Feed Consumption Data Research Articles

Capturing resilience from phenotypic deviations: a case study using feed consumption and whole genome data in pigs

BackgroundIn recent years, interest has grown in quantifying resilience in livestock by examining deviations in target phenotypes. This method is based on the idea that variability in these phenotypes reflects an animal’s ability to adapt to external factors. By utilizing routinely collected time-series feed intake data in pigs, researchers can obtain a broad measure of resilience. This measure extends beyond specific conditions, capturing the impact of various unknown external factors that influence phenotype variations. Importantly, this method does not require additional phenotyping investments. Despite growing interest, the relationship between resilience indicators—calculated as deviations from longitudinally recorded target traits—and the mean of those traits remains largely unexplored. This gap raises the risk of inadvertently selecting for the mean rather than accurately capturing true resilience. Additionally, distinguishing between random phenotype fluctuations (white noise) and structural variations linked to resilience poses a challenge. With the aim of developing general resilience indicators applicable to commercial swine populations, we devised four resilience indicators utilizing daily feed consumption as the target trait. These include a canonical resilience indicator (BALnVar) and three novel ones (BAMaxArea, SPLnVar, and SPMaxArea), designed to minimize noise and ensure independence from daily feed consumption. We subsequently integrated these indicators with Whole Genome Sequencing using SLEMM algorithm, data from 1,250 animals to assess their efficacy in capturing resilience and their independence from the mean of daily feed consumption.ResultsOur findings revealed that conventional resilience indicators failed to differentiate from the mean of daily feed consumption, underscoring potential limitations in accurately capturing true resilience. Notably, significant associations involving conventional resilience indicators were identified on chromosome 1, which is commonly linked to body weight.ConclusionWe observed that deviations in feed consumption can effectively serve as indicators for selecting resilience in commercial pig farming, as confirmed by the identification of genes such as PKN1 and GYPC. However, the identification of other genes, such as RNF152, related to growth, suggests that common resilience quantification methods may be more closely related to the mean of daily feed consumption rather than capturing true resilience.

육계농장유래 ICT-데이터의 분석을 통해 미생물의 정족수감지 (Quorum Sensing) 현상의 발견을 위한 연구

The current study obtained biometric data yielded by information and communication technology (ICT) equipment installed in the mobile phones of farmers from broiler farms and evaluated quorum sensing (QS) phenomenon (QSP), which can be considered as an emergency rescue request signal for chickens and the starting point of a disease. The results indicated that QSP was identified the most rapidly and sensitively during the analysis of digital data yielded by the ICT-equipped automatic feed feeder, followed by the water consumption data. In particular, in the data on daily feed consumption, QSP was identified to be the point where the consumption rapidly decreased by more than 100% compared with that on the previous day. It is believed that if farm owners responded to the QSP or chicken rescue signals and rapidly implemented disease prevention measures, then it would be the wisest field use of ICT data to minimize loss and damage to farms. In addition, the results of this study revealed the priority order of the introduction of ICT equipment. and the most urgent and important for farm management is daily feed consumption data by applying the scientifically based QS approach, for the first time, to our knowledge, in Korea. The results of this study uncovered the importance of installing ICT equipments.

Evaluation of the inclusion of three oils on productive parameters and carcass characteristics in broiler

An experiment was conducted to determine the effect of three oil sources with the inclusion of three levels on some performance variables, carcass quality, and broiler organs. The sources used were palm oil (Elaeis guineensis), chicken oil, and Sacha inchi oil (Plukentia volubilis). A total of 324 female Ross 308 line were assigned in a completely random design to nine treatments with six repetitions of six birds per repetition, which were fed with a diet based on corn and soybean meal containing 3, 6, and 9% inclusion of each one of the oil sources for the periods between 8 to 21 days of age and 22 to 42 days of age. Live weight and feed consumption data were recorded weekly to calculate the feed conversion ratio, considering mortality. On day 42, one female broiler from each repetition was randomly selected, weighed, and sacrificed, to obtain upgraded data characteristics from the carcass. The results suggest that there was no significant difference in animal response variables or channel quality. Regarding the carcass variables and some poultry organs, the only one affected by the source was the deposition of abdominal fat. Sacha inchi oil produced carcasses with a lower average of abdominal fat in relation to weight and slaughter, with no differences between palm and chicken oils.

