Cage Density Research Articles

Indoor and Deep Sub-Tidal Intermediate Culture of Trochus niloticus for Restocking

The high demand for shells of the large reef-associated gastropod Trochus niloticus in the manufacture of mother-of-pearl buttons has resulted in a widespread decline of its population. As a consequence, juvenile mass production and restocking has been practiced as one of the many conservation measures. Trochus has long been successfully bred in captivity, but culturing of juveniles until ready for release is faced with many problems, including the shortage of natural food. Terrestrial plants have traditionally been used by fishermen as food in keeping wild trochus juveniles, but their potential use in intermediate culture of trochus has not been evaluated. We conducted four growth trials for 60–120 days, rearing hatchery-produced juveniles (10–28-mm shell diameter) at different stocking densities in indoor tanks and sea cages, with coconut leaves as the main or an additional substrate. An average growth rate of 4.4 mm mo−1 (95% CL 4.0–4.7 mm mo−1) for all stocking densities was achieved in growth trials using small cages deployed at 5–6 m on the reef slope, which was comparable to growth rates in the wild. This growth rate was three times higher than in trials using large metal cages on the reef slope, and 2 to 23 times higher than indoor trials using wooden tanks or small cages in concrete tanks. Survival rates were as high as 99%. Incidence of escape in sub-tidal cages was low except when some cages were damaged by strong waves. The results indicate that trochus juveniles can be successfully cultured at high density in sub-tidal cages with coconut leaves as substrate.

GROWTH PERFORMANCE OF FATTENING RABBITS AS AFFECTED BY STOCKING DENSITY AND ADDED DIETARY ORGANIC ACIDS

An experiment of 3×2 factorial arrangement of treatments was undertaken to investigate the influence of stocking density and dietary supplementation with organic acids on growth performance, carcass characteristics, and some blood parameters of fattening rabbits. A total of 54, 7-week-old New Zealand White × California rabbits were randomly divided into 6 experimental groups, of three replicates of 2, 3 or 4 rabbits each. Two experimental pelleted diets (a basal diet and a 0.4% Salkil-supplemented diet; Salkil is a mixture of formic and propionic acids.) were formulated and used from 7 to 13 weeks of age. The rabbits were individually weighed, kept in battery cages at three stocking densities (8.6, 12.9 and 17.2 rabbits/m2), fed their respective experimental diets and managed similarly up to 13 weeks of age. Criteria of response were the performance of rabbits for growth, feed intake and feed conversion, mortality rate, economic efficiency of feeding, and some carcass traits. Some blood plasma parameters (levels of glucose, total protein, albumin, triglycerides and cholesterol as well as activity of the transaminases: alanine aminotransferase and aspartate aminotransferase) were also determined. The results obtained could be summarized as follows: No deaths of rabbits occurred during the course of this study. Regardless of the effect of dietary supplemental organic acids, growth performance of rabbits was not significantly affected by stocking density during the whole experimental period, whereas means of daily feed intake, daily weight gain and performance index of rabbits insignificantly decreased when stocking density reached 17.2 rabbits/m2. Neither carcass traits nor blood parameters of rabbits, measured herein, was affected by stocking density. Irrespective of the effect of stocking density, added dietary organic acids did not significantly affect growth performance, carcass traits or blood parameters of the experimental rabbits. No significant interaction effects of stocking density and added dietary organic acids were detected for all criteria examined in the present study. Taking the performance of rabbits and economic aspect into account, the results revealed that the maximum rate of cage density (17.2 rabbits/m2) had no adverse effects under the condition of the present experiment during the spring season. The dietary inclusion of Salkil at a level of 0.4% was an extravagance; because it had no positive effects on either growth performance or economic efficiency of rabbit production, under the conditions of the present study.

