Robert Mayes - Academia.edu (original) (raw)
Papers by Robert Mayes
Proceedings of the British Society of Animal Science, 2007
Proportions of polyunsaturated fatty acid (PUFA) in ruminant tissues are generally low as dietary... more Proportions of polyunsaturated fatty acid (PUFA) in ruminant tissues are generally low as dietary PUFA including linoleic acid (LA) and α-linolenic acid (ALA) undergo biohydrogenation to stearic acid in the rumen. Conjugated linoleic acid (CLA) is formed during biohydrogenation as an intermediate metabolite. Feeding PUFA-rich sources can enhance deposition in the tissues of ruminants (Bolte et al, 2002), but the degree of lipid hydrogenation may depend on the source form and the ruminant species (Rowell-Schäffer et al, 2001). Bolte et al, (2002) showed that oilseed-fed sheep had higher PUFA proportions in their tissues than sheep fed a beet pulp-based diet but Rowell-Schäffer et al (2001) found in deer tissues higher PUFA proportions than in those of sheep. Possible effects of the form of the lipid source and the ruminant species on the fatty acids deposited were tested.
Proceedings of the British Society of Animal Science, 1999
N-alkanes are components of plant cuticular wax which have been successfully used as markers for ... more N-alkanes are components of plant cuticular wax which have been successfully used as markers for the estimation of grass intake and digestibility in grazing ruminants (Dove and Mayes, 1991). Natural n-alkanes are predominately odd chain, and a known dose of an artificial even chain n-alkane (normally c32 or c36) is used to enable intake to be measured. Dietary n-alkanes may behave differently in the gastro-intestinal tract of ruminants and non-ruminants (Mayes et al, 1995). Therefore, in order to utilise this methodology in studies of outdoor pigs, this experiment was carried out to validate the faecal recovery of n-alkanes in this species. Since n-alkanes are soluble in lipid, which is often incorporated at high inclusion levels in pig diets, the experiment was also designed to determine whether n-alkane recovery is influenced by dietary lipid content.
Advances in Animal Biosciences, 2010
Radioprotection, 2002
We have previously demonstrated a relationship between dry matter (DM) intake and the degree of t... more We have previously demonstrated a relationship between dry matter (DM) intake and the degree of transfer of radiocaesium to the muscle of adult sheep. Here, we present the results of an experiment during which we examined the effect of lamb growth and protein turnover rates, brought about by controlling feed DM intakes, on radiocaesium transfer and turnover. Lambs with high DM intakes and, as a consequence, high rates of growth, had a lower mean radiocaesium transfer coefficient from the diet to muscle than lambs with lower intake and growth rates. Furthermore, high rates of dry matter intake decreased the biological half-life of radiocaesium from muscle. The administration of [ 3 %]-ntethionine to the study lambs enables us to suggest that radiocaesium transfer may be related to protein turnover. When the results were compared with those of other studies using sheep, a consistent relationship between DM intake and radiocaesium transfer across all animals regardless of age or physiological status was observed. Extrapolation of the relationship to DM intake rates appropriate to cattle predict radiocaesium transfer coefficients in broad agreement with reported values.
Journal of Nutrition
The nutrient status of the herbivore depends on the nutritive value of the plants available, the ... more The nutrient status of the herbivore depends on the nutritive value of the plants available, the botanical composition of the consumed diet and the intake of the animal. It has always been difficult to quantify these last two. At present, intake is usually calculated from separate estimates of fecal output and diet digestibility. In this review we discuss the errors inherent in this approach, especially those associated with the determination and application of digestibility in vitro. We then critically evaluate a new approach to the estimation of intake, based on the use of plant cuticular wax alkanes as markers. Plant alkanes are predominantly odd-chain and substantially indigestible. They can be used, in combination with orally dosed even-chain alkanes, to obtain an intake estimate which is essentially independent of marker recovery in feces and which is more truly "individual" because it accommodates the level of digestibility occurring in individual animals. We presen...