Animal dietary exposure in the risk assessment of feed derived from genetically modified plants.

EFSA carries out the risk assessment of genetically modified plants for food and feed uses under Regulation (EU) No 503/2013. Exposure assessment - anticipated intake/extend of use shall be an essential element of the risk assessment of genetically modified feeds, as required by Regulation (EU) No 503/2013. Estimates of animal dietary exposure to newly expressed proteins should be determined to cover average consumption across all the different species, age, physiological and productive phases of farmed and companion animals, and identify and consider particular consumer groups with expected higher exposure. This statement is aimed at facilitating the reporting of the information that applicants need to provide on expected animal dietary exposure to newly expressed proteins and to increase harmonisation of the application dossiers to be assessed by the EFSA GMO Panel. Advice is provided on the selection of proper feed consumption and feed concentration data, and on the reporting of exposure's estimates. An overview of the different uncertainties that may be linked to the estimations is provided. This statement also explains how to access an Excel calculator which should be used in future applications as basis to provide a more consistent presentation of estimates of expected animal dietary exposure.

Growth Performance and Meat Quality of White Pekin Ducks Reared in Backyard Farming System

Background: The growth and popularity of white pekin duck farming is increasing among farmers due to assured return and marketing linkages in peri-urban areas. The growth performance and meat quality of pekin ducks under backyard farming was evaluated in the present study. Methods: Body weight and feed consumption data of 140 white pekin ducks managed under rice bran-based feeding in backyard farming, were recorded weekly up to 8th week of age. Gompertz’s growth model was used to calculate growth parameters. Meat quality parameters were recorded after slaughter on 56th day. Result: White pekin ducks attained 2.003 kg at 56 days of age with 3.2 FCR (Feed conversion ratio). The asymptote weight calculated from Gompertz’s equation was 4513.25 g. Inflection points of bodyweight and time was determined as 1659.28 g and 49.9 days respectively. The maximum growth rate was 58.17 g/day. The high growth rate of pekin ducks in backyard condition indicates suitability of rice bran-based diet in this farming system.Dressing percentage (57.9%) of eviscerated carcass was however less than earlier reports. Lipid peroxidation activity of breast-meat was measured and found to be less than previous reports. Reduced lipid peroxidation in muscle might be due to liberal access to natural feeding system by pekin ducks that is unique in backyard farming.

EVALUATION OF BREWERS DRIED YEAST PROTEIN IN BROILER DIET

The value of brewers dried yeast protein (BDY) as a replacement of fishmeal in the diet for broiler starters was investigated. In the experiment BDY replaced 0, 25, 50, 75 amd 100% of the fishmeal in the fiet. The average liveweight gain response to increasing levels of BDY at 6 weeks of age was 950.3g, 980.78, 981.8g, 950.5g and 953.2g respec tively. While the figures for the feed/gain ratio were 2.35, 2.28, 2.30, 32 36 and 2.39 respectively. There was no significant differences between these values. Also, the mean feed consumption data for different dietary treatment through the period showed no significant differences. This result suggests that under the conditions of this experiment BDY could replace completely all the fishmeal in the broiler starter diet without any adverse effect on the rate of gain, feed efficiency, or feed consumption of broiler chicks.

