Lower Food Conversion Ratio Research Articles

Comparison of the effects of the prebiotics (Bio-Mos ® and β-1,3-D-glucan) and the customised probiotics ( Pseudomonas synxantha and P. aeruginosa) on the culture of juvenile western king prawns ( Penaeus latisulcatus Kishinouye, 1896)

The present study investigated the effects of dietary immunostimulants on the growth, survival and immune responses of juvenile western king prawns ( Penaeus latisulcatus). The immunostimulants used were two prebiotics Bio-Mos ® and β-1,3-D-glucan and two customised probiotics Pseudomonas synxantha and P. aeruginosa. The prawn juveniles (4.63 ± 0.39 g) were fed the formulated feed (control), supplemented with Bio-Mos ® at 0.5%, β-1,3-D-glucan at 0.2% and a combination of two probiotics (10 5 CFU/mL at 50:50 v/v) at 20 mL/kg for 84 days of culture. The specific growth rate (SGR), survival and food conversion ratio (FCR) were higher in the prawns fed the immunostimulants than in the control. Although no significant effects on the SGR, survival and FCR were found when the prawns were fed either any prebiotics or probiotics, the higher survival was observed in the prawns fed the probiotics, while the higher SGR and lower FCR were observed in the prawns fed β-1,3-D-glucan, which had the most influence in increasing the surface structure of the prawn intestines. The healthier prawns showed the higher total haemocyte count (THC), the lowest clotting time and lowest bacterial load in the haemolymph when they were fed the probiotics. Continuous supplementation with the immunostimulants to the prawns for 84 days showed considerable improvement in the growth, survival and immune response of the prawns.

Probiotic P. acidilactici application in shrimp Litopenaeus stylirostris culture subject to vibriosis in New Caledonia

We studied the effects of a lactic acid bacterium, Pediococcus acidilactici (strain MA 18/5M, CNCM), as a dietary probiotic on growth performance and some nutritional and microbiological aspects of the shrimp Litopenaeus stylirostris. Experimental shrimp culture was carried out over 10 weeks, using floating cages of 14 m2 each set in earthen ponds, in a New Caledonia farm affected by “Summer syndrome”, a septicaemic vibriosis caused by Vibrio nigripulchritudo. The experiment design testing probiotic-coated pellets against control was replicated in two earthen ponds. High mortalities, characteristic of Summer syndrome, were observed during the first 2 weeks of the trial. The probiotic improved production in the treated cages from both ponds with increases in the survival rate (7% and 15% respectively) and final biomass (8% and 12% respectively). No differences were recorded among treatments on growth performances, but significant lower food conversion ratios were obtained with probiotic treatment. After 5 weeks of rearing, the Hepatosomatic Index and the adjusted dry weight of the digestive gland were significantly increased by 10% and by 9% respectively in shrimps treated with probiotic. In the meantime, the specific activities of α amylase and trypsin in the digestive gland showed a significant effect of the probiotic treatment with respective increases by 35% and 55%. The rise in total trypsin activity following morning feeding was also enhanced by the probiotic treatment (P<0.001).The highest concentration of probiotic (between 104–105 CFU g−1 of fresh gut) in the shrimp gut was obtained 2 h after feeding. The concentration remained high for 4 h after feeding before decreasing until the next meal. Total bacterial counts on Marine agar and TCBS in the gut were significantly lowered by the probiotic treatment over the 10 weeks of the experiment. Additionally, during the first 2 weeks, prevalence and load of V. nigripulchritudo strains in haemolymph was lower in animals fed with the probiotic diet.This study demonstrated, under pond conditions, that feeding shrimp with live terrestrial lactic acid bacteria can be an effective treatment for improving shrimp culture affected by vibriosis.

