A high dose of monensin does not reduce methane emissions of dairy cows offered pasture supplemented with grain

The primary objective of our research was to determine the effect of a high dose of monensin supplementation on enteric CH₄ emissions of dairy cows offered a ryegrass pasture diet supplemented with grain. An additional objective was to evaluate effects on milk production and rumen function, because a commensurate improvement in milk production could lead to adoption of monensin as a profitable strategy for methane abatement. Two experiments were conducted (grazing and respiratory chambers) and in both experiments monensin (471 mg/d) was topdressed on 4 kg (dry matter)/d of rolled barley grain offered in a feed trough twice daily at milking times. In the grazing experiment, 50 Holstein-Friesian cows were assigned randomly to 1 of 2 groups (control or monensin). Cows grazed together as a single herd on a predominantly ryegrass sward and received monensin over a 12-wk period, during which time measurements of milk production and body weight change were made. The SF₆ tracer technique was used to estimate methane production of 30 of the 50 cows (15 control cows and 15 monensin cows) for 3 consecutive days in wk 3, 5, 8, and 12 of treatment. Samples of rumen fluid were collected per fistula from 8 of the 50 cows (4 per diet) on 2 consecutive days in wk 3, 5, 8, and 12 of treatment and analyzed for volatile fatty acids and ammonia-N. In the metabolic chamber experiment, 10 pairs of lactating dairy cows (control and monensin) were used to determine the effects of monensin on methane emissions, dry matter intake, milk production, and body weight change over a 10-wk period. Methane emissions were measured by placing cows in respiration chambers for 2 d at wk 5 and 10 of treatment. Cows received fresh ryegrass pasture harvested daily. Monensin did not affect methane production in either the grazing experiment (g/d, g/kg of milk) or the chamber experiment (g/d, g/kg of dry matter intake, g/kg of milk). In both experiments, milk production did not increase with addition of monensin to the diet. Monensin had no effect on body weight changes in either experiment. Monensin did not affect volatile fatty acids or ammonia-N in rumen fluid, but the acetate to propionate ratio tended to decrease. Monensin did not improve milk production of grazing dairy cows and no effect on enteric methane emissions was observed, indicating that monensin cannot be promoted as a viable mitigation strategy for dairy cows grazing ryegrass pasture supplemented with grain.     

Transport properties of liquid egg related to spray drying behaviour

The viscosities, critical moisture contents and effective water diffusivities were determined on samples of fresh and incubated liquid whole eggs at various temperatures. The liquid eggs were pretreated to simulate the possible effects of homogenisation and pasteurisation. The drying characteristics were based on measurements of weight losses against time of liquid egg films formed on glass spheres. The experimental results were used to obtain correlations appropriate for the expected temperature dependence of each property, for convenience in modelling of the spray drying operation. The ranges of the measured values are 5·6–14·5 mPa. s for coefficient of viscosity, 0·73–1·09 kg water kg⁻¹ dry matter for critical moisture content and 10–19 × 10⁻¹² m² s⁻¹ for effective water diffusivity. The results indicate similar magnitudes for the properties of fresh and incubated eggs.     

The simultaneous determination of the ionophore antibiotics in animal tissues and eggs by tandem electrospray LC–MS–MS

A method has been developed for the simultaneous extraction and determination of the four most currently used Ionophore antibiotics (lasalocid, monensin, narasin and salinomycin) by LC–MS–MS from different animal tissues and eggs. Results show good repeatability, and mean spiked recoveries for lasalocid, monensin, narasin and salinomycin in animal livers are in the average range 93–103, 96–103, 93–102 and 97–106%, respectively, and in eggs the mean spiked recoveries are 101, 103, 98 and 102% for lasalocid, monensin, narasin and salinomycin, respectively. The detection limit is at 1 ng ml⁻¹ for all the named ionophorous compounds. A quantitation level of 50 ng g⁻¹ for lasalocid, monensin at 2.5 ng g⁻¹, and 10 ng g⁻¹ for narasin and salinomycin is achieved which represents half the action limit prescribed by the UK Regulation in compliance with the European Council Directive 96/23/EC. A high throughput of samples is achievable using this method which allows the analysis of 30–40 samples by one analyst in a day.     

