Individual Feed Conversion Ratio Research Articles

Feed Conversion Ratio (FCR) and Performance Group Estimation Based on Predicted Feed Intake for the Optimisation of Beef Production.

This paper reports on the use of estimates of individual animal feed intake (made using time spent feeding measurements) to predict the Feed Conversion Ratio (FCR), a measure of the amount of feed consumed to produce 1 kg of body mass, for an individual animal. Reported research to date has evaluated the ability of statistical methods to predict daily feed intake based on measurements of time spent feeding measured using electronic feeding systems. The study collated data of the time spent eating for 80 beef animals over a 56-day period as the basis for the prediction of feed intake. A Support Vector Regression (SVR) model was trained to predict feed intake and the performance of the approach was quantified. Here, feed intake predictions are used to estimate individual FCR and use this information to categorise animals into three groups based on the estimated Feed Conversion Ratio value. Results provide evidence of the feasibility of utilising the 'time spent eating' data to estimate feed intake and in turn Feed Conversion Ratio (FCR), the latter providing insights that guide farmer decisions on the optimisation of production costs.

Changes in transcriptomic and behavioural traits in activity and ventilation rates associated with divergent individual feed efficiency in gilthead sea bream (Sparus aurata)

Feed conversion ratio (FCR) is an important trait to target in fish breeding programs, and the aim of the present study is to underline how the genetic improvement of FCR in gilthead sea bream (Sparus aurata) drives to changes in transcriptional and behavioural patterns. Groups of fish with high (FCR+) and low (FCR-) individual FCR were established at the juvenile stage (161–315 dph) by rearing isolated fish on a restricted ration. Fish were then grouped on the basis of their individual FCR and they grew up until behavioural monitoring and gene expression analyses were done at 420 dph. The AEFishBIT datalogger (externally attached to operculum) was used for simultaneous measurements of physical activity and ventilation rates. This allowed discrimination of FCR+ and FCR- groups according to their different behaviour and energy partitioning for growth and locomotor activity. Gene expression profiling of liver and white muscle was made using customized PCR-arrays of 44 and 29 genes, respectively. Up to 15 genes were differentially expressed in liver and muscle tissues highlighting a different metabolic scope of FCR+ and FCR- fish. Hepatic gene expression profile of FCR- fish displayed a lower lipogenic activity that was concurrent with a down-regulation of markers of mitochondrial activity and oxidative stress, as well as a reallocation of body fat depots with an enhanced flux of lipids towards skeletal muscle. Muscle gene expression profile of FCR- fish matched with stimulatory and inhibitory growth signals, and an activation of energy sensors and antioxidant defence as part of the operating mechanisms for a more efficient muscle growth. These new insights contribute to phenotype the genetically mediated differences in fish FCR thanks to the combination of transcriptomic and behavioural approaches that contribute to better understand the mechanisms involved in a reliable FCR improvement of farmed gilthead sea bream.

Verifying the relationship between δ13C isotope profile variables and individual feed conversion ratio in large rainbow trout (Oncorhynchus mykiss)

The study aimed to verify the relationship found between individual indicator traits, derived from an isotope ratio of 13C/12C in various tissues (muscle, liver, and adipose), and individual feed efficiency. A 50-day experiment was performed with 46 rainbow trout (Oncorhynchus mykiss) kept in individual tanks after a dietary switch, using an experimental feed based on maize gluten with an enhanced level of 13C, during the grow-out phase. Individual growth, feed intake, and isotope profiles (muscle, liver, fin, and adipose tissue) were recorded. Using a Lasso-regression model, feed efficiency was found to be positively associated with visceral adipose tissue synthesis, meaning that feed efficiency was worsened when visceral adipose synthesis increased. The results indicated that deposition efficiency through lipid metabolism (δ13C in adipose tissue) was the most important determinant of feed efficiency of rainbow trout at this life stage. The results suggest that phenotyping of lipid deposition efficiency is possible through the use of feed ingredients with a natural abundance of stable isotopes.

