Solid pig manure (240 g kg(-1) DM) and solid cattle manure (150-180 g kg(-1) DM) were stored in an open storage facility during spring-summer and autumn conditions for periods of 9-14 weeks during 1994 and 1995. Concentrations of C, N, P and K were determined prior to and after storage, corrected for dry matter losses and distance from the surface. Temperature and, in experiments with pig manure, gas phase composition inside the manure heap were monitored during storage. Nitrogen losses as ammonia volatilization, nitrous oxide emission and leaching were measured, while total denitrification was estimated from mass balance calculations. For both cattle and pig manure there was little difference between seasons with respect to the pattern of decomposition, as reflected in temperature dynamics and C/N turnover. In contrast, there was a distinct difference between manure types. Pig manure was characterized by maximum temperatures of 60-70 degrees C, although the concentrations of oxygen and methane clearly demonstrated that anaerobic conditions dominated the interior parts of the heap for several weeks. Losses of C and N from pig manure both amounted to c. 50%. In contrast, the temperature of cattle manure remained close to the air temperature throughout the storage period and cattle manure had lower, not significant losses of C and N. Leaching losses of N constituted 1-4% with both manure types. Ammonia volatilization from cattle manure constituted 4-5% of total N, and from pig manure 23-24%. In pig manure a similar amount of N (23-33%) could not be accounted for after storage, a loss that was attributed to denitrification. Nitrous oxide emissions amounted to <2% of estimated denitrification losses.
The response of cultivars to applied nitrogen was examined in 11 seasons, 1982-92, in two experiments per year, normally testing seven cultivars at seven rates of fertilizer nitrogen. In all, 27 cultivars were tested in 22 experiments throughout Nottinghamshire, Lincolnshire, Northamptonshire and Suffolk. Cultivars ranged in their date of introduction from Maris Huntsman (1969) to Hereward (1988). For each cultivar in each experiment, the economic optimum yield (Y-opt), the amount of fertilizer N needed to produce it (N-opt), the grain % N at N-opt, the offtake of N in the grain at nil N (N-off(N0)) and N (N-off(opt)) and the estimated recovery of fertilizer in the grain at N-opt (AFR(opt)) were estimated by fitting linear plus exponential curves to data for grain yield and two-straight-line models to data for grain N offtake. From cross-site analysis, normalized cultivar means were calculated for each variate. Over the 20-year period relating to the cultivars in the trial, the contribution of new genotypes to grain yield improvement was 1.92 t/ha, Y-opt increasing by 96 kg/ha per year. There was no change in grain % N at N-opt. The effect of changes through breeding from 1969 to 1988 was to increase N-off(opt) by 42 kg/ha (2.1 kg/ha per year), that was associated with a decrease in N-off(N0) (equivalent of soil N offtake) of 15 kg/ha (0.77 kg/ha per year). Part of the increased requirement for fertilizer N was fulfilled by an increase in AFR(opt) of 18% over the 20-year period. The net effect was for N-opt itself to increase by 56 kg/ha (2.8 kg/ha per year). Since survey evidence indicates no general increase in N use on wheat by farmers since the mid-1980s, it appears that current fertilizer use by farmers may be underestimating the requirement for N now. Alternatively in previous years N requirements may have been overestimated. The change in N available for loss to the environment, from the balance of grain N-off(opt) and N-opt, was from 11 kg N/ha in 1969 compared to 25 kg N/ha in 1988. It seems possible that the potential increase in nitrate levels in groundwater associated with plant type may not have been realised because farmers have conserved the amount of N they use.