Dynamics of methanogenesis,ruminal fermentation,and alfalfa degradation during adaptation to monensin supplementation in goats

This study aimed to examine the temporal (hourly within a day and daily over the long term) effects of monensin on CH₄ emissions, ruminal fermentation, and in situ alfalfa degradation in dairy goats during dietary monensin supplementation by controlling the confounding effects of feed intake and ambient temperature. Six ruminally cannulated dairy goats were used, and they were housed in environmental chambers and fed a restricted amount of ration throughout the experiment. The experiment included a baseline period of 20 d followed by a treatment period of 55 d with 32 mg of monensin/d. During the whole experiment, CH₄ production was measured every 5 d, whereas fermentation characteristics and in situ alfalfa degradation were analyzed every 10 d. The CH₄-depressing effect of monensin was time dependent on the duration of treatment, highly effective at d 5 but thereafter decreased gradually until d 55 even though CH₄-suppressing effect still remained significant. The decreasing effects of monensin on ruminal acetate proportion and acetate to propionate ratio also faded over days of treatment, and the acetate proportion returned up to the pre-supplementation level on d 50. Monensin supplementation elevated ruminal propionate proportion and decreased the effective ruminal degradability of alfalfa NDF, but both measurements tended to recover over time. The postprandial increase rate of hourly CH₄ emissions was reduced, whereas that of propionate proportion was enhanced by monensin supplementation. However, the postprandial responses to monensin in CH₄ emission rates, ruminal VFA profiles, and in situ degradation kinetics declined with both hours after feeding and days of treatment. Our results suggest that the CH₄-suppressing effect of monensin supplementation in goats was attributed to reductions in both ruminal feed degradation and acetate to propionate ratio, but those reductions faded with time, hours after feeding, and days of treatment.     

Evolution of ascorbic acid and peroxidase during industrial processing of broccoli

The ascorbic acid content and peroxidase activity of raw, canned and frozen (after blanching times of 60, 90, 120 and 150 s) broccoli florets and stems were determined. The ascorbic acid content represented 1.12 and 0.78 g kg⁻¹ fresh weight in raw florets and stems respectively. After blanching (for different times) and freezing, the ascorbic acid content decreased to values of 0.55–0.56 g kg⁻¹ fresh weight in florets and 0.35–0.36 g kg⁻¹ fresh weight in stems. The industrial processing involved in canning decreased the ascorbic acid content to 0.18 g kg⁻¹ fresh weight in florets. The peroxidase activity observed in the florets and stems of raw broccoli was 308.8 and 278.6 µmol min⁻¹ per 100 g fresh weight respectively. The peroxidase activity remaining in frozen florets varied from 0.9 to 0.2%, while that in stems showed values of between 7.5 and 8.4%. These values for stems were within the range recommended for residual activity after blanching and freezing. The peroxidase activity of canned broccoli florets was practically undetectable. © 2000 Society of Chemical Industry     

A meta-analysis of the impact of monensin in lactating dairy cattle. Part 1. Metabolic effects