Effects of different boiling time of soybean (&lt;i&gt; Glycine max&lt;/i&gt; (L) merril) on growth performance of tilapia (&lt;i&gt; Oreochromis niloticus&lt;/i&gt;) fingerlings

A 56-day feeding trial was conducted with Oreochromis niloticus (Tilapia) fingerlings fed soybean boiled at different periods. The period treatment variations were unboiled soybean as control (T 1 ); soybean seeds boiled for 20 minutes (T 2 ); 30 minutes (T 3 ); 40 minutes (T 4 ) and for 50 minutes (T 5 ). The soybean seeds so treated were sun dried, milled and were used to formulate iso-nitrogenous diets (25% crude protein). The trials were conducted in hapas of 1m 3 submerged in a pond. The diets were fed at 5% body weight and each hapa was stocked with 20 fingerlings. Evaluation of growth parameters and nutrient utilization of fish fed the experimental diets was based on mean weight gain (MWG); specific growth rate (SGR); protein efficiency ratio (PER); food conversion ratio (FCR) and survival rate. There was significant difference (P 4 had the highest MWG (2.40g); SGR (0.63% day -1 ); PER (1.76) and conversely the lowest FCR (0.41). While fish fed diet T 1 had the lowest MWG (0.32g) SGR (0.14% day -1 ); PER (0.25) and highest FCR (2.39). Therefore fish fed raw soybean had the lowest growth and least utilized the diet. Keywords : boiling time, soybean, Oreochromis niloticus Journal of Aquatic Sciences Vol. 21(1) 2006: 15-18

Effects of natural and synthetic pigments in diets on flesh coloration and growth of rainbow trout (Oncorhynchus mykiss W.)

The desired pink to red color of rainbow trout flesh (Oncorhynchus mykiss W.) can be obtained by adding carotenoids to the fish diet. This study was conducted to determine the effects on growth and color retention of natural pigments (30 ppm red pepper meal, 60 ppm red pepper meal, 30 ppm shrimp by-products meal, 60 ppm shrimp by-products meal), synthetic carotenoids (30 ppm astaxanthin, 60 ppm astaxanthin), and a control group (no added pigment). Duplicates of each of the seven treatments were reared for three months. The best specific growth rates were obtained with 30 ppm astaxanthin (0.83%) and 60 ppm red pepper meal (0.84%); the low- est was in the control (0.54%). The lowest food conversion ratio was obtained with 30 ppm astax- anthin (1.38) and highest in the control (2.23; p&lt;0.05). Visual coloration values ranged from 14.46±0.23 in the 30 ppm astaxanthin group to 11.55±0.25 in the control. Retention coefficients ranged from 6.63 in the 30 ppm astaxanthin group to 1.79 in the 60 ppm shrimp by-products meal (p&lt;0.05). Tristimulus chromometer a values ranged from 0.87±0.47 in the control to 6.96±0.47 in the 60 ppm astaxanthin treatment, b values from 10.94±0.27 in the control to 12.90±0.27 in the 60 ppm red pepper meal treatment, and L values from 46.81±0.50 in the 60 ppm astaxanthin group to 54.57±0.26 in the control (p&lt;0.05).

Effects of dietary fish oil replacement on growth and carcass proximate composition of juvenile barramundi (Lates calcarifer )

An experiment was carried out to determine the effects of dietary fish oil replacement at an optimal level on the growth and carcass proximate composition of juvenile barramundi or sea bass (Lates calcarifer). Ten fish feeds were formulated to contain iso-ingredients with theoretically identical dietary lipid levels but with different sources of lipids (fish oil, soybean oil, canola oil and linseed oil) replacing dietary fish oil. Three hundred fish were equally divided into 30 70-L plastic tanks (three replicate tanks for each treatment). Fish were fed with experimental diets for 40 days within closed recirculating freshwater systems (70 L h−1, 28°C and 12L:12D). Growth, specific growth rate, food conversion ratio (FCR) and carcass proximate composition were determined. Dietary lipids significantly affected (P<0.05) the growth of the fish. Good growth and low FCR were observed in all treatments. Therefore, fish oils can be partially replaced by vegetable oils to reduce the feed cost. There were no significant differences (P>0.05) in lipid, moisture and protein content in fish carcasses among the group. However, juvenile barramundi showed increasing lipid and moisture content in muscle, whereas decreasing protein content when compared to the initial fish.

