Oxidative metabolism of the neutrophils in sheep treated with sodium monensin and experimentally submitted to ruminal acidosis.

Ruminal acidosis is due to excessive ingestion of carbohydrates of rapid fermentation without previous adaptation of the microorganisms, causing severe metabolic disturbances to the animals. The objective of the present study was to assess the neutrophilic oxidative metabolism in sheep treated with sodium monensin in experimentally induced ruminal lactic acidosis. A total of 18 male sheep, half-bred (ideal x Merino), fistulated in the rumen, were used; nine of them received 33 mg/kg of the ionophore diet per day, for 30 days; the others were controls. The acidosis was induced by supplying 15g of sucrose/kg of body weight. The clinical evaluation and the rumen and blood samples were obtained before (0h) and at 6, 12, 24 and 48 hours post-induction. In both groups, all the animals presented clinical manifestations of ruminal lactic acidosis 6 hours after the induction. From this period on, a significant pH decrease (P<0.05) was observed in the ruminal fluid, which reached levels below 5. There were relevant differences (P<0.05) between the groups 12 hours after the induction, when the sheep treated with monensin had higher values than those of the control group. During this period, the oxidative metabolism of the neutrophils remained inhibited, and the reestablishment of this function only occurred in the sheep which received monensin. Blood pH, plasmatic glucose and the ionizable calcium suffered alterations within its levels. The seric cortisol concentration rose significantly (P<0.05) in both groups, although differences (P<0.05) between them were found at the end of the observation period. The treatment with monensin did not influence the oxidative metabolism of the neutrophils inhibited by the lactic acidosis; however, a faster recovery of this metabolism was verified in the animals treated with the ionophore.

Effects of different doses of sodium monensin on rumen papillae and tissue histology of feedlot Nellore cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of different doses of sodium monensin on feeding behaviour, dry matter intake variation and selective consumption of feedlot Nellore cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Performance, carcass characteristics and non-carcass components of Texel × Santa Inês lambs fed fat sources and monensin

Performance, carcass, non-carcass and commercial cuts and components of Texel × Santa Inês crossbred lambs, managed in confinement and fed diets based on soybean oil, soybeans and a conventional diet, with or without the use of monensin (78 ppm dry matter basis) were evaluated. Thirty-six Texel × Santa Inês lambs (18 males and 18 females) were managed in intensive systems. Animals were slaughtered after 87 days of confinement, and performance, carcass characteristics, weight and percentages of carcass and non-carcass components were evaluated. The animals fed the control diet had heavier carcass and parts than animals fed soybean, while the oil diet did not differ from the controls in most parameters. The animals fed soybean showed lower intake kg dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and metabolizable energy (ME) compared with animals fed the control diet, increased ether extract (EE) intake in kg, % body weight (BW) and metabolic weight (MW) and did not differ from the soybean oil diet. Animals receiving monensin had lower DM intake, OM, CP, EE, NDF, gross energy (GE) regardless of the expression, % kg BW, or % PM, than the animals that did not receive the additive. Males produced better and had heavier cuts than the females; the latter deposited subcutaneous fat earlier. Animals that received oil or soybean showed greater body weight and small intestine percentage. Soybean oil intake did not improve performance, carcass weights or parts of Santa Ines × Texel lambs in confinement. Soybeans at 15% dry matter reduced energy intake and lamb performance. The use of monensin at 78 ppm on a dry matter basis is not recommended for lambs in confinement, especially if associated with oil or soybeans that may harm animal performance.

Nutrients balances and milk fatty acid profile of mid lactation dairy cows supplemented with monensin

The aim of this study was to evaluate the nutrients balance and milk fatty acids profile of dairy cows supplemented with monensin. Twelve Brazilian Holstein dairy cows were distributed into four balanced 3x3 Latin squares, and fed with the following diets: control (C), basal diet without addition of monensin, monensin 24 (M24), addition of 24mg/kg DM of monensin, and monensin 48 (M48), addition of 48mg/kg DM. The experimental diets influenced the efficiency of net energy of lactation utilization. A quadratic effect was observed for the energy balance. It was observed effect of diets on nitrogen balance. It was observed effect of monensin in the milk yield, composition and in the milk fatty acids profile. Monensin in diets of dairy cows in mid lactation, using corn silage, improved the nutrients balance and milk fatty acid profile with 24mg/kg DM.

Monensin supplementation of lactating cows fed tropical grasses and cane molasses or grain

