Taste plays a fundamental role in an animal’s ability to detect nutrients and transmits key dietary information to the brain, which is crucial for its growth and survival. Providing alternative terrestrial ingredients early in feeding influences the growth of rainbow trout (RT, Oncorhynchus mykiss). Thus, the present study aimed to assess the influence, via long-term feeding (from the first feeding to 8 months), of alternative plant ingredients (V diet for vegetable diet v. C diet for a control diet) in RT on the mechanism of fat sensing at the gustatory level. After the feeding trial, we studied the pathways of the fat-sensing mechanism in tongue tissue and the integrated response in the brain. To this end, we analysed the expression pattern of free fatty acid receptors (ffar) 1 and 2, markers of calcium-signalling pathways (phospholipase Cβ, Orai, Stim or Serca), the serotonin level (a key neurotransmitter in taste buds) and the expression pattern of appetite-regulating neuropeptides in the hypothalamus (central area of appetite regulation). The results revealed that the V diet modified the expression pattern of ffar1 and paralogs of ffar2 genes in tongue tissue, along with differential regulation of calcium-signalling pathways and a defect in serotonin level and brain turnover, without influencing neuropeptide expression. This study is the first to support that changes in feeding behaviour of RT fed a V diet could be due to the difference in nutrient sensing and a decrease in hedonic sensation. We revealed that RT have similar fat-detection mechanisms as mammals.

The present study evaluated the effects of increasing the dietary levels of EPA and DHA in Atlantic salmon (Salmo salar) reared in sea cages, in terms of growth performance, welfare, robustness and overall quality. Fish with an average starting weight of 275 g were fed one of four different diets containing 10, 13, 16 and 35 g/kg of EPA and DHA (designated as 1·0, 1·3, 1·6 and 3·5 % EPA and DHA) until they reached approximately 5 kg. The 3·5 % EPA and DHA diet showed a significantly beneficial effect on growth performance and fillet quality compared with all other diets, particularly the 1 % EPA and DHA diet. Fish fed the diet containing 3·5 % EPA and DHA showed 400–600 g higher final weights, improved internal organ health scores and external welfare indicators, better fillet quality in terms of higher visual colour score and lower occurrence of dark spots and higher EPA and DHA content in tissues at the end of the feeding trial. Moreover, fish fed the 3·5 % EPA and DHA diet showed lower mortality during a naturally occurring cardiomyopathy syndrome outbreak, although this did not reach statistical significance. Altogether, our findings emphasise the importance of dietary EPA and DHA to maintain good growth, robustness, welfare and fillet quality of Atlantic salmon reared in sea cages.

There is an urgent need to find alternative feed resources that can further substitute fishmeal in Atlantic salmon diets without compromising health and food quality, in particular during the finishing feeding period when the feed demand is highest and flesh quality effects are most significant. This study investigates efficacy of substituting a isoprotein (35 %) and isolipid (35 %) low fishmeal diet (FM, 15 %) with Antarctic krill meal (KM, 12 %) during 3 months with growing finishing 2·3 kg salmon (quadruplicate sea cages/diet). Final body weight (3·9 (se 0·04) kg) was similar in the dietary groups, but the KM group had more voluminous body shape, leaner hearts and improved fillet integrity, firmness and colour. Ectopic epithelial cells and focal Ca deposits in intestine were only detected in the FM group. Transcriptome profiling by microarray of livers showed dietary effects on several immune genes, and a panel of structural genes were up-regulated in the KM group, including cadherin and connexin. Up-regulation of genes encoding myosin heavy chain proteins was the main finding in skeletal muscle. Morphology examination by scanning electron microscopy and secondary structure by Fourier transform IR spectroscopy revealed more ordered and stable collagen architecture of the KM group. NEFA composition of skeletal muscle indicated altered metabolism of n-3, n-6 and SFA of the KM group. The results demonstrated that improved health and meat quality in Atlantic salmon fed krill meal were associated with up-regulation of immune genes, proteins defining muscle properties and genes involved in cell contacts and adhesion, altered fatty acid metabolism and fat deposition, and improved gut health and collagen structure.

