Fertilization and Predator Control to Improve Trout Angling in Natural Lakes

1955 ◽  
Vol 12 (2) ◽  
pp. 210-237 ◽  
Author(s):  
M. W. Smith
Keyword(s):  
Growth Rate ◽  
New Brunswick ◽  
Brook Trout ◽  
Predator Control ◽  
Stocking Rate ◽  
Natural Lakes ◽  
Natural Reproduction ◽  
Stocking Rates

A significantly faster growth rate by native and planted eastern brook trout followed the addition of commercial fertilizers in sufficient quantities to provide potential additional concentrations of 0.39 mg. P, 0.21 mg. N and 0.27 mg. K per litre in Crecy Lake (20.4 ha.; mean depth, 2.4), New Brunswick. Largely because trout planted as fingerlings attained suitable angling size when yearlings, the rate of capture and the yield by weight to anglers approximately doubled. The improved growth rate, but not yields, persisted into the second and third years after fertilization. Coincident was an increase in predation by fish-eating birds and mammals. With predator control and the same stocking rates, the yield of trout flesh produced in the lake increased from 0.9 to 5.9 kgm. per hectare over the next two-year period. With predator control extended to trapping eels in the lake, a second comparable fertilization with respect to concentrations of P, N and K, and a doubling of the stocking rate, a yield of 9.7 kgm. per hectare was realized. The growth rate was somewhat depressed with the heavier stocking, notwithstanding a second fertilization. Facilities for natural reproduction were poor and planted trout (fingerlings and yearlings) sustained the fishery. Maximum survivals of planted trout (all marked) to anglers' catches were 20 per cent for fingerlings and 88 per cent for yearlings. Cropping of trout of age II was thorough. For the most part, movements of planted trout (trapped in outlet) from the lake would have occasioned minor losses.Neighbouring Gibson Lake (24.0 ha.; mean depth, 4.0 m.) was fertilized with one-half of the concentrations of P, N and K applied to Crecy. Stocking with trout was at comparable rates but no predator control was exercised. Little improvement was noted in the growth of the trout. Only when yearlings were planted late in the fall and angled early in the spring was there any improvement in the anglers' catches.

The performance and intake of weaned lambs grazing S24 perennial ryegrass, with and without supplementation

1974 ◽  
Vol 18 (2) ◽  
pp. 191-199 ◽  
Author(s):  
J. E. Newton ◽  
N. E. Young
Keyword(s):  
Growth Rate ◽  
Perennial Ryegrass ◽  
Stocking Rate ◽  
Target Level ◽  
Target Weight ◽  
Herbage Intake ◽  
Level Increase ◽  
Stocking Rates ◽  
Lamb Growth ◽  
Better Than

SUMMARYTwo forms of supplement, barley or dried grass pellets (G) were given to weaned lambs, set-stocked at pasture, at three stocking rates (43·5, 60 and 87 per hectare). The supplements were given either from weaning or from the time growth rate fell below a target value. The supplements significantly increased the proportion of lambs reaching the target weight (35 kg) and G was significantly better than barley, but slightly more G was given. The substitution value of supplement for herbage was 0·48 ± 0·12 and there was no difference in this value between barley and G. The proportion of lambs reaching the target slaughter weight was not influenced by whether the supplement was offered at weaning or delayed until lamb growth declined below a target level. Increase in stocking rate depressed the herbage intake and growth rate of the unsupplemented control lambs.

A comparison of the sown swards of perennial ryegrass S. 24 and Italian ryegrass RvP in a two-year lamb production system, with different breeds of sheep

1976 ◽  
Vol 87 (3) ◽  
pp. 605-616 ◽  
Author(s):  
J. E. Newton ◽  
N. E. Young ◽  
R. J. Orr
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Perennial Ryegrass ◽  
Italian Ryegrass ◽  
First Year ◽  
Stocking Rate ◽  
Second Year ◽  
Stocking Rates ◽  
Lamb Growth ◽  
Intensive System

SummaryA comparison was made between an intensive system of lamb production based on Italian ryegrass RvP and one based on perennial ryegrass S. 24, over 2 years, each at three stocking rates (14, 17, 20 ewes/ha). More grass was grown in the first year than in the second when the yield of RvP was particularly reduced. The ewes and lambs ate more RvP than S. 24 but there was no difference in lamb growth rate. The lambs grew faster at the low stocking rate from 0 to 18 weeks and from 0 to slaughter than at the medium and high stocking rates, in both years. Ewe intake and lamb growth rate were higher in the second year than the first. The Masham ewes with two lambs ate significantly more grass per unit of body weight than the Finnish Landrace × Scottish Halfbred and Finnish Landrace × Scottish Blackface ewes, and their lambs grew significantly faster. It was concluded that for an intensive system of lamb production from grass, S. 24 was more suitable than RvP.

