Effects of electric and magnetic fields on nocturnal melatonin concentrations in dairy cows

Sixteen multiparous, pregnant, lactating Holstein cows (weighing 600 +/- 50 kg, at 184.8 +/- 52 d of lactation, and at 101.9 +/- 43 d of gestation) were confined to wooden metabolism cages and exposed to a vertical electric field of 10 kV/m and a uniform horizontal magnetic field of 30 microT. The trial was conducted using a switchback statistical design. Cows were divided into two sequence groups of 8 cows each. One sequence group was exposed for three periods of 28 d each. The electric and magnetic fields were off during the first period, on during the second period, and off during the final period. The second sequence group was exposed for three periods also, but the activity of the fields was reversed (on during the first period, off during the second period, and on during the third period). On d 25 of each exposure period, blood samples were obtained every 0.5 h for 14 h starting at 1700 h to determine melatonin concentration. Nocturnal melatonin concentrations did not show any variation that could be attributed to exposure to electric and magnetic fields.

High-performance liquid chromatography of selenoamino acids and organo selenium compounds. Speciation by inductively coupled plasma mass spectrometry

As part of an ongoing study to identify selenium compounds with cancer chemopreventive activity, extracts of selenium-enriched samples were analyzed by HPLC-inductively coupled plasma (ICP)-MS. Ion-exchange, ion pair and derivatization methods for reversed-phase HPLC were considered and advantages and disadvantages for each compared. Anion exchange allows separation of selenite and selenate, but otherwise provides poor separation. Pre-column derivatization and reversed-phase chromatography provides separation of compounds with terminal amine functionalities, but many other species elute in the void volume. The ion pair method gave optimal separation and was compatible with standard ICP-MS operating conditions.

Eradication of murine bladder carcinoma by intratumor injection of a bicistronic adenoviral vector carrying cDNAs for the IL-12 heterodimer and its inhibition by the IL-12 p40 subunit homodimer

IL-12 is a heterodimeric immunoregulatory cytokine composed of covalently linked p40 and p35 subunits and exhibits antitumor activity in a variety of laboratory models. The efficacy of systemically administered cytokines for cancer therapy is often limited by toxicity. The gene therapy approach provides a mechanism to achieve temporary and high local concentrations of cytokines within a tumor with less risk of systemic toxicity. We constructed replication-defective adenoviruses containing the murine IL-12 p40 subunit (Ad.mp40) or a bicistronic vector containing cDNAs for the p40 and p35 subunits (Ad.mIL-12). Murine MB49 bladder cancer cells infected with Ad.mIL-12 secrete high concentrations of biologically active IL-12, while those infected with Ad.mp40 produce the p40 homodimer. Tumors injected with Ad.mIL-12 show rapid increases in IL-12 and IFN-gamma expression over 2 to 5 days and a return to baseline by 7 to 14 days. Injection of tumors with Ad.mIL-12 (1 x 10(9) plaque-forming units) results in a complete tumor regression in all mice, while those treated with control adenovirus succumb to their tumor. Efficacy is reduced when studies are performed in mice depleted of CD4+ and CD8+ cells or in nude mice. Mice cured of their tumor by Ad.mIL-12 demonstrate specific protective immunity upon rechallenge. Ad.mp40 does not exhibit antitumor activity and may antagonize the activity of rIL-12 or Ad.mIL-12. In summary, gene therapy strategies for cancer using adenoviral vectors containing IL-12 are highly effective with no significant toxicity in mice.

Eradication of murine bladder carcinoma by intratumor injection of a bicistronic adenoviral vector carrying cDNAs for the IL-12 heterodimer and its inhibition by the IL-12 p40 subunit homodimer

IL-12 is a heterodimeric immunoregulatory cytokine composed of covalently linked p40 and p35 subunits and exhibits antitumor activity in a variety of laboratory models. The efficacy of systemically administered cytokines for cancer therapy is often limited by toxicity. The gene therapy approach provides a mechanism to achieve temporary and high local concentrations of cytokines within a tumor with less risk of systemic toxicity. We constructed replication-defective adenoviruses containing the murine IL-12 p40 subunit (Ad.mp40) or a bicistronic vector containing cDNAs for the p40 and p35 subunits (Ad.mIL-12). Murine MB49 bladder cancer cells infected with Ad.mIL-12 secrete high concentrations of biologically active IL-12, while those infected with Ad.mp40 produce the p40 homodimer. Tumors injected with Ad.mIL-12 show rapid increases in IL-12 and IFN-gamma expression over 2 to 5 days and a return to baseline by 7 to 14 days. Injection of tumors with Ad.mIL-12 (1 x 10(9) plaque-forming units) results in a complete tumor regression in all mice, while those treated with control adenovirus succumb to their tumor. Efficacy is reduced when studies are performed in mice depleted of CD4+ and CD8+ cells or in nude mice. Mice cured of their tumor by Ad.mIL-12 demonstrate specific protective immunity upon rechallenge. Ad.mp40 does not exhibit antitumor activity and may antagonize the activity of rIL-12 or Ad.mIL-12. In summary, gene therapy strategies for cancer using adenoviral vectors containing IL-12 are highly effective with no significant toxicity in mice.

Effects on nutrient and hormonal profile of long-term infusions of glucose or insulin plus glucose in cows treated with recombinant bovine somatotropin before peak milk yield

Ten Holstein cows were treated with 30.9 mg.d-1 of recombinant bST from 15 to 41 d of lactation. The Latin square design included three infusion periods of 6 d each with 3 d of rest between infusion periods. Infusions were physiological saline, glucose (50 g.h-1), and insulin plus glucose (12.5 IU.h-1 + 50 g.h-1). Blood was collected continuously during the last 24 h of each infusion period. Statistical analyses of data for energy balance, milk yield, and DMI were performed on the last 3 d of each infusion period. Production data before and after infusions (i.e., no recombinant bST) estimated that recombinant bST increased milk yield of cows infused with glucose and saline by 3.1 and 3.6 kg.d-1, respectively. Net energy intake was not affected by infusion, but glucose infusion resulted in higher BW loss than did saline infusion (2.33 vs. 0.08 kg.d-1, respectively), and insulin plus glucose infusion resulted in BW gain (0.65 kg.d-1). Milk yield was 39.9, 39.6, and 37.6 kg.d-1 for cows infused with saline, glucose, and insulin plus glucose, respectively. The insulin plus glucose infusion increased milk protein 11 and 14% compared with response to saline and glucose infusions, respectively; no change occurred in the proportion of casein and whey proteins. Serum bST was increased 109% with exogenous recombinant bST. Serum IGF-I was lower for cows infused with glucose than for those infused with saline (21.03 vs. 27.44 ng.ml-1) and increased to 46.55 ng.ml-1 for cows infused with insulin plus glucose. Serum concentrations of insulin and glucose were 13.7 and 56.7, 18.5 and 61.9, and 30.5 muIU.ml-1 and 39.4 mg.dl-1 for cows infused with saline, glucose, and insulin plus glucose, respectively. The results of this study suggest that low concentrations of plasma insulin in early lactation may limit the IGF-I response to recombinant bST (uncoupling). Despite higher IGF-I, milk yield was lower, probably as a result of low blood glucose. These results suggest that, in early lactation, insulin is still anabolic because the BW gain of cows increased. However, milk yield was still higher than that for cows in late lactation with similar insulin concentrations.