The primary aim of this experiment was to evaluate the intestinal barrier permeability in vivo in rainbow trout (Oncorhynchus mykiss) fed increasing levels of soyabean meal (SBM). The relationship between SBM-induced enteritis (SBMIE) and the permeability markers was also investigated. Our results showed that the mean score of morphological parameters was significantly higher as a result of 37·5 % SBM inclusion in the diet, while the scores of fish fed 25 % SBM or lower were not different from those of the fish meal-fed controls (P < 0·05). SBMIE was found in the distal intestine (DI) in 18 % of the fish (eleven of sixty): ten in the 37·5 % SBM-fed group and one in the 25 % SBM-fed group. Sugar markers in plasma showed large variation among individuals probably due to variation in feed intake. We found, however, a significant linear increase in the level of plasma d-lactate with increasing SBM inclusion level (P < 0·0001). Plasma concentration of endotoxin was not significantly different in groups with or without SBMIE. Some individual fish showed high values of endotoxin in blood, but the same individuals did not show any bacterial translocation. Plasma bacterial DNA was detected in 28 % of the fish with SBMIE, and 8 % of non-SBMIE fish (P = 0·07). Plasma concentration of d-lactate was significantly higher in fish with SBMIE (P < 0·0001). To conclude, SBMIE in the DI of rainbow trout was associated with an increase in bacterial translocation and plasma d-lactate concentration, suggesting that these permeability markers can be used to evaluate intestinal permeability in vivo.

Barramundi (Lates calcarifer), a catadromous teleost of significant and growing commercial importance, are reported to have limited fatty acid bioconversion capability and therefore require preformed long-chain PUFA (LC-PUFA) as dietary essential fatty acid (EFA). In this study, the response of juvenile barramundi (47·0 g/fish initial weight) fed isolipidic and isoenergetic diets with 8·2 % added oil was tested. The experimental test diets were either devoid of fish oil (FO), and thus with no n-3 LC-PUFA (FO FREE diet), or with a low inclusion of FO (FO LOW diet). These were compared against a control diet containing only FO (FO CTRL diet) as the added lipid source, over an 8-week period. Interim samples and measurements were taken fortnightly during the trial in order to define the aetiology of the onset and progression of EFA deficiency. After 2 weeks, the fish fed the FO FREE and FO LOW diets had significantly lower live-weights, and after 8 weeks significant differences were detected for all performance parameters. The fish fed the FO FREE diet also had a significantly higher incidence of external abnormalities. The transcription of several genes involved in fatty acid metabolism was affected after 2 weeks of feeding, showing a rapid nutritional regulation. This experiment documents the aetiology of the onset and the progression of EFA deficiency in juvenile barramundi and demonstrates that such deficiencies can be detected within 2 weeks in juvenile fish.

The objective of the present study was to examine the effect of diets with descending fish meal (FM) inclusion levels and the addition of salt to the diet containing the lowest FM level on growth performances, feed conversion ratio, and intestinal solute carrier family 6 member 19 (SLC6A19) and oligopeptide transporter 1 (PEPT1) transcript levels, in freshwater-adapted European sea bass (Dicentrarchus labrax). We first isolated by molecular cloning and sequenced a full-length cDNA representing the neutral amino acid transporter SLC6A19 in sea bass. The cDNA sequence was deposited in GenBank database (accession no. KC812315). The twelve transmembrane domains and the ‘de novo’ prediction of the three-dimensional structure of SLC6A19 protein (634 amino acids) are presented. We then analysed diet-induced changes in the mRNA copies of SLC6A19 and PEPT1 genes in different portions of sea bass intestine using real-time RT-PCR. Sea bass were fed for 6 weeks on different diets, with ascending levels of fat or descending levels of FM, which was replaced with vegetable meal. The salt-enriched diet was prepared by adding 3 % NaCl to the diet containing 10 % FM. SLC6A19 mRNA in the anterior and posterior intestine of sea bass were not modulated by dietary protein sources and salt supplementation. Conversely, including salt in a diet containing a low FM percentage up-regulated the mRNA copies of PEPT1 in the hindgut. Fish growth correlated positively with the content of FM in the diets. Interestingly, the addition of salt to the diet containing 10 % FM improved feed intake, as well as specific growth rate and feed conversion ratio.

