Feed Utilization Parameters Research Articles

Evaluation of Cow Pea Seed Meal, Vigna sinensis, as a Dietary Protein Replacer for Nile tilapia, Oreochromis niloticus (L.), Fingerlings

Abstract The main objectives of this study were to evaluate the effect of partial and total replacement of fish meal (FM) protein by cow pea seed meal (CPSM) protein in practical diets on growth performance, feed utilization, and body composition of Nile tilapia, Oreochromis niloticus (L.). Fish of an average initial weight of 4.6 ± 0.2 g were stocked in 15 glass aquariums (80 L each) at a rate of 15 fish per aquarium. FM protein (30% of the diet) was used as the sole source of animal protein in the control diet. Percent replacement of FM by CPSM on the basis of crude protein were as follows: 0% (control diet A), 25% (diet B), 50% (diet C), 75% (diet D), and 100% (diet E). Diets were fed to fish at a rate of 4% of the total fish biomass daily, for a period of 16 wk. The results of this study revealed that the fish fed control diet A (100% FM) had the best average final body weight, specific growth rate (SGR %/d), weight gain (g/fish), weight gain %, while the poorest results for all parameters were obtained with fish fed diet E (100% CPSM). The same parameters of fish fed diets B (25% CPSM) and C (50% CPSM) were not significantly different (P > 0.05) from those of fish fed the control diet A. Feed utilization parameters of fish fed diets A, B, C, and D were better than for diet E. Proximate composition of whole‐body moisture and ash contents were not significantly different (P > 0.05) among all experimental diets and control diet. Whole‐body protein contents for fish fed diets B and C were superior to the control diet A. Incorporation of CPSM in the diets significantly increased whole‐body fat content. Incorporation of CPSM in the diets significantly decreased apparent digestibility coefficient of crude protein crude fat and energy. Diets B and C were not significantly different from control diet A. Therefore, these findings suggest that up to 50% of FM protein can be replaced by CPSM protein in Nile tilapia diets without any adverse effects on growth performance, feed utilization, body composition, and digestibility.

Effect of feeding apidaecin on common carp ( Cyprinus carpio) growth performances and immune function

Effect of apidaecin on common carp ( Cyprinus carpio) based on growth performance, feed utilization (Feed Conversion Ratio, FCR) and immune parameters were investigated. Twelve aquaria with three replicates for G1-3 and control were used. The synthesized apidaecin peptide was added to common carp basal diets (Control) as additives in three concentrations: 10.0 mg kg − 1 (G1), 15.0 mg kg − 1 (G2) and 30.0 mg kg − 1 (G3) by wet weight of basal diet. After an 80-day feeding experiment, G2 and G3 showed significantly better ( P < 0.05) results of growth performances and FCR than the control. However, there was no remarkable difference ( P > 0.05) between G2 and G3. As for G1, the final weight, SGR (Specific Growth Rate) and DG (Daily Gain) were increased and the FCR was decreased, but not significantly ( P > 0.05) compared with the control. The serum lysozyme activity of G2 and G3 was significantly increased ( P < 0.05) than the control. As for the alternative complement pathway activity, G2 and G3 were also higher ( P < 0.05) than the control. However, no significant difference ( P > 0.05) was found whichever between G2 and G3 or between G1 and G2 in both lysozyme and the alternative complement pathway activities. Furthermore, there was no remarkable difference between G1 and the control in immune parameters.

Evaluation of fermented silage made from fish, tomato and potato by-products as a feed ingredient for Nile tilapia, Oreochromis niloticus