Metabolic rate and its relationship with ascites in chicken genotypes

1. Male chickens of 7 genetic lines, consisting of two pure sire and two pure dam populations, a commercial broiler cross and two slow-growing chicken lines (Label Rouge, LR and Mechelse Koekoek, MK) were reared from 1 to 37 d of age. The chickens received a two-phase dietary regime and were subjected to low ambient temperature. 2. The experimental aim was to investigate relationships between susceptibility to ascites and heat production. 3. Body weight gain (BWG), food intake and food conversion ratio (FCR) were determined. Ascites mortality, arterial pressure index (API=right ventricular/total ventricular weight ratio), haematocrit values, proportional lung weight (lung weight/body weight × 100), plasma thyroid hormones (thyroxine, T4 and triiodothyronine, T3) and arterial blood gas pressures ( pCO2 and pO2) were determined. The heat production per kg metabolic body weight (H/W0·75) and total heat production (H) were calculated for the period 16 to 33 d using an energy balance study according to the comparative slaughter method. 4. The two breeder sire lines had high BWG and low FCR and high but different incidences of ascites compared with the slow-growing ascites resistant LR and MK lines with notable high FCR. The broiler cross and slower-growing breeder dam lines had a similar and relatively lower incidence of ascites mortality. 5. The fast-growing chickens had low H/W0·75 values compared with slow-growing lines. 6. These fast-growing breeder sires had lower plasma thyroid hormone, reduced proportional lung weights, low arterial pO2 and high arterial pCO2 pressures compared with the slower-growing lines. 7. In conclusion, ascites incidence was associated with lower heat production per metabolic body weight and therefore a lower oxygen requirement per metabolic weight.

Influences of light intensity and photoperiod on moulting and growth of Penaeus merguiensis cultured under laboratory conditions

The effects of light intensity ( I, 750 and 75 lx) and photoperiod ( P, 12L/12D and 7L/5D) on moulting and growth of Penaeus merguiensis were investigated over 12 weeks under laboratory conditions. Both light intensity and photoperiod significantly ( P<0.05) influenced the percentage weight gain (PWG), but did not influence moult frequency or moult interval. Mean PWG of prawns cultured at 750 lx was 198.4%, significantly ( P<0.01) higher than those cultured at 75 lx (168.1%). Imposing two light/dark cycles (7L/5D) in 24 h resulted in a significantly higher growth of prawns ( P<0.05) than the normal photoperiod (12L/12D). Prawns cultured at 750 lx had a lower food conversion ratio (FCR, 1.485) than those cultured at 75 lx (1.590, P<0.05). The effect of light intensity on prawn growth was found to be stronger and more immediate than that of photoperiod. There was no interaction between light intensity and photoperiod. Although not significantly different ( P>0.05), prawns cultured at 750 lx tended to moult more frequently. Sexual dimorphism was not observed within the range of tested prawns.

Serum neuropeptide Y (NPY) and leptin concentrations in pigs selected for components of efficient lean growth

Responses in log transformed serum neuropeptide Y (NPY) concentration and leptin concentration after six generations of divergent selection on components of efficient lean growth in pigs were measured. From an animal breeding perspective, serum NPY and/or leptin concentrations could be used as physiological predictors of genetic merit if there were significant responses to selection. At 90 kg liveweight, log transformed serum NPY concentrations were increased with divergent selection for low food conversion ratio (LFC) (6.31 versus 5.72, SED 0.09 log(pmol/L)) or for high lean growth rate (LGA) (5.80 versus 5.37 log(pmol/L)) but not with selection on daily food intake (DFI) (6.26 versus 6.14 log(pmol/L)). Selection for high DFI was associated with increased serum leptin concentration (3.06 versus 2.45, SED 0.21 ng/mL human equivalent (HE)) as was selection for low LFC (3.04 versus 2.46 ng/mL HE). Correlations between leptin and predicted lipid weight increased with stage of test (0.13, 0.34 and 0.43, SE 0.08 at 30, 50 and 75 kg). The high correlations between successive serum NPY concentrations (0.80, SE 0.11) suggest that changes in body composition with time would not be reflected in serum NPY concentrations. Serum NPY and, to a lesser extent, serum leptin concentrations were insensitive to dietary differences in total lysine: energy and indicated that studies using a genetic resource population of animals may be more powerful than nutritional studies using isoenergetic diets differing in lysine content to examine aspects of function of serum concentrations of NPY and leptin in pigs.

Alternative Protein Sources As Substitutes For Fishmeal In The Diet Of Young Tilapia Oreochromis Niloticus (LINN.)