Comparative production of lean meat from Friesian bulls and steers over a range of nutritional planes at pasture

1981 ◽  
Vol 21 (110) ◽  
pp. 249 ◽  
Author(s):  
FJ Mickan ◽  
GW Thomas ◽  
SA Spiker
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Entire Range ◽  
Meat Production ◽  
Stocking Rate ◽  
Average Growth ◽  
Lean Meat ◽  
Manufacturing Trade ◽  
Stocking Rates

The growth rate and carcase characteristics of Friesian bulls and steers were compared when the animals were fed solely on pasture from 8 to 18 months of age. The animals were set stocked at rates ranging from 3.0 to 6.0 animals ha-1, so that average growth rates of the steers ranged from 0.87 to 0.57 kg d-1. All were slaughtered at 18 months of age for the manufacturing meat trade. For each additional animal per hectare the average daily liveweight gain of both bulls and steers was reduced by 0.1 0 kg d-1. However, at all stocking rates bulls maintained a 0.06 kg d-1 advantage over the steers. These results do not support the suggestion that as the plane of nutrition increases, so does the advantage in growth rate of the bulls over that of the steers. Seasonal liveweight gains of the two sex types and the effect of stocking rate on these are discussed. For each 0.1 0 kg d-1 increase in steer liveweight gain carcase weight per animal increased by 19 kg and the bulls produced 25 kg more carcase weight than the steers. As the plane of nutrition increased, the percentage of saleable meat produced by the steers was constant (66.2%) while that of the bulls increased (68.7%-72.3%). This trend was reversed for the percentage of fat trimmed out of the carcases. The fat trim of the bulls was 3.6% while that of the steers increased from 6.4% to 8.9%. Over the entire range of nutrition levels, bulls were superior to steers in all attributes considered necessary for the manufacturing trade. However, under Australian conditions, seemingly unjustifiable penalty rates for slaughtering and, to a lesser extent, farmer prejudice, severely restrict the use of young grazing bulls for lean meat production.

Fertilization and Predator Control to Increase Growth Rate and Yield of Trout in a Natural Lake

1968 ◽  
Vol 25 (10) ◽  
pp. 2011-2036 ◽  
Author(s):  
M. W. Smith
Keyword(s):  
Rainbow Trout ◽  
New Brunswick ◽  
Brook Trout ◽  
Productive Capacity ◽  
Predator Control ◽  
Increase Growth Rate ◽  
Fish Flesh ◽  
Before And After ◽  
Made In ◽  
Comparable Size

Enrichment in 1946 of Crecy Lake (20 ha; mean depth, 2.4 m), New Brunswick, with commercial fertilizers to provide 210 ppb of nitrogen (N), 390 ppb of phosphorus (P), and 270 ppb of potassium (K) had increased the growth rates of native and planted brook trout. In further studies, control of predation by fish-eating birds and mammals and reduction in number of eels, along with another application of fertilizers in 1951, improved the percentages of planted brook trout taken by anglers. Maximum percentages before and after predators were controlled were 17 and 88 for planted yearlings and 4 and 42 for planted underyearlings. Yields of planted trout to anglers and catches per unit effort improved commensurately. Autumn-stocked yearlings were largely (96%) angled in April before appreciable growth was made in the lake. Increases in yields of trout flesh produced in the lake resulted largely from the growth and higher survival of planted underyearlings. Harvested weights were greater than weights of plantings only when 16% or more of planted underyearlings were angled.When underyearling and yearling rainbow trout were planted instead of brook trout, with a third fertilization in 1959 and continued predator control, they grew faster than brook trout of comparable size. Rainbow trout produced more fish flesh in the lake than brook trout when the percentage returns to anglers for the two species were similar. However, the percentage return to the anglers from most plantings of underyearling rainbow trout was low, with the net result that the rainbow trout did not provide as consistently good angling as the brook trout nor did they utilize the productive capacity of the lake more effectively.Brook and rainbow trout spawned in the littoral areas of the lake. However, yields of naturally reared trout were poor, particularly when the survival of planted trout was high.Killifish increased in numbers with fertilization, with or without predator control. Cyprinids were much less abundant than killifish, and sticklebacks disappeared from the lake.

