Effect of stocking density of fish on water quality and growth performance of European Carp and leafy vegetables in a low-tech aquaponic system

Aquaponics (AP) is a semi-closed system of food production that combines aquaculture and hydroponics and represents a new agricultural system integrating producers and consumers. The aim of this study was to test the effect of stocking densities (APL, 2.5 kg m-3; APH, 4.6 kg m-3) on water quality, growth performance of the European Carp (Cyprinus carpio L.), and yield of leafy vegetables (catalogna, lettuce, and Swiss Chard) in a low-technology AP pilot system compared to a hydroponic cultivation. The AP daily consumption of water due to evapotranspiration was not different among treatments with an average value of 8.2 L d-1, equal to 1.37% of the total water content of the system. Dissolved oxygen was significantly (p < 0.05) different among treatments with the lowest median value recorded with the highest stocking density of fish (5.6 mg L-1) and the highest median value in the hydroponic control (8.7 mg L-1). Marketable yield of the vegetables was significantly different among treatments with the highest production in the hydroponic control for catalogna (1.2 kg m-2) and in the APL treatment for Swiss Chard (5.3 kg m-2). The yield of lettuce did not differ significantly between hydroponic control and APL system (4.0 kg m-2 on average). The lowest production of vegetables was obtained in the APH system. The final weight (515 g vs. 413 g for APL and APH, respectively), specific growth rate (0.79% d-1 vs. 0.68% d-1), and feed conversion (1.55 vs. 1.86) of European Carp decreased when stocking density increased, whereas total yield of biomass was higher in the APH system (4.45 kg m-3 vs. 6.88 kg m-3). A low mortality (3% on average) was observed in both AP treatments. Overall, the results showed that a low initial stocking density at 2.5 kg m-3 improved the production of European Carp and of leafy vegetables by maintaining a better water quality in the tested AP system

Influence of group housing, lactation system and floor type on performance and injuries in rabbit does

To evaluate the effect of group housing, lactation system, and floor type, 40 crossbred multiparous pregnant rabbit does were transferred to individual pens (0.5 m x 1.0 m); 8 does were kept individually during all the trial (I; n=8); the other 32 does were kept in 8 collective pens (2.0 m x 1.0 m, by joining 4 individual pens) in stable groups of 4 individuals (G; n=8) from 8 d until 2 d before kindling and from 2 d until 33 d after kindling. Half pens had wire net floor covered with plastic mats (W; n=8) and the other half plastic slatted floor (P; n=8). Within G does, in half pens (n=4) each doe nursed its own litter (fixed lactation, F); in the remaining half, each doe randomly nursed the litters of the group (random lactation, R). Doe performance at kindling and during lactation, litter performance from standardization until weaning (33 d), and skin injuries on G does (5, 12, 19, 26 and 34 d after kindling) were controlled. The effect of the housing system on performance was tested by PROC GLM of SAS. Within G does, the effect of the lactation system and floor type was evaluated by PROC MIXED (pen as random effect); the injury frequency was analysed by PROC FREQ according to observation day, lactation system, and floor type. Housing system did not affect doe kindling or lactation performance; litter weight at standardization was higher for G than I does (680 vs 619 g, P<0.05), but differences disappeared at weaning. The lactation system showed some residual effects when controlled lactation finished, nests were opened, and kits free of moving. In fact, from 19 to 33 d after kindling, does and litters had higher feed intake (679 g/d vs 602 g/d; P<0.05) and, at 33 d, kits were heavier (775 vs 748 g, P<0.05) in R than in F pens. Floor type (W vs P pens) affected milk production (244 vs 225 g/d; P=0.06), and kit weight at the end of controlled lactation (301 vs 290 g; P<0.05), without residual effects at weaning. The injury frequency changed after the group formation: 34% at 5 d, 47% at 12 d, 13% at 19 and 26 d, and 10% at 34 d of lactation (P<0.05). In conclusion, under our conditions, group housing did not negatively affect doe performance; lactation system and floor type had minor effects; aggressiveness among does was evident after group formation during early lactation but decreased in the late lactation. Further recordings on more reproductive cycles would be necessary to confirm the present results

Effect of pre-slaughter conditions in European sea bass (Dicentrarchus labrax)

The increasing attention towards animal welfare also concerns aquaculture species, with special regards to husbandry and slaughter conditions. Both the extent and the duration of stressful events especially before slaughter may affect post-mortem evolution of biochemical processes and product shelf-life (Pottinger, 2001; Zampacavallo et al., 2003). The present work aimed to evaluate the effects of preslaughter conditions in European sea bass according to i) stocking density and ii) time spent in confinement tanks after catch and before slaughter on physiological indicators of stress and meat quality during storage