A meta-analysis of the impact of monensin on metabolism of dairy cattle was conducted following a search of the literature. A total of 59 studies with monensin feeding in dairy cattle were identified in which 30 papers and 45 trials contained metabolic data. The β-hydroxybutyrate (BHBA) data were obtained from over 4,000 cows and 115 trial sites. Data for each trial were extracted and analyzed using meta-analysis software in Stata. Estimated effect sizes of monensin were calculated on blood concentrations of BHBA, acetoacetate, nonesterified fatty acids (NEFA), glucose, cholesterol, urea, calcium, insulin, and milk urea. Monensin use in lactating dairy cattle significantly reduced blood concentrations of BHBA 13%, acetoacetate 14%, and NEFA 7%. Monensin increased glucose 3% and urea 6%. Monensin had no significant effect on cholesterol, calcium, milk urea, or insulin. Heterogeneity was significant for BHBA and cholesterol [I² (measure of variation beyond chance) = 37 and 54%, respectively]; therefore, random effects models were used for those analytes. Publication bias existed with the monensin effect on BHBA, with a tendency for studies to be published if there was a significant reduction in this ketone. Meta-regression analysis of the effect sizes obtained from the metabolic data showed that method of delivery, timing of administration, stage of lactation, and diet were influential in modifying effect size of monensin treatment. Use of top dress or delivery via a controlled release capsule reduced the magnitude of effect on BHBA (coefficient +0.353); however, top dress use compared with controlled release capsule or total mixed ration enhanced the monensin effect on glucose (coefficient +0.296). There was a greater impact with monensin on reducing BHBA in early lactation (coefficient −0.151) and in pasture-based trials (coefficient −0.194). Use of monensin in both the pre- and postcalving periods was associated with an enhanced impact on NEFA (coefficient −0.254). Monensin had less impact on serum glucose in the pre-calving time period (coefficient −0.237). These findings demonstrate an improvement in the energy metabolism of dairy cows supplemented with monensin.     

The effect of monensin supplementation of dried grass or barley diets on aspects of propionate metabolism,insulin secretion and lipogenesis in the sheep

The effects of 33 mg kg ^?1 monensin supplementation (+M) of barley (HC) or dried grass (HF) diets on aspects of propionate metabolism, insulin secretion, rumen vitamin B₁₂ synthesis and lipogenesis in sheep were investigated. Monensin had no significant effect on the estimated metabolisable energy intake, or the liveweight gain, but increased the proportion of propionate in rumen volatile fatty acids (VFA), P<0.01 and P<0.05 for HC and HF diets respectively, and increased rumen ammonia concentration, P<0.01 for both diets. Plasma propionate concentrations were increased (P<0.01) with the HC+M diet. Significant increases in adipose tissue and liver-propionyl-CoA carboxylase (P<0.001), a non-significant trend toward increases in fatty acid synthetase and significant increases in malic enzyme (P<0.01), indicated an induction of the pathways of propionate metabolism and lipogenesis; this was also supported by a trend toward increases, or significant increases, in total propionate derived fatty acids (PDFA), branchedchain fatty acids (BCFA) (P<0.01) and 18:1/18:0 ratio (P<0.02) in adipose tissue triacylglycerols of sheep fed the HC+M diet. Dietary monensin did not influence plasma glucose but reduced plasma insulin concentrations with both diets, P<0.001 and P<0.05 for HC and HF diets respectively, possibly due to a direct effect of monensin on insulin secretion. Monensin supplementation led to significant increases (P<0.02) or a trend toward increases in serum vitamin B₁₂, for HC and HF diets respectively, and to significant increases in liver vitamin B₁₂ (P<0.02) for the HF diet.     

Polyether ionophores residues in Minas Frescal cheese by UHPLC-MS/MS

ABSTRACT

An analytical method was developed and validated for the determination of three polyether ionophores (monensin, lasalocid, and salinomycin) in 60 samples of Brazilian Minas Frescal cheese by UHPLC-MS/MS. Linearity ranged from 1 to 8 μg kg^?1 for monensin and salinomycin, and from 0.50 to 4 μg kg^?1 for lasalocid. Limits of detection and quantitation were 0.50 μg kg^?1 and 1 μg kg^?1, respectively, for both monensin and salinomycin, and 0.25 μg kg^?1 and 0.50 μg kg^?1, respectively, for lasalocid. Recoveries were between 69% and 84% with coefficients of variation up to 16.28% for repeatability and 13.79% for intermediate precision. A total of 60 samples of Minas Frescal cheese were analysed and only monensin residues were found. Monensin was detected in 55% of the samples and quantified in 5 of them at mean levels varying from 1.00 to 1.73 μg kg^?1. The proposed method demonstrated the suitability for monitoring these substances in cheese.     