Mixed v. mono-grazing by steers and sheep

1989 ◽  
Vol 48 (3) ◽  
pp. 519-533 ◽  
Author(s):  
T. Nolan ◽  
J. Connolly
Keyword(s):  
Growth Rate ◽  
Carrying Capacity ◽  
Live Weight ◽  
Individual Animal ◽  
Stocking Rate ◽  
Annual Average ◽  
Animal Growth ◽  
Stocking Rates ◽  
Selection Of ◽  
Main Factor

ABSTRACTThe effects of mixed v. mono-grazing by steers and sheep on individual animal growth rate, pasture carrying capacity and live-weight output per ha were measured in a 4-year (1978 to 1981) experiment, after a preliminary familiarization year, 1977. Annual stocking rate treatments consisted of three monosteer, three mono-sheep and seven mixtures of steers and sheep. Annual average stocking rates were 2·11 steers † 8·1 ewes per ha under mixed grazing and, under mono-grazing, 4·44 steers and 15·2 ewes per ha. The range from low to high in stocking rate in mono- or mixed grazing was close to 40%. Over the 4 years a total of about 280 steers, 900 ewes and 1100 lambs were used.Overall, mixed grazing increased average lamb daily live-weight gain (ADG) to weaning and to drafting from 246 to 265 g (P < 0001) and from 211 to 223 g (P < 0·001) respectively. Steer ADG for these periods was increased from 1·419 to 1·520 kg (P < 0·01) and from 0·950 to 1·094 kg (P < 0·001). The choice of reference mono-grazing stocking rates for comparisons of mixed v. mono-grazing ADG can affect these results. Average live-weight outputs (kg/ha) from grazing for the mono-steers, mono-sheep, and mixed grazing were 663, 690 and 714, the range in the latter over the seven mixed grazing treatments being from 605 to 805. Stocking rate was the main factor affecting output per ha. Because of the management rules used in this experiment mixed grazing effects are more appropriately assessed through ADG and measures based on it than on output per unit of area.Models were fitted relating steer and lamb ADG to lamb weaning and lamb and steer drafting to stocking rates of steers and ewes. Mixed grazing benefits to steer and lamb ADG to drafting were greater as their proportion in the mix declined and increased with stocking rate. At the 50% proportion, lamb and steer ADG were improved by 5·2 and 3·4% respectively at low stocking rate and 9·4 and 6·6 at high stocking rate. Predicted steer ADG to lamb weaning for a given steer stocking rate increased with increases in ewe proportion up to five ewes per ha and decreased rapidly with further increments in ewe proportion.Mixed grazing efficiency was also evaluated through the Relative Resource Total. This showed that under mono-grazing 10 to 13% more area was required to produce the same grazing season output as under mixed grazing. The 10% improvement in carrying capacity was exceeded for ewe: steer frequencies ranging from 1·5: 1 to 10: 1. Explanations for this greater efficiency in resource capture/use under mixed grazing are discussed.Substitution rates for lamb ADG to weaning (2·35) and to drafting (2·86) and for steer ADG to drafting (0·21) were fairly constant over the 4 years 1978 to 1981.Selection of mixed stocking rates to suit growth rate targets for different animal types and to match food supply with demand under varying soil/climatic/topographical conditions is discussed.

scholarly journals Can lambs compensate for less milk by grazing more often?

2002 ◽  
pp. 103-105
Author(s):  
C.A.M. Moffat ◽  
J.M. Deaker ◽  
G.J. Wallace ◽  
M.W. Fisher ◽  
P.D. Muir ◽  
...  
Keyword(s):  
Growth Rate ◽  
Milk Production ◽  
Growth Rates ◽  
Stocking Rate ◽  
Milk Supply ◽  
High Quality ◽  
Machine Milking ◽  
Stocking Rates ◽  
Lamb Growth

