Advances in Food Technology and Nutritional Sciences

Open journal

ISSN 2377-8350

Feed Efficiency: A Key Production Trait and A Global Challenge

Sami Dridi*, Nicholas Anthony, Byung-Whi Kong and Walter Bottje

Sami Dridi, PhD, HDR

Associate Professor, Avian Endocrinology and Molecular Genetics, Center of Excellence for Poultry Science , University of Arkansas,1260 W. Maple Street ,Fayetteville AR 72701, USA, Tel. (479)-575-2583, Fax: (479)-575-7139, E-mail:

Animal agriculture is facing substantial challenges from a steep projected increase in global demand for high quality animal protein and the need to adapt to higher temperature due to climate change. Indeed, with predictions that the world human population will increase to between 9 and 10 billion, United Nations Food and Agriculture Organization (FAO) estimates that by 2050 there will be increased demand for meat and egg protein by 73% and dairy products by 58% over 2011 levels.1 Meeting the expected growth in global demand for high quality animal protein will be very strenuous, especially under environmental temperature constraints due to climate change and increased feed cost.

Large, abrupt, and widespread extreme heat waves have occurred repeatedly in the past2 and resulted in estimated total annual economic loss to the US livestock production industry of $1.69 to 2.36 billion.3 More intense and frequent heat waves are predicted to increase for the next century.4 Thus, there is a critical need for extensive applied and basic research efforts to improve animal adaptability and tolerance to high ambient temperature and to maximize their productivity. Our research is devoted, using top-down/bottom-up approaches and multidisciplinary area ranging from integrative physiology and genetics to molecular and cellular biology, to understanding the molecular mechanisms that regulate energy homeostasis and feed efficiency in avian species as well as the basis of their response to environmental stress.

Although it is moderately heritable, Feed Efficiency (FE) that defines the animal’s ability to convert feed into body weight, is a trait of vital importance for maintaining sustainable agriculture. Two parameters are widely used to assess FE in chickens and in livestock: 1) Feed Conversion Ratio (FCR) that is defined as the amount of feed consumed per unit of weight gain5 and 2) Residual feed consumption or intake (RFC or RFI) which is the variation between animal’s actual and expected feed intake based on the estimated requirement for maintenance and growth/production.6 Genetic selection based on these parameters has made spectacular progress in meat production traits. For instance, as seen in Figure 1, under optimal husbandry conditions, body weight and breast yield have dramatically increased however FCR decreased. The selection methods however have been applied without knowledge of the fundamental molecular mechanism changes that might be induced by the selection. Associated with these successes (increased muscle yield and high growth rate) there have been a number of undesirable changes in modern chickens such as muscle disorders (muscle myopathy, white striping), heart failure syndrome, ascites, lameness and fat deposition. Thus, a deep molecular and mechanistic understanding of traits of breeding interest may help to avoid the above mentioned unfavourable consequences.

Figure 1: Time trends increase of economically important broiler traits (body weight, FCR, and breast yield). The graph is presented based on the data published by Siegel PB.7


Our group has developed several avian (chicken and quail) genetic populations designed to attack specific (patho) physiological and environmental challenges facing the modern poultry industry. As the regulation of energy homeostasis (energy intake and expenditure) and the stress response are coupled physiological processes,8 we have unique experimental models including quails that were divergently selected for high or low feed efficiency and for sensitivity or resistance to stress.9As the hypothalamus, which contains the satiety and hunger centers, plays a crucial role in the regulation of body energy balance,10 we determined the feeding- related hypothalamic neuropeptide profile in two chicken lines divergently selected for low (R- ) or high residual feed consumption (R+ ). For the same body weight and egg production, the R+ chickens consume 40% more feed than their counterparts Rlines.11 We identified several feeding-related hypothalamic key genes that are differentially expressed between the two lines that might explain the difference in feed intake.12 We also identified avian mitochondrial uncoupling protein and found that it was highly expressed in the muscle of R+ compared to R- chicken suggesting that the R+ chickens dissipate energy as heat and they are thereby inefficient.13 Our previous studies have also revealed a link between mitochondrial bioenergetics and dynamics and FE in broiler chickens. Low FE birds exhibited lower mitochondrial electron transport chain coupling and higher hydrogen peroxide compared to high FE counterparts.14 Interestingly, we recently found that the orexigenic peptide, orexin, was highly expressed in chicken muscle and orexin treatment altered mitochondrial biogenesis, bioenergetics and dynamics (fission and fusion) in avian muscle cells,15 however the role of orexin in high and low feed efficiency warrants further studies.