ish by-products were fermented with Lactobacillus plantarum at 30°C using molasses as carbohydrate source. The ensilage process was completed after 30 days and at the end, a desirable and stable pH (4.5) was attained. Dried tomato by-product meal (TBM) and potato by-product meal (PBM) were used as alternative filler and blended with the liquid silage (40:30:30 w/w) and sundried. The resulting dried silage meal was included in the experimental diets to replace 0, 10, 20, 30, 40 or 50% of dietary protein (by weight) in isonitrogenou s (30% CP) and isocaloric (2700 kcal ME/kg) pelleted diets. No significant differences were found for apparent digestibility coefficient (ADC) of dry matter (DM), crude protein (CP), ether extract (EE) and nitrogen free extract (NFE) up to 30% inclusion level, while the highest inclusion levels (40 or 50%) significantly reduced ADC for DM, CP, EE and NFE. In a 90-day growth trial, the replacing of dietary protein by fish silage protein up to 30% of dietary protein in tilapia diet had no significant effect on growth performance including final body weight (BW), body length (BL), condition factor (K), weight gain (WG) and specific growth rate (SGR). The highest replacing levels (40 or 50%) significantly (P<0.001) reduced BW, BL, K, WG and SGR. Results of growth were relatively parallel to those of feed intake, feed conversion ratio (FCR) and protein efficiency ratio (PER) indicating the possibility of replacing 30% of dietary protein by fermented silage in Nile tilapia diets to reduce feed costs, DM and CP contents of the whole fish for the different experimental fish groups were not significantly affected, while EE in the whole fish body was significantly decreased with increasing the inclusion levels of silage in the diets and the opposite trend was observed for ash content. From the economic view, results obtained in the present study indicated the possibility of replacing 30% of dietary protein by silage in tilapia diets without adverse effect on growth or feed utilization parameters and this replacement reduced feed costs/kg diet and feed costs/kg weight gain by 22.43 and 22.02%, respectively.

Growth performance and feed utilization of Nile tilapia Oreochromis niloticus (Linnaeus, 1758) and tilapia galilae Sarotherodon galilaeus (Linnaeus, 1758) fingerlings fed plant protein-based diets

This study was designed to determine the effect of complete substitution of fish meal (FM) by three plant protein sources including extruded soybean meal (SBM), extruded full-fat soybean (FFSB) and corn gluten meal (CGM) on growth and feed utilization of Nile tilapia Oreochromis niloticus and tilapia galilae Sarothrodon galilaeus. Four isonitrogenous of crude protein (ca. 28.0%) and isocaloric (ca. 19 MJ kg−1) experimental diets were formulated. The control diet (diet 1) was prepared with FM as the main protein sources. Diets 2–4, each FM control diet, were completely substituted with SBM (diet 2), FFSB (diet 3) and CGM (diet 4). l-lysine and dl-methionine were added to plant protein diets to cover the nutritional requirements of tilapia. Each treatment was allocated to three net pens and fed for 17 weeks. Nile tilapia fed the control diet showed significantly higher (P≤0.05) values for final body weight (FBW), feed intake (FI), weight gain (WG) and specific growth rate (SGR), whereas fish fed the diet with CGM achieved the lowest values. Tilapia galilae fed SBM diet recorded the highest (P≤0.05) values for growth performance. Better feed conversion ratio (FCR) for both Oreochromis niloticus and Sarothrodon galilaeus was observed when fish were fed SBM diet, whereas the worse FCR was recorded for FFSB diet. Feed utilization parameters including protein productive value (PPV), fat retention (FR) and energy retention (ER) showed significant differences (P≤0.05) for both the species fed different dietary protein sources. The present results suggest that, for Nile tilapia, both SBM and FFSB supplemented with dl-methionine and l-lysine can completely replace dietary FM. Meanwhile, S. galilaeus fed SBM diet exhibited comparable growth and feed utilization with those fish fed a fish-meal-based diet.

The Effect of Different Levels of Krill Meal Supplementation of Soybean-based Diets on Feed Intake, Digestibility, and Chemical Composition of Juvenile Nile Tilapia Oreochromis niloticus, L

— The main objective of this study was to determine the effect of different levels of krill meal (KM) as a feed attractant in juvenile Nile tilapia fed soybean (SBM) diets on growth performance, feed utilization, and body composition. Fish of an initial average weight 0.8 × 0.01g were stocked in 18 glass aquaria (80 L each) at a rate of 25 fish per aquarium. Fish meal (FM 20% of the diet) was used as the sole source of animal protein in the control (Diet 1). Diets 2 to 6 had (SBM) protein with various levels of krill meal (0.0,1.5,3.0,4.5, and 6.0%, diets 2-6 respectively). Test diets were fed to satiation to triplicate groups of Nile tilapia four times daily for 20 wk. Fish fed krill meal supplemented diets had significantly (P < 0.05) better growth performance compared with fish fed the unsupplemented and FM control diets. The krill meal increased growth of Nile tilapia by 31.9% compared to control diets (average Anal wet weight, 14.15 × 0.95 g and 10.72 × 0.2 g, respectively). Moreover, weight gains were not significantly different for fish fed diets with different levels of krill meal. Feed utilization parameters such as feed intake, feed conversion ratio, protein efficiency ratio differed significantly for fish fed krill meal diets compared with control. Digestibility of nutrient and energy of diets increased with increasing levels of krii meal. The incorporation of krill meal in diets significantly affected the protein, fat, ash, and energy of whole body composition. These results suggest that supplementation of krill meal at 1.5% in the diets of Nile tilapia as attractant or stimulant may lead to increased feed intake, growth performance, and feed utilization. Soybean meal can completely replace fishmeal in diets for juvenile tilapia.