Reductions ofListeria innocuaandBrochothrix thermosphactaon beef following nisin spray treatments and vacuum packaging

Sections of UV sterilized lean and adipose tissues from the surfaces of post-rigor (24 h post-mortem) beef carcasses were inoculated withBrochothrix thermosphactaorListeria innocuato obtain approximately 4.50 log₈cfu cm⁻²and subjected to spray treatments with sterile water or nisin (5000 AU ml⁻¹). Untreated and spray treated samples were vacuum-packaged, and incubated at 4°C for up to 4 weeks. Bacterial populations from untreated vacuum-packaged tissues and spray treated, vacuum-packaged tissues were enumerated on non-selective and selective media at 0, 7, 14, 21 or 28 days. Nisin spray treatments of lean and adipose vacuum-packaged tissues reduced the numbers ofL. innocuaup to 2.83 log₈cfu cm⁻². Additionally, nisin sprays and vacuum packaging effectively suppressedL. innocuaduring the 4-week incubation such that the remaining bacteria did not grow to the same level as untreated or water-treated, vacuum-packaged tissues. Nisin spray treatments and vacuum packaging of lean and adipose tissues reducedB. thermosphactato undetectable levels. Data from this study demonstrate that nisin spray treatments followed by vacuum packaging under refrigerated conditions could increase the shelf life by suppressing or inhibiting the growth of undesirable bacteria present on fresh beef.     

Monensin for lactating dairy cows grazing mixed-alfalfa pasture and supplemented with partial mixed ration

The effect of monensin on milk production was evaluated in 58 lactating Holstein cows (48 multiparous; 10 primiparous) grazing a mixed-alfalfa pasture and supplemented with a partial mixed ration in a completely randomized design with repeated measurements. Cows were paired by calving date, lactation number, previous lactation milk production, body weight, and body condition score and were assigned to one of 2 treatments: control or monensin. Cows on the monensin treatment received 2 monensin controlled-release capsules (335 mg/d for 90 d), one 30 d before the expecting calving date and the other 60 d after calving. Short-term (0 to 150 d in milk) and long-term (305-d adjusted lactation) effects of monensin were evaluated. Pasture (measured by difference between pre- and postgrazing pasture mass), supplements, and total dry matter intake did not differ between treatments and averaged 8.7, 14.1, and 22.9 kg/d, respectively. In the short-term, monensin increased milk production (27.7 vs. 26.6 kg/d) and milk protein yield (0.890 vs. 0.860 kg/d); milk fat yield was not affected (0.959 kg/d). Monensin decreased milk fat content (3.51 vs. 3.60%) with no changes in milk protein content (3.25%). In the long term, milk production and milk protein yield were also increased by monensin: 214 and 7 kg, respectively. Monensin reduced the loss of body condition score and increased percentage of pregnancy at first service (44.8 vs. 20.7%). Monensin improves production and reproduction performance of dairy cows grazing a mixed-alfalfa pasture and supplemented with a partial mixed ration.     

The use of pimaricin as an additive to improve the aerobic stability of silage

Pimaricin was added to samples from each of five crop species to give the following nominal rates of application: 0, 0.011, 0.022, 0.034, 0.045, 0.09 and 0.27 kg t^?1 fresh weight and the materials were ensiled in 100 g and 10 kg fresh weight quantities. Pimaricin applied at ensiling at 0.011 or 0.022 kg t^?1 reduced aerobic deterioration in three of the five crops—ryegrass, lucerne and tall fescue; a much higher rate of 0.27 kg t^?1 was required with silages made from red clover and maize. This beneficial effect occurred even though only from 1-66% of the pimaricin initially applied was recovered after the period of anaerobic storage in the silos. Pimaricin had no apparent effect on the course of fermentation nor on the composition of the silages, all of which were well preserved.     