In recent years, livestock producers have been supplementing animal diets with fish meal (FM) to produce value-added products for health conscious consumers. As components of FM have unique neuroendocrine–immunomodulatory properties, we hypothesize that livestock producers may be influencing the overall health of their animals by supplementing diets with FM. In this study, 40 pregnant ewes were supplemented with rumen protected (RP) soybean meal (SBM: control diet) or RP FM, commencing gestation day 100 (gd100), in order to evaluate the impact of FM supplementation on the innate and acquired immune response and neuroendocrine response of sheep during pregnancy and lactation. On gd135, half the ewes from each diet (n = 10 FM, n = 10 SBM) were challenged iv with lipopolysaccharide (LPS) to simulate a systemic bacterial infection and the febrile, respiratory and neuroendocrine responses were monitored over time; the other half (n = 10 FM, n = 10 SBM) of the ewes received a saline injection as control. On lactation day 20 (ld20), all ewes (n = 20 FM, n = 20 SBM) were sensitized with hen egg white lysozyme (HEWL) and the serum haptoglobin (Hp) response was measured over time. The cutaneous hypersensitivity response (CHR) to HEWL challenge was measured on ld30 (n = 20 FM, n = 20 SBM), and blood samples were collected over time to measure the primary and secondary immunoglobulin G (IgG) response to HEWL. There was an attenuated trend in the LPS-induced febrile response by the FM treatment when compared with the SBM treatment (P = 0.06), as was also true for the respiratory response (P = 0.07), but significant differences in neuroendocrine function (serum cortisol and plasma ACTH) were not observed between treatments. Basal Hp levels were significantly lower in the FM supplemented ewes when compared with the SBM supplemented ewes (P < 0.01), and the Hp response to HEWL sensitization differed significantly over time between treatments (P < 0.01). The CHR to HEWL was also significantly attenuated in the FM treatment compared with the SBM (P < 0.01); however, treatment differences in the primary and secondary IgG responses to HEWL were not observed. These results indicate that FM supplementation differentially affects the innate and acquired immune responses in pregnant and lactating sheep compared with a typical SBM diet of commercial flocks. The long-term implications of this immunomodulation warrant further investigation.

In order to study whether lipid metabolism may be affected by maximum replacement of dietary fish oil and fish meal with vegetable oils (VO) and plant proteins (PP), Atlantic salmon (Salmo salar L.) smolts were fed a control diet containing fish oil and fish meal or one of three plant-based diets through the seawater production phase for 12 months. Diets were formulated to meet all known nutrient requirements. The whole-body lipid storage pattern was measured after 12 months, as well as post-absorptive plasma, VLDL and liver TAG. To further understand the effects on lipid metabolism, expression of genes encoding for proteins involved in VLDL assembly (apoB100), fatty acid uptake (FATP1, cd36, LPL and FABP3, FABP10 and FABP11) were measured in liver and visceral adipose tissue. Maximum dietary VO and PP increased visceral lipid stores, liver TAG, and plasma VLDL and TAG concentrations. Increased plasma TAG correlated with an increased expression of apoB100, indicating increased VLDL assembly in the liver of fish fed the high-plant protein- and VO-based diet. Atlantic salmon fed intermediate replacement levels of VO or PP did not have increased body fat or visceral mass. Overall, the present results demonstrate an interaction between dietary lipids and protein on lipid metabolism, increasing overall adiposity and TAG in the body when fish meal and fish oil are replaced concomitantly at maximised levels of VO and PP.