Impact of gastrointestinal parasitism on dry matter intake and live weight gain of lambs: A meta-analysis to estimate the metabolic cost of gastrointestinal nematodes

This study aimed to estimate the effect of gastrointestinal nematodes (GIN) on the productive performance assessed by the live-weight change (LWC) of lambs, and the metabolic cost associated with parasitism by means of a meta-analysis. Data used in the meta-analyses were obtained from twenty papers selected using the following criteria: (a) lambs with (I) and without (NI) GIN; (b) lambs fed ad libitum; (c) LWC data; (d) feed consumption data; and (e) chemical composition of diets. The effect of diet composition (crude protein [CP] and metabolizable energy [ME]) on dry matter intake (DMI), and the effect of composition and nutrient intake (DMI and CP intake [CPI]) and ME intake (MEI) on LWC was evaluated using respective regression analyses. The metabolic cost of worm burden was determined as the difference in CP and ME requirements between NI and I lambs for each adult parasite. The CP and ME cost were evaluated for lambs at two different levels: maintenance level 0 g LWC and 100 g LWC. The worm burden had an impact on the DMI and LWC of lambs (P < 0.05). The association of CP x infection level was the best predictor of DMI. The association between MEI and infection level were the best predictors of LWC. The metabolic cost of GIN increased to 0.30 mg CP/kg LW0.75 and 0.0056 kJ ME/kg LW0.75 for each adult parasite. The metabolic cost was not modified by diet quality (maintenance level 0 g LW/day or 100 g LW/day). In conclusion, GIN has a negative effect on DMI and LWC. The metabolic cost of GIN infection can be covered by supplying the additional requirements for protein and energy in the diet of infected lambs.

Condensed tannin intake and sheep performance: A meta-analysis on voluntary intake and live weight change

This study estimated the impact of condensed tannin (CT) consumption on dry matter intake (DMI) and live weight change (LWC) of growing sheep by means of a meta-analysis. A metabolic cost associated to CT intake was also estimated. Data included in the meta-analysis were obtained from scientific literature with the following inclusion criteria: (a) growing lambs fed ad-libitum without gastrointestinal nematode infection, (b) feed consumption data, (c) chemical composition of diets, and (d) CT consumption data. Data were analyzed as a whole data-set or grouped into three categories: (a) sheep consuming CT (CT group), (b) sheep not consuming CT (non-CT group) and (c) sheep consuming CT + polyethylene glycol (CT + PEG group). The effect of diet composition and quality (crude protein (CP), organic matter (OM), neutral detergent fiber (NDF), condensed tannins (CT), metabolizable energy (ME), dry matter digestibility (DMD), OM digestibility (OMD) and CP digestibility (CPD)) on DMI (g/kg0.75) was evaluated using regression analyses. The effect of diet composition and consumption of those same variables (g/kg0.75) on LWC (g/kg0.75) were also evaluated using respective regression analyses. The metabolic cost of CT consumption was estimated in terms of digestible crude protein (DCP) and ME requirements. The cost was estimated for a diet to sustain maintenance and a diet to supply 100 g/d LWC requirements. No effect was found of CT intake on DMI or LWC (P > 0.05). The DMI was best predicted by CP and DMD concentration (g/kg DM), when analyzed as a whole data-set. When analyzed as separate categories for CT and non-CT group was best predicted by ME (MJ/kg DM) (P < 0.05). For the CT + PEG group the DMI was best predicted by NDF (P < 0.05). The LWC was best predicted by DCPI2 when analyzed as a whole data-set. The best predictor of LWC was the DCP intake (for the CT data) and the ME intake (for non-CT data and CT + PEG data) (P < 0.05). Although CT intake do not have an effect on DMI and LWC, it was observed that at low dietary CP level increases DCP requirement and hence it does have a metabolic cost associated. The metabolic cost of CT consumption estimated for animals consuming a maintenance diet was 0.33 MJ of ME/kg0.75 and 1.04 g of DCP/kg0.75 and for animals fed a 100 g LWC diet was 0.13 MJ of ME/kg0.75 and 0.87 g DCP/kg0.75. Thus, a higher cost for CT intake was found for groups of lambs at low feeding level and the metabolic cost was reduced when lambs were at higher feeding levels.