The colonization of Lactobacillus spp., enterobacteria and facultatively anaerobic gram-positive cocci was monitored in intestinal samples of growing broiler chicks from 24 h to 28 days of age. Rapid bacterial growth occurred within the first week, followed by stabilization and decline of colony forming units (CFU). Xylanase supplementation led to significantly lower CFU per gram of wet weight for total presumptive enterobacteria and total gram-positive cocci in luminal and tissue samples in the first 3 weeks. Lactobacillus spp. colony counts from tissue samples were higher for animals with the xylanase-supplemented diet, but luminal CFU were not. The composition of dominant Lactobacillus spp. strains was different in duodenal and jejunal tissues, but distribution of Lactobacillus spp. colony forms was unaffected by xylanase treatment. Mucosa-associated Enterococcus spp, displaced the dominant gram-positive cocci in the jejunal samples. D- and L-lactic acid and acetic acid concentrations were significantly higher in ileal samples from the control group on days 7 and 14, while butyric acid concentrations were higher in the xylanase-treated group. It is concluded that the less viscous intestinal environment caused by the xylanase slowed proliferation of gram-positive cocci and presumptive enterobacteria in enzyme-supplemented animals in the first 3 weeks of life.
Laboratory studies on the biology of oilseed rape (Brassica napus L.) showed that the induction of secondary dormancy is influenced by light environment, time of exposure to light and darkness, temperature regime and genotype. Seeds did not become dormant while exposed to light but were increasingly likely to become dormant the longer they were exposed to water stress and darkness. Dormancy was broken by alternating warm and cold temperatures. Conclusions from results obtained in Petri dishes have been tested in the field and hypotheses regarding the effects of post-harvest cultivation have been proposed. In July 1995, field experiments were initiated on a flinty silty clay loam and a sand to test the implications of post-harvest cultivation on the development of a persistent seedbank. The results largely confirmed assumptions made on the basis of laboratory findings. Seeds that had been exposed to water stress and darkness for longest, by cultivating the soil at the beginning of the experiment, immediately after seed distribution, exhibited the highest persistence rates. Seeds that were exposed to light for 4 weeks and then incorporated into the soil built up a much smaller seedbank. The seedbank was very small or nonexistent in plots that had not been cultivated at all.
Two field experiments in Canterbury, New Zealand, were conducted during 1993-95 following the ploughing of temporary pasture leys. These experiments investigated the effects of cover crop management on the accumulation of soil mineral N and nitrate leaching during winter, and the growth and N uptake of the following spring cereal crop. The cover crops used were ryegrass (Lolium multiflorum L.), oats (A venn sativa L.), lupins (Lupinus angustifolius L.), mustard (Sinapis alba L.) and winter wheat (Triticum aestivum). Ploughing of temporary pasture in autumn (March) resulted in extensive net N mineralization of organic N by the start of winter (June). In fallow soil, mineral N in the profile in June ranged from 98 kg N/ha in 1993 to 128 kg N/ha in 1994. When cover crops were established early in the autumn (March) in 1993, both the above-ground dry matter production (1440-3108 kg DM/ha) and its N content (50-71 kg N/ha) were substantial by the start of winter. In 1994, establishment of cover crops one month later (April) resulted in very little dry matter production and N uptake by June. In both years, compared with fallow soil, winter wheat planted in May had little effect on soil mineral N content by the start of winter. Compared with fallow, cover crops had little effect on soil drainage over winter. Cumulative nitrate leaching losses from fallow soil were much smaller in 1993 (23 kg N/ha) than in 1994 (49 kg N/ha), mainly due to differences in rainfall distribution. Cover crops reduced cumulative nitrate leaching losses in 1993 to 1-5 kg N/ha and in 1994 to 22-30 kg N/ha. When cover crops were grazed, soil mineral N contents were increased due to the return of ingested plant N to urine patch areas of soil. Elevated soil mineral N contents under grazing persisted throughout the winter. Grazing had little effect on cumulative nitrate leaching losses, mainly because of the small amount of drainage that occurred after grazing in either year. Compared with fallow, incorporation of large amounts of non-leguminous above ground dry matter depressed the yield and N uptake of the following spring-sown cereal crop. Where cover crops were grazed, yields of the following cereal crops were similar to those for soil fallow over the winter.
