Growth, efficiency, and yield of commercial broilers from 1957, 1978, and 2005

Abstract

The effect of commercial selection on the growth, efficiency, and yield of broilers was studied using 2 University of Alberta Meat Control strains unselected since 1957 and 1978, and a commercial Ross 308 strain (2005). Mixed-sex chicks (n = 180 per strain) were placed into 4 replicate pens per strain, and grown on a current nutritional program to 56 d of age. Weekly front and side profile photographs of 8 birds per strain were collected. Growth rate, feed intake, and measures of feed efficiency including feed conversion ratio, residual feed intake, and residual maintenance energy requirements were characterized. A nonlinear mixed Gompertz growth model was used to predict BW and BW variation, useful for subsequent stochastic growth simulation. Dissections were conducted on 8 birds per strain semiweekly from 21 to 56 d of age to characterize allometric growth of pectoralis muscles, leg meat, abdominal fat pad, liver, gut, and heart. A novel nonlinear analysis of covariance was used to test the hypothesis that allometric growth patterns have changed as a result of commercial selection pressure. From 1957 to 2005, broiler growth increased by over 400%, with a concurrent 50% reduction in feed conversion ratio, corresponding to a compound annual rate of increase in 42 d live BW of 3.30%. Forty-two-day FCR decreased by 2.55% each year over the same 48-yr period. Pectoralis major growth potential increased, whereas abdominal fat decreased due to genetic selection pressure over the same time period. From 1957 to 2005, pectoralis minor yield at 42 d of age was 30% higher in males and 37% higher in females; pectoralis major yield increased by 79% in males and 85% in females. Over almost 50 yr of commercial quantitative genetic selection pressure, intended beneficial changes have been achieved. Unintended changes such as enhanced sexual dimorphism are likely inconsequential, though musculoskeletal, immune function, and parent stock management challenges may require additional attention in future selection programs.

Breeding for efficiency in the broiler chicken: A review

“…Nevertheless, there is anecdotal evidence also to show the involvement of genetics in decreasing feed spillage. For instance, although it was not the aim of the experiment to examine differences in feed spillage between breeds, relatively high feed wastage was observed by Zuidhof et al (2014) in less selected broiler breeds compared to modern breeds (i.e. birds which have a genotype similar to what could be expected to be grown commercially nowadays).…”

“…Much progress has been made in artificial selection technologies over the last century: from mass selection to the use of pedigree charts and hybridisation, to the introduction of selection indices and artificial insemination, to the development of modern breeding value estimation techniques (Rishell 1997;Muir and Aggrey 2003). Consequently, Zuidhof et al (2014) showed chicken broiler growth rate to have increased by over 400 % between the years of 1950 and 2005 ( Fig. 1), when genetically representative birds of those years were grown in identical environments.…”

“…1 can all be attributed to the advancements made in their genetics (Havenstein et al 2003a, b;Zuidhof et al 2014) and this has environmental impact implications. For instance, feed provision represents the industry's greatest environmental hotspot (Pelletier 2008;Leinonen et al 2012Leinonen et al , 2013Prudêncio da Silva et al 2014); as such, a bird that requires less feed to achieve the same slaughter weight will embody a lower environmental burden.…”

“…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. For this reason, experiments which have compared different breeds on the same diet are of particular interest, from which biological traits such as digestive efficiency and body composition can be compared (Sherwood 1977;Havenstein et al 2003b;Mussini 2012;Zuidhof et al 2014). Until now, the consequences of genetic selection on the biological traits aforementioned and ultimately the energy use efficiency of the birds have not been analytically reviewed in such a way as to show how artificial selection has led to an improvement in broiler performance.…”

Intestinal permeability induced by lipopolysaccharide and measured by lactulose, rhamnose and mannitol sugars in chickens

“…Limited in vivo research has shown that increased IP can lead to increased bacterial translocation , coccidiosis (Chapman, 2014) and lameness (Wideman et al, 2012) in chickens. These diseases can impact health and welfare leading to reduced efficiency and economic loss (Zuidhof et al, 2014).…”