Potential for genomic selection on feed efficiency in gilthead sea bream (Sparus aurata), based on individual feed conversion ratio, carcass and lipid traits

Genetic improvement of feed efficiency is key to improve the economic and environmental sustainability of fish farming. However, it requires individual phenotypes of feed efficiency, which are difficult if not impossible to obtain when fish are reared in tanks or cages. Here, we applied and validated on gilthead sea bream a method to evaluate individual feed efficiency based on individual rearing of fish in aquariums under restricted feeding. We collected individual phenotypes of feed efficiency in aquariums on 538 sea bream (average weight = 54.50 g). Based on these individual phenotypes, fish (average weight = 174.6 g) were reared in groups of divergent phenotypes (high or low feed efficiency), validating that individual feed efficiency had an impact on group feed efficiency at a later stage. All 538 fish, their parents as well as 794 sibs reared in cages in a production environment, were genotyped on a 57k SNP array to estimate genomic heritability and correlations between traits. We showed that feed efficiency was heritable but did not find significant associated QTLs. We also showed that feed efficiency was negatively genetically correlated to viscera yield, indicating that the most efficient fish had less viscera than the least efficient ones. Altogether, these results support that measuring individual feed efficiency in aquariums under restricted feeding may be used as a reliable phenotyping method to genetically improve feed efficiency, despite the bias intrinsically linked to individual rearing.

Impact of a divergent selective breeding programme on individual feed conversion ratio in Nile tilapia Oreochromis niloticus measured in groups by video-recording

Feed conversion ratio (FCR) is an important trait to target in breeding programs in order to improve fish farming sustainability and increase environmental efficiency. Due to the complexity of accurately measuring the individual feed consumption of fish, developing a selective breeding programme to improve FCR is a challenge. Using video-recordings of several consecutive meals in tilapia groups, we selected two divergent lines of Nile tilapia for high (FCR+) and low (FCR-) FCR at juvenile stage (12.2 g) combining BLUP and within family selection. After two generations, we observed a 12% realized difference in FCR between both divergent lines, indicating that the inclusion of FCR in a selective breeding programme can be efficient in practice. This divergence was in line with a realized heritability of 0.19 for FCR. The divergence in estimated breeding values of FCR between the two lines was reduced (3%) but still present. Another important result was that the realized genetic correlation between FCR and Daily Weight Gain (DWG) was highly negative (rg = −0.69 ± 0.16), meaning that improving growth by selective breeding would also indirectly improve FCR in juvenile Nile tilapia, although direct selection for FCR would be more efficient than indirect selection through growth to improve FCR.

Analysis of merged whole blood transcriptomic datasets to identify circulating molecular biomarkers of feed efficiency in growing pigs

BackgroundImproving feed efficiency (FE) is an important goal due to its economic and environmental significance for farm animal production. The FE phenotype is complex and based on the measurements of the individual feed consumption and average daily gain during a test period, which is costly and time-consuming. The identification of reliable predictors of FE is a strategy to reduce phenotyping efforts.ResultsGene expression data of the whole blood from three independent experiments were combined and analyzed by machine learning algorithms to propose molecular biomarkers of FE traits in growing pigs. These datasets included Large White pigs from two lines divergently selected for residual feed intake (RFI), a measure of net FE, and in which individual feed conversion ratio (FCR) and blood microarray data were available. Merging the three datasets allowed considering FCR values (Mean = 2.85; Min = 1.92; Max = 5.00) for a total of n = 148 pigs, with a large range of body weight (15 to 115 kg) and different test period duration (2 to 9 weeks). Random forest (RF) and gradient tree boosting (GTB) were applied on the whole blood transcripts (26,687 annotated molecular probes) to identify the most important variables for binary classification on RFI groups and a quantitative prediction of FCR, respectively. The dataset was split into learning (n = 74) and validation sets (n = 74). With iterative steps for variable selection, about three hundred’s (328 to 391) molecular probes participating in various biological pathways, were identified as important predictors of RFI or FCR. With the GTB algorithm, simpler models were proposed combining 34 expressed unique genes to classify pigs into RFI groups (100% of success), and 25 expressed unique genes to predict FCR values (R2 = 0.80, RMSE = 8%). The accuracy performance of RF models was slightly lower in classification and markedly lower in regression.ConclusionFrom small subsets of genes expressed in the whole blood, it is possible to predict the binary class and the individual value of feed efficiency. These predictive models offer good perspectives to identify animals with higher feed efficiency in precision farming applications.