The feeding behaviour of Mamber dairy goats grazing on Mediterranean woodland in the Upper Galilee mountains of Israel was studied throughout a year (1991/92). The percentages of crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and condensed tannins (CT) were determined in samples collected by hand to simulate the plant parts selected by the goats. Total feed intake was evaluated by using Cr-sesquioxide as an external marker to determine the amount of faeces excreted, and 48 h in sacco degradability to assess the digestibility of samples. Overall, more time was spent by goats in feeding on ligneous material (tree and shrub foliage) than herbaceous vegetation (60 and 40 % of total feeding time, respectively, P < 0.05). The main ligneous species consumed by the goats were Quercus calliprinos, Sarcopoterium spinosum and Calicotome villosa (20, 13 and 7% of total grazing time, respectively). There was considerable variability in the 48 h dry matter (DM) in sacco degradability, and in the concentration of CP, NDF, ADF, ADL and CT, within and between seasons and plant species. Although requirements for nutrients varied according to the physiological stage of the goats, 48 h in sacco DM degradability and the concentration of non-ADF linked (available) CP, NDF, ADF, ADL and CT in the diet did not vary greatly: respective ranges were 45.0-49.4; 9-12.5; 44-53; 33-39; 12-17 and 3.5-4.7%. It is concluded that Mamber goats (i) may not select the best quality diet available, but may avoid wide variations in nutrient content of their diets throughout the year; and (ii) may not select a diet consistent with maximization of milk yield, but rather with optimization of body condition at the onset of the mating season.
Increasing the efficiency with which crops use supplied nitrogen (N) can minimize the impact on the environment. In the growing seasons 1990/91 to 1992/93, the effects of different cropping systems on yield, N uptake by the grain and apparent N-use efficiency (NUE) of the grain of winter wheat and winter barley were investigated in a factorial held experiment at Hohenschulen Experimental Station near Kiel in NW Germany. The crop rotation was oilseed rape-winter wheat-winter barley, and soil tillage (conservation tillage without ploughing, conventional tillage), application of pig slurry (none, autumn, spring, autumn + spring), mineral N fertilization (0-240 kg N ha(-1)) and application of fungicides (none, applications against pathogens of the stems, leaves and ears) were all varied. Each year, the treatments were applied to all three crops of the rotation and were located on the same plots. Averaged over all factors, wheat yield was > 7 t ha(-1) dry matter in all years and N uptake of the harvested grain varied between 140 and 168 kg N ha(-1). Pig slurry application in autumn increased grain yield and N uptake more than spring slurry in two out of three years. Mineral N unfertilized wheat yielded only 5.3-6.3 t ha(-1) depending on the year, mineral N fertilization increased wheat yield up to 8 t ha(-1). Barley yield was lower than wheat yield, ranging from 4.5 t ha(-1) in 1993 to 6.3 t ha(-1) in 1992. Unlike wheat, spring slurry N affected barley yield and N uptake more than autumn slurry. Wheat apparently utilized 12-21% and barley up to 13% of the applied slurry N for its grain development. In 1991, the highest apparent slurry N-use efficiency (SNUE) of wheat and barley occurred after the late spring slurry application. However, in the following years, autumn SNUE of wheat was similar to (1992) or higher than (1993) spring SNUE, presumably because of vigorous tiller growth before winter. Additionally applied mineral fertilizer N decreased SNUE. Apparent mineral fertilizer N-use efficiency (FNUE) was higher than SNUE and ranged in wheat from 40 to 59% and in barley between 19 and 37% of the applied mineral fertilizer N. FNUE decreased with increasing N fertilization. To improve the N-use efficiency of both slurry N and mineral fertilizer N, more information is needed about the combined use of both N sources, with special emphasis on split applications of slurry as is common practice for mineral N fertilizer.