The first limiting nutrients in typical laying hen diets are the sulphur-containing amino acids and, in particular, methionine. To fulfil the birds’ recommended requirement, conventional diets are supplemented with synthetic methionine. As this is not allowed in organic production it becomes very important to have access to alternative high-quality protein feed ingredients. An experiment was performed to evaluate the possibility to compose a diet with 100% organically approved feed ingredients using mussel meal as a major source of methionine. The experiment included 678 Lohman Selected Leghorn (LSL) and 678 Hyline White, W-98, layers during 20 to 72 weeks of age. There were 12 aviary pens with 113 birds in each. The birds were fed one of the two experimental diets containing either 3.5% or 7% dried mussel meat meal or a commercial organic diet from a Swedish feed manufacturer for comparison. Production and mortality were recorded daily per group, and egg weight was recorded once weekly. At 33, 55 and 70 weeks, 10 eggs from each treatment group were collected and analysed for internal egg quality. Diets had no significant effect on laying percentage, egg mass, feed intake, feed conversion ratio, mortality, bird live weight or proportion misplaced, cracked or dirty eggs. Egg quality, that is, shell deformation, shell breaking strength, albumen height, shell percentage and proportion of blood and meat spots were also unaffected. There was a significant difference in egg yolk pigmentation, that is, the egg yolk was more coloured when feeding 7% mussel meal compared with the other diets. Hyline hens had lower feed intake and laying percentage, and higher egg weight, but lower egg mass production than LSL birds. The age of the birds influenced all egg quality traits except for meat and blood spots. The dry matter of the excreta was significantly lower for both genotypes fed the 7% mussel meal diet. These results indicate that mussels may be a high-quality protein source and may replace fishmeal in organic diets for layers.

Meta-analysis was applied to quantify the effect of replacement of fish meal by soyabean products in diets on fish growth. Measurement of growth in different units among studies required the use of a standardised effect size (Hedges' d). From a total of ninety-nine studies concentrating on fish meal replacement by defatted soyabean meal, 53 % were eliminated due to, among others, absence of a fish meal control diet (n 18), or no statistical differences or measurement of dispersion (n 6) indicated. Replacement of 4 to 40 % fish meal by soyabean meal (inclusion levels of 71–366 g/kg) resulted in a mean effect size of − 0·1142 (95 % CI − 0·4665, 0·2382) obtained in forty-eight comparisons evaluated with seventeen different fish species. However, at higher fish meal replacement levels the 95 % CI calculated for combined effect sizes did not overlap with zero. With soya protein concentrate replacing 25 to 100 % of fish meal in diets for seven fish species, methionine supplementation (mean − 2·4373 (95 % CI − 3·9004, − 0·9742); n 10) did not have a substantial influence on the magnitude of cumulative effect sizes relative to no supplementation (mean − 2·7306 (95 % CI − 3·7991, − 1·6620); n 16). Information on other soyabean products (full-fat soyabeans, soya flour) used as protein sources in fish diets was found as too limited for analysis and definite conclusions. The present study contributes by putting a numerical value to the magnitude of growth differences in fish when replacing dietary fish meal by soyabean products.

Dietary nitrogen and phosphorus utilisation were evaluated in rainbow trout, Oncorhynchus mykiss, fed fish meal and soy protein concentrate-based diets. Two short term trials were conducted with rainbow trout having initial mean weights of 24 and 156 g maintained at a water temperature of 17 ± 1 °C, during which triplicate groups of trout were fed the respective diets two times a day to apparent satiety by hand. In both trials, fish fed fish meal-based diet exhibited significantly higher growth. In small trout, feed/gain ratio and protein utilisation were slightly higher in groups fed the fish meal-based diet; however, in larger fish, there was no significant difference between treatments. Nitrogen retention and loss were not affected by dietary treatments, while phosphorus retention was higher in fish fed diet containing fish meal (30 and 17 %) than in fish fed diet containing soy protein concentrate (25 and 15 %) and greatly reduced in larger fish. Phosphorus losses were 10 and 13 g·kg gain−1 of fish fed the fish meal-based diet, while those for fish fed the diet without fish meal were 14 and 17 g.