Fifteen test diets were theoretically formulated to contain 33.32% dietary protein, dry matter, using a mixture of alternative protein sources and fishmeal in various proportions. Test diets were fed to fingerlings (initial weight 3.2±0.2 g) in triplicate tanks for eight weeks at 5% body weight per day in three portions. At the end of each experimental phase, fish carcass from the feeding groups was homogenized. Freeze-dried samples of fish at the beginning and end of the experiments as well as samples of the test diets were analyzed for proximate composition. Fish fed diet 1 containing 43% fishmeal recorded the highest weight gain, highest specific growth rate (SGR, 3.46%/d) and lowest food conversion ratio (FCR, 1.11). When part of the fishmeal was substituted with 18% soy- bean meal and 5% blood meal (diet 8), SGR and FCR were 3.02%/d and 1.34, respectively, not significantly different from diet 1 at 0.05 probability. Results showed that proper combination of alternative protein sources can provide 42-45% of the protein required by Oreochromis niloticus (33.32% dietary protein, dry matter). In such a combination, soybean meal can replace up to 25% of the fishmeal as a protein source. Blood meal exceeding 6%, groundnut cake beyond 10%, soy- bean meal above 20%, and wheat bran beyond 10% retarded fish growth. High mortality was gen- erally observed when these levels were exceeded, even in only one of the protein sources.

Effects of background color on growth performances and physiological responses of scaled carp ( Cyprinus carpio L.) reared in a closed circulated system

Growth performances and physiological responses of Cyprinus carpio after long-term (14 weeks) background color adaptation were investigated. Six groups of ten individuals each (initial body weight 116 g) were reared in black, green and white tanks (two replicate groups for each color). At the end of the experiment, blood (cortisol, glucose, haematocrit, cholesterol, triglycerides, total lipids, osmolality, electrolytes, pCO 2, pH), liver (total lipids, glycogen, hepatosomatic index) and growth (body weight, specific growth rate, food conversion ratio, condition factor, proximate carcass composition) parameters were determined. Plasma cortisol levels in white-adapted carp were significantly ( P<0.05) lower than those in black, while in green-adapted fish did not differ significantly from those in both other counterparts. White-adapted carp showed the highest specific growth rate and the lowest food conversion ratio, whereas black-adapted fish exhibited the opposite pattern. In addition, mean (%) increase of body weight in white-adapted carp was 4.66 and 3.58% higher than that in black- and green-adapted fish, respectively. Furthermore in white-adapted carp, blood pCO 2 and pH were significantly higher and lower, respectively, than those obtained in black- and green-adapted fish. In black-adapted carp, liver total lipid levels were significantly lower, and plasma total lipid levels were significantly higher, than those in white- and green-adapted fish. No significant variations were observed in the other parameters. It is concluded that different background colors may lead to different growth performances of scaled carp depending upon rearing conditions.

Performance and physiological variables in broiler chicken lines differing in susceptibility to the ascites syndrome: 1. Changes in blood gases as a function of ambient temperature

1. Male broilers of 5 genetic stocks (A, B, C, D, E) selected in different ways for fast growth and low food conversion ratio (FCR) and differing in ascites sensitivity were subjected to 2 different ambient temperature step down regimens: high temperature (HT: 33 to 20degreeC over 33 d) and low temperature (LT: 30 to 15degreeC over 17 d). 2. Ascites incidence was recorded daily. Food intake and body weight gain were measured weekly and FCR was calculated. Heat production (Hp) was calculated using the comparative slaughter method. At 28 d venous samples were taken for blood gas analysis and haematocrit and relative heart, lung and liver weights were recorded. 3. Populations A and C showed the highest growth rates combined with a low FCR and a higher ascites incidence. A low FCR in these stocks was attributable to low values for Hp. These stocks also had low pO2 and high pCO2 in venous blood at low ambient temperature compared with other stocks. Stock B, which exhibited the slowest growth rate and the highest FCR, was not susceptible to ascites and showed higher Hp and pO2 and pCO2 at low ambient temperature. Populations D and E were intermediate for almost all variables. Heart and lung weights were both increased at LT , while liver weight did not differ between temperature regimes. 4. Our results show that a high haematocrit is not necessarily linked with an increased susceptibility to ascites.