Drought stress and virus yellows disease are two of the major problems of sugarbeet crop production in the UK. We have calculated the annual national drought losses from 1980 to 1995 by using long term data sets for two sites (IACR-Broom's Barn, Suffolk and ADAS Gleadthorpe, Nottinghamshire) to relate yield loss to cumulative potential summer moisture deficit, and combining these relationships with regional meteorological records, soil type and crop distribution data. Experimentally measured relationships between yield losses and the timing of virus yellows infection were combined with annual survey data of the extent of the problem, and calculated infection dates from the UK aphid suction trap network, to calculate actual national annual losses to the disease. Potential losses in the absence of control measures were then calculated by use of data from trials and surveys of pesticide use. The results showed a mean annual loss of production to drought stress of 141000 t/year of sugar, 10.5% of production, with a loss to the industry of 27.9 million. Losses in individual years varied from zero to 25 times the mean figure. Actual losses to virus yellows were much smaller, due to the efficacy of treatments, averaging 24700 t/year of sugar (1.8% of national yield, financial loss 5.5 million). Average potential virus yellows losses in the absence of control measures were approximately double this.Control of virus yellows is a major, cost-effective contributor to rising and consistent sugarbeet production. Nationally, irrigation has made little impact on drought losses and, due to constraints in surface water supply, this situation appears likely to continue. Improved drought stress tolerance represents the largest single opportunity for yield and profitability improvement of the sugarbeet crop in the UK at present. Predicted climate change appears likely to increase the severity of both drought and disease stresses. Drought stress appears relatively less important in other NW European sugarbeet-growing areas.
Diverse cultivars of winter wheat (Triticum aestivum L.) were grown in the field in 1993/94 and 1994/95 at Reading UK in temperature gradient tunnels at normal atmospheric (c. 370) or elevated CO2 concentration (c. 700 mu mol CO2 mol(-1) air). In 1993/94, grain yield of cv. Avalon was insensitive to mean temperature (between 8.8 and 10.9 degrees C), while elevated CO2 increased yield by 1.3 t ha(-1) (12.6%). In all other cultivars, warming reduced grain yield and CO2 increased grain yield. In 1993/94, in cvs Galahad and Mercia the effects of CO2 and temperature on yield were additive. However, for cv. Hereward in both years and for cv. Soissons in 1994/95, there were negative interactions between the effects of CO2 and temperature on yield: the maximum benefit of doubling CO2 to grain yield, 4.5 and 2.7 t ha(-1) (65 and 29%) respectively, occurred at cooler temperatures; there was no benefit from doubling CO2 (i.e. 0%) once the temperature had increased above the seasonal mean by 2.2-2.6 degrees C in cv. Hereward and by 1.3 degrees C in cv. Soissons. The beneficial effect of doubling CO2 on grain yield in cvs Galahad, Hereward, Mercia and Soissons was negated by an increase in mean seasonal temperature of only 0.7-2.0 degrees C. Warming decreased root dry mass at anthesis in 1994/95 while it increased at elevated CO2 (49 and 186%, coolest and warmest regime, respectively). Carbon partitioned to roots declined progressively with warming, while at elevated CO2 there was an average of 56% increase in allocation to roots. The relative impacts of both CO2 and temperature were greater on root dry mass than on either grain yield or total above-ground biomass, while the effects on grain and biomass yield varied considerably between cultivars, suggesting that the impact of rising CO2 and temperature are likely to be dependent on cultivar.
Metabolizable energy intake and heat production were measured in a series of calorimetry experiments carried out at the Agricultural Research Institute of Northern Ireland, Hillsborough, between 1993 and 1996 with beef cattle and sheep. A total of 75 estimates were made with cattle: 23 with Charolais cross steers; 16 with Simmental cross steers and 36 with Angus cross steers (450-628 kg liveweight). Fifty-six estimates were made with lambs: 24 with Blackface cross, eight with Suffolk cross and 24 with Texel cross (23-53 kg liveweight). The diets offered to both cattle and sheep contained proportionately 0.0-0.8 cereal-based concentrates, the remainder being grass silage. Linear regressions of energy retention (measured by calorimetry) against metabolizable energy intake were produced for the cattle and sheep studies. From these linear regressions an estimate of metabolizable energy required for maintenance (MEm) was obtained. For cattle, the derived MEm was 0.614 MJ/kg LW0.75 per day, and for sheep the derived MEm was 0.460 MJ/kg LW0.75 per day. The estimates were proportionately 0.34 higher in cattle and 0.32 higher in sheep than the 1990 values of the UK Agricultural and Food Research Council.