Effects of stocking density and feeding duration in cage-cum-pond-integrated system on growth performance, water quality and economic benefits ofLabeo victorianus(Boulenger 1901) culture

We evaluated the effect of varying cage stocking density (60, 90 and 120 fish m−3) and feeding duration (10, 30 and 60 min) in a cage-cum-pond-integrated system on growth performance, water quality and economic benefits in Labeo victorianus culture. Interactions between stocking density and feeding duration significantly (P < 0.05) affected the fish growth performance and yields in the cages-cum-pond system. Stocking density of 60 fish m−3 resulted in the highest growth in cages and in ponds regardless of the feeding duration, but produced lower yields than at stocking density 90 fish m−3. The lowest Apparent Food Conversion Ratio (AFCR) in cages occurred at stocking density of 60 fish m−3 and feeding duration of 30 min. Growth performance in the open ponds declined with increased feeding duration of the caged fish. Survival in cages and in the open ponds decreased with increased cage density, but was not affected by feeding duration. Low dissolved oxygen were recorded, at stocking density of 120 fish m−3, the lowest DO occurred when feeding of caged fish lasted 60 min. Growth performance, water quality and economic benefits in Labeo victorianus culture positively respond to interaction between stocking density and feeding durations.

The Seasonal Egg Production, Quality and Profitability of a Commercial Layer Farm with Different Cage Density in Subtropical Environment

The Seasonal Egg Production, Quality and Profitability of a Commercial Layer Farm with Different Cage Density in Subtropical Environment

Controlling the Plasmonic Properties of Supported 2D Arrays of Gold Nanocages

ABSTRACTThe enhancement of the plasmonic signatures, indicated by the shifting of the localized surface plasmon resonances, of three-dimensional, hollow, gold nanocages with respect to substrate nature and cage density is reported. The effect of substrate nature was investigated using absorbance, reflection, and transmission by ultraviolet-visible and near-infrared spectrophotometry. The gold nanocages were deposited on substrates as monolayers primarily by Langmuir-Blodgett technique. The density of the deposited monolayers and the nature of the surface of the substrates were determined using AFM and SEM/TEM imaging. The position of the LSPR signatures, primarily the dipolar plasmonic resonances, with respect to changing environment and nanostructure characteristics determined the tuneability of the plasmonic enhancements.

Insect predators in northeast China and their impacts on Aphis glycines

AbstractPredators of Aphis glycines Matsumura (Hemiptera: Aphididae) were surveyed and their ability to suppress A. glycines population growth was determined in Harbin, northeast China (45.4°N, 126.4°E). Field surveys were conducted on 21 fixed sampling sites in 2004 and 17 in 2005. Impacts of natural enemies of A. glycines were studied using exclosure experiments. Thirteen natural enemies were found, the most abundant of which was Propylaea japonica (Thunberg), Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), Chrysopa sinica Tjeder, Chrysopa phyllochroma Wesmael, Chrysopa formosa Brauer (Neuroptera: Chrysopidae), Hemerobius humuli Linnaeus (Neuroptera: Hemerobiidae), Orius Wolff sp. (Heteroptera: Anthocoridae), Nabis stenoferus Hsiao (Heteroptera: Reduviidae), Deraeocoris punctulatus (Fallén) (Heteroptera: Miridae), and Episyrphus balteata (De Geer) (Diptera: Syrphidae). Three exclosure treatment types were established, large-mesh cages, small-mesh cages, and no cages. In exclosures, A. glycines density in small-mesh cages peaked at numbers 3.75-fold higher than in large-mesh cages and 17.44-fold higher than on plants with no cages in 2004. In 2005, these numbers were 4.59-fold and 60.98-fold. Temperature was not a factor in exclosures, but relative humidity had significant effects. These results indicated that existing predator communities could partially suppress soybean aphid population density in soybean fields in northeast China.