Apparent digestibility of insect protein meals for rainbow trout

Insect meals are considered to be promising future ingredients for aquaculture feeds. In past feeding trials in rainbow trout, insect meals were included in diets only on the basis of their nutrients content and energy density without taking into account their biological availability due to the lack of their digestible values. Apparent digestibility (ADC) provides good indication of the bioavailability of nutrients and energy thus providing rational basis for the correct inclusion of feedstuffs. The aim of this research was to assess, in an in vivo trial on rainbow trout, the ADC of five full fat insect meals: one Tenebrio molitor (TM), two Hermetia illucens obtained through two different process (HI1 and HI2), one Musca domestica (MD), and one Alphitobius diaperinus (AD). Fish were fed a high-quality reference diet (R) and test diets obtained mixing the R diet with each of the test ingredients at a ratio of 70:30. Diets contained 1% celite as inert marker. Fish were fed to visual satiety twice a day and faecal samples collected using a continuous automatic device. Faeces were freeze dried and frozen (-20 \ub0C) until analyses. The ADC of dry matter, crude protein and ether extract of each insect meal diet were calculated. ADC for dry matter varied between 70.07 (HI1) and 80.85 (TM). ADC for protein was above 84% in all treatments and resulted the highest in MD, TM and AD treatments. Ether extract apparent digestibility significantly differed among diets with the highest value reported for TM treatment. All treatments reported values higher than 96%. Observed differences could be due to the insect species and meal treatment but in general, tested insect meals were highly digestible for rainbow trout. The results from this research could be useful to optimize the diet formulation

Evaluation of carcass and meat traits of Muscovy duck fed with black soldier fly partially defatted meal

The aim of this study was to evaluate the carcass characteristics and breast meat quality in Muscovy duck (Cairina moschata domestica) fed different inclusion levels of a partially defatted black soldier fly larva (BSF) meal. A total of 256 Muscovy ducklings (average live weight, LW: 71.32\ub12.70 g) were reared from day 3 to day 48 and randomly allotted in 32 pens (8 replicates/treatment). Four different diets were formulated with increasing substitution level of corn gluten meal with BSF larva meal (0, 3, 6 and 9%; BSF0, BSF3, BSF6 and BSF9, respectively) and divided in 3 feeding phases: starter (1-14 days), grower (14-35 days) and finisher (35-48 days). At day 48, 2 animals/replicate were slaughtered and dissected to determine their carcass yields. The weights of spleen, bursa of Fabricius, liver, heart and abdominal fat were recorded. Breast and thigh muscles were then excised from 16 ducks/treatment and weighted. Ultimate pH (pHu) and L*, a*, b* colour values were then measured on breast muscle. The collected data were tested by means of oneway ANOVA evaluating the effect of dietary BSF inclusion level by polynomial contrasts. Significance was declared at P<0.05. The inclusion of BSF did not affect final LW (2,515.68\ub192.42 g on average). Hot and cold carcass weights showed a quadratic response (P<0.05) to increasing BSF larva meal, with a minimum corresponding to BSF6; however, refrigeration losses were not affected by treatments. Weight of spleen, bursa of Fabricius, liver and heart did not differ among treatments. The weight of abdominal fat showed a quadratic response to increasing BSF meal with a minimum corresponding to BSF6 group (P<0.05). Breast and thigh yields, pHu and L*, a*, b* colour values did not differ among groups. With the exception of BSF6, the inclusion of BSF meal did not affect meat traits and carcass characteristics, confirming the potential use of BSF meal in Muscovy duck diets

Feeding programmes based on highly-digestible fibre weaning diets: effects on health, growth performance and carcass and meat quality in rabbits