Temperature effects on cotton yield and fibre properties of three cotton cultivars were determined. Plants were grown in pots maintained in growth rooms at varying day and night temperatures representing seasonally constant or varying (C) or daily varying (V) regimes. Yield and fibre characters responded to variation of daily mean and amplitude of temperature. Mean temperature reduction improved yield components, but fibre length, uniformity, strength and micronaire were increased by high, particularly high day, temperatures. A large daily temperature amplitude produced an intermediate number of flowers and the lowest retention percentage. Fruiting and yield were increased by reduction in temperature down to the threshold mean temperature of 22 degrees C. However, V-regimes with a low minimum temperature acted as a further drop (below 22 degrees C) of temperature and adversely affected these characters, An adverse effect of low minimum temperature combined with a moderate day temperature was observed also on lint percentage and fibre properties. Varietal differences were more pronounced for highly heritable characters such as fibre properties, for which significant interactions between varieties and temperature also occurred. Differences in reproductive development were not sufficient to be of much practical importance.
Slurry was collected from two groups of finishing pigs fed either a standard commercial diet (containing 205 g/kg crude protein (CP)) or a specially formulated lower CP content diet (140 g/kg CP). The slurries were surface applied to grass/clover plots on a freely draining soil in SW England in mid-March 1995 at three application rates: 25, 50 and 70 m(3)/ha. Measurements were made from the 50 m(3)/ha plots of ammonia volatilization, denitrification, nitrous oxide and methane emissions and nitrate leaching. Measurements of herbage yield and apparent N recovery (ANR) were made from all plots. Decreasing the CP content of the pigs' diet reduced N excretion by the pigs and also changed other characteristics of the slurry. Slurry from pigs fed the lower CP diet (the slurry referred to hereafter as LS) had a higher dry matter (DM) content, lower pH, lower total ammoniacal N (TAN), total N and VFA content with a similar total C content compared with slurry from pigs fed the standard commercial diet (the slurry hereafter referred to as CS). From the 50 m(3)/ha treated plots, losses by ammonia volatilization represented 38 and 58% of the applied TAN and net losses through denitrification represented 5.3 and 12% of the applied TAN for LS and CS respectively. Nitrous oxide emission was similar from the two slurries, with net emissions of c. 0.5% of the applied TAN. Methane emission was significantly less from LS. No nitrate leaching was detected either in spring or in the following autumn. Yield and ANR increased with increasing slurry application rate up to 50 m(3)/ha. The best % N recovery was from the 50 m(3)/ha application rate with 58 and 47% of the applied TAN being recovered from LS-and CS-treated plots respectively. Changes in the slurry characteristics due to the lower CP diet resulted in lower losses to the environment and an improved utilization of the slurry N by the herbage.
The effects of four rates of fertilizer phosphorus (P) application (0, 9.8, 19.6 and 39.2 kg P/ha per year) on soil and crop P and cadmium (Cd) contents were measured in a field trial begun in 1968 and cropped each year with barley in south west England. In 1996, available and total soil P and Cd were measured in seven soil layers (0-20, 20-25, 25-30, 30-35, 35-40, 40-45 and 45-50 cm). Offtake of P in the crop was measured, or could be estimated, throughout the trial period. There was a linear relationship between P balance (total applied - total offtake) and P application rate with a balance of zero at a rate equivalent to 17 kg P/ha per year. The rate of P required for the economically optimum grain output was equivalent to 30 kg P/ha per year. No evidence was found for available P enrichment of soil layers below 25 cm. There was no evidence of Cd enrichment of either soil or crop after 29 years of P applications.