Effect of dietary lipid source on the growth, tissue composition and hematological parameters of largemouth bass ( Micropterus salmoides)

We conducted a 12-week feeding trial with LMB fed practical diets differing primarily in lipid source. We reduced the fish oil content of commercially solvent-extracted menhaden fish meal to 0.5–1.2%, and used it as the primary protein source in all test diets. Diets were supplemented with 10% lipid as canola (CAN), chicken (CHK), menhaden fish oil (MFO) or CHK + MFO (50/50%). An additional diet contained non-extracted fish meal and 10% CHK (NEF + CHK), and a commercial trout diet (SC) was also included. Growth, survival, feed utilization, body composition and health parameters were measured to assess diet effects. Weight gain, survival, feed intake, feed conversion ratio, and protein efficiency ratio of LMB fed the test diets did not differ. Weight gain of LMB fed the SC diet was higher than that of LMB fed the test diets. Muscle lipid of fish fed the diet with 10% MFO was higher than that of fish fed diets with an equal mixture of CHK + MFO or NEF + CHK, and muscle lipid of LMB fed the SC diet was higher than that of fish fed the test diets. The n-3 to n-6 fatty acid ratio of the test diets was lower than expected because the poultry meal contained 16% lipid (high in 18:2n-6). The ratio of n-3 to n-6 fatty acids was higher in muscle and liver of fish fed the SC diet than those of fish fed the test diets. Docosahexaenoic acid (22:6n-3) and 20:4n-6 were conserved in fish fed diets without HUFA, but 20:5n-3 declined sharply from initial values. The index of atherogenicity (IA) and the index of thrombogenicity (IT) of LMB fed the test or SC diets were below 1.0 (considered healthful). Lymphocytes were higher in fish fed diets with > 4% n-3 fatty acids, including the CAN diet without HUFA. There were no differences in the Hk, Hb, MCHC, or serum lysozyme of LMB fed the test diets, but lysozyme was lower in LMB fed the SC diet than those fed the CHK + MFO diet. Fish fed diets with 10% MFO or CAN had higher alternative complement activity than fish fed diets with CHK. Tissue concentrations of HUFA (especially 20:4n-6 and 22:6n-6) were not depleted in 12 weeks, possibly due to conservation of initial HUFA, synthesis of HUFA from 18:3n-3 and 18:2n-6, or both. Therefore, non-fish oils might reduce diet cost with few deleterious effects for at least a quarter of the production cycle of LMB.

Dietary l-methionine requirement of juvenile grouper Epinephelus coioides at a constant dietary cystine level

The present experiment was conducted to determine the methionine requirement and the effect of dietary methionine levels on growth, feed utilization, body composition, haematological and morphometrical parameters in juvenile grouper. Diet 1 with fish meal as the sole protein source was used as a reference. Diets 2–7 were formulated to contain 48% crude protein and supplemented with graded concentrations of l-methionine, resulting in six levels of dietary methionine (0.55–1.81% of dry matter) at a constant dietary cystine level of 0.26%. Fish (initial weight of 13.25 ± 0.19 g, mean ± S.D.) were reared in twenty-one 500-l circular fibreglass tanks provided with flow-through seawater at 28–30.5 °C and salinity of 24–28 mg/l for 8 weeks. Fish fed the reference diet had significantly higher weight gain (WG), specific growth rate (SGR), feed utilization efficiency, protein and lipid contents of whole body, plasma protein and cholesterol concentrations ( P < 0.05). Among other treatments fed the diets containing CAAs, increasing dietary methionine up to 1.34% increased growth performance and feed utilization, whole-body protein and lipid contents, condition factor (CF), viscerosomatic index (VSI) and intraperitoneal fat ratio (IPR), beyond which they remained nearly unchanged. Plasma protein concentration showed no significant differences for fish fed the diet containing more than 1.11% methionine. Triacylglycerol increased with increasing dietary methionine levels, but showed a relatively lower value for fish fed the 1.59% methionine diet. Plasma glucose could not be related to dietary treatments. Cholesterol was the highest for fish fed the 1.34% methionine diet but showed no significant difference among other treatments. Fish fed higher-methionine diets exhibited relatively higher essential amino acid (EAA) contents in muscle than fish fed the lower methionine diet ( P < 0.05). Broken-line regression analysis of WG against dietary methionine level indicated that optimal dietary methionine requirement for juvenile grouper was 1.31% of the diet (corresponding to 2.73% of dietary protein on a dry weight basis).