Lamb behaviour was investigated where varying stocking rates and rearing rank indirectly induced differences in ewe milk production. 24 Romney x Poll Dorset ewes, with either twin or single lambs, were stocked at either 25 or 15 ewes per hectare, three weeks after lambing (2 August ± 1.0 days). Lamb activity (grazing, otherwise active, or inactive) was determined by instantaneous scan sampling at 3-min intervals over 4 hours at 3, 6, 9 and 12 weeks of age. Milk production, estimated by machine milking and lamb live weights were also measured at these ages, on the day prior to observations. Ewes with twin lambs produced slightly more milk than ewes with singles (213 vs. 183 ml per 4 hours, respectively). Ewes on the high stocking rate produced an average of 181 ml milk per 4 hours compared with 216 ml per 4 hours in the low stocking rate group. Twin lambs spent significantly more time grazing than did single lambs (52.3% vs. 41.0% overall, respectively) and lambs on the higher stocking rate spent on average 10% more time grazing, than those stocked less densely. These results suggest that lambs with access to less milk spend more time by grazing, but this does not adequately compensate for the lower milk supply which resulted in reduced lamb growth rates. This raises the possibility of enhancing lamb growth rates prior to weaning by providing high quality, lamb-specific forage to the lamb independently of the ewe. Keywords: ewe milk production, grazing, lamb behaviour, lamb growth rate

Some factors which affect the liveweight change and wool growth of adult Corriedale wethers grazed at various stocking rates on perennial pasture in southern Victoria.

1981 ◽  
Vol 32 (2) ◽  
pp. 353 ◽  
Author(s):  
HA Birrell
Keyword(s):  
Growth Rate ◽  
Regression Analysis ◽  
Multiple Regression Analysis ◽  
Multiple Regression ◽  
Growth Rates ◽  
Stocking Rate ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Wool Growth ◽  
Stocking Rates

Monthly observations were taken on a number of animal and pasture characteristics during a 24-year study with adult Corriedale wethers which were grazed at 10, 15, 20 and 25 sheep ha-1. The seasonal patterns in all the observed parameters varied with the stocking rate. The more notable were the fluctuations in digestible organic matter intake (DOMI) which increased with stocking rate in summer (10 and 25 sheep ha-1 having 426 and 818 g DOMI d-1 respectively) and decreased in winter (655 and 448 g DOMI d-1). Both liveweight and wool growth rate (WGR) declined during autumn and increased in the spring at the two high stocking rates but not at the two low stocking rates. The herbage present and its relative growth rate both influenced the amount of herbage voluntarily eaten when the pasture was green. When the dry matter of herbage was < 1.5 t ha-1, the amount of herbage eaten increased as the yield and relative growth rates > 0.05 g g-1 d-1 increased. Sixty-two per cent of the variance in DOMI was accounted for. An exponential function fitted the overall data when relative growth rates were <0.05 g g-1 d-1. DOMI asymptoted at 740 g d-1 when herbage yields exceeded 2.0 t ha-1 (R2 = 0.70). Liveweight loss was very rapid in autumn at high stocking rates despite a high DOMI (c. 650g d-1). This was found, by using multiple regression analysis, to be associated with shearing stress, poor quality feed and long grazing times. In spring, on better quality feed, a long grazing time was associated with an enhanced liveweight response. A multiple regression analysis accounted for 73 % of the variance in WGR. The expression suggested that WGR increased and had a slightly curvilinear relationship with DOMI, was positively related to digestibility and negatively related to the daily time spent grazing. Wool growth slowed concurrently with liveweight losses, the magnitude of the decrease depending upon DOMI.

Effects of grazing management and stocking rate on pasture production, ewe liveweight, ewe fertility and lamb growth on subterranean clover-based pasture in Western Australia

2001 ◽  
Vol 41 (2) ◽  
pp. 161 ◽  
Author(s):  
H. Lloyd Davies ◽  
I. N. Southey
Keyword(s):  
Growth Rate ◽  
Western Australia ◽  
Subterranean Clover ◽  
Grazing Management ◽  
Stocking Rate ◽  
Pasture Production ◽  
Continuous Grazing ◽  
Grazing System ◽  
Stocking Rates ◽  
Lamb Growth