Individual phenotyping of feed efficiency in lambs fed stable isotopes through maize silage

Recording feed intake and thus feed efficiency in ruminants is challenging. Hence, there is a need to establish indicator traits that can capture the individual variation in feed efficiency, without requiring individual feed intake recordings. This study aimed to explore whether the methodology established in salmon using individual indicator traits for feed efficiency based on stable isotope profiling could be transferred to lambs since the product for both species is meat. We used a total mixed ration based on maize silage to record the individual indicator traits for feed efficiency. The experiment was done with twelve weaned female lambs of the Norwegian White Sheep grouped equally in three, one group fed a total mixed ration enriched with 13C for 42 days, the second group grazed for 21 days and then fed the total mixed ration for 21 days, and the third group grazed for 42 days. The latter group was included to establish a baseline value for the stable isotope percentage in the back and thigh muscle tissues. Recording of 13C in the back muscle of the animals in the first two groups, resulted in a phenotypic correlation as large as 0.92 between individual feed conversion ratio and the individual indicator traits for feed efficiency based on stable isotope profiling. An assessment through individual indicator traits would be independent of the recording of individual feed intake.

Can individual feed conversion ratio at commercial size be predicted from juvenile performance in individually reared Nile tilapia Oreochromis niloticus?

Feed conversion ratio (FCR), the ratio between feed intake and body weight gain, is of major interest for improving aquaculture sustainability through reduced feed costs and environmental impacts. Demonstrating whether FCR measured in juvenile fish is an accurate predictor of their performance during the whole rearing period is critical to developing genetic improvement programs for this trait. This is especially true for estimates obtained in individually reared fish, for which this has high implications regarding the size of the necessary rearing structures. We obtained individual FCR from 30 male Nile tilapia Oreochromis niloticus from the GIFT strain individually reared in a recirculating system, from 36 to 260 g mean weight. They were fed twice a day and uneaten pellets were counted every day to determine the feed intake of each fish. Individual growth was monitored every week. Feed conversion ratio was estimated over two-week periods and over the whole rearing period (210 days). Phenotypic correlations between the two-week FCRs and global FCR estimations were mostly significant (ranged from 0.38 to 0.64). A significant phenotypic correlation between growth and FCR was also found: faster-growing fish had a better (lower) FCR. Individual breeding values for global FCR were estimated using FCR phenotypes from the present study and previously published heritabilities for FCR in Nile tilapia. Potential estimated genetic gain for global FCR was 2.2% per generation with 50% selection intensity. When selecting fish on their FCR from only a two-week period, approximately 50% of the reference genetic gain could be obtained with the same selection intensity. FCR measured during a two-week period at juvenile stage could be a moderately accurate approximation of the whole rearing period FCR, and could be used as a lower cost criterion to select for FCR in future genetic improvement programs using individual rearing of fish.

Correlations between intestinal innate immune genes and cecal microbiota highlight potential for probiotic development for immune modulation in poultry.

Immune function is influenced by the diversity and stability of the intestinal microbiota. A likely trade-off of immune function for growth has been demonstrated in heavier breeds of poultry that have been genetically selected for growth and feed efficiency traits. We investigated the expression of selected innate immune genes and genes encoding products involved in intestinal barrier function to determine whether function changes could be consistently linked to the phenotypic expression of feed conversion ratio (FCR), a common measure of performance within poultry broiler flocks. In addition, we compared individual cecal microbial composition with innate immune gene expression. Samples were utilised from two replicate trials termed P1E1 and P1E2. High (n = 12) and low (n = 12) performing birds were selected based on their individual FCR data from each replicate and combined for microbiota phylogenetic composition and immune gene expression analysis. Toll-like receptor 1 (TLR1La) and zonula occludens 1 (ZO1) were differentially expressed between high- and low-performing broilers. Several taxa were correlated with FCR; of these, unclassified YS2 and ZO1 were also positively correlated with each other. Interactions between taxa and differentially expressed innate immune genes between P1E1 and P1E2 were much greater compared to relationships between high- and low-performing birds. At the level of phylum, reciprocal correlations between tight junction proteins and Toll-like receptors with Bacteroidetes and Firmicutes were evident, as were correlations at the genus level.