The effect of three different dietary programmes on health, growth performance and carcass and meat quality in young rabbits weaned at 28 d was studied using a diet (F) rich in highly-digestible fibre, from 17 to 63 d of age (group FF); using diet F from 17 to 42 d followed by a diet poor in highly-digestible fibre and rich in starch and fat (S) until 63 d (group FS); and using a standard diet C with intermediate highly-digestible fibre and starch content, containing 100 ppm of zinc-bacitracin, from 17 to 63 d (group CC). A highly-digestible fibre diet could be useful to reduce the incidence of digestive disorders. However, it decreased slaughter weight (2294 g in FF vs. 2406 g in CC; P<0.05) and carcass and meat traits, e.g. dressing out percentage (55.4% in FF vs. 56.7% in CC; P<0.05), meat to bone ratio (5.73 in FF vs. 5.94 in CC; P<0.05) and hind leg fat content (3.81% in FF vs. 4.71% in CC; P<0.05) at 63 d of age. Switching to a high starch and fat diet at late fattening improved chilled carcass weight at 63 d of age (1339 g in FS vs. 1263 g in FF; P<0.05) mainly through the promotion of liver development (7.53% in group FS vs. 6.47% in group FF; P<0.05) and fat deposition (3.89% in FS vs. 2.63% in FF; P<0.05), and increased hind leg fat content (+1.2 points of fat percentage; P<0.05). However, this switch increased health risk (35.1% in FS vs. 17.6% in FF; P<0.05).This study was supported by the Interministerial Commission for Science and Technology (CICYT) from the Spanish Government Grant number AGL2011-30170-C02-01 is gratefully acknowledged. Funding from the Spanish Ministry of Economy and Competitiveness for Madam Pascual's contract (PTA2011-5888-T) is also gratefully acknowledged.Pascual Amorós, MDLD.; Soler Sanchis, MD.; Cervera Fras, MC.; Pla Torres, M.; Pascual Amorós, JJ.; Blas Ferrer, E. (2014). Feeding programmes based on highly-digestible fibre weaning diets: effects on health, growth performance and carcass and meat quality in rabbits. Livestock Science. 169:88-95. https://doi.org/10.1016/j.livsci.2014.07.007S889516

The use of environmental enrichments affects performance and behavior of growing rabbits housed in collective pens

This study assessed the effects of an elevated plastic-slatted platform and/or a plastic hiding tube in collective pens with large group sizes (27 or 36 rabbits/pen; 16 rabbits/m2) on the performance and welfare of rabbits kept from weaning (at 33 days of age) to slaughter (at 68 or 75 days of age). Growth performance, injuries, and behavior (video recorded for 24 h) of rabbits (n = 504) were recorded. The platform allowed rabbits to adopt the rearing position more frequently (+0.14 events during 2 min every 30 min across 24 h) and to rest with stretched body for longer (+3.8% of observed time) (p < 0.001). Production parameters and reactivity at the open field test were not modified, but the occurrence of injured rabbits at the trial end was higher in pens with platforms (+8.9%; p < 0.01). This result was possibly related to the higher group size in pens with platforms (36 rabbits) compared to those without platforms (27 rabbits). The inclusion of the tube decreased growth (-2.2 g/d; p < 0.05), whereas it was scarcely used by rabbits and it did not substantially change their behavior or the occurrence of injuries. In conclusion, under the experimental conditions of this study, elevated platforms worked as a useful structural enrichment in view of animal behavior but negatively impacted on the rate of injuries, whereas the usefulness of the tube was not confirmed

Effect of breast myopathies on quality and microbial shelf life of broiler meat

To evaluate the impact of emerging myopathies on meat quality and microbial shelf life, 48 normal, 48 white striped (WS), and 48 wooden breasts (WB) were stored for 11 d at 4°C aerobically and analyzed at 24, 72, 120, 168, 216, and 264 h post-mortem. Normal breasts showed lower (P < 0.001) redness index (−0.88 vs. −0.41 and −0.43) and cooking losses (22.0 vs. 23.8 vs. 26.9%) than those of WS and WB meat. Normal and WS breasts exhibited higher protein content than that in WB meat (23.9 and 23.2 vs. 21.4%; P < 0.001). Normal meat also had a lower ether extract content than that in WB meat (1.09 vs. 1.88%; P < 0.001), with intermediate values for WS meat. Normal breasts exhibited higher saturated fatty acid (FA) rate (31.3 vs. 28.0% of total FA on average) and lower unsaturated FA rate (68.7 vs. 72.0%) than those in WS and WB meat (P < 0.001). Differences were mainly due to polyunsaturated FA (30.5% in normal vs. 35.3 and 35.4% in WS and WB meat; P < 0.001). Normal breasts had higher initial total viable count (TVC) and a shorter TVC lag phase than those of WS and WB meat (46.3 vs. 85.2 and 77.8 h). The microbial shelf life threshold (7 log10 CFU TVC/g) was achieved first in normal (130 h) and then in WS (149 h) and WB (192 h) meat. TVC and Pseudomonas spp. counts were significantly higher in normal than those in the affected breasts between 72 and 216 h of storage. Enterobacteriaceae spp. and lactic acid bacteria counts were significantly higher in normal meat, lower in WB meat, and intermediate in WS meat until 216 h. All differences in microbial targets across meat types disappeared by 264 h of storage. Further studies are necessary to elucidate the factors and the mechanisms that may modulate microbial growth and composition during storage in broiler breast meat affected by myopathies