The effect of cage density on laying hen performance, egg quality, and excreta minerals

SUMMARY This study was conducted to evaluate the effects of cage density on laying hen performance, egg quality parameters, blood indices, and excreta mineral concentration. Eighty White Leghorns were housed at 4 cage densities of 2,000, 1,000, 667, and 500 cm2 per hen, corresponding to 1, 2, 3, and 4 hens per cage. Throughout the study, hens were fed a diet containing 2,852 kcal of ME/kg and 18% CP from 35 to 47 wk of age. Hen-day egg production and egg quality parameters were recorded weekly. Blood plasma was also subjected to several biochemical tests. The hens in the treatment having 4 hens per cage had significantly lower (P

The effect of group size and stocking density on the welfare and performance of hens housed in furnished cages during summer

AbstractThe aim of this study was to investigate the effect of group size and stocking density on the welfare and performance of hens housed in furnished cage systems during summer. A total of 924 Hy-Line Brown hens were assigned to three housing systems: a standard battery cage system (control, 4 hens per cage and 398 cm2per hen), two furnished systems (including perches and nest); one with a small (SFC, 21 hens per cage; 586 cm2per hen) and one with a large group size (LFC, 48 hens per cage; 543 cm2per hen). The results showed that hens housed in SFC and LFC had a higher feed intake and a poorer feed efficiency compared to control hens. Laying rate and egg weight were not significantly affected by housing systems. Hens housed in LFC and SFC systems showed less sitting and more walking behaviours than control hens. SFC hens showed more nesting and less perching behaviours than LFC hens. Hens kept in SFC systems showed fewer signs of heat stress during summer, with less panting activity than LFC or control hens, and a relatively lower rectal temperature than controls. The rectal temperature of LFC hens did not differ from the SFC hens and controls. Blood concentrations of luteinising hormone, follicle-stimulating hormone and oestradiol were not significantly influenced. In conclusion, group size and stocking density in furnished cages have an effect on behaviour and performance of hens. The furnished cage systems with small group sizes were favourable for hen welfare without markedly affecting performance. Group size should be considered in the development of furnished cage systems.

Maternal antibody transfer to broiler progeny varies among strains and is affected by grain source and cage density

Two experiments were conducted to examine the effects of broiler breeder dietary grain source and cage density on maternal antibody (MatAb) transfer to progeny in 2 genetic strains (A and B). Broiler breeders were assigned to 16 litter floor pens and fed either corn- or wheat-based diets. Breeders were administered 4 live vaccines against Newcastle disease virus (NDV). At 23 wk of age, pullets and cocks, which reflected the full BW distribution from each treatment, were moved to a cage breeder house and placed at 1 or 2 hens/cage. Breeders were artificially inseminated at 44 wk (experiment 1) and 52 wk of age (experiment 2). Eggs were collected for 8 d, incubated, and placed in individual pedigree bags at d 19 of incubation. Blood samples from 5 chicks per treatment combination were collected at hatch in both experiments. Spleen and bursa were collected from the same chicks for histomorphometry analyses in experiment 2. In the second experiment, 12 chicks per treatment were placed in cages. Progeny were provided diets based on the same grain (corn or wheat) as their parents. Serum samples were collected at 5, 9, and 13 d of age and analyzed for anti-NDV MatAb. Data were analyzed as a 2 × 2 × 2 factorial design considering strain, dietary grain source, and cage density as main factors. Interaction effects were observed in breeders and progeny. Experiment 1 showed that strain A chicks had lower levels of MatAb when hens were housed at 2 hens/cage rather than 1 hen/cage. The MatAb levels of strain B chickens were not affected by cage density in either experiment. Experiment 2 demonstrated similar effects of cage density on MatAb levels and the area of bursa follicles for both strains. Progeny of breeders fed corn-based diets had smaller spleen white pulp only when hens were housed at 2 hens/cage compared with 1 hen/cage. The results of these experiments suggest that breeder strain and cage-density conditions affected MatAb transfer to progeny and embryo development of spleen and bursa.