Dietary supplements of methionine increase breast meat yield and decrease abdominal fat in growing broiler chickens

The response of male broiler chickens to graded amounts of an essential amino acid (methionine) or an amino acid analogue (methionine hydroxy analogue free acid, MHA-FA) was examined in this experiment. The effects of each supplement on food intake, food conversion and the masses of a demand tissue (breast meat) and an indicator of body fat (abdominal fat pad) were measured. Birds grew significantly faster, ate more and had a lower food conversion ratio when there was more DL-methionine or MHA-FA in the diet. After standardising the differences in food intake between treatments, there were still highly significant differences in liveweight between diets. After removing the variation due to treatment differences in body mass, the data showed that adding either DL-methionine or MHA-FA to the diet increased the mass of breast meat and reduced the size of the abdominal fat pad. Exponential equations fitted to the body mass and feed conversion ratio data indicate that, in an equimolar comparison, MHA-FA is 78 and 70% as potent as DL-methionine for growth and feed conversion ratio respectively. Similar equations fitted to the carcass data show that MHA-FA is only 71% as potent as DL-methionine in depositing breast tissue. Increasing amounts of DL-methionine reduced the variability in liveweight and carcass, breast and abdominal fat pad weights. Adding 0.05% MHA-FA reduced variability in these traits compared with the basal ration but higher amounts of MHA-FA had no additional effect.

Compensatory growth in Belgian Blue bulls previously grazed at two stocking rates: animal performance and meat characteristics

AbstractA comparison was made between fattening systems with Belgian Blue bulls of the double-muscle type, in order to assess the reponse in terms of compensatory growth when the bulls were grazed at a high stocking rate. Two groups of eight bulls were grazed on Lolium perenne and Trifolium repens pasture during an initial period of 135 days (period I). One group grazed at a stocking rate of six animals per ha allowing for normal growth at pasture (NGP); the other group grazed at stocking rate of 10 animals per ha (low growth at pasture, LGP). Both groups were then finished indoors (period II) with a concentrate based on dried sugar-beet pulp. Eight control bulls were also fattened indoors on the concentrate diet during periods I and II (CG). The bulls were slaughtered according to similar finishing fattening state. Live-weight gains were 1·47, 1·10 and 0·52 kg/day (P &lt; 0·002) during period I in CG, NGP and LGP groups respectively. Corresponding live-weight gains during period II were 1·22, 1·37 and 1·50 kg/day (P &gt; 0·05). The LGP group had lower food conversion ratios, slaughter weights (P &lt; 0·05) and dressing proportions (P &lt; 0·01). The meat from the grazed bulls had lower cooking losses (P &lt; 0·05) and tended to have lower drip losses (P &gt; 0·05) and higher tenderness (P &gt; 0·05). It also had a higher cholesterol (P &lt; 0·05) content. Large differences were observed in the fatty acid composition according to fat location (subcutaneous, intermuscular or intramuscular). The proportions of mono and polyunsaturated acids were increased in the fats of the animals previously grazed (P &gt; 0·05, P &lt; 0·05).

Effects of stocking density on behavior and growth rate of European sea bass ( Dicentrarchus labrax) juveniles reared in a closed circulated system

Four duplicated groups of sea bass juveniles (mean initial body wet weight 6.6±1.1 g and mean total length 8.56±0.52 cm) were reared under closed circulated water system conditions at different stocking densities (80, 165, 325 and 650 specimens/m 3) for 168 days. The aim of the experiment was to determine the general behavior and the effect of fish stocking density on fish growth, feeding and metabolism during the critical period of the first 6 months of the commercial life of sea bass. Statistically significant differences ( P<0.05) for final fish weight were observed between groups of the two highest and the lowest stocking densities. The highest specific growth rate and the lowest food conversion ratio were observed for fish of the highest stocking density. No statistically significant differences ( P<0.05) were found in haematocrit values, while no meaningful statistical differences were found in hepatosomatic indices in the groups of fish held at any stocking density. Significant differences in water quality among treatments was observed, with relatively poorer water quality occurring at the higher fish densities. The results suggest that schooling behavior of the sea bass may have been a factor in the observed differences in fish performance. However, no formation of clear dominance hierarchies was observed. It is concluded that sea bass, within the range of stocking densities tested and at least at its early stages, does not belong to that fish category which is characterised by an inverse correlation between stocking density and growth rate.