In summer 1993 we measured the transfer Of Pu-239/240 to milk from herbage from a pasture located... more In summer 1993 we measured the transfer Of Pu-239/240 to milk from herbage from a pasture located 5 km from the Chernobyl nuclear power plant. In one treatment cows were allowed to graze freely on the pasture. In a second treatment, cows were fed herbage collected from the pasture in stalls. The milk transfer coefficient; F-m did not vary significantly between treatments and the mean value of 7.5 x 10(-6) d l(-1) was higher than previously reported values. Despite many values of F-m for Pu in the literature we identified few relevant original data sets. Transfer coefficient values for Pu are only appropriate when used in conjunction with a specitied time period or an appropriate model which allows for the biological half-life. We recommend for screening purposes an F-m value of 1 x 10(-5) d l(-1) for Pu, with an order of magnitude lower value being appropriate for cows which are only exposed for one grazing season. (c) 2007 Elsevier Ltd. All rights reserved.
Soil Biology and Biochemistry, 2011
... BIOSS for assistance with statistical analysis. Serita Frey and Steve Chapman and two anonymo... more ... BIOSS for assistance with statistical analysis. Serita Frey and Steve Chapman and two anonymous reviewers are acknowledged for their helpful comments on earlier versions of this manuscript. References. Ali et al., 2004 HAM Ali ...
Soil-based materials found during forensic enquiry can provide powerful intelligence relating to ... more Soil-based materials found during forensic enquiry can provide powerful intelligence relating to provenance. Traditionally, mineralogy and palynology have been used to provide complementary information on geology and plant community structure from soil. We evaluated the potential of plant wax compounds and microbial DNA profiles in providing land-use based intelligence within two localized urban study areas. Soil physico-chemical, mineralogical, spectroscopic and n-alkane profiling did not provide data characteristic of land-use. Bacterial DNA analysis was indicative of land-use and correlated to physico-chemical drivers. Soil fatty-alcohol and fungal DNA analyses provided the most promising indicators of broad-scale land-use category, providing independent and complementary information to mineral-based analyses. These results demonstrate the potential of soil fatty-alcohol and fungal analyses as screening approaches to complement mineralogy in gaining forensic intelligence from soi...
Grass and Forage Science, 2014
ABSTRACT Feed intake and diet choice affect production efficiency in livestock. Plant waxes, in p... more ABSTRACT Feed intake and diet choice affect production efficiency in livestock. Plant waxes, in particular n-alkanes, have been used as markers to predict intake and diet preferences. Still, when n-alkane profiles of plants within mixed swards are similar, they alone may not produce reliable predictions. Including long-chain alcohols (LCOHs) may help. In this study, the reliability of predicting forage mixtures was assessed using n-alkanes and LCOH separately and in combination. Reliability was characterized as the regression of observed on predicted fescue proportion in forage mixtures and the Kulczyński similarity index. Two technicians performed extractions of n-alkanes and LCOHs of pure red clover and ‘Fawn’ tall fescue, and nine mixtures of them. The concentrations of n-alkanes C27, C29, C31 and C33 and alcohols C26-OH, C28-OH and C30-OH were compared among forage mixtures and between technicians. Technicians were consistent in their measures of n-alkanes (P > 0·12), but differed in their measures of C26-OH and C28-OH (P < 0·002). Longer-chained compounds were more consistently quantified. Forage delineations were not improved by C26-OH. With n-alkanes alone, estimated and actual fescue proportions closely agreed. Including LCOH offered no improvement. Despite variation in measured concentrations between technicians, fescue and red clover mixtures were reliably predicted using n-alkanes alone.
Advances in Animal Biosciences, 2010
In animals consuming known amounts of supplement, total intake of roughage plus supplement could ... more In animals consuming known amounts of supplement, total intake of roughage plus supplement could be estimated by dividing known supplement intake by the supplement proportion in the diet, if the latter were estimated using the alkane patterns in roughage, supplement and the faeces of the animals consuming them. The roughage intake could then be obtained by multiplying total intake by the estimated roughage proportion in the diet. This approach was tested using data from a previous study, and the results of a second experiment. In the first experiment, perennial ryegrass chaff and sunflower meal labelled with beeswax alkanes were fed in different proportions to young sheep. Known roughage intake was significantly under-estimated (P<0.05) by about 8% using this approach, due mainly to the 12% under-estimate in animals receiving the lowest level of supplement. This reflected the compounding of errors in estimating the dietary proportion of supplement in that treatment. In the other ...
Vadose Zone Journal, 2010
... University of Ontario Institute of Technology, 2000 Simcoe St N, Oshawa ON, L1H 7K4, Canada S... more ... University of Ontario Institute of Technology, 2000 Simcoe St N, Oshawa ON, L1H 7K4, Canada Sean Forrester Centre for ... xxii Contributors Stephen Mudge School of Ocean Sciences, Bangor University, Menai Bridge LL59 5AB, UK Ekaterina Nesterina Russian Federal Centre ...