The effect of ensiling grass and supplementing the resulting silage with water-soluble carbohydrate in the form of sucrose and undegradable dietary protein (UDP) in the form offish meal on forage intake and milk production and composition were evaluated in an experiment involving 63 mid-lactation Holstein-Friesian cows. Herbage from the primary growth of a predominantly perennial ryegrass sward was zero-grazed (ZG) from 19 April to 16 May 1993. The herbage was mown and picked up with a precision-chop harvester and offered as the sole diet, twice daily, to 18 cows which were on average 186 days into lactation. On 13 May, herbage from the same sward was harvested identically to the ZG herbage and ensiled, treated with formic acid at a rate of 2·85 lit grass. At 53 days after ensiling the silage was offered either as the sole diet (SO) or supplemented with sucrose at 10·3 g/kg fresh silage (SS) or supplemented with sucrose and fish meal each at 10·3 g/kg fresh silage (SSF) to 15 cows per treatment which were on average 164 days into lactation. The feeding period was 28 days for ZG and 21 days for the SO, SS and SSF treatments, and the last 7 days were the main recording interval. Prior to going on to the experimental diets all animals were offered a common silage ad libitum and supplemented with 5 kg of a 180 g/kg crude protein concentrate. Dry-matter intakes (DMI), milk yields and milk composition were recorded during the pre-experimental period and subsequently used as covariates in the statistical analysis. For diets ZG, SO, SS and SSF, forage DMI (kg/day), total DMI (kg/day), milk yields (kg/day), fat concentration (g/kg) and protein concentration (g/kg) were 14·4,14·0,13·7 and 13·9 (average s.e.d. = 0·55); 14·4,14·0,14·5 and 15·4 (average s.e.d. = 0·59); 15·4, 14·4, 14·5 and 16·7 (average s.e.d. = 0·42); 36·6, 38·6, 38·6 and 37·5 (average s.e.d. = 2·67); 33·0, 30·7, 32·2 and 32·8 (average s.e.d. = 0·75). Nitrogen (N) digestibility was higher on SO and SSF (P < 0·05) relative to ZG with SS being intermediate, otherwise treatment did not alter (P > 0·05) diet apparent digestibility. Ensilage increased the immediately soluble N fraction (a value) and degradability of N (P < 0·001) relative to ZG. It is concluded that ensilage had no effect on forage DMI but decreased milk yield and protein concentration relative to the parent herbage. The positive response in milk yield due to supplementation of the silage-based diet with sucrose and fish meal and the lack of response to sucrose supplementation alone suggests that nutrients absorbed from the digestive tract of cows offered silage-based diets are more limiting in protein or specific amino acids supplied by fish meal than in energy. The decrease in animal performance due to ensiling may be overcome by supplementation of silage-based diets with UDP at sufficient levels to equate that of the parent herbage.

In each of three experiments, 60 Limousin × Holstein Friesian bulls, initially of 191, (s..e. 5·0), 177 (s.e. 5·5) and 210 (s.e. 7·2) kg mean live weight for experiments 1, 2 and 3 respectively, were offered maize silage ad libitum plus one of three barley-based, isonitrogenous compound diets containing 200 g rapeseed meal, 575 g maize-gluten feed or 100 g fish meal per kg fresh weight. Compound diets were given at the rate of 3·0 kg (fresh weight) per head per day up to 320 kg live weight and at 3·3 kg per head per day from 320 kg to 420 kg live weight. In experiment 3, when bulls were taken through to slaughter, the compound diet was further increased to 3·5 kg per head per day from 420 kg live weight to slaughter. Experiments 1 and 2 were conducted over 128 and 194 days, with mean live weights at the end of the experiments of 347 (s.e. 17·2) and 414 (s.e. 24·2) kg respectively. In experiment 3, bulls were slaughtered at 16 months of age at a mean live weight of 544 (s.e. 25·0) kg.

In experiment 1, the fish-meal diet gave the highest rate of daily live-weight gain at 1·34 compared with 1·17 and 1·16 (s.e.d. 0·041) kg for rapeseed-meal and maize-gluten diets, respectively. In experiments 2 and 3, daily gains were similar on all treatments at 1·21, 1·19 and 1·26 (s.e.d. 0·036) kg and 1·06, 1·09 and 1·11 (s.e.d. 0·035) kg for the rapeseed-meal, maize-gluten and fish-meal diets respectively. Total daily dry-matter intakes did not show consistent trends: in experiment 1, intakes were 5·8, 5·6 and 5·8 kg/day, in experiment 2, 6·2, 6·2 and 6·3 kg/day; and in experiment 3, 7·1, 7·3 and 7·1 kg/day for rapeseed-meal, maize-gluten and fish meal, respectively. The higher intakes of dry matter in experiment 3 were due to the greater intakes of maize silage by bulls taken to heavier weights in this experiment.