Partial purification and characterization of polyphenoloxidase from peppermint (Mentha piperita)

Polyphenoloxidase (PPO) of peppermint leaves ( Mentha piperita) was isolated by (NH₄)₂SO₄ precipitation and dialysis. Its pH and temperature optima were 7.0 and 30°C, respectively. On heat-inactivation, half of the activity was lost after 6.5 and 1.5 min of treatment at 70 and 80°C, respectively. Sucrose, (NH₄)₂SO₄, NaCl and KCl appeared to be protective agents of peppermint PPO against thermal denaturation. Km of this enzyme ranged from 6.25×10⁻³ M with catechol to 9.00×10⁻³ M with L-dopa. The I₅₀ values of inhibitors studied on PPO were determined by means of activity percentage (I) diagrams. Values were 1.4×10⁻⁴ M, 1.7×10⁻⁴ M, 9.7×10⁻⁵ M, 2.45×10⁻⁴ M, 2.16×10⁻¹ M, 1.83×10⁻⁵ M, 6.5×10⁻⁵ M, 1.4×10⁻² M, 7.5×10⁻⁵ M, for potassium cyanide, glutathione, ascorbic acid, thiourea, sodium azide, sodium metabisulfite, dithioerythritol, β-mercaptoethanol and sodium diethyl dithiocarbamate respectively. Therefore, sodium metabisulfite was the most effective inhibitor.     

A review of edible mushroom radioactivity

The review deals mainly with the situation in Europe where wild-growing mushrooms are widely consumed as a delicacy and some species have been found to be extensively contaminated by radioactive fallout from the Chernobyl disaster in 1986. The natural isotope ⁴⁰K usually causes activities of 0.8–1.5 kBq kg⁻¹ dry matter. Activities of ¹³⁷Cs, from nuclear weapons testing, below 1 kBq kg⁻¹ dry matter, were commonly reported until 1985. The situation changed dramatically after the Chernobyl accident and activities up to tens of kBq kg⁻¹ dry matter of ¹³⁷Cs and to a lesser extent of ¹³⁴Cs were observed in the following years in some edible species. Among the heavily accumulating species belong Xerocomus (Boletus) badius, Xerocomus chrysenteron, Suillus variegatus, Rozites caperata and Hydnum repandum. Activity concentrations have been affected by several environmental factors, such as rate of soil contamination with fallout, the horizon from which mycelium takes nutrients, soil moisture and time from the disaster. Wild mushroom consumption contributed up to 0.2 mSv to the effective dose in individuals consuming about 10 kg (fresh weight) of heavily contaminated species per year. The radioactivity of cultivated mushrooms is negligible. Contamination can be considerably decreased by soaking or cooking of dried or frozen mushroom slices. Animals, such as deer, eating mushrooms, have elevated levels of radionuclides in their tissues.     

A meta-analysis of the impact of monensin in lactating dairy cattle. Part 2. Production effects

A meta-analysis of the impact of monensin on production outcomes in dairy cattle was conducted using the 36 papers and 77 trials that contained eligible data. Statistical analyses were conducted in STATA and included a consideration of fixed or random effects models, assessment of publication bias, and impact of influential studies. Meta-regression was used to investigate sources of heterogeneity of response. There were 71 trials containing data from 255 trial sites and 9,677 cows examining milk production and composition. Monensin use in lactating dairy cattle significantly decreased dry matter intake by 0.3 kg, but increased milk yield by 0.7 kg and improved milk production efficiency by 2.5%. Monensin decreased milk fat percentage 0.13%, but had no effect on milk fat yield; however, there was significant heterogeneity between studies for both of these responses. Milk protein percentage was decreased 0.03%, but protein yield was increased 0.016 kg/d with treatment. Monensin had no effect on milk lactose percentage. Monensin increased body condition score by 0.03 and similarly improved body weight change (0.06 kg/d). Analysis of milk fatty acid profile data indicated that monensin was associated with a reduction of short-chain fatty acids (from 1 to 12% reduction) and stearic acid (−7.8%). The impact of monensin on linoleic and linolenic acids was variable, but monensin significantly increased conjugated linoleic acid (22%). Meta-regression of the effect of monensin on milk component percentages and yields indicated an influence of delivery method, stage of lactation, dose, and diet. Increasing concentrations of C18:1 in the diet enhanced the effect of monensin on decreasing milk fat yield, whereas increasing the rumen peptide balance increased the effect of monensin on milk protein yield. These findings indicate a benefit of monensin for improving milk production efficiency while maintaining body condition. The effect of monensin on milk fat percentage and yield was influenced by diet.     