The influence of dietary nutrient concentration on performance and the growth of fat depots, breast meat and leg muscles was examined in five groups of male broiler chickens fed nd libitum with combinations of high (H), commercial (C) or low (L) energy and nutrient concentration in starter and finisher diets. Diets were changed from starter to finisher at 3 weeks of age giving 200 birds on each of five treatments: HH, HL, CC, LH and LL. Ten birds per treatment were slaughtered at weekly intervals from 0 to 70 days. Five of these were dissected into component lean tissues of breast muscles (white meat) and thigh + leg muscles (dark meat) and fat depots, and the other five carcasses were minced for chemical analyses. Data were analysed by fitting Gompertz functions to each component. Analysis of body weight, carcass components and feed intake revealed that at 70 days birds on LH approached similar liveweights to those on HH with lower overall food intakes, comparable feed conversion ratios but slightly greater fat depots. The HL birds had less fat but achieved specific weights over longer periods of time with greater feed intakes and poorer feed conversion ratios. Content of white and dark meat was always greater in HH birds, with differences between treatments being greater for white meat. Decisions on which conditions are most appropriate will be influenced by time taken to reach specific liveweights if whole birds are marketed, or the rate of growth of individual portions if further processing is considered, together with feed conversion efficiency and the relative costs of diets varying in energy and nutrient concentration.
Nitrate leaching losses from intensively managed monoculture grass and grass-clover pastures were measured during 1994-96 at a long-term experimental farm in south-west Scotland. Field-size lysimeter plots were established in 1993 on the existing pastures on a silty clay loam non-calcareous gley. No fertilizer-N was applied to the grass-clover, while the monoculture grass was fertilized with c. 240 kg N ha(-1) year(-1), but both swards received 2-3 cattle slurry applications annually (120-390 kg total N ha(-1) year(-1)). The pastures supported 2-3 cuts for silage conservation, and were grated by dairy cattle and stocked with sheep during the winter months. Initially, leachate nitrate concentrations from the fertilized grass were considerably larger than those from the clover-based pasture, but became similar with time. The annual nitrate leaching losses from the grass-clover (24-38 kg NO3-N ha(-1)) were less than that from the monoculture grass (30-45 kg NO3-N ha(-1)), but the differences were not large considering the additional fertilizer-N applied to the latter treatment. Results also suggested that greater leaching losses occur during a warmer, drier year, compared to a cooler, wetter year, regardless of the source of N-input.
The occurrence of vesicular-arbuscular mycorrhizae (VAM) root colonization and spore number in soil was assessed for 18 fields under intensive lettuce (Lactuca sativa L.) production in California during July and August of 1995. Data on management practices and soil characteristics were compiled for each field, and included a wide range of conditions. The relationship between these factors and the occurrence of VAM in these fields was explored with multivariate statistical analysis. VAM colonization of lettuce tended to decrease with the use of chemical inputs, such as pesticides and high amounts of P and N fertilizers. Addition of soil organic matter amendments, the occurrence of other host crops in the rotation, and soil carbon:phosphorus and carbon:nitrogen ratios, were positively associated with VAM colonization of lettuce roots. The number of VAM spores in soil was strongly correlated with the number of other host crops in the rotation, the occurrence of weed hosts and sampling date, but was more affected by general soil conditions than by management inputs. Higher total soil N, C and P, as well as CEC, were inversely related to soil spore number. A glasshouse study of the two primary lettuce types sampled in the field showed no significant differences in the extent of root colonization under similar growing conditions. The results of this study are compared with other studies on the effects of management and soil conditions on mycorrhizal occurrence in agriculture.