Feeding Behaviour and Food Utilisation in Tilapia, Oreochromis Niloticus: Effect of Sex Ratio and Relationship With the Endocrine Status

Toguyeni, A., B. Fauconneau, T. Boujard, A. Fostier, E. R. Kuhn, K. A. Mol and J. F. Baroiller. Feeding behaviour and food utilisation in Tilapia, Orechromis niloticus: Effects of sex ratio and relationship with the endocrine status. Physiol Behav 62(2) 273–279, 1997.—The feeding behaviour of male monosex, female monosex, and mixed groups of Oreochromis niloticus was studied under conditions of self-feeding. Feeding activity was observed almost exclusively during the light period. The food intake pattern was similar whatever the sex ratio, and voluntary food intake (VFI) appeared lower in the male monosex groups than in the others. Male monosex groups displayed higher specific growth rates (SGR) and a lower food conversion ratio than female monosex and mixed groups. The SGR of males was higher in the monosex than in the mixed groups, whereas females of mixed and monosex groups displayed no significant difference in SGR. The efficiency of food utilisation was also analysed: nutrient retention ratios were higher in male monosex than in female monosex and mixed groups. Males displayed a distinctly higher metabolic capacity. Differences in sex-related hormones (11 ketotestosterone = 11-KT, 17 β-Oestradiol = 17 β- E2) and a metabolic hormone (triiodothyronine = T3) were observed between males and females. The hypothesis of an involvement of these hormones in the higher metabolic capacity of males is discussed. The observed differences in feeding behaviour between the different groups also suggest an effect of social interactions on the efficiency of food conversion and thus on the differential growth of males and females.

Food Efficiency in Pure Strains and Hybrids of Laying Hens Analysed in a Diallel Cross: I. Effect of Total Heterosis on Important Traits

Abstract The present paper describes the effect of heterosis found in a full diallel design 4×4 pure strains of laying hens. There were 36 individually measured hens per combination. In economic terms and with regard to a low food conversion ratio (FCR), positive heterosis was found for egg weight, egg number and total egg mass, while negative heterosis was found for food consumption in the rearing period 0-16 weeks, body weight, weight gain and yolk percentage. On average, there was negative but non-significant heterosis for FCR. Five of the combinations had positive but non-significant heterosis in FCR, while seven combinations had negative heterosis; three were significantly different from zero. No significant differences in mortality between the pure strains and the hybrids were found.

Effect of dietary protein level on puberty, oocyte growth and egg chemical composition in the tilapia, Oreochromis niloticus (L.)

Oreochromis niloticus were maintained on 5 isocaloric diets of different dietary protein levels (10, 17, 25, 32 and 40%). In Expt. 1, O. niloticus (initial mean weight approximately 0.3 g) maintained on diets of 10 and 17% protein levels showed lower growth rates compared to those on the higher protein levels and none reached puberty. In Expt. 2 (initial mean weight approximately 3 g), only those receiving 10% dietary protein level gave similar results; fish fed 17% reached puberty. Fish fed higher protein levels (32 and 40%) reached puberty at an earlier age, with oocytes growing and maturing faster, than those fed lower levels (≤ 25%). The former also showed higher growth rates, lower food conversion ratios and higher survival rates. When the onset of puberty and the rate of oocyte maturation were evaluated in relation to size (regardless of age), there were no significant differences among the treatments, suggesting that dietary protein may have influenced oocyte growth and puberty by its effect on growth. The chemical composition of post-vitellogenic oocytes, expressed as percent protein, lipid, moisture, and essential amino acids (mg in 100 mg protein), was not significantly different among the different dietary treatments.

Selection for components of efficient lean growth rate in pigs 4. Genetic and phenotypic parameter estimates and correlated responses in performance test traits with ad-libitum feeding

AbstractGenetic and phenotypic parameters and correlated responses in performance test traits were estimated for populations of Large White (LW) and British Landrace (LR) pigs tested in Edinburgh and Wye respectively, to four generations of divergent selection for lean growth rate (LGA), lean food conversion (LFC) and daily food intake (DFI) with ad-libitum feeding.There were differences between the two populations in genetic parameters, as LW heritabilities for growth rate, daily food intake and backfat depths were higher and the correlation between growth rate and backfat was positive for LW, but negative for LR. However, heritabilities, genetic and phenotypic correlations were generally comparable between selection groups, within each population. Genetic and phenotypic correlations indicated that animals with high daily food intakes were faster growing, had positive residual food intakes (RFI), were fatter with higher food conversion ratios. RFI was highly correlated with daily food intake and food conversion ratio, but phenotypically independent of growth rate and backfat, as expected.Selection for LGA, in LW and LR populations, increased growth rate (54 and 101 g/day), but reduced backfat (−3·9 and −2·0 mm), food conversion ratio (−0·23 and −0·25) and total food intake (−11·8 and −12·6 kg). There was no change in daily food intake in LW pigs (−19 g/day), but daily food intake increased in the LR pigs (69 g/day). With selection for LFC in LW and LR populations, there was no response in groivth rate (9 and 9 g/day), but backfat (−4·1 and −2·1 mm), total (−6·6 and −11·8 kg) and daily food intake (−90 and −172 g) were reduced, as animals had lower food conversion ratios (−0·13 and −0·22). LW and LR pigs selected for DFI ate more food in total (6·8 and 5·9 kg) and on a daily basis (314 and 230 g), grew faster (94 and 51 g/day) and had higher food conversion ratios (0·12 and 0·13). Backfat was increased in LW pigs (3·7 mm), but not in the LR population.In general, efficiency of lean growth was improved by increasing groivth rate, with little change in daily food intake from selection for LGA, but was primarily due to reduced daily food intake with selection on LFC.