The Journal of Agricultural Science, 1986
SUMMARYThe recovery in the faeces of the n-alkanes of herbage (odd-chain, C27–C35) and of dosed a... more SUMMARYThe recovery in the faeces of the n-alkanes of herbage (odd-chain, C27–C35) and of dosed artificial alkanes (even-chain, C28 and C32) was studied in twelve 4-month-old castrated male lambs. The lambs received three levels of cut, fresh perennial ryegrass or a mixed diet of perennial ryegrass (0·70) and a barley-based concentrate (0·30) (500–900 g D.M./day). C28 and C32 n-alkanes (130 mg each), absorbed onto shredded paper, were given once daily for 17 days to test whether the recoveries of herbage and dosed alkanes were similar to enable their use as markers for determining the herbage intake of grazing sheep. Stearic and palmitic acids (130 mg each) were given with the dosed alkanes to half of the animals with the objective of facilitating emulsification of the dosed alkanes within the digestive tract.With the exception of C27 n-alkane, the faecal recoveries of all alkanes were unaffected by diet, feeding level or emulsifying agent. Faecal recovery of odd- chain herbage n-al...
The Journal of Agricultural Science, 1986
SUMMARYFlow rates of metabolites in an open-compartment model can be calculated from specific act... more SUMMARYFlow rates of metabolites in an open-compartment model can be calculated from specific activity measurements taken at equilibrium during continuous infusion of an isotope. The within-animal variance gives an estimate of the precision of the flow rate.The Jack-knife method of calculating within-animal variances is described. It was evaluated using simulated data, and shown to be superior to a simpler method, the Single Section method.The increase in experimental accuracy caused by increasing the number of specific activity samples per animal depends on the ratio of between- to within-animal variance components (B/W). For three experiments with sheep, 23 of the 30 values B/W for the different flow rates ranged from 0·25 to 1·5. For this range between six and 12 samples per animal are needed.
The Journal of Agricultural Science, 2007
The estimation of dry matter intake (DMI) using the alkane pair technique has been validated in r... more The estimation of dry matter intake (DMI) using the alkane pair technique has been validated in ruminants, but not in equids. The current paper reports the finding of three comparative validation studies carried out using a total of 12 cattle, 29 donkeys and 10 horses during which directly measured intake was compared to estimated intake using the alkane pair technique. Two methods were developed to dose the even chain alkanes that were used as external markers. Study I, carried out in Zimbabwe, compared the accuracy of estimated intake with measured intake in cattle and donkeys using hexatriacontane (C36) as the external marker. Studies II and III were carried out in the UK with horses and donkeys and compared the accuracy of estimated intake with measured intake using dotriacontane (C32) as the external marker. Study III also tested the effect on the accuracy of intake estimates of two marker dosing levels (mean daily dose of 224 mg per animal and 448 mg per animal) and two dosing...
The Analyst, 1992
A simple extraction procedure has been developed to assess rapidly the probable extent of the tra... more A simple extraction procedure has been developed to assess rapidly the probable extent of the transfer of radiocaesium into ruminant food products soon after a nuclear accident. The in vitro extractions were validated against true absorption measurements of different forms of radiocaesium in the sheep gut. Extractions were performed on a range of different radiocaesium sources. Some of these sources were artificial (ionic radiocaesium adsorbed onto bentonite, silica spheres and filter-papers) and others were environmentally contaminated [silt from the Ravenglass Estuary contaminated by effluent from British Nuclear Fuels Limited (BNFL) Sellafield, and upland grass and heather contaminated by Chernobyl fallout]. Laboratory experiments concentrated primarily on the use of simple inorganic extractants in competitive ion-exchange processes. Of the reagents used, 0.1 mol dm-3 stable caesium chloride solution was the most effective extractant. The proportion of radiocaesium extracted by 0.1 mol dm-3 caesium chloride correlated well with measurements of true absorption. Extracting radiocaesium using 0.1 mol dm-3 caesium chloride proved to be an inexpensive and rapid method of predicting the availability of radiocaesium for absorption in the ruminant gut, giving results within 24 h. Further extractions were carried out using cellulase/pepsin simulated digestions and ovine rumen fluid. Results suggested that the availability of radiocaesium from some inorganic sources may be underestimated using such techniques.