Absence of renal adverse effects from β-myrcene dietary administration in OECD guideline-compliant subchronic toxicity study

β-Myrcene is a flavoring substance that occurs naturally in a large variety of foods. At the request of the European Food Safety Authority (EFSA) for additional toxicological data on β-myrcene, groups of Sprague Dawley rats (10/sex/group) were administered diets containing 0, 700, 2100, or 4200 ppm of β-myrcene designed to provide nominal doses of 0, 50, 150, or 300 mg/kg bw/day in a 90-day GLP-compliant study. Based on body weights, feed consumption, and substance stability data, final estimated daily intakes of β-myrcene were calculated to be 20.4, 58.8, and 115.2 mg/kg bw for males and 24.2, 70.0, and 135.9 mg/kg bw for females. No effects on clinical observations, hematology and clinical chemistry parameters, organ weights, or macroscopic and histopathological examinations were found attributable to ingestion of β-myrcene. The oral no-observed-adverse-effect level (NOAEL) for rats of both sexes was the highest dose tested. Based on feed consumption and test substance stability in the diet, the NOAEL was calculated to be 115 and 136 mg/kg bw/day for males and females, respectively.

Amphiphilic poly-N-vynilpyrrolidone nanoparticles: Cytotoxicity and acute toxicity study

The aim of the present study was to evaluate the cytotoxicity against MCF-7 cells and acute intraperitoneal toxicity of amphiphilic poly-N-vinylpyrrolidone nanoparticles to confirm possibility of their application for creation of novel drug delivery systems. The effect of cellular uptake of polymeric nanoparticles on human cancer cell line MCF-7 cells was investigated by MTT assay. MTT analysis showed that tested amphiphilic polymers were essentially non-toxic. In acute toxicity studies, LD50 and other toxicity indexes were evaluated, under which no deaths or treatment related complications were observed even in high concentration treatment for 14 days of experiment. For histological analysis, organs of the animals were weighed and examined. No animal died during the study and no significant changes have been observed regarding body weight, feed consumption, organ weight or histological data. Obtained results show that amphiphilic poly-N-vinylpyrrolidone nanoparticles possessed no toxicity against cells and in animals after intraperitoneal administration. Thus, amphiphilic PVP nanoparticles demonstrate high potential as carriers for novel high-effective drug delivery systems.

Ruminal Bacterial Community Composition in Dairy Cows Is Dynamic over the Course of Two Lactations and Correlates with Feed Efficiency.

Fourteen Holstein cows of similar ages were monitored through their first two lactation cycles, during which ruminal solids and liquids, milk samples, production data, and feed consumption data were collected for each cow during early (76 to 82 days in milk [DIM]), middle (151 to 157 DIM), and late (251 to 257 DIM) lactation periods. The bacterial community of each ruminal sample was determined by sequencing the region from V6 to V8 of the 16S rRNA gene using 454 pyrosequencing. Gross feed efficiency (GFE) for each cow was calculated by dividing her energy-corrected milk by dry matter intake (ECM/DMI) for each period of both lactation cycles. Four pairs of cows were identified that differed in milk production efficiency, as defined by residual feed intake (RFI), at the same level of ECM production. The most abundant phyla detected for all cows were Bacteroidetes (49.42%), Firmicutes (39.32%), Proteobacteria (5.67%), and Tenericutes (2.17%), and the most abundant genera included Prevotella (40.15%), Butyrivibrio (2.38%), Ruminococcus (2.35%), Coprococcus (2.29%), and Succiniclasticum (2.28%). The bacterial microbiota between the first and second lactation cycles were highly similar, but with a significant correlation between total community composition by ruminal phase and specific bacteria whose relative sequence abundances displayed significant positive or negative correlation with GFE or RFI. These data suggest that the ruminal bacterial community is dynamic in terms of membership and diversity and that specific members are associated with high and low milk production efficiency over two lactation cycles.

