protein (MP) and MP reaching the abomasum per 100 g dry matter digested were not influenced by either formaldehyde or monensin.

Ruminal escape protein supplementation and zeranol implantation effects on performance of steers grazing winter annuals.

Fifty-four crossbred steers (275 kg) were assigned randomly to one of three isoenergetic but not isonitrogenous ruminal escape protein (EP) supplements: high ruminal escape protein (HEP), low ruminal escape protein (LEP), or corn. The supplements contained corn, distillers' dried grains with solubles (DDGS), and fish meal. Supplements were fed at approximately 1.5 kg/d; the HEP and LEP supplements provided .25 and .12 kg more EP per day than corn, respectively. These supplements also supplied .20 and .10 kg more CP per day than corn. Fish meal and DDGS provided 66.7 and 33.3% of the supplemental EP, respectively. One-half of the steers in each supplement treatment were implanted once with 36 mg of zeranol. Steers grazed wheat (Triticum aestivum L.)-annual ryegrass (Lolium multiflorum Lam.) pastures for 73 d (March 1 to May 12). Daily gains (kg/d) increased linearly (P less than .07) as EP increased (HEP, 1.61; LEP, 1.54; corn, 1.47); responses were apparent only during the later periods as forage quality declined. Zeranol implants increased (P less than .02) ADG (kg/d) by 9.7% (1.58 vs 1.44). After grazing, all cattle were fed a finishing ration for 76 d. Pre-feedlot EP level produced a negative linear (P less than .04) response on feedlot ADG (kg/d) (HEP, 1.44; LEP, 1.50; corn, 1.59). Zeranol implantation during the grazing phase did not affect (P greater than .2) performance during the feedlot phase or carcass characteristics other than increased ribeye area (P less than .08). Compensatory feedlot performance negated all weight gain advantages elicited by EP supplementation during the grazing period.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein and fiber digestion by steers grazing winter annuals and supplemented with ruminal escape protein.

Six abomasally cannulated Hereford steers (12 mo of age, 300 +/- 10 kg) grazing annual ryegrass (Lolium multiflorum Lam.) paddocks were used in a replicated 3 x 3 Latin square design to determine effects of ruminal escape protein (EP) supplementation on forage intake, fiber digestion, and protein flow to the intestine. Steers were fed one of three isoenergetic supplements: high ruminal escape protein (HEP), low ruminal escape protein (LEP), or corn, which supplied an estimated .25, .125, or 0 kg of EP/d in addition to EP supplied by corn. Fish meal (FM) and distiller's dried grains with solubles (DDGS) were sources of EP; FM provided 66.7% and DDGS provided 33.3% of estimated EP. Steers were adjusted to each supplement for 7 d before a 4-d collection period. Both total and forage DMI responded quadratically (P less than .03 and P less than .07, respectively) to EP supplementation. Total tract DM digestion tended (P less than .13) to increase linearly with EP supplementation. Abomasal total CP flow increased linearly (P less than .10) as supplemental EP increased. Crude protein flow in steers receiving HEP, LEP, and corn was 1,137, 1,027, and 844 g/d, respectively. Likewise, abomasal nonammonia N (NAN) tended to be greater (P less than .15, linear) for steers receiving HEP. Nonammonia N flows were 1,044, 955, and 771 g/d for steers receiving HEP, LEP, and corn, respectively. Abomasal ammonia flow did not differ (P less than .20) among treatments, nor did reticuloruminal fiber digestion (P less than .20). These data indicate that EP can increase postruminal protein flow and will not negatively affect fiber digestion in steers grazing annual ryegrass pastures.

Effects of zinc sulfate concentration and feeding frequency on ruminal protozoal numbers, fermentation patterns and amino acid passage in steers.

Effects of zinc sulfate (0 vs 1,142 ppm supplemental zinc from zinc sulfate) and feeding frequency (1 x vs 12x daily) on ruminal protozoa numbers, fermentation patterns and amino acid passage were investigated using four ruminally and abomasally cannulated mature Jersey steers in a 4 x 4 Latin square experiment. Steers (530 kg) were fed a 50:50 roughage:concentrate diet at 1.5 times their NEm requirement. Experimental periods were 14 d in duration; ruminal, abomasal and fecal samples were collected at 6-h intervals during the last 3 d of each period. Protozoa numbers tended to be lowest (1.82 x 10(6)/ml) in steers fed zinc 1 x and tended to be highest (3.83 x 10(6)/ml) in steers fed zinc 12 x daily (P less than .10). Frequent feeding decreased ruminal pH .24 units and increased total VFA 20.7%, ammonia 22.7% and ruminal digestion of dietary amino acids (AA) 61.6% (P less than .05). Zinc supplementation decreased ruminal digestion of dietary AA 35.8% (P less than .05) and the abomasal passage of bacterial OM and AA 21.2% (P less than .05) and increased ruminal output of amino acids as a percentage of intake 15.1% (P less than .05). Although it increased escape of dietary AA, zinc sulfate decreased postruminal passage of bacterial AA and resulted in a net negative effect on total postruminal AA passage as a percentage of intake. The effects of zinc on ruminal AA digestion may be more closely related to an interaction of zinc with dietary CP rather than to an effect of Zn on ruminal microbial populations.