Small Ruminant Research, 1996
Twenty-four mature, dry, female goats were grazed on Brachiaria-dominated pasture to study the ef... more Twenty-four mature, dry, female goats were grazed on Brachiaria-dominated pasture to study the effects of tethering on intake. Animals were either tethered for 4 h (T4) or 8 h (1'8), or grazed freely for 8 h (FO) during a 28 day period. Intake was estimated by two methods: (1) short-term BW changes and (2) n-alkanes as internal markers. The BW technique was suitable for conditions in developing countries, although correction factors for changes in bite rate through the grazing day may be needed and expensive chemical analyses. Animals grazed for 4 h had similar total daily intakes to those grazed for 8 h: 1055 g day-J, I] 83 g day-J and 1259 g day-I for T4, T8 and FO treatments, respectively. The T4 animals compensated for the shorter time available by increasing intake rate and spending a larger proportion of available time eating. Although the reason for higher intake rates observed in T4 animals was unclear, duration of fasting was not considered to be a factor. Lower intake rates observed at the end of the day for tethered animals may have resulted from decreasing herbage mass availability and soiling. Free-grazed animals did not alter intake rate and had total intakes that did not differ from those of T8 animals. Increased rates of intake might be expected to increase rate of passage and decrease digestibility; however, in the present trial, digestibilities (0.49,0.54 and 0.51 for T4, T8 and FO animals, respectively) did not differ (P>0.05) among treatments. The results showed no serious disadvantage in terms of intake and digestibility, either of tethering per se, or of tethering for 4 h as opposed to 8 h, for mature non-productive goats, which were able to alter behaviour to compensate for limited time available for grazing.
Small Ruminant Research, 1999
The accident at the Chernobyl nuclear power plant in 1986 resulted in levels of radiocaesium in a... more The accident at the Chernobyl nuclear power plant in 1986 resulted in levels of radiocaesium in animal-derived food products above national intervention limits in a number of countries. In upland areas of the United Kingdom (UK) radiocaesium activity concentrations in the meat of some sheep exceeds (in 1998) the local intervention limit of 1000Bqkg−1 and measures are still in place
Proceedings of the British Society of Animal Science, 2007
Proportions of polyunsaturated fatty acid (PUFA) in ruminant tissues are generally low as dietary... more Proportions of polyunsaturated fatty acid (PUFA) in ruminant tissues are generally low as dietary PUFA including linoleic acid (LA) and α-linolenic acid (ALA) undergo biohydrogenation to stearic acid in the rumen. Conjugated linoleic acid (CLA) is formed during biohydrogenation as an intermediate metabolite. Feeding PUFA-rich sources can enhance deposition in the tissues of ruminants (Bolte et al, 2002), but the degree of lipid hydrogenation may depend on the source form and the ruminant species (Rowell-Schäffer et al, 2001). Bolte et al, (2002) showed that oilseed-fed sheep had higher PUFA proportions in their tissues than sheep fed a beet pulp-based diet but Rowell-Schäffer et al (2001) found in deer tissues higher PUFA proportions than in those of sheep. Possible effects of the form of the lipid source and the ruminant species on the fatty acids deposited were tested.
Proceedings of the British Society of Animal Science, 1999
N-alkanes are components of plant cuticular wax which have been successfully used as markers for ... more N-alkanes are components of plant cuticular wax which have been successfully used as markers for the estimation of grass intake and digestibility in grazing ruminants (Dove and Mayes, 1991). Natural n-alkanes are predominately odd chain, and a known dose of an artificial even chain n-alkane (normally c32 or c36) is used to enable intake to be measured. Dietary n-alkanes may behave differently in the gastro-intestinal tract of ruminants and non-ruminants (Mayes et al, 1995). Therefore, in order to utilise this methodology in studies of outdoor pigs, this experiment was carried out to validate the faecal recovery of n-alkanes in this species. Since n-alkanes are soluble in lipid, which is often incorporated at high inclusion levels in pig diets, the experiment was also designed to determine whether n-alkane recovery is influenced by dietary lipid content.