Comparative Energy Flow Analysis on Dairy Farms in North Carolina and Malawi

Milk is a major nutrient source in many Western diets, but in developing countries like Malawi, milk intake is low; increasing its availability from local sources could significantly improve nutrient intake in the population. The objective of this study was to compare energetic inputs, outputs, and efficiencies of dairy farms in Malawi (Southeast Africa) and North Carolina to assess sustainable milk production. Feed consumption and milk production data were collected from Katete Dairy herd in Lilongwe, Malawi, consisting of 408 cattle with 108 lactating cows, and the NCSU Dairy Research and Teaching Farm, housing 245 Holstein and 55 Jersey cows and 170 lactating cows. Both are teaching farms that employ extensive record keeping. Milk production averaged 34 and 19.5 kg/cow/day at NCSU and Katete, respectively. Feed energy intake was 85.8 mcal/cow/d at NCSU and 135 mcal/cow/d at Katete. Thus, return of feed energy as milk energy was 24.7% efficient at NCSU and 11.3% efficient in the lower producing cows at Katete. Manure is recycled for crop production at Katete, and is processed with a solids separation and lagoon system at NCSU. Additional factors that impact the overall farm efficiencies include inputs of petroleum fuels and electricity, and the number of calves, heifers and dry cows fed. The project identifies factors in dairy production that should be considered to improve efficiency, sustainability and milk supply. A greater supply of locally produced milk in Malawi could improve essential nutrient intakes.

Enhancing the interpretation of statistical P values in toxicology studies: implementation of linear mixed models (LMMs) and standardized effect sizes (SESs).

In this paper, we compare the traditional ANOVA approach to analysing data from 90-day toxicity studies with a more modern LMM approach, and we investigate the use of standardized effect sizes. The LMM approach is used to analyse weight or feed consumption data. When compared to the week-by-week ANOVA with multiple test results per week, this approach results in only one statement on differences in weight development between groups. Standardized effect sizes are calculated for the endpoints: weight, relative organ weights, haematology and clinical biochemistry. The endpoints are standardized, allowing different endpoints of the same study to be compared and providing an overall picture of group differences at a glance. Furthermore, in terms of standardized effect sizes, statistical significance and biological relevance are displayed simultaneously in a graph.

Characterization of the dose decrement in regulatory rat pesticide toxicity feeding studies

In typical rodent pesticide feeding studies of 4 up to 104weeks, animals are offered the pesticide at constant concentrations in the feed. Throughout the entire study duration of up to 104weeks, the daily feed consumption per animal remains nearly constant. This results in decreasing doses per kg bodyweight from the first day of treatment onwards as the bodyweight increases. Recently, we have identified this dose decrement as the major cause for lower No Observed Effect Levels (NOAEL, expressed as mg/kg bodyweight) in longer-term studies compared to shorter-term studies, rather than the exposure duration itself. In the current evaluation we investigated the nature of the dose decrement in more detail by using male and female bodyweight and feed consumption data from 118 feeding studies of three rat strains to calculate dose development over time. In male rats, after a steep initial dose decrement, the mean dose at week 7 of treatment is on average half of the initial dose and after 29weeks one third of the initial dose. In females, 50% of the initial dose is reached at week 18 and in 25% of the studies one third of the initial dose is reached at approximately 75weeks of treatment. Although bodyweights and feed intakes per animal were different between strains, doses and dose development curves over time are similar. The fact that ingested doses in rats continually decrease, especially in the first 13weeks, should be taken into account in dietary risk assessments.