Effects of a salivary stimulant, slaframine, on ruminal fermentation, bacterial protein synthesis and digestion in frequently fed steers.

Slaframine (SF), a parasympathomimetic salivary stimulant, was administered i.m. (10, 15 or 20 micrograms SF/kg BW) to ruminally and abomasally fistulated steers at 12-h intervals for 18-d periods in a latin square-designed experiment. Steers were fed semicontinuously (12 times daily) a 40:60 roughage:concentrate diet at twice their net energy requirement for maintenance. Ruminal digestion coefficients for DM, ADF and starch were 10 to 16% lower and linearly related in an inverse manner to the level of SF administered (P less than .05). Postruminal digestion of DM, ADF and starch increased as much as 46.7, 9.5 and 44.0%, respectively, in a fashion linearly related (P less than .05) to the level of SF administered. Total tract digestion of DM and ADF were not affected by SF; however, total tract starch digestion was increased as much as 5% and was related linearly (P less than .05) to SF treatment. With SF administration, as much as 13% more bacterial protein exited the rumen, resulting in a 16.5% linear improvement (P less than .1) in the efficiency of ruminal bacterial protein production per 100 g of OM fermented. Ruminal concentrations of VFA, ammonia and pH were not affected by SF. These results demonstrate a positive relationship between salivation and ruminal bacterial protein synthesis and suggest that feed utilization by ruminants may be improved by pharmacological stimulation of salivary secretions.

Effect of dietary energy source and level on serum growth hormone, insulin-like growth factor 1, growth and body composition in beef heifers.

Effects of fiber vs starch energy supplements on endogenous growth hormone (GH), insulin-like growth factor (IGF-1) and animal performance from weaning to breeding age were evaluated in 18, 9-mo-old beef heifers. Heifers had ad libitum access to wheat silage plus an average daily supplement intake of 1) 4.08 kg corn-soybean meal (SBM) (high energy-starch, HS), 2) 4.54 kg soyhulls (SH)-SBM (high energy-fiber, HF) or 3) 1.36 kg SH-SBM (low energy-fiber, LE). Serum samples were collected via jugular puncture every 10 d and were analyzed for IGF-1 by RIA. On d 45 and d 176, four heifers per treatment were fasted 18 h and serial blood samples collected via jugular cannulas every 15 min for 6.5 h. Arginine (.5 g/kg BW) was administered intravenously (ARG) to induce release of GH, and four additional samples of blood were collected. Samples were analyzed by RIA for GH. Mean fasted GH (6.4 +/- .4, 8.3 +/- .4 and 13.8 +/- .4 ng/ml for HS, HF and LE, respectively) varied with energy source and level (P less than .01). Mean GH following ARG was higher (P less than .01) in heifers receiving LE (46.2 +/- 4.7) than in those receiving HS and HF (23.5 +/- 4.4 and 24.1 +/- 4.6 ng/ml). Basal GH concentration and peak amplitude were higher (P less than .05) in LE than in HS and HF treatments. Diet did not influence number or frequency of GH peaks.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitrogen metabolism and hormonal responses of steers fed wheat silage and infused with amino acids or casein.

Four Holstein steers (159 kg) surgically fitted with abomasal-infusion cannulas were used in a 4 x 4 Latin square study to test amino acid (AA) and casein (CAS) infusions on nitrogen balance and hormonal status of steers consuming vegetative wheat (Triticum aestivum L.) silage (12.3% CP). Treatments were 5-d infusions of 1) water (CONT), 2) arginine (ARG; 13.69 g/d), 3) limiting amino acids (LAA, 13.69 g/d arginine + 10.92 g/d histidine + 28.97 g/d lysine + 10.88 g/d methionine + 16.96 g/d threonine, and 4) Na-CAS (300 g/d). Whole blood was collected for plasma AA, growth hormone (GH), insulin, and IGF-I concentrations. Data were analyzed by ANOVA, and the following orthogonal contrasts were used to separate treatment means: CONT vs ARG; ARG vs LAA; and LAA vs CAS. Urinary N increased (P < .02) for CAS vs LAA. Arginine increased N retention, as did CAS, compared to LAA. Total plasma essential AA were decreased by arginine. Mean plasma insulin concentrations were increased by CAS (P < .034). Arginine increased mean plasma GH levels, but not IGF-I. The CAS treatment increased (P < .015) IGF-I levels, but not GH. These data suggest that performance of steers fed wheat silage was limited by duodenal AA flow and that arginine was the first-limiting AA. Casein infusion increased plasma insulin and IGF-I, which would explain the improved growth noted in calves and lambs fed forages supplemented with ruminally undegraded protein.