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Rangeland grazing management strategies have been developed in an effort to sustain efficient use of forage resources by livestock. However, the effects of grazing on the redistribution and cycling of carbon (C) and nitrogen (N) within the plant-soil system are not well understood. We examined the plant-soil C and N balances of a mixed-grass rangeland under three livestock stocking rates using an area that had not been grazed by domestic livestock for more than 40 years. We established nongrazed exclosures and pastures subjected to continuous season-long grazing at either a light stocking rate (20 steer-days/ha) or a heavy stocking rate (59 steer-days/ha, ∼50% utilization of annual production). Twelve years of grazing under these stocking rates did not change the total masses of C and N in the plant-soil (0-60 cm) system but did change the distribution of C and N among the system components, primarily via a significant increase in the masses of C and N in the root zone (0-30 cm) of the soil profile. The mass of soil C (0-60 cm) under heavy grazing was comparable to that of the light grazing treatment. Grazing at the heavy stocking rate resulted in a decrease in peak standing crop (PSC) of aboveground live phytomass, an increase in blue grama (Bouteloua gracilis [H.B.K.] Lag. Ex Steud.), and a decrease in western wheatgrass (Pascopyrum smithii [Rydb.] A. Love) compared to the light grazing treatment. The dominant species under light grazing was western wheatgrass, whereas in the nongrazed exclosures, forbs were dominant and appeared to have increased at the expense of western wheatgrass. The observed increase of soil C and N in the surface soil where roots dominate indicates a greater opportunity for nutrient availability and cycling, and hence enhanced grazing quality.

Condition of all fins was assessed in intensively cultured perch (n = 300) in comparison with control pond-reared perch (n = 30). Measurements of maximum fins length as well as a four point photographic scale were used. No damage to any fin was visually observed in the pond-reared group. The first dorsal fin showed the least damage in cultured perch with 93 % of fish demonstrating no erosion. The most affected were paired fins, with only 7 % and 2 % of pectoral and ventral fins, respectively, being non-eroded. No difference between culture systems was found in fin length for the first dorsal and the caudal fin. Pectoral, second dorsal, ventral, and anal fins of intensively cultured perch showed reductions up to 52, 49, 35, and 28 %, respectively. The relationship between fin lengths and standard body length (SL) were described for both groups (SL range 104–170 mm). Results of this study are discussed in relation to aesthetic, welfare and fish survival issues.

The effects of many single stressors have been reported, but how pigs perform when subjected to more than one or two stressors at a time, as is common in commercial swine production, has not. To study this, 256 Yorkshire x Hampshire or purebred Duroc pigs (34.7 +/- .5 kg) were subjected to one of the eight treatment combinations (2 x 2 x 2 factorial) of ambient temperature (constant thermoneutral [24 degrees C] or high cycling temperature [28 to 34 degrees C]), stocking density (.56 or .25 m2/pig), and social group (static group or regrouped at the start of wk 1 and 3) during a 4-wk experiment. The temperature regimens were imposed in two adjacent mechanically ventilated rooms, and each temperature was imposed in each room across two trials. Four barrows and four gilts were assigned to each of the eight pens in the two rooms, and they always had free access to water and a corn-soybean meal-based diet. Treatments were imposed after a 7-d acclimation period at 24 degrees C and .56 m2/pig. Weight gain and feed intake were measured weekly. The main effects of each of the stressors for 4-wk ADG and ADFI were significant (P .05). The stress of high temperature, high stocking density, and regrouping depressed 4-wk ADG by 12, 16 and 10% and ADFI by 7, 6, and 5%, respectively. Of the possible 60 stressor interactions for ADG, ADFI, and gain:feed (G:F), there were no significant three-way interactions and only six two-way interactions, suggesting that the effects of the individual stressors were additive. Accordingly, the growth rate of pigs subjected to the single stressor of high cycling temperature, restricted space allowance, or regrouping was depressed 10, 16, and 11%, respectively, and ADG of pigs subjected to all three stressors simultaneously was depressed by 31%. Stressor additivity was further corroborated by examining the effect of stressor order, or the number of stressors imposed simultaneously. As the number of stressors increased from 0 to 3, ADG, ADFI, and...

