Genetic properties of feed efficiency parameters in meat-type chickens

Abstract

BackgroundFeed cost constitutes about 70% of the cost of raising broilers, but the efficiency of feed utilization has not kept up the growth potential of today's broilers. Improvement in feed efficiency would reduce the amount of feed required for growth, the production cost and the amount of nitrogenous waste. We studied residual feed intake (RFI) and feed conversion ratio (FCR) over two age periods to delineate their genetic inter-relationships.MethodsWe used an animal model combined with Gibb sampling to estimate genetic parameters in a pedigreed random mating broiler control population.ResultsHeritability of RFI and FCR was 0.42-0.45. Thus selection on RFI was expected to improve feed efficiency and subsequently reduce feed intake (FI). Whereas the genetic correlation between RFI and body weight gain (BWG) at days 28-35 was moderately positive, it was negligible at days 35-42. Therefore, the timing of selection for RFI will influence the expected response. Selection for improved RFI at days 28-35 will reduce FI, but also increase growth rate. However, selection for improved RFI at days 35-42 will reduce FI without any significant change in growth rate. The nature of the pleiotropic relationship between RFI and FCR may be dependent on age, and consequently the molecular factors that govern RFI and FCR may also depend on stage of development, or on the nature of resource allocation of FI above maintenance directed towards protein accretion and fat deposition. The insignificant genetic correlation between RFI and BWG at days 35-42 demonstrates the independence of RFI on the level of production, thereby making it possible to study the molecular, physiological and nutrient digestibility mechanisms underlying RFI without the confounding effects of growth. The heritability estimate of FCR was 0.49 and 0.41 for days 28-35 and days 35-42, respectively.ConclusionSelection for FCR will improve efficiency of feed utilization but because of the genetic dependence of FCR and its components, selection based on FCR will reduce FI and increase growth rate. However, the correlated responses in both FI and BWG cannot be predicted accurately because of the inherent problem of FCR being a ratio trait.

Inferences on the effects of selection for feed conversion over meat quality traits in broiler

“…Genetic variability in feed conversion ratio and meat quality traits has been investigated and heritability for these traits in broilers can be found in the literature, ranging from 0.13 to 0.45, and 0.04 to 0.48, respectively (Gaya et al, 2006;Aggrey et al, 2010;Verdal et al, 2011;Howie et al, 2011;Chabault et al, 2012;Felício et al, 2013). However, reports on the co-variation between feed conversion ratio and meat quality traits in commercial poultry are unavailable; therefore, the association between them is so far unknown and should be investigated.…”

“…According to Aggrey et al (2010), feed conversion ratio is a trait highlighted in a selection program, once feed expenses account for a great part of the costs in the broiler industry, and it is economically important the dissemination of genetic profiles to allow feed conversion more efficiently. In this context, the understanding of selection effects for feed conversion ratio on meat quality traits in genotypes commercially used has a great importance in broiler breeding program, since the existence of indirect selection for these variables may represent many losses for the industry.…”

Breeding for efficiency in the broiler chicken: A review

“…the mass of the feed consumed divided by the body mass gain. Data in literature shows that feed efficiency has increased considerably since its adoption into breeding programs in the 1970s (Emmerson 1997;Faraday 2007;Laughlin 2007;Aggrey et al 2010;de Beer et al 2011). However, when used to evaluate the changes in the energy efficiency of the birds, such data have no value unless the dietary energy content is known.…”

Gut metagenomic analysis reveals prominent roles of Lactobacillus and cecal microbiota in chicken feed efficiency

“…Koch et al 20 proposed the concept of RFI, which accounts for both maintenance requirements and growth. Because of its phenotypic independence from maintaining body weight and body weight gain, RFI has been proposed for measuring feed efficiency in breeding, with the heritability of RFI in chickens ranging from 0.2 to 0.8 [21][22][23][24] . Feed efficiency is a complex trait because it is influenced not only by the host genetics and physiological state but also by the intestinal microbiota, which would affect the nutrient digestion and energy absorption of the host.…”