Use of monensin controlled-release capsules to reduce methane emissions and improve milk production of dairy cows offered pasture supplemented with grain.

We examined the effects of monensin, provided by controlled-release capsules, on the enteric methane emissions and milk production of dairy cows receiving ryegrass pasture and grain. In a grazing experiment, 60 Holstein-Friesian cows were assigned randomly to 1 of 2 groups (control or monensin). Cows in the monensin group received 2 controlled-release capsules, with the second capsule administered 130 d after the first. Milk production was measured for 100 d following insertion of each capsule. The sulfur hexafluoride tracer gas technique was used to measure enteric methane emissions for 4 d starting on d 25 and 81 after insertion of the first capsule, and on d 83 after insertion of the second capsule. All cows grazed together as a single herd on a predominantly ryegrass sward and received 5 kg/d of grain (as-fed basis). In a second experiment, 7 pairs of lactating dairy cows (control and monensin) were used to determine the effects of monensin controlled-release capsules on methane emissions and dry matter intake. Methane emissions were measured on d 75 after capsule insertion by placing cows in respiration chambers for 3 d. Cows received fresh ryegrass pasture harvested daily and 5 kg/d of grain. The release rate of monensin from the capsules used in both experiments was 240 +/- 0.072 mg/d, determined over a 100-d period in ruminally cannulated cows. The monensin dose was calculated to be 12 to 14.5 mg/kg of dry matter intake. There was no effect of monensin on methane production in either the grazing experiment (g/d, g/kg of milk solids) or the chamber experiment (g/d, g/kg of dry matter intake). In the grazing study, there was no effect of monensin on milk yield, but monensin increased milk fat yield by 51.5 g/d and tended to increase milk protein yield by 18.5 g/d. Monensin controlled-release capsules improved the efficiency of milk production of grazing dairy cows by increasing the yield of milk solids. However, a higher dose rate of monensin may be needed to reduce methane emissions from cows grazing pasture.

Residues of zeta-cypermethrin in bovine tissues and milk following pour-on and spray application.

The depletion of zeta-cypermethrin residues in bovine tissues and milk was studied. Beef cattle were treated three times at 3-week intervals with 1 ml 10 kg-1 body weight of a 25 g litre-1 or 50 g litre-1 pour-on formulation (2.5 and 5.0 mg zeta-cypermethrin kg-1 body weight) or 100 mg kg-1 spray to simulate a likely worst-case treatment regime. Friesian and Jersey dairy cows were treated once with 2.5 mg zeta-cypermethrin kg-1 in a pour-on formulation. Muscle, liver and kidney residue concentrations were generally less than the limit of detection (LOD = 0.01 mg kg-1). Residues in renal-fat and back-fat samples from animals treated with 2.5 mg kg-1 all exceeded the limit of quantitation (LOQ = 0.05 mg kg-1), peaking at 10 days after treatment. Only two of five kidney fat samples were above the LOQ after 34 days, but none of the back-fat samples exceeded the LOQ at 28 days after treatment. Following spray treatments, fat residues were detectable in some animals but were below the LOQ at all sampling intervals. Zeta-cypermethrin was quantifiable (LOQ = 0.01 mg kg-1) in only one whole-milk sample from the Friesian cows (0.015 mg kg-1, 2 days after treatment). In whole milk from Jersey cows, the mean concentration of zeta-cypermethrin peaked 1 day after treatment, at 0.015 mg kg-1, and the highest individual sample concentration was 0.025 mg kg-1 at 3 days after treatment. Residues in milk were not quantifiable beginning 4 days after treatment. The mean concentrations of zeta-cypermethrin in milk fat from Friesian and Jersey cows peaked two days after treatment at 0.197 mg kg-1 and 0.377 mg kg-1, respectively, and the highest individual sample concentrations were 2 days after treatment at 0.47 mg kg-1 and 0.98 mg kg-1, respectively.

Efficacy of zeta-cypermethrin as pour-on or spray formulations for the control of buffalo fly (Haematobia irritans exigua) in cattle.

OBJECTIVE: To determine the efficacy of zeta-cypermethrin in controlling buffalo fly (Haematobia irritans exigua). DESIGN: Five field trials in northern and central Queensland. PROCEDURE: Zeta-cypermethrin pour-on at 2.5 mg/kg, spray at 62.5 ppm, deltamethrin pour-on and pour-on vehicle were applied to groups of 20 cattle. Buffalo fly counts were conducted three times before treatment and 3, 7, 14, 21, 28 and 35 days after treatment. RESULTS: In central Queensland where synthetic pyrethroid resistance in buffalo fly populations was rare, 2.5 mg/kg of zeta-cypermethrin pour-on gave good control of buffalo fly for 4 weeks and was better than a deltamethrin product. A zeta-cypermethrin spray used at 62.5 ppm gave 14 days control. In far-north Queensland where resistance to synthetic pyrethroids and heavy rain was common, the maximum period of efficacy of zeta-cypermethrin pour-on was reduced to 2 weeks. CONCLUSION: In areas where there is low resistance to synthetic pyrethroids among buffalo flies, zeta-cypermethrin pour-on can be expected to give good control for 4 weeks.

Therapeutic efficacy of zeta-cypermethrin pour-on for the treatment of biting and sucking lice in cattle under field conditions.