Social, stocking density and dietary effects on the failure of farmed cod Gadus morhua

A large proportion of cod juveniles fail following transfer to sea cages from the hatchery. Failed cod take and then eject feed and are thin and emaciated fish of low weight compared with “normal” siblings. Failed fish comprised 70% of total mortalities and 10% of fish stocked in the first eight months of production on a cod farm in Scotland. Failed cod comprised from 0 to 8% of fish reared in twelve hatchery tanks over 3 months. These failed cod were graded from larger fish in five consecutive grades at four to six weekly intervals and, after being reared separately, over 90% of these fish were “recovered”. No significant differences were found in food acceptance of six alternative diets and a standard marine commercial diet by failed cod. Smaller pellets or feed moistened in seawater were offered but this did not significantly increase the rate of feed acceptance. The effects of stocking density on the development of failed cod were assessed by comparing performance at densities of 0.2, 2 and 20 kg m − 3 . Aggressive interaction was lowest at an intermediate stocking density of 2 kg m − 3 and highest at a density of 20 kg m − 3 . Fin nipping was concentrated on the first dorsal fin and was not significantly different between stocking densities, but the other dorsal fins, pectoral fins and tail were also attacked more frequently at the highest stocking density. It is concluded that failed cod can be recovered by grading from the main population and feeding these cod separately. Stocking densities in sea cages should initially be similar to hatchery levels and this may be achieved by holding the cod in small enclosures within the main net.

ANALISIS FAKTOR-FAKTOR PENGELOLAAN MANAJEMEN USAHA PETERNAKAN AYAM RAS PETELUR DI KABUPATEN 50 KOTA PROVINSI SUMATERA BARAT

This research was conducted to address micro climate problem of tropical country such as Indonesia on layer production performance. Thise research is aimed to investigate determinant factors on productivity and technical aspects applied in layer farming of Lima puluh Kota District. Fourty Eight breeders were selected using simple random sampling based on their production scale. Cobb – duglass model was appliedto determine significant factors of productivity and Benefit Cost Ratio is applied to measure economic efficiency. Results showed that there were significant differences on rectal temperature (P&lt;0.05), cage density (P&lt;0.05) and protein intake (P&lt;0.01). The layers farming scales were categorized into three groups; small scale (SI), medium scale (SII) and big scale (SIII). In addition, the strains reared by the farmers were Dekalb Warren, Super Harco, Lochmann did not significantly affect the layers performance. t-test results revealed that the farming scale did not have correlation (P&gt;0.05) with the temperature of layer cages; which was 25.580C. The highest humidity level recorded was 80.54 measured in SI. The rectal temperatures were insignificant among scales; however, there were significant differences between Dekalb Warren and Lochmann (P&lt;0.05). The highest rectal temperature was Lochmann. t-test results on cage density found that there was very insignificant between SII and SIII (P&lt;0.01); which was 6.588 chicken/m2. Another parameter measured was protein intake, which was highly significantly differed among groups (P,0.01). The highest on SIII (19.42 g per chicken per day). In contrast, other parameters such as energy intake, age of laying period, feed in take, feed conversion, egg weight and egg shell thickness were insignificant among groups of farming scales as well as chicken strains (P&gt;0.05). Economical analysis on the groups of layer farming scales showed that SI was different from SII (P&lt;0.05); in addition, SI was highly significantly different from SIII, SII and SIII were insignificantly different (P&lt;0.01). The higher the scale of the layer farming, the higher profits gained. Keywords: Layer productivity, determinant factors, economic efficiency

Evaluation of Cucurbitacin-Based Gustatory Stimulant to Facilitate Cucumber Beetle (Coleoptera: Chrysomelidae) Management With Foliar Insecticides in Melons

The bitter plant-derived compounds cucurbitacins are known to stimulate feeding of adult cucumber beetles (Coleoptera: Chrysomelidae). A cucurbitacin-based gustatory stimulant applied as a flowable bait combined with either spinosad or carbaryl was compared with foliar sprays of spinosad and carbaryl for controlling two cucumber beetle species (Diabrotica undecimpunctata undecimpunctata Mannerheim and Acalymma trivittatum Mannerheim) in honeydew melons (Cucumis melo L.). Field studies were conducted on the University of California-Davis plant pathology farm in 2008 and 2009. Beetle densities after applications and fruit damage from beetle feeding were compared among treatments. In addition, beetle survival was compared within field cages placed over the treated foliage infested with beetles. Using all three measures of efficacy, we determined that the addition of cucurbitacin bait had no effect on the level of cucumber beetle control with carbaryl in either 2008 or 2009. In both years, spinosad did not significantly reduce cucumber beetle densities in either field cages or field plots and did not reduce fruit damage relative to the untreated control. The addition of the bait to spinosad did not improve its efficacy. A laboratory bioassay of the spinosad formulation used in the field showed it had significant lethal effects on adults of both cucumber beetle species. Results indicated that the bait formulation used did not improve cucumber beetle control but may benefit from the addition of floral attractants or using a different type of cucurbitacin.