With the new cutting edge techniques involving genomics, proteomics, transcriptomics, mobilomics, microbiomics and metabolomics we will have the potential to identify molecular signatures for feed efficiency and to solve the intervening puzzle between nutrients, genes, environment and performances. A personalized nutrition approach based on identification, selection and optimization of nutrients fine-tuned with animal genetic profiles and animal’s capability to withstand environmental stress will improve performances, health and wellness.

1.Economic and Social Development Department. World Agriculture towards 2030/2050. Available at: economic/esa/esag/esag- home/en/ 2003; Accessed 2015.

 2.Alley RB, Clark PU, Huybrechts P, Joughin I. Ice-sheet and sea-level changes. Science. 2005; 310: 456-460. doi: 10.1126/ science.1114613

3. St-Pierre NR, Cobanov B, Schnitkey G. Economic losses from heat stress by US livestock industries. J Dairy Sci. 2003; 86: E52-E77. doi: 10.3168/jds.S0022-0302(03)74040-5

4. Mora C, Frazier AG, Longman RJ, et al. The projected timing of climate departure from recent variability. Nature. 2013; 502: 183-187. doi: 10.1038/nature12540

5. Willems OW, Miller SP, Wood BJ. Aspects of selection for feed efficiency in meat producing poultry. Worlds Poult Sci J. 2013; 69: 77-88. doi: 10.1017/S004393391300007X

6. Aggrey SE, Karnuah AB, Sebastian B, Anthony NB. Genetic properties of feed efficiency parameters in meat-type chickens. Genet Sel Evol. 2010; 42: 25. doi: 10.1186/1297-9686-42-25

7. Siegel PB. Evolution of the modern broiler and feed efficiency. Annu Rev anim Biosci. 2014; 2: 375-385. doi: 10.1146/ annurev-animal-022513-114132

8. Valles A, Marti O, Garcia A, Armario A. Single exposure to stressors causes long-lasting, stress-dependent reduction of food intake in rats. Am J Physiol Regul Integr Comp Physiol. 2000; 279: R1138-R1144.

9.Satterlee DG, Johnson WA. Selection of Japanese quail for contrasting blood corticosterone response to immobilization. Poult Sci. 1988; 67: 25-32. doi: 10.3382/ps.0670025

10.Sawchenko PE. Toward a new neurobiology of energy balance, appetite, and obesity: The anatomists weigh in. J Comp Neurol. 1998; 402: 435-441. doi: 10.1002/(SICI)1096-9861 (19981228)402:4<_x0034_35:_x003a_AID-CNE1>3.0.CO;2-M

11.Bordas A, Merat P. Genetic variation and phenotypic correlations of food consumption of laying hens corrected for body weight and production. Br Poult Sci. 1981; 22: 25-33. doi: 10.1080/00071688108447860

12. Sintubin P, Greene E, Collin A, et al. Expression profile of hypothalamic neuropeptides in chicken lines selected for high or low residual feed intake. Neuropeptides. 2014; 8: 213-220. doi: 10.1016/j.npep.2014.04.007

13.Raimbault S, Dridi S, Denjean F, et al. An uncoupling protein homologue putatively involved in facultative muscle thermogenesis in birds. Biochem J. 2001; 353: 441-444

14.Bottje W, Iqbal M, Tang ZX, et al. Association of mitochondrial function with feed efficiency within a single genetic line of male broilers. Poult Sci. 2002; 81: 546-555. doi: 10.1093/ ps/81.4.546

15.Lassiter K, Greene E, Piekarski A, et al. Orexin system is expressed in avian muscle cells and regulates mitochondrial dynamics. Am J Physiol Regul Integr Comp Physiol. 2015; 308: R173-R187. doi: 10.1152/ajpregu.00394.2014


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