Over the last 25 years more than 70 million ha of the native vegetation in Brazil have been replaced by pastures for beef production planted to grasses of the genus Brachiaria, and to a lesser extent Andropogon gayanus, both of African origin. Some years after implantation, these pastures decline in productivity, probably due to low availability of P, and immobilisation of N in the soil due to the large quantities of senescent leaves (litter) of high C:N ratio deposited on the soil surface. In this paper we report the effects of the introduction of a forage legume (Desmodium ovalifolium) and different animal stocking rates on the deposition and decomposition of plant litter in pastures of Brachiaria humidicola at a site in the coastal Atlantic forest region of the south of Bahia State (Brazil). Litter existing on the ground, and that deposited in 14-day periods, was monitored at monthly intervals during 3 years of the study. Doubling the stocking rate from 2 to 4 animals ha-1 caused a highly significant decrease in litter deposition, but the presence of the legume in the sward had little effect. Calculations made directly from the quantities of litter deposited in the 14-day periods showed that between 15 and 18 tons of litter dry matter (dm) were deposited annually, but the relatively small quantities of existing litter (annual means of 0.8 to 1.5 t dm ha-1), showed that decomposition was rapid, showing values for half life of between 22 and 33 days. This technique was assumed to underestimate true litter disappearance rates, as with such rapid decomposition a significant proportion of the litter disappeared within the 14-day collection periods. An equation was developed to correct for this loss of litter during the collection periods and corrected litter decomposition constants of 0.037 to 0.097 g g-1 day-1 were recorded resulting in half lives of between 9 and 20 days. Using these data and adding them to estimates of animal consumption the net aerial primary productivity (NAPP) of the pastures ranged from 28 to 34 t dry matter ha-1 yr-1. Experiments with litter bags, and a \"covered litter\" system which allowed access of soil fauna to the litter, indicated that soil faunal activity had little impact on litter disappearance and such techniques underestimated true litter decomposition by at least an order of magnitude. We suggest that this underestimation is due to the fact, that in contrast to litter bags, in the open field situation fresh litter is being added continuously. As this material consists of both easily degradable (\"active\") and recalcitrant fractions, the easily degradable fraction fuels an active microbial biomass which continuously degrades the less decomposable material. It is concluded that the approach used in this study gives more realistic, and much higher estimates, of net primary aerial production of tropical grasslands and pastures than techniques heretofore utilised.

The following international comparison of selected indicators of farms stems from the official results of investigations on holdings incorporated in the Farm Accountancy Data Network (FADN). It is based on the standard outputs recalculated for the average agricultural holding in each member state. The paper accepts the mandatory concept that defines the basic indicators serving to illustrate the creation and division of income from farming in the FADN system. The presentation of the results develops from the indicators assessing the overall agricultural production divided into its basic components. Production and cost indicators, operational subsidies, gross and net added value per one hectare of agricultural land, or per one AWU and other derived indicators are analysed.

Six group sizes and three levels of floor area allowance were studied in a 6 X 3 factorial arrangement. Group sizes were 3, 5, 6, 7, 10, and 15 pigs per pen. Floor area allowances were .030, .039, and .048 m2 X BW(.)667. All pens were square and equipped with a single space feeder and nipple drinker near one corner. Pigs were fed a pelleted diet. Initial weights averaged 25.0 kg, and pigs remained on test for 12 wk. Pigs were weighed, feed intake was determined, and size of pens was increased at 2-wk intervals. Pen size was adjusted to provide the space required for the midpoint of each weigh period. Two replicates of the study were conducted. The ADG was reduced with increasing group size (899, 851, 868, 872, 857, and 821 g, SEM = 16.4, for 3, 5, 6, 7, 10, and 15 pigs, respectively; P .05), but the CV for gain (mean