Border Leicester x Merino ewes joined to Dorset Horn rams were grazed for 3 years on subterranean clover-based pastures established on virgin ground at Bakers Hill, Western Australia, at 3 stocking rates and 2 systems of grazing management (viz. continuous grazing compared with a deferred grazing system which was designed to ensure that pasture availability met the nutritional requirements of breeding ewes at critical phases of their reproductive cycle). Both stocking rate and grazing management affected pasture availability: there was always a greater amount of pasture available on offer under the deferred grazing system. However, this extra pasture rarely increased animal production; the effect of the deferred grazing compared with continuous grazing was inconsequential for ewe liveweight in late pregnancy and for lamb growth rate. The deferred grazing system promoted grass dominance at all stocking rates whereas there was only 24% grass under continuous grazing at the high stocking rate. Stocking rate on some occasions affected ewe liveweight at joining but always affected the prelambing weight. The highest stocking rate on some occasions reduced twinning rate. Stocking rate (particularly in 1966) affected lamb growth rate. The combination of the effect of stocking rate on twinning rate, lamb survival and lamb growth rate resulted in a lower proportion of lambs achieving 30 kg liveweight per lamb marked at higher stocking rates (3-year mean low stocking rate 106% lambs marketed; medium stocking rate 95% and high stocking rate 80%). In 1966, total plasma ketones were lower and plasma glucose (measure of ewe metabolic status) was higher on the deferred system than on the continuously grazed system.

The effect of stocking rate and deferred Autumn grazing of pasture on liveweight and wool production of Merino wethers in a Mediterranean-type climate

1976 ◽  
Vol 16 (79) ◽  
pp. 189 ◽  
Author(s):  
TH Brown
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
South Australia ◽  
Management Systems ◽  
Research Centre ◽  
Stocking Rate ◽  
Wool Production ◽  
Wool Growth ◽  
The Cost ◽  
Stocking Rates

Liveweight, seasonal wool growth rates, annual wool production, wool quality and hand feeding requirements were recorded for Merino wethers when autumn deferred or continuously grazed. The two management systems were compared at a series of eight stocking rates from 12.4 to 29.7 sheep per hectare for five years from 1967 to 1971 at the Kybybolite Research Centre, South Australia. Autumn deferment resulted in increased liveweight and wool growth rate during the months of June to September. However, liveweights and wool production under either management were similar for the remainder of the year. Because deferred grazing did not increase liveweights during the critical autumn period, and since hand feeding requirements were similar under either management system at the higher stocking rates, it is suggested that yearly stocking rates can not be increased by autumn deferment. Apart from the drought year of 1967, the continuously grazed sheep required little or no hand feeding up to 22.2 wethers per hectare. It is unlikely that the cost of hand feeding deferred sheep up to this stocking rate would be covered by the small increase in wool production. However, this would depend on the cost of conserved fodder and price received for the wool.

Body composition of young sheep: II. Effect of stocking rate on body composition of Dorset Horn cross lambs

1969 ◽  
Vol 72 (1) ◽  
pp. 77-84 ◽  
Author(s):  
G. W. Arnold ◽  
H. R. Gharaybeh ◽  
M. L. Dudzinski ◽  
W. R. McManus ◽  
A. Axelsen
Keyword(s):  
Growth Rate ◽  
Body Composition ◽  
Body Weight ◽  
Moisture Content ◽  
Composition Studies ◽  
Carcass Composition ◽  
Stocking Rate ◽  
Internal Organs ◽  
Eye Muscle ◽  
Stocking Rates

SUMMARYEmpty body weight and body measurements were made on 142 lambs from Border Leicester × Merino and Merino ewes mated to Dorset Horn rams, grazed at three stocking rates and slaughtered at approximately 32·3 kg full body weight (FBW). Carcass composition studies were made on 58 of these lambs. An approximate doubling of growth rate during the first 6 weeks of life occurred between stocking rates for lambs from Merino ewes. A smaller difference was found in lambs from Border Leicester × Merino ewes. Growth rates of lambs from Merinos were significantly lower at all times from birth to slaughter. Stocking rate, breed and sex effects on growth rate resulted in lambs reaching mean weight of 32·3 kg at 80–150 days.A three-way analysis of variance was performed on data for all parameters measured using FBW as a covariate. These parameters were of carcass measurements and composition, and of composition of the internal organs. There were no effects of stocking rate on empty body weight, carcass weight, or any carcass measurements. The weight of dry edible meat was depressed at the high stocking rate due to a higher moisture content. The fresh weight of internal organs was lower at the high stocking rate. A number of sex differences were found. Ewes had lighter carcasses and heavier cannon bones; their edible meat had a higher moisture content and higher ash content than wethers. Eye muscle width was less in ewes than in wethers. Internal organs of ewes had a lower EE % and higher CP % than those of wethers. The only breed type differences were in the weights of internal organs and eye muscle widths at the 9–10th and lOth–llth ribs, and age to slaughter.

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