OBJECTIVE: To assess the efficacy of zeta-cypermethrin pour-on to control cattle lice. DESIGN: Five field trials in south-eastern Australia. PROCEDURE: Zeta-cypermethrin pour-on, deltamethrin pour-on and pour-on vehicle were applied to groups of 10 cattle. Lice were counted before treatment and 14, 28, 42 and 56 days after treatment. RESULTS: Zeta-cypermethrin pour-on given at 2.5 mg/kg was equivalent to, or marginally more effective than a deltamethrin pour-on at 0.75 mg/kg. It eliminated B bovis and H eurysternus and gave good control of L vituli and S capillatus. Zeta-cypermethrin at 1 mg/kg gave good control of B bovis and H eurysternus but was not satisfactory against L vituli and S capillatus. CONCLUSION: Zeta-cypermethrin pour-on, given at 2.5 mg/kg, is an effective treatment for cattle lice control. Zeta-cypermethrin, and other synthetic pyrethroid pour-ons, are the treatment of choice to control B bovis.

Monensin controlled-release intraruminal capsule for control of bloat in pastured dairy cows.

Monensin, a polyether ionophore antibiotic, is potentially an important agent for bloat relief in dairy cows grazing temperate legume-based pasture. A series of studies was undertaken to determine the effect of monensin, when delivered continuously in the rumen of lactating dairy cows by means of controlled-release capsules (monensin CRC). Such devices release approximately 300 mg/head/day for 100 d. A short-term pilot study made at Ruakura, New Zealand, tested monensin CRC in cows selected for high susceptibility to bloat and grazing lucerne (Medicago sativa) or red clover (Trifolium pratense). Treatment significantly reduced the incidence of bloat, while milk yield and protein yield were increased. There was no effect on fat yield. Following the pilot study, 6 large-scale field experiments involving a total of 368 lactating dairy cows, were made in Australia and New Zealand to confirm the effectiveness of monensin CRC for bloat control and to measure the effect of such treatment on milk production and composition. A severe bloat problem occurred in 2 experiments, mild bloat occurred in 2 others, while no visual signs of bloat were observed in the remaining 2 experiments. Bloat was significantly (P less than 0.05) reduced by monensin CRC treatment when data was pooled over the 4 experiments in which bloat occurred. Daily milk yield was increased in all experiments from a mean of 17.7 in untreated groups to 18.8 kg/head/day (P less than 0.05) in monensin CRC-treated cows. Protein percentage was not affected by treatment, while there was a decrease from 4.29 to 4.10% fat, although total fat yield was not affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Endosperm protein of wheat seed as a determinant of seedling growth.

Seed of a Mexican semidwarf wheat (Triticum aestivum L. cv. Inia 66), was obtained from a nitrogen fertilizer field trial grown in Mexico. A high positive correlation was obtained between seed protein content and seedling dry weight after 3 weeks growth (r = +0.92(**)). The seedling dry weight was positively related to the protein content of the aleurone layer and endosperm, but not to the embryo. Small, 35 milligrams, high protein seeds (4.7 milligrams protein per seed) produced larger seedlings than large, 45 milligrams, low protein seeds (4.3 milligram protein per seed). There was no difference in the weight or protein content of embryos from low and high protein seeds and their growth was similar. Composite seeds of the two protein levels were produced by transferring embryos from one endosperm type to the other. After 4 weeks, there was no difference between the different embryo types grown on the same endosperm type. High protein endosperm produced more vigorous seedlings regardless of the embryo type grown on it, indicating that the factor(s) responsible for the greater growth of high protein seed is in the endosperm.

The "will to live" as perceived by nurses and physicians.

This study investigated the "will to live" as nurses and physicians perceive it. A sample of 221 practicing health professionals completed a questionnaire that was designed to measure this construct. Semantic differential scales were used to assess the psychological characteristics of patients with a strong and weak will to live, while Likert scales were used to rate overt behaviors associated with a strong will to live. The respondents were also asked to rate activities that might be used to strengthen the will to live in patients who lacked it. Results showed that almost 100% of the respondents believed in a will to live, had observed its effects, and felt that a strong will to live was an important factor in patient recovery. Both nurses and physicians showed surprising agreement in their perception of the will to live, as well as in their suggestions about how to strengthen patient morale. The results are generally consistent with those from related studies on psychological variables associated with cancer survival and recovery from catastrophic illness. It is concluded that regardless of whether a will to live is a "real" attribute of patients, it certainly seems to exist in the eyes of those who treat them.

Effects of monensin on the metabolism of periparturient dairy cows.

The effects of monensin on plasma concentrations and changes in plasma concentrations of energy metabolites and minerals over time were investigated using 24 multiparous Holstein cows. Cows were paired according to farm, predicted date of calving, and body condition score and were randomly allocated to two groups. Treated cows were given a ruminal bolus containing 32 g of monensin at 50 +/- 7 d before predicted calving. Treated cows had lower plasma concentrations of glucose, free fatty acid (FFA), and beta-hydroxybutyrate (BHBA) than did control cows before calving, indicating that monensin influenced energy metabolism. However, no significant differences in plasma concentrations of glucose, FFA, and BHBA were found between groups after calving. Plasma BHBA concentrations increased more before calving in control cows, and plasma FFA and urea concentrations increased significantly before calving in all cows. No significant differences in body weight, plasma concentrations of urea, or whole blood concentrations of glutathione peroxidase were detected between groups before or after calving. Plasma ceruloplasmin activity did not differ between groups before calving, but was significantly higher in treated cows after calving. Plasma concentrations of Ca did not significantly differ between groups before or after calving. Monensin altered both energy and mineral metabolism and has the potential to improve the health and production of dairy cows.