Gizzerosine [2-amino-9-(4-imidazoyl)-7-azanonanoic acid] was isolated from a fish meal which caused black vomit in broiler chicks. Those given a diet containing fish meal which caused black vomit or synthetic DL-gizzerosine secreted excess gastric juice. The excess juice resulted in gizzard erosion and black vomit. In all the experiments, amongst chicks that died, those without gizzard perforation were greater in number than those with such lesions. It is considered that gizzard perforation by excess gastric juice is not the most serious lethal effect of gizzerosine. Chicks have been found to exhibit wide variation in sensitivity to gizzerosine. In a 4-week feeding trial of a fish meal that caused black vomit, 25 out of 100 died but nine grew normally. It should therefore be possible to estimate the maximum permissible concentration of gizzerosine in practical broiler diets. In the case of manufacturing facilities in which vapour is used to dry the fish meal indirectly, the conditions which avoid gizzerosine formation are known. It is desirable to determine safe conditions for fish meal drying when the process uses hot air heated by a flame.

Eight non-pregnant, non-lactating adult ewes weighing 56 kg were fed for 26 days on a meadow hay (organic matter 937 g, crude protein 107 g, metabolizable energy (ME) 8·3 MJ per kg dry matter) to satisfy half of their daily energy and protein maintenance requirements i.e. 200 kj ME and 1·3 g truly digestible protein per kg M0·75. They were then allotted to two groups of four each. Control ewes continued to receive the initial diet for another 74 days while the others were supplemented with 60 g/day fish meal to receive 200 kj ME and 2·7 g truly digestible protein per kg initial M0·75 per day.

In spite of its high nitrogen content, the digestibility of the hay was increased by the protein supplementation, e.g. from 0·56 to 0·60 for neutral-detergent fibre and from 0·54 to 0·59 for energy.

The supplemented ewes lost significantly less body weight than the controls (96 v. 134 g/day) essentially because of their higher ME intake (272 v. 252 kj/kg average M0·75 during the experimental period). The measurements of blood metabolites suggest that the daily amounts of mobilized body protein increased with duration of underfeeding. The additional amino acids provided by fish meal were principally used as a source of energy and for wool growth.

Thirty-six individually penned lambs (mean live weight 32·4 (s.d. 2·27) kg) were offered maize silagead libitumand one of three concentrate mixes, two of which contained extracted rapeseed meal (control and HR) and the other fish meal (FM). The concentrates were given according to live weight and in sufficient quantities to provide proportionately about 0·4 of the dry matter (DM) intake of the lambs. The dietary concentrations of nitrogen (N) g/kg DM were 22·4, 27·4 and 27·5 and of rumen undegradable N 6·6, 7·3 and 11·6 for the control, HR and FM diets respectively.

Both the HR and FM diets depressed maize silage intakes compared with the control during the first 21 days (P < 0·05) and lambs given the FM diet continued to have lower intakes than control lambs (P < 0·05) throughout the experiment. The live-weight gain of HR lambs was considerably depressed in comparison with the control and FM lambs during the first 21 days of the experiment (P < 0·05). Overall HR lambs gained weight more slowly than control and FM lambs up to 45 kg live weight but the difference was not statistically significant. Food conversion ratio was better for FM than HR (P < 0·01). There were no treatment differences in wool growth.

The results obtained provide little evidence that fish meal had any beneficial effects upon lamb growth compared with the control diet except a possible increase in the efficiency of metabolizable energy utilization.

Thirty-six individually penned lambs (mean live weight 32·4 (s.d. 2·27) kg) were offered maize silage ad libitum and one of three concentrate mixes, two of which contained extracted rapeseed meal (control and HR) and the other fish meal (FM). The concentrates were given according to live weight and in sufficient quantities to provide proportionately about 0·4 of the dry matter (DM) intake of the lambs. The dietary concentrations of the nitrogen (N) g/kg DM were 22·4, 27·4 and 27·5 and of the rumen undegradable N 6·6, 7·3 and 11·6 for the control, HR and FM diets, respectively. All lambs were slaughtered at 45 kg live weight and chemical composition of the empty body and some of the component parts determined. A further 12 lambs were slaughtered at the beginning of the experiment to establish body composition before the dietary treatments were imposed.