Advances in Animal Biosciences, 2010
Radioprotection, 2002
We have previously demonstrated a relationship between dry matter (DM) intake and the degree of t... more We have previously demonstrated a relationship between dry matter (DM) intake and the degree of transfer of radiocaesium to the muscle of adult sheep. Here, we present the results of an experiment during which we examined the effect of lamb growth and protein turnover rates, brought about by controlling feed DM intakes, on radiocaesium transfer and turnover. Lambs with high DM intakes and, as a consequence, high rates of growth, had a lower mean radiocaesium transfer coefficient from the diet to muscle than lambs with lower intake and growth rates. Furthermore, high rates of dry matter intake decreased the biological half-life of radiocaesium from muscle. The administration of [ 3 %]-ntethionine to the study lambs enables us to suggest that radiocaesium transfer may be related to protein turnover. When the results were compared with those of other studies using sheep, a consistent relationship between DM intake and radiocaesium transfer across all animals regardless of age or physiological status was observed. Extrapolation of the relationship to DM intake rates appropriate to cattle predict radiocaesium transfer coefficients in broad agreement with reported values.
Journal of Nutrition
The nutrient status of the herbivore depends on the nutritive value of the plants available, the ... more The nutrient status of the herbivore depends on the nutritive value of the plants available, the botanical composition of the consumed diet and the intake of the animal. It has always been difficult to quantify these last two. At present, intake is usually calculated from separate estimates of fecal output and diet digestibility. In this review we discuss the errors inherent in this approach, especially those associated with the determination and application of digestibility in vitro. We then critically evaluate a new approach to the estimation of intake, based on the use of plant cuticular wax alkanes as markers. Plant alkanes are predominantly odd-chain and substantially indigestible. They can be used, in combination with orally dosed even-chain alkanes, to obtain an intake estimate which is essentially independent of marker recovery in feces and which is more truly "individual" because it accommodates the level of digestibility occurring in individual animals. We presen...
In summer 1993 we measured the transfer Of Pu-239/240 to milk from herbage from a pasture located... more In summer 1993 we measured the transfer Of Pu-239/240 to milk from herbage from a pasture located 5 km from the Chernobyl nuclear power plant. In one treatment cows were allowed to graze freely on the pasture. In a second treatment, cows were fed herbage collected from the pasture in stalls. The milk transfer coefficient; F-m did not vary significantly between treatments and the mean value of 7.5 x 10(-6) d l(-1) was higher than previously reported values. Despite many values of F-m for Pu in the literature we identified few relevant original data sets. Transfer coefficient values for Pu are only appropriate when used in conjunction with a specitied time period or an appropriate model which allows for the biological half-life. We recommend for screening purposes an F-m value of 1 x 10(-5) d l(-1) for Pu, with an order of magnitude lower value being appropriate for cows which are only exposed for one grazing season. (c) 2007 Elsevier Ltd. All rights reserved.
Soil Biology and Biochemistry, 2011
... BIOSS for assistance with statistical analysis. Serita Frey and Steve Chapman and two anonymo... more ... BIOSS for assistance with statistical analysis. Serita Frey and Steve Chapman and two anonymous reviewers are acknowledged for their helpful comments on earlier versions of this manuscript. References. Ali et al., 2004 HAM Ali ...
Soil-based materials found during forensic enquiry can provide powerful intelligence relating to ... more Soil-based materials found during forensic enquiry can provide powerful intelligence relating to provenance. Traditionally, mineralogy and palynology have been used to provide complementary information on geology and plant community structure from soil. We evaluated the potential of plant wax compounds and microbial DNA profiles in providing land-use based intelligence within two localized urban study areas. Soil physico-chemical, mineralogical, spectroscopic and n-alkane profiling did not provide data characteristic of land-use. Bacterial DNA analysis was indicative of land-use and correlated to physico-chemical drivers. Soil fatty-alcohol and fungal DNA analyses provided the most promising indicators of broad-scale land-use category, providing independent and complementary information to mineral-based analyses. These results demonstrate the potential of soil fatty-alcohol and fungal analyses as screening approaches to complement mineralogy in gaining forensic intelligence from soi...