Evolution of insulin-like growth factor-1, prostaglandin E2, and mitogenic activity of bovine mammary primary lymph during the dry period and lactogenesis

Four pregnant cows near the end of lactation were fitted with a catheter in a lymph duct afferent to the supramammary lymph node. Cows were dried off 3 d after surgery, and samples of lymph were collected daily from the day of surgery until 4 d postpartum. Samples of blood and mammary secretions were taken before and after drying off and at parturition. Concentrations of most metabolites were lower in lymph than in serum. Concentrations of IGF-I and prostaglandin E2 were not affected at drying off but decreased and increased, respectively, at parturition. All IGF-binding proteins that were present in serum were also present in lymph fluid, but the binding activity was lower. Mitogenic activities of lymph samples taken at various physiological stages were determined on mammary epithelial (MAC-T) and fibroblast cell lines. Lymph was mitogenic, but mitogenic activity was not related to physiological stages. The correlation was high between mitogenic activity of lymph on MAC-T cells and the content of prostaglandin E2 in lymph. Supplementation of lymph with additional prostaglandin E2 increased mitogenic activity, and neutralization of lymph by antibodies reduced mitogenic activity. Basal medium conditioned by the epithelial cell line contained 100 to 250 pg/ml of immunoassayable prostaglandin E2.

Biological effects of electric and magnetic fields on productivity of dairy cows

Sixteen multiparous Holstein cows (weighing 600 +/- 50 kg, in 184.8 +/- 52 d of lactation, and at 101.9 +/- 43 d of gestation) were confined to wooden metabolic cages and exposed to a vertical electric field of 10 kV/ m and to a uniform horizontal magnetic field of 30 microT (microtesla). The trial was conducted as a switch-back statistical design. Cows were divided into two replicates of 8 cows each. One replicate was exposed for three periods of 28 d each. During the first period, the electric and magnetic fields were off; during the second period, they were on; and, during the final period, they were off. The second replicate was exposed for three periods also, but the activity of the fields was reversed (first period, on; second period, off; and third period, on). Blood samples were obtained twice weekly for the determination of cortisol and progesterone and once weekly for the determination of pH and blood gases. Milk samples were collected once weekly to determine milk components (fat, protein, SNF, and SCC). Milk yield and feed consumption were measured daily. Most of the variables studied (bicarbonate, pH, O2 and CO2 partial pressures, cortisol concentration in blood, uncorrected milk yield, and milk components other than milk fat) showed no variation that could be attributed to exposure to electric and magnetic fields. Associations were found between the electric and magnetic fields and increased DMI, 4% FCM yield, milk fat content, and plasma progesterone.

Dietary cation-anion difference, acid-base status, mineral metabolism, renal function, and milk production of lactating cows

Three switchback experiments were conducted with 12 cows in early lactation, 12 cows in midlactation, and 12 cows in late lactation. Each experiment compared two dietary cation-anion differences. Increasing dietary cation-anion difference increased DMI and milk production in early and midlactation. These effects were not observed in late lactation. Production of milk protein and lactose and concentration of lactose were increased by the higher dietary cation-anion difference in early lactation. Higher dietary cation-anion difference reduced milk fat concentration in midlactation because of the higher milk production. In late lactation, none of the milk components were affected by dietary cation-anion difference. In early and midlactation, apparent absorption of water and urine volume were increased by a higher dietary cation-anion difference; these effects were not caused by higher intake of Na or by higher glomerular filtration rate. Intake, balance, and concentration of S in plasma were increased by the lower cation-anion difference at all stages of lactation. Excretion of HCO3- in urine was reduced by a lower dietary cation-anion difference at all stages of lactation, but secretion of protons in milk was reduced in late lactation only. Increasing dietary cation-anion difference does affect acid-base parameters in urine at all stages of lactation, but DMI and milk production of cows were affected in early and midlactation only.

The effects of changing ration ingredients on acid-base status, renal function, and macromineral metabolism

Ten Holstein and 2 Ayrshire cows were used in a switchback design to compare diets based on alfalfa haylage and corn silage. Both diets had a similar cation-anion difference and contained 1% NaHCO3. Dietary treatment did not affect DMI, DM digestibility, milk production, or milk composition. Intake, absorption, and urinary excretion of N were significantly increased by the ration based on haylage, but the overall balance remained unaffected. Cows consuming haylage absorbed and excreted significantly more water than did cows consuming corn silage and consequently had significantly larger urine volumes. Blood volume was increased by the ration based on haylage. Intakes of Mg, K, Cl, and S differed between diets, but only K balance was increased by the diet based on haylage. The fractional excretion of K, Cl, and S in urine was increased by the diet based on haylage, demonstrating that the kidneys responded to the increased intakes by diminishing the reabsorption or by increasing the secretion of these minerals. Acid-base parameters for blood, urine, and milk were unaffected by dietary treatment. A diet based on alfalfa haylage, compared with a diet based on corn silage with similar cation-anion difference, resulted in different water and mineral metabolism but did not affect the acid-base status of cows in early lactation.

Acid-base status, renal function, water, and macromineral metabolism of dry cows fed diets differing in cation-anion difference

Dietary cation-anion difference was defined as the summation of the milliequivalents of Na and K minus the sum of the milliequivalents of Cl and S per kilogram of DM. Twelve Holstein cows were used in a crossover experiment to compare the effects of changing the cation-anion difference of a diet based on haylage. Two cation-anion differences, 481.8 and 327.2 meq/kg, were compared. Increased dietary cation-anion difference had no significant effects on BW or intake and digestibility of DM, ADF, NDF, and N. The diet with a cation-anion difference of 481 meq/kg of DM increased apparent absorption of water and urine volume. Fecal excretion of Na and absorption and urinary excretion of S were increased by a cation-anion difference of 327 meq/kg of DM. Although blood concentrations were unaffected, lower dietary cation-anion difference reduced concentrations of H+ and HCO3- in urine and total urinary excretion of HCO3-. Plasma volume, packed cell volume, glomerular filtration rate, and effective renal plasma flow were unaffected by diet. Small changes in dietary cation-anion differences, even within the positive range, affected acid-base status and water metabolism of dry pregnant cows without affecting renal function or blood volume.