Effects of monensin (Mon) on performance of Holstein-Friesian cows fed tropical grasses and cane molasses (M) or cereal grain were examined in three experiments. In experiment I (incomplete 4 x 4 Latin square), three rumen-fistulated cows [188 I I days in milk (DIM)] were fed mixed diets based on rhodes grass (Chloris gayana cv. Callide) bay where M was substituted for wheat grain (W) at rates of 0 (MO), 125 (M 125) or 250 (M250) g/kg dry matter (DM). A fourth diet contained M250 plus 0.02 g Mon/kg DM (M250 + Mon). Substituting M for W tended (P < 0.10) to decrease the ratio of rumen molar proportions of acetate+butyrate (Bu):propionate (Pr) (4.3 versus 3.8 and 4.0 for M0, M125 and M250, respectively). There were no treatment effects (P> 0.10) on intake, organic matter digestibility, milk production or liveweight (LW) change. In experiment 2, 48 cows (173 &PLUSMN; 28.3 DIM) grazing kikuyu (Pennisetum clandestinum cv. common) pastures and supplemented with maize silage and a grain-based concentrate were offered either M (2.6 kg DM/(cow day)) or barley grain (B) (2.7 kg DM/(cow day)). Within each supplement type, half were fed 0 or 320 mg of Mon/(cow day). There were Mon x supplement interactions (Mon x S; P < 0.05) on the rumen molar proportion of Pr and Bu at 15:00 h, with B + Mon having the highest value for Pr (0.259 mmol/mmol) and lowest value for Bu (0.121 mmol/mmol). A Mon x S effect (P < 0.05) on milk fat content was noted with Mon causing a lower value regardless of energy source (31 and 36 g/l versus 40 and 38 g/l for B + Mon, M + Mon, B - Mon and M - Mon, respectively). As a main effect, M as opposed to B, reduced yields of milk (P < 0.05; 16.21/(cow day) versus 18.01/(cow day)) and protein (P < 0.05; 479 g/(cow day) versus 538 g/(cow day)). Monensin reduced milk fat yield (P < 0.05; 669 g/(cow day) versus 562 g/(cow day)), raised milk protein concentration (P < 0.05; 31 g/l versus 29 g/l) and caused LW gain rather than loss (P < 0.05; +0.06 kg/(cow day) versus -0.30 kg/(cow day)). No treatment effects on pasture intake were noted. In experiment 3, 48 cows (91 &PLUSMN; 16.1 DIM) grazing kikuyu pasture and supplemented with grain-based concentrate, sugar cane silage and 2.7 kg DM(cow day) of M were supplemented with either 0 or 320 mg Mon/(cow day). Monensin reduced (P < 0.05) milk fat content (33 g/l versus 30 g/l) and tended (P < 0.10) to reduce milk protein content (29 g/l versus 28 g/l). No effects of Mon on other milk production parameters, LW change or pasture intake were noted. Feeding monensin to mid-lactation Holstein-Friesian cows offered diets based on tropical grasses, and cane molasses or grain, improves rumen fermentation efficiency, thereby improving energy efficiency resulting in higher LW gain. Monensin had no effect on milk yield, but reduced milk fat concentration.

Self-assembled monolayers of thiols on gold electrodes for bioelectrochemistry and biosensors

Monolayers of biological compounds including redox proteins and enzymes, and phospholipids have been immobilized on a gold electrode surface through self-assembling. These proteins and enzymes, such as cytochrome c, cytochrome c oxidase and horseradish peroxidase (HRP), immobilized covalently to the self-assembled monolayers (SAMs) of 3-mercaptopropionic acid on a gold electrode, communicate directly electrons with the electrode surface without mediators and keep their physiological activities. The electron transfer of HRP with the gold electrode can also be mediated by the alkanethiol SAMs with electroactive group viologens on the gold electrode surface. All these direct electrochemistries of proteins and enzymes might offer an opportunity to build a third generation of biosensors without mediators for analytes, such as H2O2, glucose and cholesterol. Monensin and valinomycin have been incorporated into the bilayers on the gold electrode consisting of the SAMs of alkanethiol and a lipid monolayer, which have high selectivity for monovalent ions, and the resulting Na+ or K+ sensor has a wide linear range and high stability. These self-assembly systems provide a good mimetic model for studying the physiological function of a membrane and its associated enzyme. (C) 1997 Elsevier Science S.A.

Observations on the mechanism of eggshell formation in the liver fluke, Fasciola hepatica

A mechanism for eggshell production in Schistosoma mansoni has been proposed (Wells & Cordingley, 1991), and suggests that the release of eggshell protein globules from the vitelline cells occurs under alkaline conditions within the ootype followed by their subsequent fusion to form the eggshell. Fusion and tanning of these components produces eggshell which autofluoresces. The present study was carried out to determine whether a similar process operates in Fasciola hepatica. A number of drug treatments were used to disrupt key steps in the maturation of vitelline cells. Treatment with the calcium ionophore lasalocid (1 x 10(-5) M) led to the premature release of eggshell globules from the vitelline cells but not their fusion. Incubation in monensin (1 x 10(-6) M), a sodium ionophore and ammonium chloride (NH4Cl) (5 x 10(-2) M), a weak base, resulted in the premature fusion of eggshell protein globules within the vitelline cells and premature tanning of the eggshell protein material. The copper-containing enzyme, phenol oxidase, is thought to be involved in the tanning process during the production of eggs. Diethyldithiocarbamate (DDC, 1 x 10(-3) M) is a phenol oxidase inhibitor and treatment with this compound, in combination treatments with monensin and NH4Cl, prevented fusion of the vitelline cell globules and tanning of the shell protein material. The results of the study suggest that the mechanism for eggshell formation in F. hepatica is similar to that proposed for S. mansoni and may be common to other trematodes as well.