From 1990-1993 juvenile pike (Esox lucius) were stockedeach spring in the eutrophic Lake Lyng (9.9 ha, max. depth 7.6 m,mean depth 2.4 m) in densities between 515 and 3616 pikeha^sup -1^. In 1989-90 the fish population consisted mainly ofroach (Rutilus rutilus), rudd(Scardinius erythrophthalmus), perch (Percafluviatilis) and ruffe (Gymnocephalus cernuus), andtotal fish biomass was estimated at 477 kg ha^sup -1^. Prior tostocking pike was not present in the lake. Following the first year ofstocking, the density of roach, rudd and ruffe fry expressedas catch per unit effort decreased significantly by 64 to 97%.In 1991 ruffe disappeared completely. The pike stocking did notaffect the density of perch significantly.The growth of pike was high and also the growth of perchincreased significantly from 1990 to 1991 (p<0.001) and from1991 to 1994 (p<0.001). We found a linear negativerelationship between stocking density of pike in May or June and theabundance of juvenile planktivorous fish (r^sup 2^=0.85, p<0.05) in the littoral zone in August. No relationship was found inthe pelagic zone (r^sup 2^=0.21, p>0.4). Pikesurvival was low in late August/early September. We suggest that growthof the piscivorous perch increased due to increased Secchi depthand a continuous high density of 0+ planktivores in the pelagiczone of the lake during the years of pike stocking, possibly caused bybehaviourial changes and the forcing of the 0+ planktivoresinto the pelagic zone.[PUBLICATION ABSTRACT]

Catches for the last 25 years are analyzed for beluga Huso huso, stellate sturgeon A. stellatus and Russian sturgeon Acipenser gueldenstaedtii, which are the three commercially important species of sturgeons found in the Caspian Sea Basin. Population sizes for generations born between 1961 and 1970 are estimated, and found to depend on natural reproduction and the number of young fish stocked annually from sturgeon hatcheries located in the Volga River Delta. A ban on sea fishing from 1962 to 1991 positively impacted the number and total biomass of commercial stocks. Sturgeon growth rates depend on water levels in the Caspian Sea. In order to preserve Caspian Sea sturgeon populations, it will be necessary to coordinate efforts of all countries surrounding the Caspian Sea to achieve rational harvests, preserve juveniles, and produce at least 100 million juveniles annually from hatcheries.

We conducted two trials with growing-finishing pigs (Pig Improvement Company line 405 x Camborough 15) to evaluate the effects of space allocation on performance and CP requirements. In Trial 1, a 2 x 3 factorial (two levels of space, three CP regimens) was used with 252 pigs. Pigs were allocated to either .23, .28, .37, or .50 m2 per pig (crowded) or .37, .47, .60, or .74 m2 per pig (uncrowded) during the 18 to 36, 36 to 55, 55 to 91, and 91 to 127 kg weight periods, respectively. Diets contained 16.1, 18.6, or 21.1% (18 to 36 kg), 15.3, 17.8, or 20.3% (36 to 55 kg), 14.7, 17.2, or 19.7% (55 to 91 kg), and 12.8, 15.3, or 17.8% (91 to 127 kg) CP. The 16.1,15.3, 14.7, and 12.8 % CP (control) diets contained 1.09, .86, .82, and .65% lysine, respectively. Crude protein levels (Trials 1 and 2) were achieved by substituting soybean meal for corn. In Trial 1, a CP x space interaction (P .03) for gain:feed suggested that feed efficiency of grower pigs was improved to a greater extent in uncrowded pigs than in crowded pigs. Grower pigs (18 to 55 kg) with less space had depressed (P .05) feed intake and gain and a lower (P .10) feed efficiency than uncrowded pigs. Added CP improved (P .05) rate and efficiency of gain in grower pigs. Overall (18 to 127 kg), crowded pigs had reductions (P .05) in gain (17.6%), feed intake (11.3%), and gain:feed ratio (7.1%) compared to uncrowded pigs. Trial 2 involved 216 finishing pigs in a 2 x 2 factorial (two levels of space, two CP regimens). Pigs were provided with either .37 or .50 m2 per pig (crowded) and .60 or .74 m2 per pig (uncrowded) during the 55 to 91 and 91 to 127 kg weight periods, respectively. The diets contained 14.1 or 17.1% CP (55 to 91 kg) and 12.1 or 15.1% CP (91 to 127 kg). Lysine levels were .67 and .53% for the 14.1 and 12.1% CP diets, respectively. Overall (55 to 127 kg), crowded pigs had depressed (P .05) gains (15.4%), feed intakes (9.5%), and feed efficiencies (6.8%) compared with uncrowded pigs. Increa...