A review of bovine growth hormone

Unprecedented numbers of technical papers, abstracts, and short communications have been published in the past decade regarding the effects of exogenous bovine growth hormone on milk production, health, and reproductive efficiency of treated dairy cows. In well-managed dairy herds, exogenous growth hormone increases milk production without altering normal variability in milk composition. This has held true regardless of dairy breed tested, geographical location studied, or feeding management system used. Also consistent across studies is the rapidity of the galactopoietic effect of administered bovine growth hormone, which arises from altered partitioning and use of post-absorptive nutrients and increased synthetic capacity of the mammary gland. Growth hormone and its associated peptide, insulin-like growth factor-I, are now known to provide chronic lipolytic, diabetogenic, and gluconeogenic signals to target tissues culminating in increased mammary gland availability of glucose and nonesterified fatty acids. Together with yet ill-defined effects on mammary secretory tissue, this homeorhetic control of metabolism elicited by exogenous growth hormone is so efficient that treated cows are not more susceptible to metabolic disorders than untreated cows. However, some studies have reported an increased frequency of mastitis in groups of treated cows. This has been attributed mainly to increased milk volume in the mammary glands of treated cows and no convincing data are available that show decreased mammary gland immunity as a result of growth hormone treatments. On the contrary, an expanding body of evidence implicates growth hormone as a key neuroendocrine factor that is required for immunological competence. Trends of decreased reproductive efficiency in cows treated with growth hormone have also been reported, but available data imply that this is probably an indirect effect via prolonged negative energy balance in cows treated in early lactation rather than a direct negative effect on estrous cycling via altered reproductive hormone profiles. The objectives of the present review are to bring into focus and summarize pertinent biological discoveries regarding the treatment of dairy cows with recombinant bovine growth hormone, and to explore areas where additional growth hormone research is needed or warranted. Key words: Growth hormone, somatotropin, dairy cows, insulin-like growth factor-I

Manipulation of dietary cation-anion difference on nutritionally related production diseases, productivity, and metabolic responses of dairy cows

Dietary cation-anion difference has been defined as milliequivalents of (Na+K)-(Cl+S) per kilogram of DM and has a direct impact on blood acid-base metabolism. As this difference decreases, one or more of the following blood parameters change: increased H+, decreased HCO3-, and decreased pH. These changes are accompanied by reduced urinary HCO3- excretion and pH as compensatory mechanisms. Although other minerals have an impact on acid-base metabolism, the four minerals used in dietary cation-anion difference have the greatest effect. Manipulation of acid-base balance can be used to manipulate other biological functions to benefit health and productivity of cows. Low cation-anion difference prepartum can mitigate hypocalcemia peripartum via increased urinary Ca, blood-ionized Ca, and responsiveness to Ca homeostatic hormones. These changes reduced the incidence of paresis and increased productivity by reducing the severity and length of hypocalcemia in all cows (periparturient), regardless of the occurrence of paresis. Reduced cation-anion differences prepartum have been related to a reduced severity of udder edema, likely related to increased renal loss of water and unchanged water intake. However, the effects on acid-base balance cannot be ruled out because of effects on biochemical and transport processes. Elevated cation-anion difference in lactation has been shown to increase DMI and production and to mitigate the effects of heat stress. Because production and heat stress are acidogenic, elevated cation-anion difference improves blood-buffering capacity to cope with H+. In heat stress, elevated water intake with elevated cation-anion difference cannot be ignored. Other diseases related to metabolic acid, such as laminitis and ketoacidosis, may be influenced by elevated cation-anion difference in lactation; however, research in these areas has not been forthcoming.

Supercritical fluid chromatography of garlic (Allium sativum) extracts with mass spectrometric identification of allicin

Supercritical fluid chromatography-mass spectrometry has been used successfully to identify allicin (2-propene-1-sulfinothioic acid S-2-propenyl ester), the predominant thiosulfinate in freshly cut garlic (Allium sativum). A low oven temperature (50 degrees C) and low restrictor tip temperature (115 degrees C) were needed in order to obtain a chemical ionization (CI) mass spectrum of allicin with the protonated molecular ion, m/z 163, as the major ion. The effects of tip temperature on the CI mass spectrum of allicin are presented.

Effect of plane of nutrition before and during gestation on the concentration of hormones in dairy heifers

Forty heifers (1 yr of age; 313 +/- 27 kg of BW) were assigned to one of four treatments in a 2 x 2 factorial design. Main effects were plane of nutrition (ad libitum vs. moderate feeding) during the second isometric phase (1 yr of age to 3 mo of gestation) and during the second allometric phase (3 mo of gestation to 14 d before calving) of mammary development. Jugular blood samples were collected from 16 heifers before the onset of treatment, at the end of the isometric phase, and at the end of the allometric phase. Additional daily blood samples were collected from 32 heifers from 14 d before expected calving to 10 d postpartum and then thrice weekly until 70 d postpartum. High plane of nutrition reduced average growth hormone concentrations during the isometric and allometric phases. Serum concentrations of prolactin tended to be higher in heifers on ad libitum intake during the isometric phase and were higher during the allometric phase. Prolactin was positively correlated with BW and average daily gain during allometric phase. Plasma IGF-I concentrations were not affected by plane of nutrition. No effect was found for previous plane of nutrition on concentrations of growth hormone, prolactin, IGF-I, and progesterone during either prepartum or postpartum periods. Average postpartum IGF-I concentrations were negatively correlated with milk production. A positive relationship existed between mean postpartum concentrations of growth hormone and both peak milk production and feed intake during lactation.

Random access processing of optical memory by use of photon-echo interference effects

Photon-echo interference effects are used to manipulate the amplitude and polarization of a single echo generated by the read pulse in a long-lived stimulated echo pulse sequence. Interference is selective in time, frequency, and space, permitting modification of the multiplexed echo code.