Environmental conditions and occurrence of hypoxia within production cages of Atlantic salmon on the south coast of Newfoundland

Dissolved oxygen (DO) levels were monitored in two marine Atlantic salmon (Salmo salar L.) cage sites on the south coast of Newfoundland (Canada) during the summer and fall of 2008 and 2009. In 2008, sites A and B had cages with stocking densities of approximately 9 kg m−3. In 2009, site A was being fallowed while stocking density at site B was of 10 kg m−3. During 2008 and 2009, few hypoxic events (defined as DO <6 mg L−1 O2) were recorded at site A; however, at site B intermittent hypoxic events (4–6 mg L−1 O2) were observed. Our study provides a description of intermittent hypoxia occurring in salmon cages. These hypoxic events occur mostly during the summer season and last for as long as 2.5 months. Fish swimming behaviour show that water layers exhibiting low DO did not cause avoidance behaviour. This confirms results found by other authors. Site B exhibited low water currents below 5 m suggesting that caution should be taken before considering an increase in stocking densities in cages. Questions remain about the effect of this intermittent hypoxia on fish health and growth, and will be the focus of future research.

Laying Performance of Wareng Chicken under Free Choice Feeding and Different Cage Density

The aim of the experiment was to explore the possibility of using free choice feeding technique under different cage density for unselected native chicken. Eighty hens of laying Wareng chicken were divided into two feeding systems. Half of them were fed complete commercial diet of 17% crude protein, with 2800 kcal ME/kg and the other half were subjected to free choice diet. The diets were in mash form and placed in sufficient feed troughs in front of each cage. Each cage was occupied by four or six hens. Free choice feeding hens were served with commercial concentrate (30% crude protein), ground corn and oyster shell, placed separately in feed troughs. Observation was carried out during 24 weeks laying period, starting from 20 to 44 weeks of age. The results showed that egg production (9.35% hen day), and the intake of feed (42.74 g/day), protein (7.01 g/day), energy (116.6 kcal ME/day), calcium (1.99 g/day and phosphorus (0.22 g/day) were not affected (P&gt;0.05) by feeding system nor by cage density. The results however indicated that free choice feeding technique provided sufficient nutrients in supporting maximum egg production of unselected native chicken.

Relative Hooking Mortality among Walleyes Caught on Barbed and Barbless Octopus Hooks and Barbed Jigs

AbstractAnglers sometimes use alternatives or modifications to J‐shaped hooks to reduce hooking mortality in fish that are caught with live baits and then released. One such modification, the removal of barbs, has been evaluated for several fish species but has shown little promise for reducing hooking mortality; however, barbless hooks have not been evaluated for walleye Sander vitreus. We evaluated relative mortality for walleyes (228–419 mm total length) that were caught by means of bobber fishing with leeches on barbed (n = 179 fish) or barbless (n = 209) live‐bait octopus hooks or on barbed jigs (n = 193); after capture, the fish were held for 120 h in net pens. Holding mortality was a function of water temperature, cage density, bleeding level, and hook location; fish length and angler handling time did not significantly affect mortality. We combined hook location and bleeding level to create a single variable, hooking damage, which was used to replace the two variables in the initial model. This second model was similar to the first, indicating that hooking damage was correlated with mortality when controlling for the effects of water temperature and cage density. We also determined that hooking damage was correlated with hook type. For the 228–419‐mm walleyes in our study, barbed jigs caused less damage than live‐bait hooks and damage levels were similar between barbed and barbless live‐bait hooks. Given specified levels of hooking damage, holding mortality was independent of hook type. We hypothesize that the fish in this study were too small to swallow the jigs well and thus were hooked less critically and bled less than fish that were caught with live‐bait hooks. This study illustrates how gear type can affect hooking mortality based on the amount of damage caused when the fish is caught and adds to the body of literature indicating that the removal of barbs from hooks does not increase fish survival.Received March 15, 2010; accepted November 17, 2010