Use of cottonseed meal supplemented with iron for detoxification of gossypol as a total replacement of fish meal in Nile tilapia, Oreochromis niloticus (L.) diets

The objective of this study was to determine the effect of total replacement of fish meal by cottonseed meal (CSM) supplemented with various levels of iron in practical diets on growth performance, feed utilization, body composition and some biological and haematological parameters of Nile tilapia, Oreochromis niloticus (L.). Juvenile fish (average weight 3.78±0.1 g) were stocked in 18 glass aquariums (80 L each) at 25 fish per aquarium. Fish meal (50% of the diet) was used as the sole source of animal protein in the control diet 1. Diets 2–6 had 100% CSM (0.145% free gossypol) protein with various levels of supplemented iron (86, 486, 972, 1458 and 1944 mg Fe kg diet−1) in diets 2–6 respectively. Diets were fed to fish twice daily at a rate of 3% of body weight during the first 12 weeks then 2% of the total fish biomass daily until the end of the experiment (30 weeks). The results of this study revealed that, groups of fish fed diets 1, 4, 5 and 6 had significantly (P≤0.01) the higher average body weight and specific growth rate than those of fish fed diet 2 (100% CSM without iron supplementation) and diet 3 (100% CSM plus 486 mg Fe kg diet−1). The best values for feed conversion ratio, protein efficiency ratio and condition factor (K) were recorded with groups of fish fed diet 4 (100% CSM plus 972 mg Fe kg diet−1). Red blood cell count, haematocrit and haemoglobin were increased with increasing levels of iron and significantly affected by dietary iron. Hepatosomatic index for diets 3–6 were not significantly different (P>0.05) and superior to that of diet 1 control [100% fish meal (FM)]. The gonadosomatic index of males of Nile tilapia was not influenced by CSM diets with or without iron, while females of Nile tilapia were significantly influenced with iron and the lowest values were recorded with groups of fish fed diet 2 (100% CSM without iron supplementation). Apparent digestibility coefficients of protein, fat dry matter and energy were relatively high for most diets supplemented with iron and increased by increasing iron supplementation. There were no significant differences between groups of fish fed diet 1 (100% FM) and diets 5 and 6 which contained 100% CSM with additional 1458 and 1944 mg Fe kg diet supplemental iron−1 respectively. Proximate composition of whole body was not influenced by diet. Adding 972 mg Fe kg diet−1 from ferrous sulphate to the CSM-based diets that contained 972 mg free gossypol (1:1 iron to free gossypol ratio) for Nile tilapia reduce the negative effects of gossypol and improved growth performance, feed utilization and blood parameters and can totally replace fish meal in tilapia diets.

Performance of Crossbred Gilts Fed on Diets with Higher Levels of Fat and Fibre through Addition of Rice Bran