Effect of plane of nutrition of dairy heifers before and during gestation on milk production, reproduction, and health

Fifty-nine heifers (1 yr of age; 320 +/- 12 kg) were assigned to one of four treatments of a 2 x 2 factorial design. Main effects were plane of nutrition (ad libitum vs. moderate feeding) during the second isometric phase (1 yr of age to 3 mo of gestation) and during the second allometric phase (3 mo of gestation to 14 d before calving) of mammary development. During the isometric phase, average daily gain were .72 and .84 kg/d for heifers fed a moderate or ad libitum diet, respectively. During the allometric phase, average daily gain was affected by previous plane of nutrition and averaged .84, .66, .95, and .73 for continuous ad libitum, ad libitum followed by moderate, moderate followed by ad libitum, and continuous moderate feeding, respectively. The BW at the end of gestation and BW after calving were increased by ad libitum feeding during the allometric phase (643 vs. 605; 588 vs. 558 kg, respectively). Milk production, protein content, and withers height were not affected by plane of nutrition. Milk fat was increased by ad libitum feeding during the isometric phase (3.9 vs. 3.6%). Cows on ad libitum feeding during the allometric phase had reduced average daily gain during lactation (.02 vs. .15 kg/d). The resumption of ovarian activity (progesterone > 1 ng/ml) was not affected by treatment, but days to first observed estrus increased with ad libitum feeding during the allometric phase. Finally, ad libitum feeding during isometric phase resulted in a higher incidence of displaced abomasum after calving, 9 versus 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of somatotropin on the casein profile and κ-casein glycosylation in milk

Twenty-nine Holstein cows were used to determine the effects of subcutaneous injections of a placebo (control, n = 9), 10.3 mg d−1 of a recombinant bovine somatotropin (rbST) (n = 10), and 175 mg 14 d−1 rbST in a sustained-release formulation (n = 10) on milk composition, the relative proportions of αs1+s2-casein, β-casein and κ-casein, and the degree of glycosylation of κ-casein. The latter was evaluated by measuring the N-acetylneuraminic acid (NANA) content of casein. Once a week, morning and evening milk samples were collected and composited beginning 4 wk prior to and for 7 wk following the initial injections (105 ± 7 d postpartum). Treatment with rbST increased milk yields (P < 0.06) from 28.4 kg d−1 (control) to 30.6 kg d−1 (daily injections) and 30.9 kg d−1 (biweekly) without affecting percentages of fat, protein and non-fat solids in milk or the relative proportions of the caseins. The NANA content of casein in milk of treated cows (5.6 μg mg−1) was significantly lower (P < 0.05) than in milk from control cows (6.3 μg mg−1). The NANA content of κ-casein was, however, not affected by rbST treatment. Neither the extent of stimulation of milk production due to rbST treatment nor the level of milk production during the treatment significantly affected the NANA content of casein. In conclusion, injection of rbST increased milk yield without affecting degree of κ-casein glycosylation. Key words: Somatotropin, casein, κ-casein glycosylation, lactation

Pneumocystis carinii pneumonia in patients with ulcerative colitis treated with corticosteroids

Today, Pneumocystis carinii pneumonia (PCP) is typically associated with AIDS. However, in the pre-AIDS era, PCP was known to be associated with various immunodeficiency states, malignancies, and immunosuppressive therapy, particularly the use of corticosteroids. PCP has been reported to occur during immuno-suppressive therapy of some chronic inflammatory states, but it has never been reported in patients with inflammatory bowel disease. We report two patients with ulcerative colitis who developed PCP during high-dose corticosteroid therapy, and review the literature regarding non-AIDS PCP. PCP should thus be added to the list of bronchopulmonary complications in inflammatory bowel disease. This report should give gastroenterologists further impetus to limit immunosuppressive therapy to its minimal effective dose.

Effects of dietary fat supplementation and recombinant bovine somatotropin on milk production, nutritional status and lipid metabolism of dairy cows

Sixty dairy cows were used to evaluate the effect on performance, metabolism and liver function of adding dietary fat during early lactation (weeks 3–15 postpartum) and injecting recombinant bovine somatotropin (rbST) over the entire lactation. Fat was added to an 18% protein concentrate that was offered in a 1:1 ratio of haylage:concentrate and fed as a total mixed ration. Corn in the control (CRT) concentrate was exchanged for either 2.5% animal fat (AFA), 2.5% Megalac™ calcium salts of fatty acids (CSFA) (ML1), 2.5% Purina CSFA (RP1) or 5% Purina CSFA (RP2). RbST treatment consisted of a subcutaneous injection of either a placebo, 10.3 mg rbST daily or 350 mg rbST every 14 d. Fat-corrected milk production was higher (P < 0.05) in RP2-fed cows than CTR-fed cows and higher for cows injected with rbST daily than in those injected biweekly. Plasma-urea nitrogen and insulin concentrations were lower in RP2-fed cows than in CTR-fed cows and were also lower in rbST-injected cows than in placebo-injected cows (P < 0.05). Plasma triglyceride (TG) and cholesterol concentrations, but not non-esterified fatty acid and phospholipid concentrations, were higher (P < 0.05) in RP2-fed cows than in CTR-fed cows. CSFA supplementation increased C16:0 of the plasma TG fraction and decreased that of C18:0. Dietary fat supplementation did not affect hepatic lipid composition, but liver-TG concentration increased (P < 0.05) with rbST injections. Dietary fat supplementation together with somatotropin injections did not change production parameters from those found with fat supplementation or somatotropin alone. Key words: Dietary fat, dairy cows, bovine somatotropin, lipids

Effect of recombinant bovine somatotropin on estradiol-induced estrous behavior in ovariectomized heifers

To evaluate whether bST administration could affect the intensity of estrous behavior in the absence of the ovary, 17 ovariectomized heifers were assigned to receive a placebo or 500 mg/14 d of recombinant bST and were induced to display behavioral estrus by administration of 2 mg of estradiol cypionate. Estrous behavior was monitored for the following 60 h with a surveillance camera and a video recorder, and mounting activity was quantified. Blood samples were collected before and after bST administration. Administration of bST numerically elevated plasma insulin and NEFA and caused a significant increase in concentration of insulin-like growth factor-I in plasma. Heifers that received bST started to display estrous behavior later (24.5 +/- 1.1 and 21.9 +/- 1.1 h after estradiol administration for bST and placebo treatments, respectively), displayed estrous behavior of shorter duration (bST, 13.2 +/- 1.2 vs. placebo, 15.8 +/- 1.1 h), and instigated fewer mounting events (bST, 45.5 +/- 5.9 vs. placebo, 62.6 +/- 5.7 mounts) than control heifers, although only the number of mounting events was significantly different between the two groups.

Effects of manipulating dietary cation-anion balance on macromineral balance in sheep

Effect on macromineral balance in sheep of dietary excess of inorganic anions (Cl and S) or inorganic cations (Na and K) was studied. Dietary cation-anion balance was calculated as milliequivalents [(Na + K) - (Cl + S)] kg-1 of DM. Eight crossbred wethers were fed two levels of Ca, designated high Ca (.82%) or normal Ca (.48%), with four treatment each, three of which differed in dietary cation-anion balance. Control and two treatments had +284, +61, and -27 meq kg-1 of DM for high Ca and +343, +218, and +63 meq kg-1 of DM for normal Ca, respectively. A fourth treatment was control plus injection of vitamin D3 (16,670 IU kg-1 of BW). Reducing dietary cation-anion balance reduced Ca retention by increasing excretion of urinary Ca. Apparent absorption of Ca was similar across cation-anion balances. There was no correlation observed between dietary cation-anion balance and concentration of plasma Ca. No difference was observed in apparent absorption of Ca between high and normal Ca. This result may be related to an oversupply of dietary Ca. Magnesium retention as a proportion of that absorbed for lowest cation-anion balance was smaller than that for the intermediate balance and control plus vitamin D3, although not different from control. Results showed that reduced dietary cation-anion balance resulted in a reduction of Ca retention.