The effect of stocking density on yield, growth, and survival of Asian river catfish (Pangasius bocourti Sauvage, 1880) cultured in cages

Asian river catfish (Pangasiusbocourti Sauvage, 1880) were cultured at five different stocking densities in cages (submerged volume 1 m3) suspended in a dugout pond from August to November 2009. Pangasiusbocourti fingerlings (mean weight 27.09 ± 0.54 g) were stocked at densities of 12, 25, 50, 100, and 200 fish m−3. At the end of 3 months, the harvest weights (gross yields) were, respectively, 2.05 ± 0.30, 5.20 ± 0.31, 10.60 ± 0.42, 19.98 ± 0.78, and 42.37 ± 0.41 kg m−3. The mean fish weights among the stocking densities of 25, 50, 100, and 200 fish m−3 were not significantly different, but were significantly higher than that of the 12 fish m−3 density. The specific growth rates among high stocking densities of 50, 100, and 200 fish m−3 were not significantly different; however, they were significantly higher than those of the low stocking densities of 12 and 25 fish m−3. Asian river catfish performed poorly at the lowest density. The results indicate an initial lower stocking threshold for Asian river catfish of above 5.20 kg m−3. The Asian river catfish cultured in small cages placed in a pond reached the desirable market size (>200 g) within a 90-day grow-out period. The results show that the maximum yield for Asian river catfish during a 3-month production cycle was not reached.

Beak condition and cage density determine abundance and spatial distribution of northern fowl mites, Ornithonyssus sylviarum, and chicken body lice, Menacanthus stramineus, on caged laying hens

Adult White Leghorn hens (Hy-Line strain W-36) were inoculated with either northern fowl mites or chicken body lice, and the ectoparasite populations were monitored over periods of 9 to 16 wk. Two beak conditions (beak trimmed or beak intact) and 2 housing densities (1 or 2 hens per 25 × 31 cm suspended wire cage) were tested. Populations of both ectoparasites were at least 10 times lower on beak-intact hens compared with populations on beak-trimmed hens. Cage density did not influence mite numbers, but higher numbers of lice (2 to 3 times) developed on hens held at the higher cage density. Louse distribution on the body and louse population age structure were also influenced by host beak condition. Beak-intact hens had a higher proportion of lice under the wings, whereas beak-trimmed hens had the majority of lice on the lower abdomen. Louse populations on beak-trimmed hens also comprised relatively more immature stages than populations found on beak-intact hens. The effects are likely related to decreased grooming efficiency by beak-trimmed hens and, in the case of lice, the higher host density. The high mite and louse populations on most commercial caged laying hens are probably a direct result of beak trimming. However, selection of more docile breeds that can be held without trimming may allow the hens themselves to reduce ectoparasites below economically damaging levels. This could benefit producers, animal welfare advocates, and human health by reducing 1) costs of beak trimming, 2) pesticide treatment costs (including human and bird chemical exposure concerns), and 3) objections to beak trimming from the animal welfare community.

Stocking densities in cage rearing of Amazon river prawn ( Macrobrachium amazonicum) during nursery phases