Feed consumption and weight gaining behavior of zucker fatty fafa rats with single and in combination treatment of clonidine and metformin

Background: Diabetes is metabolic disorder with high blood glucose level. Type-2 diabetes is associated with obesity, insulin resistance, and chronic hyperglycemia. So agents that are efficiently reduces weight gain along with diabetic control may play beneficial role in obese diabetic subjects. Methods: Zucker Fatty Rats were used for the study. Animals were divided in four groups, (control group, Clonidine group, metformin group and combination group). Normal weight gain and feed consumption data were obtained up to 9 weeks of age there after animals were started treatment according to above mentioned groups. During treatment again feed consumption and weight gain data were generated. The experimental results are expressed as the Mean ± SEM in each group. Statistical analysis has been performed by one way analysis of variance (ANOVA). Results: The data suggest that there is decrease in body weight gain during the treatment with clonidine and in combination of clonidine and metformin. If we consider weight gain of control as 100 % weekly than clonidine group shows 10.45 % weight gain while metformin shows 96.5 % weight gain and in combination group it shows 33.63 % weight gain. So, there is significant reduction in weight gain of the group treated with clonidine and combination of clonidine and metformin. Same time there is reduction in feed consumption of animals. Conclusions: The centrally acting drug Clonidine affects the feed consuming behavior and weight gain of animals. It shows hypophagic effect and reduces weight gain in single as well as in combination with metformin.

Farm level impact of feeding improved diets to pigs in the Jomoro District of Ghana

The economic impact at farm-level for feeding improved diets to grower-finisher pigs in the Jomoro District of Ghana was assessed using partial budgeting techniques. Three diets were considered: the farmers’ diet, which contained mainly coconut chaff and cake; a cereal based commercial diet and improved agro-industrial by-products (AIBP) based diet. The category of farmers considered reared mainly large-white pig breed. The study uses growth, feed consumption and price data, obtained from an on-farm feed evaluation studies, which results, in terms of nutrition, growth performance, and economy of gain, have been reported elsewhere. The paper estimates alternative measures of the economics of using improved feed by accounting for the reduction in the time to slaughter (70 kg) in the computation of benefits. The net additional benefit resulting from the use of AIBP diet instead of farmer’s diet was ¢1,879,227. The simple benefit-cost ratio was 1.71. The additional benefit due to the use of AIBP diet is about two times more than the extra cost incurred.

Developmental Toxicity of Homobrassinolide in Wistar Rats

Brassinosteroids (BRs) are close analogues of animal cholesterol. Brassinosteroids have shown their great value as yield promoters of a variety of plants. In view of its steroidal moiety and recent use in agriculture in many countries, the teratogenic potential of homobrassinolide (HBR) was evaluated in Wistar rats. Homobrassinolide was administered by oral gavage at doses 0, 100, and 1000 mg/kg body weight in water during gestation days (GD) 6 to 15 in groups of 20 mated females. Maternal and embryo-fetal toxicity was analyzed by studying the effects such as clinical signs, mortality/morbidity, abortions, body weight, feed consumption, and pregnancy data, gravid uterine weights, implantation losses, litter size, external, visceral, and skeletal malformations. No treatment-related effect was observed on any of the maternal/fetal end points in any dose group. From the results, it can be concluded that HBR is nonteratogenic at doses as high as up to 1000 mg/kg body weight in Wistar rats.

Evaluation of two soybean meals fed to yellow perch (Perca flavescens)

Aquaculture of yellow perch (Perca flavescens) has been increasing, yet there have been few nutritional studies and no evaluations of alternative protein sources in diets. Solvent-extracted, dehulled soybean meal (SBM) and expelled-extruded soybean meal (exSBM) were fed to yellow perch to evaluate their effectiveness in replacing dietary fish meal (FM) in isonitrogenous practical feed formulations. Both soy ingredients were incorporated in graded amounts from 100 to 730 g kg−1 of the diet. Feed consumption, weight gain, feed efficiency (FE) and survival were significantly affected by type of soy ingredient, concentration and the interaction of the two main effects. Consumption was significantly lower in fish fed diets containing 400, 600 and 730 g kg−1 compared to fish fed diets containing lower concentrations. Weight gain was significantly lower in fish fed diets containing 600 g kg−1 and FE significantly lower in fish fed diets containing 500 g kg−1 compared to fish fed the control diet or lower concentrations of soy ingredients. Most fatty acid concentrations were affected by feeding exSBM compared to fish fed the control diet, but long chain fatty acids remained at relatively high concentrations. Based on feed consumption, weight gain and FE data, yellow perch are able to effectively utilize both soy ingredients in practical diets. A conservative recommendation of 300 g kg−1 diet appears appropriate for growout diets.