Effects of various dietary cation-anion balances on response to experimentally induced hypocalcemia in sheep

We examined the effect of dietary cation-anion balance on bone Ca mobilization, measured by challenging wethers with a 5.6% EDTA infusion at a rate of 1.4 ml kg of BW-1. Dietary cation-anion balance was calculated as milliequivalents [(Na + K) - (Cl + S)]. Six crossbred wethers (average BW, 67.8 kg) were fed rations with high Ca (.74% dry basis) or normal Ca (.45%) and three different dietary cation-anion treatments, which differed in their mineral supplementation. Dietary cation-anion balances were 354, 125, and 32 meq kg of DM-1 for control and two treatments. A 6 x 4 incomplete Latin square design (six treatments, four periods) was used with five 15-d periods of 14 d of adaptation followed by 1 d of EDTA infusion. Concentrations of total and EDTA titratable plasma Ca were not affected by the level of dietary Ca or treatments. The decrease in plasma EDTA titratable Ca at conclusion of EDTA infusion (120 min) was least in wethers fed the lowest cation-anion balance within high Ca, and recovery of plasma EDTA titratable Ca during the 240-min postinfusion period was faster for sheep fed this diet than for the control. The amount of Ca mobilized and its rate of mobilization during the EDTA infusion period tended to be higher for diets with reduced cation-anion balances than for the control. Thus, reducing cation-anion balance increased the sheep's ability to mobilize Ca during hypocalcemia.

Effects of reducing dietary cation-anion balance on calcium kinetics in sheep

A Ca kinetic study with a four-compartment model being fitted to radioisotope and balance data using the CONSAM (conversational, simulation, analysis, and modeling) computer program was conducted to examine the effects of dietary cation-anion balance, calculated as milliequivalents [(Na + K] - (Cl + S)]. Twelve crossbred wethers were used as eucalcemic control (period 1); then Ca loss during lactation was simulated by continuous infusion of ethylene glycol tetraacetate (period 2). Dietary cation-anion balance was manipulated by supplementation of various mineral salts and was +339, +35, and -127 meq of kg DM-1 during period 1 and +429, +68, and -147 meq of kg DM-1 during period 2 for control and two treatments, respectively. Animals responded to the simulated lactational Ca loss (period 2) by increasing true intestinal absorption of Ca and bone resorption and by reducing Ca accretion by bone. No difference was observed in concentration of total Ca in plasma, but treatments produced increased concentration of plasma ionized Ca during both periods. Both treatments produced hypercalciuria during both periods, and the lowest cation-anion balance increased true intestinal absorption of Ca and reduced bone accretion during period 2. The size of total exchangeable Ca pool did not differ between treatments or periods, but amount of Ca movement between the pools increased with the intermediate cation-anion balance during period 1 and with both treatments during period 2 compared with control. These results indicated that feeding reduced cation-anion balance diets increased Ca flux through the exchangeable Ca pool with no changes in the size of the pool, particularly when Ca demand was increased.

Effects of recombinant bovine somatotropin on hypophyseal and ovarian functions of lactating dairy cows

Three trials were conducted to determine the effects of recombinant bovine somatotropin (rbST) on reproductive functions of lactating Holstein dairy cows. In Trial 1, 49 cows were used to investigate the effects of 0, 320 or 640 mg of rbST in a sustained-release formulation injected every 28 d on plasma progesterone (P4) concentration during estrous cycles. Total P4 area and P4 mean were increased (P < 0.05) in rbST-treated cows during the 1st and 2nd detected estrous cycle post-rbST injection. Maximum P4 value, slope of the P4 decline and length of cycles were not affected by rbST treatment. In Trial 2, 56 cows were used to investigate the effects of 0, 320, 640 and 960 mg of rbST in a sustained-release preparation injected every 28 d on plasma P4 concentration from weeks 1 to 34 of pregnancy. Mean P4 was increased (P = 0.08) in rbST-treated cows proportionally to the rbST dose received. In Trial 3, 18 cows were used to investigate the effects of 0 or 25 mg d−1 of rbST injected from days 3 to 15 postpartum (pp) on the gonadotropin-releasing hormone (GnRH) induced luteinizing hormone (LH) response curve at 14 d pp. Total area under the LH curve and LH peak value were increased (P < 0.05) in rbST-treated cows, but LH baseline and time to LH peak were not different among groups. Cows receiving rbST were in a more negative energy balance due to higher milk production. In summary, long-term administration of rbST increased the concentration of plasma progesterone during the first two estrous cycles post-treatment and during pregnancy, and enhanced the GnRH-induced LH response at 14 d pp. Key words: Bovine somatotropin, GnRH-LH induction, progesterone, estrous cycle, pregnancy

Effect of somidobove sustained release administration on the lactation performance of dairy cows

Lactation performance was determined on 190 multiparous Holsteins from five herds supplemented with 0, 320, 640, or 960 mg of somidobove every 28 d. The experiment consisted of 21 d of pretreatment and treatment periods of various lengths, depending upon stage of lactation of animals at first administration. Somidobove beginning in early (28 to 45 d in milk), mid (111 to 166 d in milk), or late (166 to 334 d in milk) stages of lactation consisted of 9, 6, or 3 administrations. Milk and 3.5% FCM yields were increased by each dose of somidobove in all stages. Milk composition and dry matter and energy intakes were similar among treatments within stage. Milk to DMI ratio and milk energy to net energy intake ratio were improved by somidobove. Gain was positive for all treatments, but less in somidobove-supplemented cows. Lower body weight and condition score at the completion of somidobove treatment resulted. For early cows, days to first estrus and days to first breeding were similar; however, total number of inseminations for cows receiving somidobove was twofold greater than control, resulting in a longer calving interval. Results demonstrated efficacy of somidobove administered every 28 d to lactating dairy cattle for increased milk yield.