Grass and Forage Science, 2014
ABSTRACT Feed intake and diet choice affect production efficiency in livestock. Plant waxes, in p... more ABSTRACT Feed intake and diet choice affect production efficiency in livestock. Plant waxes, in particular n-alkanes, have been used as markers to predict intake and diet preferences. Still, when n-alkane profiles of plants within mixed swards are similar, they alone may not produce reliable predictions. Including long-chain alcohols (LCOHs) may help. In this study, the reliability of predicting forage mixtures was assessed using n-alkanes and LCOH separately and in combination. Reliability was characterized as the regression of observed on predicted fescue proportion in forage mixtures and the Kulczyński similarity index. Two technicians performed extractions of n-alkanes and LCOHs of pure red clover and ‘Fawn’ tall fescue, and nine mixtures of them. The concentrations of n-alkanes C27, C29, C31 and C33 and alcohols C26-OH, C28-OH and C30-OH were compared among forage mixtures and between technicians. Technicians were consistent in their measures of n-alkanes (P > 0·12), but differed in their measures of C26-OH and C28-OH (P < 0·002). Longer-chained compounds were more consistently quantified. Forage delineations were not improved by C26-OH. With n-alkanes alone, estimated and actual fescue proportions closely agreed. Including LCOH offered no improvement. Despite variation in measured concentrations between technicians, fescue and red clover mixtures were reliably predicted using n-alkanes alone.
Advances in Animal Biosciences, 2010
In animals consuming known amounts of supplement, total intake of roughage plus supplement could ... more In animals consuming known amounts of supplement, total intake of roughage plus supplement could be estimated by dividing known supplement intake by the supplement proportion in the diet, if the latter were estimated using the alkane patterns in roughage, supplement and the faeces of the animals consuming them. The roughage intake could then be obtained by multiplying total intake by the estimated roughage proportion in the diet. This approach was tested using data from a previous study, and the results of a second experiment. In the first experiment, perennial ryegrass chaff and sunflower meal labelled with beeswax alkanes were fed in different proportions to young sheep. Known roughage intake was significantly under-estimated (P<0.05) by about 8% using this approach, due mainly to the 12% under-estimate in animals receiving the lowest level of supplement. This reflected the compounding of errors in estimating the dietary proportion of supplement in that treatment. In the other ...
Vadose Zone Journal, 2010
... University of Ontario Institute of Technology, 2000 Simcoe St N, Oshawa ON, L1H 7K4, Canada S... more ... University of Ontario Institute of Technology, 2000 Simcoe St N, Oshawa ON, L1H 7K4, Canada Sean Forrester Centre for ... xxii Contributors Stephen Mudge School of Ocean Sciences, Bangor University, Menai Bridge LL59 5AB, UK Ekaterina Nesterina Russian Federal Centre ...
The Journal of Agricultural Science, 1986
SUMMARYThe recovery in the faeces of the n-alkanes of herbage (odd-chain, C27–C35) and of dosed a... more SUMMARYThe recovery in the faeces of the n-alkanes of herbage (odd-chain, C27–C35) and of dosed artificial alkanes (even-chain, C28 and C32) was studied in twelve 4-month-old castrated male lambs. The lambs received three levels of cut, fresh perennial ryegrass or a mixed diet of perennial ryegrass (0·70) and a barley-based concentrate (0·30) (500–900 g D.M./day). C28 and C32 n-alkanes (130 mg each), absorbed onto shredded paper, were given once daily for 17 days to test whether the recoveries of herbage and dosed alkanes were similar to enable their use as markers for determining the herbage intake of grazing sheep. Stearic and palmitic acids (130 mg each) were given with the dosed alkanes to half of the animals with the objective of facilitating emulsification of the dosed alkanes within the digestive tract.With the exception of C27 n-alkane, the faecal recoveries of all alkanes were unaffected by diet, feeding level or emulsifying agent. Faecal recovery of odd- chain herbage n-al...
The Journal of Agricultural Science, 1986
SUMMARYFlow rates of metabolites in an open-compartment model can be calculated from specific act... more SUMMARYFlow rates of metabolites in an open-compartment model can be calculated from specific activity measurements taken at equilibrium during continuous infusion of an isotope. The within-animal variance gives an estimate of the precision of the flow rate.The Jack-knife method of calculating within-animal variances is described. It was evaluated using simulated data, and shown to be superior to a simpler method, the Single Section method.The increase in experimental accuracy caused by increasing the number of specific activity samples per animal depends on the ratio of between- to within-animal variance components (B/W). For three experiments with sheep, 23 of the 30 values B/W for the different flow rates ranged from 0·25 to 1·5. For this range between six and 12 samples per animal are needed.