Glucosinolate content of brassica vegetables: Analysis of twenty-four cultivars of calabrese (green sprouting broccoli,Brassica oleracea L. var. botrytis subvar. cymosa Lam.)

The contents of glucosinolates in twenty-four cultivars of calabrese, green sprouting broccoli, have been determined using glucose release and high performance liquid chromatographic methods. The levels of total glucosinolates (range, 42·1–94·5 mg 100 g⁻¹ fresh weight; mean, 62·3 mg 100 g⁻¹ fresh weight) were comparable with those reported previously for cauliflower, but lower than those found in cabbage and, especially, Brussels sprouts. Analysis of the individual components revealed the main species to be 4-methylsulphinylbutyl glucosinolate (glucoraphanin) and, particularly, glucobrassicin and neoglucobrassicin, containing 3-indolylmethyl and 1-methoxy-3-indolylmethyl side chains, respectively. The individual glucosinolate contents of calabrese and cauliflower are compared and differences are considered in the context of biosynthetic pathways. The consequences of these findings for the flavour and biological properties of calabrese are briefly discussed.     

Deep‐fat frying of cassava: influence of raw material properties on chip quality

Thirteen cultivars of cassava (Manihot esculenta Crantz) were used to obtain chips by deep frying slices of fresh cassava flesh in palm oil. The cultivars were representative of three different levels of four major characteristics (water, cyanide, starch and amylose content) in parenchyma. The effects of raw material composition and crop age (10 and 12 months) on mass transfer (dehydration and oil uptake), texture and colour were assessed for 1.5 mm thick chips with a final water content of 0.04 kg kg⁻¹ wet basis, corresponding to a water activity of about 0.3. Frying time varied from 70 to 90 s and oil bath temperature from 140 to 160 °C. All cultivars gave a high frying yield (>0.5 kg chips kg⁻¹ fresh cassava) and a chip fat content of between 0.23 and 0.37 kg kg⁻¹ wet basis, with the highest frying yields and lowest fat contents being obtained from roots with the lowest water content and cyanide content. The intensity of darkening reactions increased in accordance with the level of reducing sugars, while the rigidity modulus of the chips was negatively correlated with the fibre content. The other characteristics (starch, amylose and total sugar content) were either not or poorly correlated with any of the chip quality parameters studied. Cyanoglucosides were only partially eliminated during frying (over 40% retention), so cultivars with a high cyanide content gave bitter chips. For a similar composition, drying rates and cooking rates were much lower when crop age increased. This could be attributed to a structural effect characterising crop age. © 2000 Society of Chemical Industry     

Anti-methanogenic effects of monensin in dairy and beef cattle: A meta-analysis

Monensin is a widely used feed additive with the potential to minimize methane (CH₄) emissions from cattle. Several studies have investigated the effects of monensin on CH₄, but findings have been inconsistent. The objective of the present study was to conduct meta-analyses to quantitatively summarize the effect of monensin on CH₄ production (g/d) and the percentage of dietary gross energy lost as CH₄ (Y_m) in dairy cows and beef steers. Data from 22 controlled studies were used. Heterogeneity of the monensin effects were estimated using random effect models. Due to significant heterogeneity (>68%) in both dairy and beef studies, the random effect models were then extended to mixed effect models by including fixed effects of DMI, dietary nutrient contents, monensin dose, and length of monensin treatment period. Monensin reduced Y_m from 5.97 to 5.43% and diets with greater neutral detergent fiber contents (g/kg of dry matter) tended to enhance the monensin effect on CH₄ in beef steers. When adjusted for the neutral detergent fiber effect, monensin supplementation [average 32 mg/kg of dry matter intake (DMI)] reduced CH₄ emissions from beef steers by 19 ± 4 g/d. Dietary ether extract content and DMI had a positive and a negative effect on monensin in dairy cows, respectively. When adjusted for these 2 effects in the final mixed-effect model, monensin feeding (average 21 mg/kg of DMI) was associated with a 6 ± 3 g/d reduction in CH₄ emissions in dairy cows. When analyzed across dairy and beef cattle studies, DMI or monensin dose (mg/kg of DMI) tended to decrease or increase the effect of monensin in reducing methane emissions, respectively. Methane mitigation effects of monensin in dairy cows (–12 ± 6 g/d) and beef steers (–14 ± 6 g/d) became similar when adjusted for the monensin dose differences between dairy cow and beef steer studies. When adjusted for DMI differences, monensin reduced Y_m in dairy cows (–0.23 ± 0.14) and beef steers (–0.33 ± 0.16). Monensin treatment period length did not significantly modify the monensin effects in dairy cow or beef steer studies. Overall, monensin had stronger antimethanogenic effects in beef steers than dairy cows, but the effects in dairy cows could potentially be improved by dietary composition modifications and increasing the monensin dose.     