Effects of recombinant bovine somatotropin on nutritional status of dairy cows during pregnancy and of their calves

Objectives of this trial were to evaluate effects of rbST on the nutritional status of 24 Holstein cows during pregnancy and of their calves from birth to weaning. All cows conceived during injection with either a placebo or 350 mg of rbST in a sustained-release vehicle every 14 d commencing 98 to 112 d postpartum for their entire lactation. In Experiment 1, blood samples were collected at 90, 180, and 270 d postconception in cows. Concentrations of urea, glucose, albumin, total proteins, Ca, P, insulin, cortisol, hemoglobin, and hematocrit were unaffected by treatment as well as BW, body condition scores, and energy balances at conception and during pregnancy. Days open and calving interval were not significantly different but were numerically increased by 31 d in rbST-injected cows. Nonesterified fatty acids, bST, and insulin-like growth factor-I in plasma were elevated significantly in rbST-injected cows. In Experiment 2, blood samples were collected at birth and at 1, 3, 5, and 7 wk in calves born from cows of Experiment 1. Circulating concentrations of glucose, nonesterified fatty acids, albumin, total proteins, hemoglobin, insulin, cortisol, bST, insulin-like growth factor-I, and hematocrit, blood pH, blood gases and buffer capacity, birth weight and rate of weight gain, height at withers, and heart girth from birth to weaning were not different due to treatment of dam. However, some parameters were significantly different based on age and sex. These data support previous assumptions that the magnitude of the modifications in nutrient partitioning produced by rbST do not affect the hierarchy of the partitioning process for the calf.

Effects of recombinant bovine somatotropin on nutritional status and liver function of lactating dairy cows

Twenty-four high producing, multiparous Holstein cows were utilized to evaluate effects of long-term administration of sustained-release rbST on blood pH, gases, buffer capacity, circulating metabolites and hormones, and on liver lipid content and functions during lactation. Treatment, commencing 98 to 112 d postpartum and continued until d 305, consisted of a subcutaneous injection of a placebo or 350 mg of rbST every 14 d. Milk and 3.5% FCM were increased significantly by rbST, but milk fat and protein content, feed intake, energy balance, corrected feed efficiency for milk production, and body condition scores were unaffected. Somatotropin decreased blood pH and buffer capacity by decreasing bicarbonate without affecting blood partial pressures of oxygen or carbon dioxide. Concentration of plasma albumin was decreased and nonesterified fatty acids, glucose, insulin, rbST and insulin-like growth factor-I were increased by treatment. Total plasma proteins and cortisol, hemoglobin, and hematocrit were unaffected. Liver DM, total lipid and triacylglycerol contents, and plasma 3-hydroxybutyrate and glutamic oxalacetic transaminase were not affected by rbST, but the percentage of triacylglycerol in total lipids was increased. Results of this experiment suggest that rbST exhibited lipolytic and diabetogenic activities in lactating dairy cows in vivo and that these effects might be important for the increase in nutrient partitioning toward the mammary gland elicited by rbST.

Effect of somatotropin on the plasminogen and plasmin system in the mammary gland: proposed mechanism of action for somatotropin on the mammary gland

Somatotropin exerts a powerful galactopoietic effect when it is administered to dairy cattle. The mechanism by which somatotropin increases milk yield is currently unknown. This study describes the relationship between long-term exogenous somatotropin injections, milk plasmin concentrations, and milk yield. Plasmin is a serine-protease involved in rodent mammary gland involution. Thirty-five control cows were shown to increase milk plasmin concentrations and decrease milk yield as their lactation period advanced past the 2nd mo. In 42 somatotropin injected cows, milk plasmin was maintained at low concentrations, and milking performance was enhanced. Cessation of somatotropin injections at drying off led to a rapid elevation of milk plasmin to control values. Our hypothesis is that somatotropin suppresses plasmin production within the mammary gland, thereby suppressing involution and allowing a persistence of milk production. During a normal lactation, gradually increasing amounts of plasmin within the mammary gland results in the gradual involution process.

1-Butyryl-glycerol: a novel angiogenesis factor secreted by differentiating adipocytes

Differentiation of adipocytes is accompanied by secretion of molecules stimulating angiogenesis in vivo and endothelial cell growth and motility in vitro. We demonstrate that the angiogenic and motility-stimulating activities secreted by adipocytes are separable from the endothelial cell mitogenic activity by fractionation of adipocyte-conditioned medium. The major differentiation-dependent angiogenic molecule was purified and identified by GCMS as 1-butyryl-glycerol (monobutyrin). Monobutyrin levels increase at least 200-fold during adipocyte differentiation and represent a major fraction of the total angiogenic activity. Synthetic monobutyrin shows the same spectrum of biological activities as the adipocyte-derived factor: stimulation of angiogenesis in vivo and microvascular endothelial cell motility in vitro, with no effect on endothelial cell proliferation. Angiogenesis is stimulated at doses as low as 20 pg when tested in the chick chorioallantoic membrane assay. These results strongly suggest that monobutyrin is a key regulatory molecule in an angiogenic process linked to normal cellular and tissue development.

Influence of exercise on a heart transplant patient

A treadmill training protocol was implemented to examine the effects of a 12-week exercise program on the physiologic status of a patient who had a heart transplant in 1980. The patient was tested for exercise tolerance before programming, midway through the study, and immediately upon completing endurance training. Maximal METS levels achieved were 3.2 METS, 5.6 METS, and 6.3 METS, respectively. The subject began an anaerobic program consisting of 48 exercise sessions over a three-month period. Exercise sessions were interval in nature, walking at 2.5 mph, 0% grade, three repetitions, five minutes each and increasing to 3.0 mph, 2.5% grade, two repetitions, 15 minutes each. The patient improved from Class III (METS = 3.0), where less than ordinary physical activity causes fatigue, to Class I (METS = 6.5), where ordinary physical activity can be sustained without undue fatigue. These findings suggest that selected heart transplant patients may achieve up to 85% maximum oxygen consumption and maximum heart rate which demonstrates the need for endurance training programs in this population. This form of cardiovascular conditioning has enabled the participant to engage in higher levels of activities of daily living within the community.

Sodium chloride supplementation and urinary calcium excretion in postmenopausal women

It was hypothesized that variations within the range of usual salt intakes of North Americans influence urinary excretion of calcium in healthy postmenopausal women. The effects of sodium chloride supplements of 0.51, and 102 mmol/d, randomly assigned to 17 healthy, noninstitutionalized, postmenopausal women consuming their usual diets were compared. Diets and discretionary salt intake were repeated exactly for three experimental periods of 4 d each for 3 consecutive weeks. Supplementing with 51 mmol NaCl/d increased average daily urinary excretion of Ca, Na, and Cl by 0.5, 51.0, and 48.9 mmol respectively, urine pH by 0.1, and serum Cl by 1.5 mmol/L (p less than 0.05). Supplementing with 102 mmol/d induced additional increases in these variables (p less than 0.05). Assuming a total body mass of 900 g Ca and no decrease in renal or fecal losses, additions of 51 and 102 mmol/d NaCl to the diet for 10 y would mobilize Ca stores of 7.5% and 10%, respectively, and could thus constitute a risk factor for osteoporosis.

Plasmin and plasminogen in bovine milk: a relationship with involution?