Crossbred gilts (n=54) of about 26.38t0.85 kg body weight and 25 weeks of age were randomly divided into 18 groups of 3 animals each. Three dietary treatments viz., T 1 , T 2 and T 3 were formulated. The treatment T 1 containing maize grain (35%) and wheat bran (47%) along with soybean meal and fish meals served as control diet. Rice bran (RB) was selected as a single source of fat (13.02%) and fibre (17.12%), which was gradually increased in diets T 2 (41%) and T 3 (82%) replacing maize grain and wheat bran of T 1 at 50% and 100% in the diets T 2 and T 3 , respectively. The fat and fibre levels of the diets were thus 3.46 and 5.24, 9.3 land 9.69 and 11.61 and 13.26% in T 1 , T 2 and T 3 , respectively. All the diets, however, contained almost similar concentration of CP (18.35′0.29%). Each dietary treatment was offered to six replicated groups of 3 piglets in following completely randomized design and feeding was continued for 112 days during the growing phase. Growth, feed utilization, reproductive performance, nutrient utilization and different blood biochemical parameters were studied. Growth rate, feed intake and feed conversion were lower (p<0.01) in T 3 in comparison to T 1 or T 2 . Digestibility of all the nutrients except EE was reduced significantly (p<0.01) in T 3 . Serum glucose level decreased (p<0.01), whereas the urea and cholesterol concentration in the blood increased (p<0.01) in T 3 . The duration of estrus of pigs fed diet containing 82% RB (T 3 ) was highly variable within the group, but all the groups showed statistically similar duration of estrous. Feed cost per unit gain was found to be comparable between control (T 1 ) and T 2 group. The results indicated that RB can be included up to 41% in swine diets replacing 50% of maize and wheat bran. Higher concentrations of ether extract and fibre beyond 9.31 and 9.69% in diet had detrimental effect on growth, nutrient utilization and reproductive performance.

Pigmenting efficacy of astaxanthin and canthaxanthin in fresh-water reared Atlantic salmon, Salmo salar

A 25-week feeding trial was performed to evaluate the efficacy of astaxanthin versus canthaxanthin, at mixed, graded levels in diets of freshwater reared Atlantic salmon, growing from an initial body weight of 408 g to a final weight of 1.2 kg. Five dietary pigment ratios were tested in five replicates. Dietary treatments were set-up to provide pigment ratios ranging from 1.00 of pigment from astaxanthin (45 mg/kg feed), to 1.00 from canthaxanthin (72 mg/kg feed). Growth and feed utilisation parameters were unaffected by dietary treatment ( P>0.05). In contrast to work on rainbow trout, there was no difference in the flesh pigment deposition of astaxanthin or canthaxanthin ( P>0.05) in Atlantic salmon. Flesh deposition was linearly related to feed dose for both carotenoids, indicating that even at 70 mg/kg, canthaxanthin deposition had not reached a plateau in the fish under test. This could support the practice of feeding of levels of carotenoid at around 70 mg/kg in early grow-out phases of salmon since a significant incremental flesh response was observed ( P<0.05). Linearity of the dose/ deposition relationship indicated that feed astaxanthin and canthaxanthin did not interact. Despite the relatively low flesh pigment levels attained, raw fillet colour was seen to be close to colour targets adopted for harvest-size fish.

A note on the use of breadfruit meal (&lt;i&gt;Artocarpus incisus&lt;/i&gt;) as a feed ingredient for broiler chickens

Breadfruit meal (BFM) (Artocarpus incisus) was evaluated as a poultry feed ingredient in a pilot study. Diets containing 0, 25, 50 and 75 BFM/kg were fed, ad libitum, to 240 day-old broiler chickens for a period of 8 weeks. Birds had free access to water. Performance criteria studied included feed intake, growth rate, efficiency of feed utilization, mortality, carcass and blood parameters. The concentration of BFM in the diet had significant negative influence on feed consumption. The level of BFM had no significant impact on carcass yield, mortality or blood parameters

Growth, feed utilization and nutrient digestibility in tilapia fingerlings (Oreochromis aureusSteindachner) fed diets containing bacteria-treated coffee pulp

The effectiveness of bacteria treated-coffee pulp (BT-CoP) in fish diets was evaluated in a feeding trial with Oreochromis aureus (Steindachner) fingerlings. Five diets were formulated to contain 0%, 6%, 12%, 18% and 24% BT-CoP, replacing wheat meal. Fish were reared in a recirculating unit consisting of 16 aquaria. Each aquarium was stocked with 10 fish of 1.1-2.4?g. Fish were fed ad libitum twice daily (10 and 15?h) for 4?weeks. Fish fed diets without BT-CoP and with 6% BT-CoP showed similar growth (body weight, growth rate: RGRm) and feed utilization (feed conversion ratio, protein efficiency ratio, apparent net protein utilization). Diets containing 0% and 6% BT-CoP gave similar dry matter and protein digestibility coefficients, but dietary BT-CoP levels higher than 6% produced lower digestibility values, except for carbohydrate. It is concluded that O. aureus fingerlings may assimilate only small amounts (6%) of BT-CoP in the diets without adverse effects on growth and feed utilization parameters. The CoP-containing diets did not affect fish survival (100%). The depression in tilapia performance may be associated mainly with the high level of fibre present in the CoP diets.