Growth rate and carcass traits in three genotypes of capons

Growth performance and carcass characteristics of capons (castrated cockerels) from three breeds/strains locally presented in Slovenia and Austria were investigated. Growth and feed consumption data were collected for a 156-d and 199-d period, when randomly chosen animals were slaughtered and their carcasses dissected. The feed conversion rate in barred Prelux, Sulmtaler and Styrian capons for the whole growing period was 6.24 kg, 6.32 kg and 7.53 kg, respectively. Average body weight in barred Prelux and Styrian capons increased only in the first 156 days of age, but not further on. Cumulative mortality rate in Sulmtaler capons was 19.05 % and was 2.7- to 4.4-fold higher as compared with Styrian and barred Prelux capons (6.90 % and 4.31 % respectively). Sulmtaler capons had the lowest abdominal fat content. Barred Prelux capons, as compared to capons from other two breeds were characterized by higher pre-slaughter weight, higher carcass weight and higher dressing out percentages. This indicates that the layer type barred Prelux cockerels have a potential to be as capons put to profitable use.

Depletion of emamectin residues following oral administration to rainbow trout, Oncorhynchus mykiss

The depletion of emamectin B 1a in the edible tissues of rainbow trout ( Oncorhynchus mykiss) was studied at two temperatures following treatment with emamectin benzoate (Slice®) in feed. Fish approaching market size (400–1500 g) were held in tanks supplied with temperature-controlled seawater at 6 ± 1 °C (cold water) or 15 ± 1 °C (warm water). In each study the medicated group was offered feed containing emamectin benzoate at a nominal dose rate of 50 μg kg − 1 fish day − 1 for 7 days and the control group was offered unmedicated feed. Actual dose rates, calculated from growth rate and feed consumption data, and measured emamectin benzoate concentrations in feed, were 88.6% nominal in the cold water study (96.6% adjusted for feed assay recovery) and 96.8% nominal in the warm water study (105.1% adjusted for feed assay recovery). Concentrations of emamectin B 1a were determined in fillet samples collected at intervals from 6 h to 77 days post-treatment in the cold water study and 6 h to 49 days post-treatment in the warm water study. In the cold water study, mean emamectin B 1a residues ranged from 81.8 ± 44.5 ng g − 1 at 1 day post-treatment (102.3 ± 55.7 ng g − 1 adjusted for recovery) to 13.7 ± 10.5 ng g − 1 at 77 days post-treatment (17.2 ± 13.1 ng g − 1 ). In the warm water study, mean residue concentrations ranged from 64.5 ± 50.3 ng g − 1 at 6 h post-treatment (80.7 ± 62.9 ng g − 1 adjusted for recovery) to 1.6 ± 1.6 ng g − 1 at 49 days post-treatment (2.0 ± 2.0 ng g − 1 ). In the cold water study, residues in skin and muscle were also determined separately. On average, emamectin B 1a concentrations in skin were approximately 1.8 times higher than in muscle. Measured residue levels ranged widely and no detectable residues were found in at least a few individual fish at all time points. This high variability was considered to be due to differences in medicated feed consumption within the experimental population. Depletion of emamectin was faster at 15 °C than at 6 °C. In both studies the depletion curve showed a small secondary peak at around 90 degree-days. This observation is consistent with recirculation of the compound from a body store.