Amazon river prawn ( Macrobrachium amazonicum) is widely distributed along Brazilian rivers, being one of the native species with a major cultivation potential. This study evaluated stocking densities during primary and secondary nursery phases for M. amazonicum in cages, regarding survival, growth, biomass, food conversion and productivity. The experiment was carried out in 12 cages of 0.5 m 2 (iron frames recovered with polyethylene mash) placed inside of a 1500 m 2 earthen pond. Early metamorphosed postlarvae (PL) (0.009 ± 0.006 g) were stocked for 28 days (primary nursery phase), at densities of 4, 6, and 8 prawns L −1. In the secondary nursery phase (62 days), densities were 200, 400 and 800 prawns m − 2 (0.12 ± 0.01 g). Prawns were fed commercial pellets (35% crude protein). Water quality parameters were within the adequate range for freshwater prawn culture. In the primary nursery phase, the productivity for density of 8 PL L −1 was two times greater compared to 4 PL L −1 (6.17 and 3.35 juveniles I L −1, respectively) and differed significantly ( P < 0.05). In the secondary nursery phase, mean survival was above 95% and did not differ significantly, while mean weight differed ( P < 0.05) for the densities of 200 (0.44 g) and 800 (0.36 g) prawns m −2. The highest biomass (143.6 g) was registered at 800 prawns m −2 density and differed significantly ( P < 0.01) from lower densities. The productivity of juveniles II also differed significantly among densities, being about four times greater at 800 prawns m −2 compared to lower densities. Net income was positive only at densities greater than 400 prawns m −2, being highest at a density of 800 prawns m −2. Thus, on an experimental basis, the nursery system for M. amazonicum at high densities in cages showed to be viable.

Effect of cage density on growth and carcass performance of fattening rabbits under tropical heat stress conditions.

Three hundred crossbred New Zealand, California, Butterfl y, Dutch, and Satin rabbits, weaned at 30 d and weighing 535±8 g (standard error) were assigned randomly to four treatments: 6, 12, 18 and 24 rabbits/m2 (3, 6, 9 and 12 rabbits/cage, respectively, each cage measuring 0.5 m2) resulting in 10 cages/treatment. During the experimental period (from weaning to 2.2 kg body weight) weekly individual live weight, cage feed intake, incidence of diarrhoea, ringworm, and injured rabbit data was recorded. The maximum temperature-humidity index ranged from 31 to 35, and so indicating severe heat stress. At the end of the experimental period 10, 20, 30 and 30 rabbits under densities of 6, 12, 18 and 24 rabbits/m2, respectively, were slaughtered and carcass performance recorded. Average daily gain and feed intake from weaning to the end of the experimental period decreased by 0.31±0.070 and 1.20±0.25 g, respectively, for each unit that the density increased at the beginning of the experiment (P=0.001). The length of the fattening period increased by 0.91±0.16 d (P=0.001) for each unit of increment of density. However, rabbit production (expressed in kg/m2) increased linearly and quadratically with density (P<0.008). Cage density did not affect feed effi ciency, which on average was 0.214 g/g (P=0.37). Animals housed at the highest density, compared to the average of those caged at lower densities, tended to show higher incidence of ringworm (68.9 vs 39.4%; P=0.075) and injury (16.8 vs 3.03%; P=0.12), and showed higher mortality (20.5 vs 9.63%; P=0.043). Density did not alter the dressing out percentage nor chilled carcass weight. The proportion of scapular fat (P=0.042) increased linearly with increasing levels of density, but perirrenal fat was unaffected (P=0.22). Increasing density reduced dorsal length linearly (P=0.001), and reduced drip loss percentage linearly and quadratically (P=0.097 and 0.018, respectively).Based on these results, under our heat stress conditions, avoiding densities higher than 18 rabbits/m2 or 34 kg/m2 at the end of fattening is recommended.

The effect of stocking density and feeder types on the performance of growing rabbits under conditions prevailing in Cameroon.

Weaned rabbits fed with a maize based diet supplemented with Guatemala grass were used in a factorial experiment to compare the effects of stocking rate (5 vs 10 per m²) and feeder type on production parameters and mortality over an 8 week period under Cameroon conditions. Stocking rate did not affect (p>0.05) feed intake, feed conversion efficiency or mortality rates. Increasing the number of animals from 2 to 4 in a cage resulted in a significant decrease in daily weight gain (P 0.05) effect on feed intake, growth rate, feed conversion efficiency or mortality rate. However, feed wastage was significantly (P 0.05) any of the parameters measured. The interaction between sex, feeder type, and cage density had a significant (P<0.01) effect only on feed wastage. The results of the study showed that rearing rabbits in pairs per cage and using a cylindrical metallic tin feeder would enhance faster growth and reduce the amount of feed wasted.