Effects of Dietary Lipid and Energy to Protein Ratio on Growth and Feed Utilization of Juvenile Mutton Snapper Lutjanus analis Fed Isonitrogenous Diets at Two Temperatures

AbstractGrowth and feed utilization of juvenile, hatchery‐reared mutton snapper Lutjanus analis (mean weight = 12.2 g) were compared for 40 d in laboratory aquaria on four isonitrogenous diets (45% crude protein) of varying lipid content (6, 9, 12 and 15%) with energy:protein ratios (E: P; kJ/g protein) of 33.9, 36.3, 38.8, and 41.2, respectively. Growth on these diets was compared under temperatures of 25 and 30 C. Final weights (Wtr) and specific growth rates (SGR) were higher (P &lt; 0.05) at lower dietary E: P ratios of 33.9 and 36.3 (Wtr= 20.3–22.0 g; SGR = 1.25–1.35%/d) than at E:P ratios of 38.8 and 41.2 (Wtr= 17.2‐17.7 g; SGR = 0.84–0.85%/d). Growth at 30 C (Wtr= 21.5 g, SGR = 1.35%/d) was higher (P &lt; 0.05) than at 25 C (Wtr= 17.3 g; SGR = 0.82%/d). Feed consumption (FC) was higher (P &lt; 0.05) at a dietary E: P ratio of 33.9 (1.57%/d) than at 36.3 (1.27%/d) or 38.8–41.2 (0.89–0.98%/d). Growth was highly correlated (P &lt; 0.01) to E: P ratio and to feed consumption. Feed conversion ratio (FCR = 2.17–3.98), protein efficiency ratio (PER = 0.58–1.03) and apparent net protein retention (ANPR = 15.8–20.0%) were not significantly (P &gt; 0.05) affected by dietary E: P ratio. Apparent net energy retention (ANER) was higher (P &lt; 0.05) at E: P ratios of 33.9 and 36.3 (9.50–9.98%) than at E: P ratios of 38.8 and 41.2 (7.15–7.10%). Feed utilization parameters were significantly (P &lt; 0.05) better at 30 C (FC = 1.36%/d; FCR = 2.6; PER = 0.88; ANER = 10.2%) than at 25 C (FC = 1.03%/d; FCR = 3.38; PER = 0.69; ANER = 6.72%), with the exception of ANPR (17.0–17.8%). Maximum growth and energy retention in juvenile mutton snapper using a diet containing 45% crude protein was obtained at dietary lipid levels of 6–9% and E: P ratios of 33.9–36.3 kJ/g protein. Studies which determine optimum protein levels and the effects of reducing E: P ratios below 33.9 kJ/g are needed to improve feed conversion and growth.

Balance trials with African catfish Clarias gariepinus fed phytase-treated soybean meal-based diets

Balance trials were conducted with African catfish Clarias gariepinus to assess the effect of phytase treatment of soybean meal-based diets on growth, feed utilization and nutrient budgets. Isocaloric (20–22 kJ g−1) and isonitrogenous (47–50% protein) diets were tested. In a first experiment the control diet (58% fish meal and 18% soybean meal) was compared with two diets containing 6% fish meal and 69% soybean meal, and two diets containing 29% fish meal and 41% soybean meal. One of each of these two diets had been pretreated with phytase (1000 units per kg dry diet). In the second experiment, the control diet (6% fish meal and 69% soybean meal, pretreated with 1000 units phytase kg−1 dry diet) was compared with four diets that were similar in composition but supplemented with increasing amounts of phytase (15, 380, 750, 1000 units kg−1 dry diet). Replacement of fish meal by soybean meal in the first experiment led to a depression in growth rate and feed utilization parameters. Results of both experiments clearly indicated a positive effect of phytase treatment, particularly on phosphorus digestibility and retention, and consequently the phosphorus conversion efficiency and the phosphorus budget. No differences in these parameters were found between addition of equal amounts of phytase by pretreatment or supplementation.