The Journal of Agricultural Science, 2007
The estimation of dry matter intake (DMI) using the alkane pair technique has been validated in r... more The estimation of dry matter intake (DMI) using the alkane pair technique has been validated in ruminants, but not in equids. The current paper reports the finding of three comparative validation studies carried out using a total of 12 cattle, 29 donkeys and 10 horses during which directly measured intake was compared to estimated intake using the alkane pair technique. Two methods were developed to dose the even chain alkanes that were used as external markers. Study I, carried out in Zimbabwe, compared the accuracy of estimated intake with measured intake in cattle and donkeys using hexatriacontane (C36) as the external marker. Studies II and III were carried out in the UK with horses and donkeys and compared the accuracy of estimated intake with measured intake using dotriacontane (C32) as the external marker. Study III also tested the effect on the accuracy of intake estimates of two marker dosing levels (mean daily dose of 224 mg per animal and 448 mg per animal) and two dosing...
The Analyst, 1992
A simple extraction procedure has been developed to assess rapidly the probable extent of the tra... more A simple extraction procedure has been developed to assess rapidly the probable extent of the transfer of radiocaesium into ruminant food products soon after a nuclear accident. The in vitro extractions were validated against true absorption measurements of different forms of radiocaesium in the sheep gut. Extractions were performed on a range of different radiocaesium sources. Some of these sources were artificial (ionic radiocaesium adsorbed onto bentonite, silica spheres and filter-papers) and others were environmentally contaminated [silt from the Ravenglass Estuary contaminated by effluent from British Nuclear Fuels Limited (BNFL) Sellafield, and upland grass and heather contaminated by Chernobyl fallout]. Laboratory experiments concentrated primarily on the use of simple inorganic extractants in competitive ion-exchange processes. Of the reagents used, 0.1 mol dm-3 stable caesium chloride solution was the most effective extractant. The proportion of radiocaesium extracted by 0.1 mol dm-3 caesium chloride correlated well with measurements of true absorption. Extracting radiocaesium using 0.1 mol dm-3 caesium chloride proved to be an inexpensive and rapid method of predicting the availability of radiocaesium for absorption in the ruminant gut, giving results within 24 h. Further extractions were carried out using cellulase/pepsin simulated digestions and ovine rumen fluid. Results suggested that the availability of radiocaesium from some inorganic sources may be underestimated using such techniques.
Small Ruminant Research, 1996
Twenty-four mature, dry, female goats were grazed on Brachiaria-dominated pasture to study the ef... more Twenty-four mature, dry, female goats were grazed on Brachiaria-dominated pasture to study the effects of tethering on intake. Animals were either tethered for 4 h (T4) or 8 h (1'8), or grazed freely for 8 h (FO) during a 28 day period. Intake was estimated by two methods: (1) short-term BW changes and (2) n-alkanes as internal markers. The BW technique was suitable for conditions in developing countries, although correction factors for changes in bite rate through the grazing day may be needed and expensive chemical analyses. Animals grazed for 4 h had similar total daily intakes to those grazed for 8 h: 1055 g day-J, I] 83 g day-J and 1259 g day-I for T4, T8 and FO treatments, respectively. The T4 animals compensated for the shorter time available by increasing intake rate and spending a larger proportion of available time eating. Although the reason for higher intake rates observed in T4 animals was unclear, duration of fasting was not considered to be a factor. Lower intake rates observed at the end of the day for tethered animals may have resulted from decreasing herbage mass availability and soiling. Free-grazed animals did not alter intake rate and had total intakes that did not differ from those of T8 animals. Increased rates of intake might be expected to increase rate of passage and decrease digestibility; however, in the present trial, digestibilities (0.49,0.54 and 0.51 for T4, T8 and FO animals, respectively) did not differ (P>0.05) among treatments. The results showed no serious disadvantage in terms of intake and digestibility, either of tethering per se, or of tethering for 4 h as opposed to 8 h, for mature non-productive goats, which were able to alter behaviour to compensate for limited time available for grazing.
Small Ruminant Research, 1999
The accident at the Chernobyl nuclear power plant in 1986 resulted in levels of radiocaesium in a... more The accident at the Chernobyl nuclear power plant in 1986 resulted in levels of radiocaesium in animal-derived food products above national intervention limits in a number of countries. In upland areas of the United Kingdom (UK) radiocaesium activity concentrations in the meat of some sheep exceeds (in 1998) the local intervention limit of 1000Bqkg−1 and measures are still in place