Intensive polyculture of common carp ( Cyprinus carpio L.) and herbivorous fish [silver carp, Hypophthalmichthys molitrix (Val.), and grass carp, Ctenopharyngodon idella (Val.)

Intensive polyculture of common carp and herbivorous fish (silver carp and grass carp) at high stocking densities and with intensive feeding with fodder and mineral and organic fertilization was carried out without mechanized aeration and automated feeding. Two stocking patterns were tested. The first, in Pond 1 (with an area of 2.5 ha), had the following stocking rates: one-year carp (C 1), 8000 fish/ha; one-year silver carp (S 1), 1500 fish/ha; and one-year grass carp (G 1), 200 fish/ha. The yield was 6292 kg/ha of standard consumer fish (C 1+ 743 g, S 1+ 944 g, and G 1+ 1000 g) at a relatively low food conversion ratio (2.24) and high survival of all fish. Within the total yield, the two-year carp contributed 76%, the silver carp 21%, and the grass carp 3%. The second stocking pattern, in Pond 2 (0.25 ha), had the following rates: C 1, 8500 fish/ha; S 1, 2000 fish/ha; and G 1, 200 fish/ha, and produced a still higher total yield (6629 kg/ha) at a relatively low food conversion ratio (2.10). The two-year carp in Pond 2 contributed 88% of the total yield, and the herbivorous fish only 12% even though they accounted for 20% of the stock. Our results (Pond 2) are compared with other record yield experiments under similar conditions but including tilapia. At a total stocking rate of 10 700 fish/ha and without participation of tilapia, over a period of 186 days (as against 126 days in the other experiment), our experiments gave a total yield which was 347 kg/ha higher at a food coefficient 15% lower. The growth period was 60 days longer in our experiments but it included April and October when water temperature is much below the optimum and only 4% of the total amount of fodder was assimilated.

The effects of treatment of barley grain with sodium hydroxide and milling on its nutritive value for finishing pigs

ABSTRACTGrowing pigs were given diets based on barley (whole or milled), which was either untreated or sprayed with an aqueous solution of sodium hydroxide (270 g sodium hydroxide per kg water) to give 33·8 g sodium hydroxide per kg dry matter. The barley grain was treated with sodium hydroxide while in the whole state. A total of 48 pigs penned individually were given the diets on a restricted scale of feeding from an initial weight of 31·6 kg until slaughter at 81·7 kg live weight. In a metabolism study, eight boars were subjected to the same experimental treatments in two identical 4 × 4 balanced change-over experiments.The diet containing untreated milled barley gave significantly faster live-weight gain and lower food conversion ratio than the other three diets (P &lt; 0·001). Food conversion ratios were similar for untreated whole barley and sodium hydroxide-treated barley, whether this was whole or milled. Killingout proportion was similar for untreated and treated milled barley but was significantly lower when the diet contained untreated or treated whole barley.Milling significantly increased the digestibility of energy and nitrogen. Treatment with sodium hydroxide improved the digestibility of energy in the diet with whole barley but not in the diet with milled barley. With both whole and milled barley, treatment with sodium hydroxide increased the digestibility of crude fibre (P &lt; 0·05) but with ground barley the digestibility and retention of nitrogen were reduced considerably by treatment with sodium hydroxide.It is concluded that treatment of barley with sodium hydroxide did not improve the nutritive value of either milled or whole grain, that it reduced the digestibility of nitrogen and that it severely depressed the utilization of digested energy for growth.