Quantitative methionine requirement of yellowtail ( Seriola quinqueradiata)

The quantitative methionine requirement of juvenile yellowtail was determined by feeding diets containing six levels of L-methionine ranging from 0.57 to 1.58% of dry diet in about 0.2% increments. Duplicate tanks, each containing 20 fish, were assigned to each diet. The fish were fed to satiation four times a day for 30 days and weight gain, feed utilisation parameters, hepatosomatic index (HSI), body and liver compositions, and serum components were measured. Weight gain, feed efficiency, protein efficiency ratio, nitrogen retention and HSI increased with increasing levels of methionine up to 1.20% and remained nearly constant thereafter. Protein and fat contents of body and liver were significantly different between treatments. Fish fed the diet with the lowest methionine content gave poor haematological characteristics and serum components. Based on broken line analysis of percent weight gain and feed efficiency, the methionine requirement of juvenile yellowtail was estimated to be 1.11% of the diet or 2.56% of dietary protein in the presence of 0.31% cystine.

The use of leucaena leaf meal in feeding Nile tilapia

A 14 week experiment was carried out to study the effects of replacing three different levels (33%, 66%; and 100%;) of berseem leaf meal (BLM) by leucaena leaf meal (LLM) treated in four different ways (drying for 48 h at 60 ‡C, autoclaved for 15 min, sprayed with 1% sodium hydroxide and incubated with rumen liquor for 24 h). Groups of Nile tilapia, Oreochromis niloticus (L.), fingerlings (5.07 g mean weight) were fed one of 13 isonitrogenous (30% crude protein) and isocaloric (19.67 kJ per g dry matter) diets, with two replicates (10 fish per aquarium) for each treatment. The results indicated that weight gain, specific growth rate, feed conversion ratio and protein utilization parameters were significantly (p < 0.05) increased by the higher percentage of dried or cooked LLM in tilapia diets. On the other hand, the lowest growth performance and feed utilization parameters were observed in the groups fed LLM diets treated with sodium hydroxide or incubated with rumen liquor. Carcass protein and fat increased significantly (p < 0.05) with increasing levels of LLM and simultaneously decreasing ash content.

Can lantana seeds be utilized in lamb rations?

Lantana seeds contain 70.6 g crude protein, 12.8 g ether extract, 103.1 g crude fibre, 761.0 g nitrogen-free extract, 52.5 g total ash, 8.4 g calcium and 2.5 g phosphorus/kg dry matter. The replacement, by lantana seeds, of 200 g maize/kg of concentrate mixture for lambs was studied in two experiments lasting 3–4 months. The crude protein concentration in the lantana ration was lower than in the maize, and significantly ( P<0.01) so in the second experiment. In the first experiment, the digestibility and intakes of dietary crude protein (DCP) and total dietary nitrogen (TDN) of the lantana group were not significantly lower. In the second experiment, dry matter and crude protein digestibility and intakes of DCP and TDN of the lantana group were significantly ( P<0.01) lower than the maize group. Even after adjustment for mean protein concentration in the diets, the intakes of DCP ( P<0.01) and TDN ( P<0.05) in the lantana group were significantly lower. In a repeat metabolic trial also, the adjusted intakes of both DCP and TDN ( P<0.01) of the lantana group were significantly lower. In spite of the depression in feed utilization, the biochemical and haematological parameters of the blood of animals in the lantana group were within the normal range. The apparent non-toxicity of lantana seeds to lambs over long-term feeding trials calls for further work on their possible utilization as a feed ingredient.

Controlled propagation of the African catfish, Clarias lazera (C. & V.) : IV. Effect of feeding regime in fingerling culture

Two experiments were carried out to study the effect of different feeding levels and feeding frequencies in the culture of Clarias lazera (C. & V.) fingerlings from 0.5 to 10 g. It was found that 0.5 g fingerlings could reach an average weight of about 10 g in 3–4 weeks when they were fed continuously for 24 h per day or 12 h at night at a daily rate of 8% of the biomass or more. A feeding level of 10% of the biomass appeared to be optimal, from the point of hygiene, growth rate and feed utilization parameters. Continuous feeding during part or all of the day clearly gave better growth than feeding two or four defined meals per day. When these preferred feeding regimes were practised, the feed conversion (wet weight) ranged from 0.65 to 0.97, the protein efficiency ratio from 2.14 to 3.04 and the productive protein value from 0.34 to 0.47. These values compare favourable with values reported for other cultured species, indicating that C. lazera fingerlings are efficient feed convertors. It could be calculated that, when the rations are readjusted only once a week, the high growth rates occurring in these experiments result in a considerable difference between the designated feeding rates and the actual feeding rates.