The HR lambs had lower fleece.free empty body (FFEB) gains than either control or FM lambs (P < 0·05). This reduced gain of HR lambs was particularly associated with a reduction in fat deposition (P < 0·01) such that the FFEBs contained less fat than control and FM lambs (P < 0·01). The efficiency of conversion of metabolizable energy for growth (kg) was worse than both the control (P < 0·01) and the FM (P < 0·001) diets. The FFEBs of HR lambs also contained more ash (P < 0·05) than the lambs receiving the other diets.

The FM diet was associated with greater gains of fat and energy in the guts compared with the control diet (P < 0·05) and FM lambs had a better kg, value than control lambs (P < 0·05). There was no evidence that FM lambs had better N retention than lambs on the other two treatments.

The effect of fish-meal supplementation or cimaterol administration on the composition, cellularity and metabolism of subcutaneous and perirenal adipose tissue was examined in young Friesian steers given grass silage. Animals (approx. 117 kg live weight) received either silage alone (group C; no. = 6) or supplemented with fish meal (150 g/kg silage dry matter; group FM; no. = 6) or cimaterol (0·06 mg/kg body weight per day) administered via osmotic minipumps (group CIM; no. = 6) for a period of 6 weeks. Samples of perirenal and subcutaneous adipose tissue obtained at slaughter were used for determination of tissue composition and in vitro rates of lipogenesis, lipolysis and substrate oxidation. FM animals showed significantly greater live-weight gains (0·61 kg/day) compared with C (0·21 kg/day, P < 0·001) while CIM animals had significantly lower rates of gain (0·04 kg/day, P < 0·05). This was considered to be related to increased heat loss from the β-agonist-treated animals as a result of very cold weather encountered during the experimental period. CIM administration reduced adipocyte size suggesting an increased number of cells per g tissue. Both lipolytic and lipogenic rates were reduced by cimaterol and there was some evidence that the response to insulin was diminished, at least with respect to substrate oxidation. FM increased lipogenesis from acetate and acetate oxidation rates in subcutaneous adipose tissue with similar trends in perirenal tissue. The results indicate that both fish-meal supplementation and cimaterol administration caused substantial changes in adipose tissue metabolism as determined using in vitro procedures, even though the magnitude and direction of the changes were not in strict accord with estimates of net fat accretion from related in vivo studies.

Animal protein supplements are superior to plant protein supplements as sources of essential amino acids and are desirable components in poultry feed formulations. Fish meal and meat meal are widely used animal protein supplements in the Asian and Pacific regions. The nutritive value of these two ingredients and other potentially useful sources of animal protein are examined, with particular emphasis on protein quality. The value of some ‘novel’ animal protein sources is also discussed.

Seventy-two, 4-month-old, British Friesian steers were used to investigate the effects of feeding a supplement of fish meal on the voluntary intake and live-weight gain by young growing cattle given a well preserved ryegrass silage. The silage was offered either alone or mixed with 50,100 or 150 g fish meal per kg silage dry matter (DM) and the diets were offered either ad libitum or intakes were restricted to 16, 19 or 22 g dietary DM per kg live weight (LW). Intakes were recorded daily, LW weekly and in vivo apparent digestibility over one 7-day period during the 132-day trial.

For animals fed ad libitum, the absolute intake of dietary DM increased linearly with an increase in the level of fish-meal supplementation such that intake when the highest level of fish meal was given was significantly higher (P < 0·01) than when silage was given alone. However, DM intake per unit LW (approx. 24 g DM per kg LW) was not affected significantly (P > 0·05).

Inclusion of fish meal in the diet did not affect the apparent digestibility of dietary DM, organic matter, acid-detergent or neutral-detergent fibre (NDF) although there was a trend for slightly higher (P > 0·05) gross energy apparent digestibility when fish meal was given. Increasing the level of feeding reduced NDF digestibility. The coefficients measured at the 22 g and ad libitum levels of intake were lower (P < 0·01 and P < 0·05 respectively) than that measured at the 16 g DM per kg LW level.

Animals given silage alone to appetite achieved LW gains of 0·6 kg/day. LW gains increased linearly with increasing level of feeding (P < 0·001) and increasing level offish-meal supplementation (P < 0·001).