A total of 774 individual milk samples were collected from 66 Holstein cows between October 1987 and April 1988. Samples were analyzed for plasmin, plasminogen, and SCC. An increase in SCC from less than 250,000/ml to more than 1,000,000/ml resulted in an increase of plasmin, plasminogen, and serum albumin by 105, 74, and 140%, respectively. Plasminogen, plasmin, and serum albumin followed similar trends that are expected for components from blood that gain access to the alveolar lumen through ruptured epithelium caused by mastitis. Increased plasmin is the direct result of this process rather than an increase in activation of plasminogen to plasmin. The plasminogen to plasmin ratio supports this interpretation, being 4.7 at 250,000 SCC/ml and 4.0 when SCC exceeded 1 million/ml. Plasmin and plasminogen concentrations were also increased during lactation to reach peak values immediately before the dry period. However, in this case, ratio of plasminogen to plasmin was 6.55 during early lactation and decreased by half to 3.29 during the latest stage, indicating that considerable activation of plasminogen to plasmin occurred during the latter part of lactation. Mammary epithelium is not compromised at this stage, as shown by low (.8 mg/ml) serum albumin concentration in milk. Two mechanisms responsible for increased milk plasmin include influx of plasmin from blood during mastitis and increased activation of plasminogen as lactation progresses.

Inhibition of soybean lipoxygenase and mouse skin tumor promotion by onion and garlic components

Onion and garlic essential oils were previously shown to inhibit mouse skin tumor promotion, as were the enzymes, lipoxygenase, and cyclooxygenase. In the present study, the inhibition of soybean lipoxygenase (EC 1.13.11.12) by onion and garlic components and related compounds was investigated. The IC50 values as well as the kinetic inhibition constants were determined for the most active compounds. Di-(1-propenyl) sulfide, an analog of the substrate moiety required for oxygenase action, was the only irreversible inhibitor observed with Ki = 59 microM and k3 = 0.53/min. Inhibition in the presence of substrate was uncompetitive at 88 and 132 microM linoleic acid with Ki = 129 microM. At 173 microM linoleic acid, however, inhibition was competitive with Ki = 66 microM. Dially trisulfide, allyl methyl trisulfide, and diallyl disulfide were competitive inhibitors, while 1-propenylpropyl sulfide and (E, Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide (ajoene) were mixed inhibitors. Nordihydroguaiaretic acid (NDGA), the most potent lipoxygenase inhibitor, was a competitive inhibitor with Ki = 0.29 microM. The results indicate a relative potency of inhibition for structural features in the following order: di(1-propenyl) sulfide greater than an alkenyl trisulfide greater than an alkenyl disulfide. Di(n-propyl) disulfide, a major onion oil component, inhibited neither lipoxygenase nor promotion. Di(1-propenyl) sulfide and ajoene inhibited both. This suggests that the inhibition of lipoxygenase may be involved in antipromotion.

Efficacy of Levamisol on milk production of dairy cows: a field study

Twelve hundred ninety-six cows on 88 farms were alternately injected at calving with Levamisol or saline. Each farm was visited every 2nd wk from May to October to administer treatments to cows that would calve prior to our next visit and to collect fecal grab samples from cows for worm egg counts. Production records were collected for each cow for their first 6 mo of lactation. Fecal worm egg counts were reduced in cows treated with Levamisol for the first 2 mo postcalving. Daily milk produced was higher in cows treated with Levamisol by 1.24 kg. Milk fat and protein percentages were not different between treatment groups; however, milk fat production was higher in cows treated with Levamisol for the first 2 mo post-calving. Cows treated with Levamisol produced 235 kg more milk than control cows during their first 6 mo of lactation and were projected to produce 339 kg more milk for a 305-d lactation. Month of calving improved milk production by cows treated with Levamisol. Cows treated with Levamisol and calved in months May to July showed the highest improvement in milk production while cows that were treated with Levamisol and calved in months August to October showed no significant improvement in production. Injection of cows with Levamisol at calving improves milk production and reduces gastrointestinal worm burdens.

Ergometer modification for combined arm-leg use by lower extremity amputees in cardiovascular testing and training

A commercial arm-leg ergometer was adapted so that combined bilateral arm-single leg work could be performed by unilateral lower extremity amputees from their own wheelchairs. Three middle-aged to elderly unilateral amputees performed progressive discontinuous bilateral arm crank and combined bilateral arm-single leg cycle exercise tests on the same air-braked ergometer adapted for either form of ergometry. Select amputees may achieve greater peak oxygen uptakes (VO2), power outputs (PO), and heart rates (HR) during combined bilateral arm-single leg cycle testing versus bilateral arm crank testing. Following 14 weeks of combined arm-leg training on the modified ergometer, a 73-year-old above-knee amputee demonstrated peak VO2 and PO increases of 25% (+3.8 mL X kg-1 X min-1) and 33% (+25W) respectively. Combined arm-leg ergometry as described herein may activate the largest available muscle mass and elicit the greatest oxygen uptake during exercise testing. In addition this exercise modality may simultaneously condition the arms and leg, providing functional gains in both wheelchair propulsion and prosthetic ambulation.

Efficacy of morantel tartrate on milk production of dairy cows: a field study

Eighty Holstein herds on Quebec Dairy Herd Analysis Service were paired into 40 blocks of two herds each to test the effects of systematic deworming with morantel tartrate. Cows in treated herds were given morantel tartrate in May, June, and July, and cows in control herds were given a placebo of ground corn, wheat bran, and barley; both products were administered at 1 kg/1000 kg body weight. Records were obtained from May 1983 to April 1984. Each farm was visited monthly from May to October 1983 to obtain herbage samples and fecal grab samples from a random 10% of lactating cows. Production records were obtained for the year prior to commencement of this trial for covariate analysis. Fecal worm egg counts and infective larvae counts in pasture were reduced by 83 and 93%, respectively, in treated herds. The pattern of worm egg excretion differed between groups due to repeated treatments with morantel. Treated herds produced 323 kg more milk per cow per yr and 1.2 kg per cow per d more fat-corrected milk than controls. Milk fat and protein percentages did not differ between groups for the 12 mo. Deworming lactating dairy cows at the beginning of and during the pasture season improved production performance.