To appreciate more clearly some of the physical characteristics of forages which may be important in relation to digestibility and structural integrity, different parts of eight plant species were examined for the proportion of thick-walled, thin-walled and epidermal cells, the thickness of the cell walls and the diameter, length and volume of the cells. The eight species were: Trifolium repens L., Medicago sativa L., Desmodium intortum (Mill.) Urb., Lolium perenne L., Festuca arundinacea Schreb., Chloris gayana Kunth, Cenchrus ciliaris L. and Zea mays L. Early harvesting was compared with later harvesting in each of two years. The plants were grown in a heated glasshouse in spring-summer. The plant parts with the lowest proportion of thick-walled cells (3-6% of cross-sectional area) were the legume leaflets and those with the highest proportion (47-57%) were the leaf blades and stems of C. ciliaris. The plant parts with the highest proportion of thin-walled cells were the legume leaflets and petioles and the Z. mays stems and leaf sheaths. The walls of the cells categorized as thick-walled were thinnest (0.9 mu m) in L, perenne leaf blades and T. repens leaflets and thickest (2.0-2.3 mu m) in the leaf blade midribs, leaf sheaths and stems of Z. mays and in the stems and petioles of T. repens. The thinnest outer walls of epidermal cells (0.9 mu m) were recorded for the leaf blades of L. perenne. The largest cells within the categories and plant parts examined (1 100000 mu m(3)) were thin-walled cells in the stems of Z. mays. The longest cells recorded (180 mu m) were thin-walled cells in the petioles of T. repens. The thick-walled cells were particularly small (1800-2600 mu m(3)) in L. perenne leaf blades and sheaths and in T. repens leaflets. The largest thick-walled cells in the study were in the stems and petioles of T. repens. The epidermal cells of D. intortum leaflets, petioles and stems were particularly small (2000-3000 mu m(3)).
Growth, body composition and distribution of carcass tissues were compared in Omani sheep and goats. Animals had nd libitum access to Rhodes-grass hay (8% CP) and a concentrate diet (16% CP) from weaning until slaughter. The two species had similar birth weights but sheep had higher preweaning (181 g/day), postweaning (175 g/day) and overall (179 g/day) growth rates than goats (120, 102 and 111 g/day, respectively) and thus they reached slaughter weights earlier. Sheep had higher slaughter weight (22.26 kg), empty body weight (20.39 kg), hot carcass weight (12.48 kg) and dressing out percentage (55.94%) than goats (21.17, 18.82, 11.48 kg and 53.97%, respectively). Sheep also had higher proportions of skin, liver and lungs and trachea (P < 0.01) than goats, which had higher proportions of head, feet and gut contents. As proportions of carcass weight, sheep had higher fat (25.08%) but lower muscle content (57.24%) than goats (15.72 and 65.88%, respectively). There were no significant differences between the two species in proportion of carcass bone (13.76 and 14.17%). These effects resulted in sheep having a lower muscle:bone ratio (4.19 and 4.68) and higher fat:muscle ratio (0.44 and 0.24). Sheep had higher proportions of non-carcass, carcass and total body fat in the empty body weight (EBW) than goats. However, sheep had less non-carcass but more carcass fat than goats when fats were expressed as proportions of total body fat. Sheep had higher proportions of muscles in the proximal hind limb, distal hind limb (P < 0.01), around the spinal column, connecting forelimb to thorax and high-priced muscle group (P < 0.05), but lower proportions of muscles in the abdominal wall, proximal forelimb (P < 0.05), distal forelimb (P < 0.01), connecting neck to forelimb, intrinsic muscles of neck and thorax (P < 0.05) and total forequarter muscles (P < 0.01) than goats. As proportions in carcass bone. sheep had higher axial skeleton (P < 0.05) but lower forelimb than goats. Among species/sex/slaughter weight groups, castrated male and female goats had the lowest growth rates. Castrates and female sheep, particularly at heavier liveweights, had higher carcass and non-carcass fat contents than intact males and goats of all sexes. Although Omani goats produced leaner carcasses and had higher proportions of some non-carcass offals than Omani sheep, they had slower growth fates and a less attractive muscle distribution. This may negatively affect their potential for large scale meat production under Omani conditions.