Influence of some husbandry practices on the physical properties of spring barley grain

Specific weight, 1000 grain weight, and percentages of grain held by a 2.5 mm sieve and passing through a 2.2 mm sieve were measured in husbandry trials carried out on spring barley at Craibstone, Aberdeen, from 1975 to 1979. Sowing date had the greatest influence on these properties, apparently due more to poor crop development than to increased foliar disease following late sowing. Fungicide treatment, particularly a spray application of tridemorph, resulted in an improvement, but growth regulators, especially when applied late or at high rates, had the reverse effect and both chemicals affected specific weight less than other parameters. The mean specific weight, 1000 grain weight and grain size of a number of varieties declined at nitrogen application rates above 50 kg ha^?1, but there were significant differences between varieties, with short-strawed, small-grained varieties such as Midas and Maris Mink being most affected. Different levels and application methods of phosphatic fertiliser had little effect on the parameters measured.     

Glycoalkaloid content of potatoes and potato products sold in the UK

Potatoes and potato products were collected from six areas of the UK. Composite samples of potatoes, determined by variety, collection area and collection date, and composite samples of similar potato products were prepared. The glycoalkaloid content of the samples was determined and only two samples out of 133 analysed exceeded the recommended maximum level of 20 mg 100 g^?1 fresh weight. The mean values were: main crop 10.4mg 100g^?1, UK earlies 11.3mg 100g^?1 and imported earlies 12.3 mg 100 g^?1 Potato products, when calculated on an equivalent fresh weight basis, all contained less than 10mg 100g^?1.     

Long-term effects of feeding monensin on methane production in lactating dairy cows

The objective of this study was to determine the long-term effects of feeding monensin on methane (CH₄) production in lactating dairy cows. Twenty-four lactating Holstein dairy cows (1.46 ± 0.17 parity; 620 ± 5.9 kg of live weight; 92.5 ± 2.62 d in milk) housed in a tie-stall facility were used in the study. The study was conducted as paired comparisons in a completely randomized design with repeated measurements in a color-coded, double-blind experiment. The cows were paired by parity and days in milk and allocated to 1 of 2 treatments: 1) the regular milking cow total mixed ration (TMR) with a forage-to-concentrate ratio of 60:40 (control TMR; placebo premix) vs. a medicated TMR (monensin TMR; regular TMR + 24 mg of Rumensin Premix/kg of dry matter) fed ad libitum. The animals were fed and milked twice daily (feeding at 0830 and 1300 h; milking at 0500 and 1500 h) and CH₄ production was measured prior to introducing the treatments and monthly thereafter for 6 mo using an open-circuit indirect calorimetry system. Monensin reduced CH₄ production by 7% (expressed as grams per day) and by 9% (expressed as grams per kilogram of body weight), which were sustained for 6 mo (mean, 458.7 vs. 428.7 ± 7.75 g/d and 0.738 vs. 0.675 ± 0.0141, control vs. monensin, respectively). Monensin reduced milk fat percentage by 9% (3.90 vs. 3.53 ± 0.098%, control vs. monensin, respectively) and reduced milk protein by 4% (3.37 vs. 3.23 ± 0.031%, control vs. monensin, respectively). Monensin did not affect the dry matter intake or milk yield of the cows. These results suggest that medicating a 60:40 forage-to-concentrate TMR with 24 mg of Rumensin Premix/kg of dry matter is a viable strategy for reducing CH₄ production in lactating Holstein dairy cows.