Results of selection for breast muscle percentage and feed conversion ratio in Pekin ducks

Increasing breast muscle percentage by selection for breast layer thickness (muscle and skin) of living ducks by needle probe improves carcass quality as could be demonstrated by experiments and by applied breeding programs. In addition direct selection for individual feed conversion ratio can increase the efficiency of duck meat production. Divergent selection for feed conversion ratio from the age of 4 - 7 weeks over 11 generations has differentiated the feed efficiency by about 25 %. Causes for the reduction in feed conversion ratio are lower fat content of carcass, lower locomotor activity, higher enzymatic activity (alkaline phosphatase and creatinkinase in blood plasma) and better feed protein utilization. Because of lower feed consumption in the line selected for lower feed conversion ratio the emission of nitrogen and phosphorus via manure was reduced by about 39 and 26 %, respectively. That means, selection for better feed efficiency is not only an important economical but also an important ecological factor.

Genetic relationships between feed conversion ratio, growth curve and body composition in slow-growing chickens

1. Relationships between feed conversion ratio, growth curve parameters and carcase composition were investigated on 1061 chickens from a slow-growing line of label-type chickens. The growth curve was modelled with the Gompertz function. Individual feed conversion ratio (FCR) was recorded between 8 and 10 weeks of age and residual feed consumption (RES) was calculated over the same interval. Abdominal fat yield (AFY), breast yield (BRY) and leg yield (LY) were also measured on the birds following slaughter at 75 d of age. 2. The means for FCR and RES were 3·15 and 0·62 g, respectively. Growth curve parameters were 0·141/d for initial specific growth rate (L), 0·031/d for maturation rate (K) and 48·9 d for age at inflexion (TI). Mean values for BRY, LY and AFY were 166, 306 and 40 g/kg, respectively. 3. Heritability of FCR and RES were moderate to high (0·33 and 0·38 to 0·45). Growth curve parameters and LY were moderately heritable (0·22 to 0·34) and BRY and AFY were highly heritable (0·50 and 0·66). Genetic correlations between growth curve parameters and either FCR or RES were low to moderate (−0·31 to 0·51). LY and AFY were highly correlated with FCR (−0·70 and 0·44) and RES (−0·32 and 0·44) but BRY was not (0·00 and −0·35). These results show that indirect selection for feed conversion ratio is possible by using growth curve parameters and abdominal fatness, which do not require rearing the chickens in cages.

Genetic Changes in Efficiency of Feed Utilization of Chicks Maintaining Body Weight Constant

Selection based on individual feed conversion ratio was made for three generations in a chicken population previously selected for rate of growth and for one generation in a randombred population which had not been selected for rate of growth. Two sets of high (HL) and two sets of low (LL) feed conversion ratio lines were selected in each population: one set selected so that body weight was constant over generations (HLWK, LLWK), while in the other set (HLWV, LLWV) body weight was allowed to vary.In the three generations of selection in the chicken population the units of feed required for a unit of gain was increased .12 in the HLWV line over that of non-selected controls and .08 in the HLWK line. In the low feed conversion ratio lines the units of feed required for a unit of gain was decreased .11 in the LLWK line and .07 in the LLWV line. In both low lines more progress was made in females than in males. In the randombred stock, which had no previous selection for growth, as much progress in lowering the feed conversion ratio was made in one generation of selection as was made in three generations in the broiler population (decreased .12 in the LLWK and .13 in the LLWV) with no sex difference in response.The realized heritabilities for feed conversion for the lines selected from the broiler population were .20, .21, .33 and .26 for the LLWV, LLWK, HLWV, HLWK, respectively. In the lines selected from the randombred population the realized heritabilities were .56, .45, .35 and .31, respectively.The magnitude of the heritability values obtained indicate that even in lines previously selected for growth there is sufficient variation in efficiency of feed utilization to allow progress in selection without further change in body weight.