Efficacy of morantel tartrate in a sustained release bolus on the control of subclinical gastrointestinal parasitism in first-year grazing dairy replacements

Thirty-four heifers (24 Holstein, 8 Ayrshire, 2 Jersey) and 12 Holstein steer calves were grouped into 23 blocks of 2 animals each according to breed, sex, and body weight. Animals in each block were randomly assigned to control or treated groups. The treated group received an anthelmintic bolus containing morantel tartrate before they were permitted access to pasture. A 2.6 ha pasture was divided in half with a double fence; the resulting two pastures had separate feed and water troughs. Steer calves were slaughtered upon termination of the trial to ascertain gastrointestinal parasite burdens. Two worm-free tracer calves were placed on each pasture every 2 mo and slaughtered after 4 wk of grazing to determine parasite infectivity of pastures. Herbage samples were obtained monthly and analyzed for infective larvae. The trial was conducted for 141 d during the grazing season. Treatment resulted in 90% reduction in infective larvae on pasture, 74% reduction in fecal worm-eggs, 91% reduction in adult worm burdens, and a trend toward reduced worm burdens in tracer calves by 52%. An overall average daily gain of .68 and .88 kg was obtained for control and treated animals. Reproductive data for the heifers remaining in the herd from the trial showed that treatment resulted in 44 less days to first breeding.

Manipulating dietary anions and cations for prepartum dairy cows to reduce incidence of milk fever

Twenty preparturient dairy cows were in a 2-yr switchover design to test effects of dietary ions on incidence of milk fever. In yr 1, cows were blocked and assigned randomly 45 days prepartum to one of two diets; one diet contained an excess of anions, and the second diet contained an excess of cations. In yr 2, cows were changed to the opposite diet. Both diets were equivalent for crude protein (11%), calcium (.65%), phosphorus (.25%), and energy on a dry basis but differed for quantities of chlorine, sulfur, and sodium. Both diets were chopped alfalfa hay, corn silage, high moisture corn, and vitamin-mineral mix. Diets were available ad libitum as complete rations. There were no differences in dry matter intake of the diets. Cows consuming the anionic diet had no milk fever, but cows consuming the canionic diet had 47.4% incidence. Samples of blood plasma showed that cows consuming the anionic diet maintained calcium and phosphorus through parturition, whereas cows consuming the cationic diet decreased in these minerals around calving. Hydroxyproline was higher for cows consuming the anionic diet during the peripartal period compared to cows consuming the cationic diet. Milk produced in the lactation subsequent to prepartum treatment was 6.8% less for cows offered the cationic diet. When milk production of paretic and nonparetic cows offered the cationic diet was compared, milk was reduced 14% with milk fever.

Is there a "gold standard" for human serum vitamin B12 assay?

In a study from four laboratories using two commercial vitamin B12 radioassays (impure hog intrinsic factor concentrate containing both intrinsic factor and R binders (IF + R) to measure total corrinoids and the same concentrate presaturated with cobinamide (Cbi) to block B12 binding sites on R binder (IF + R + Cbi) to measure only cobalamins), the rank order of results was generally the same. The concordance between the two tests for classifying sera as normal or deficient was 91% in 311 serum samples. Three percent of sera below the "true B12" (B12 binding to IF + R + Cbi) normal cut-off point were not below the cut-off point for normal "total B12" (B12 binding to IF + R); 6% of sera below the total B12 normal cut-off point were not below true B12 cut-off point. The correlations between Euglena gracilis and the radioassays were 0.80 and 0.83 in the 50 serum samples that also had E. gracilis serum vitamin B12 levels. Lactobacillus leichmannii serum vitamin B12 levels were determined in 49 of the 311 serum samples and results were comparable with results obtained by four radioassay binder systems: IF + R, IF + R + Cbi, highly purified hog IF, and saliva R binder. The closest correlate with L. leichmannii was radioassay using IF + R as binder (r = 0.93), then IF + R + Cbi (r = 0.92), pure IF (r = 0.80), and pure R (r = 0.73). The key to reliable results appears not to reside in a particular assay but rather in determining for each assay its own range of results in participants determined clinically and morphologically normal vs. participants with deficient vitamin B12 (with B12 deficiency defined independently of a serum B12 assay). When laboratory assay results differ from clinical judgment, further evaluation is the appropriate course. There is no "gold standard" for human serum vitamin B12 assay.

Acid insoluble ash as a marker of digestibility for sheep fed corn plants or hay and for lactating dairy cattle fed hay

Research has shown acid insoluble ash (AIA) in feeds to be an acceptable natural marker for the determination of dry matter digestibility in sheep and steers fed diets of hay plus grain. However, in previous studies, animals were fed diets designed to ensure little or no orts. The purpose of this study was to determine the adequacy of AIA as an indicator of dry matter digestibility when sheep or dairy cows were fed ad libitum. Fecal, feed and ort samples from wethers and lactating Holstein cows from previous digestibility studies were used to determine the usefulness of AIA as an indicator of digestibility. Thirty-two wethers were fed whole corn plants or corn stover frozen and stored fresh or ensiled. Diets were fed ad libitum to ensure between 5 and 10% orts. In a second study, seven wethers and 10 lactating cows fed fed ad libitum alfalfa or orchard grass hay diets with 23% grain to ensure at least 10% orts. Correlation coefficients for digestibility determined by total collection versus AIA for wethers fed corn plants, cows fed hay diets and wethers fed hay diets were .96, .95 and .40, respectively. The low correlation for wethers fed hay was apparently due to a high quantity of orts with a variable AIA content. The range of total recovery of AIA from all animals was of total recovery of AIA from all animals was 98 to 102% when ort AIA was taken into account, and 91 to 121% when ort AIA was not taken into account. The use of AIA as a natural marker for the estimation of digestibility when diets are fed ad libitum has potential, provided that a sufficient number of animals is used and diets are adequately mixed to limit feed selection and sorting, or intake is determined and feed and orts are sampled.

Woodpulp fines or corn silage as roughages in complete rations or a pelleted complete ration for young dairy replacements from birth through 18 weeks of age

Holstein calves, 18 females and 12 males, were assigned randomly to 10 blocks of 3 calves each by sex, and within each block were assigned randomly to one of three experimental rations. All calves received sour colostrum from day 1 through day 35. The respective dry rations were offered beginning at day 8. The three rations consisted of (dry basis): 1) 11% woodpulp fines and 89% concentrate; 2) 33.7% corn silage and 66.3% concentrate; and 3) a commercially available pelleted complete ration. From birth through 8 wk, calves fed woodpulp gained more weight than those fed silage and approximately equal weight to calves fed commercial ration. From 8 through 18 wk. calves fed the latter gained more weight than other calves. Dry matter intake followed the same order as weight gain. Blood samples were obtained biweekly beginning with the 2nd wk from the jugular vein of each calf. There were no differences in glucose 2 through 18 wk. Urea nitrogen of plasma was greater in calves fed commercial ration than in other calves in six of the sampling periods. Calves fed silage had more urea nitrogen in plasma than calves fed woodpulp for three of the sampling periods. Rumen tissue from male calves at 18 wk fed woodpulp showed the most normal appearance in papillae color, density, and length. Calves fed silage had rumen tissue showing short, black, nodular papillae. Calves fed commercial ration showed long, branched, necrotic papillae that were keratotic and loosely attached.