Genetic progress in broiler traits – implications for body composition

2007 ◽  
Vol 2007 ◽  
pp. 67-67 ◽  
Author(s):  
E.C. Fleming ◽  
C. Fisher ◽  
J. McAdam
Keyword(s):  
Growth Rate ◽  
Body Composition ◽  
Recent Work ◽  
Feed Efficiency ◽  
Genetic Selection ◽  
Genetic Progress ◽  
Genetic Potential ◽  
Selection For ◽  
The Impact ◽  
Meat Type

Genetic selection has dramatically increased the potential for growth, feed efficiency and yield in meat type broilers. It is a widely held belief that these improvements in genetic potential have produced a broiler that is lower in fat content. However, some recent work has implied that the Modern broiler is actually fatter than its counterpart of 30 years ago (Wang et al., 2004). The objective of this study was to explore the impact that selection for growth rate and yield has had on broiler body composition.

Genetic progress in broiler traits – implications for welfare

2007 ◽  
Vol 2007 ◽  
pp. 50-50 ◽  
Author(s):  
E. C. Fleming ◽  
C. Fisher ◽  
J. McAdam
Keyword(s):  
Growth Rate ◽  
Genetic Selection ◽  
Growth Potential ◽  
Genetic Progress ◽  
Rapid Growth Rate ◽  
Fundamental Cause ◽  
Selection For ◽  
Using Data ◽  
The Impact ◽  
Health And Mortality

Genetic selection has dramatically increased the growth potential of broilers. A positive correlation exists between growth rate and the occurrence of leg disorders (Sørensen et al., 1999), and rapid growth rate is widely presumed to be a fundamental cause of leg ill-health in the modern broiler. However, it is recognised that the simultaneous improvement of growth rate and reduction in incidence of leg disorders is possible (Sørensen, 1992). The objective of this study was to explore the impact that selection for growth has had on broiler welfare, as measured by leg health and mortality, using data from genetic control strains.

Issues arising from genetic selection for growth and body composition characteristics in poultry and pigs

2000 ◽  
Vol 27 ◽  
pp. 39-53 ◽  
Author(s):  
G. C. Emmans ◽  
I. Kyriazakis
Keyword(s):  
Growth Rate ◽  
Body Composition ◽  
Metabolic Rate ◽  
Support Systems ◽  
Genetic Selection ◽  
Fitness Traits ◽  
Environmental Requirements ◽  
Selection For ◽  
Rate Selection ◽  
Composition Characteristics

AbstractBreeders of poultry and pigs have selected for some combination of increased growth rate, decreased fatness and increased muscularity. Increasingly various fitness traits are included in the index used. The consequences of such selection include complex effects on nutritional and environmental requirements, at least some of which are reliably predictable using suitable models. Appropriate changes to the environment and to nutrition as selection proceeds will help to avoid unwanted effects occurring. Among the predictable effects are that higher ratios of nutrients to energy, and lower temperatures, will be needed by the improved genotypes. Selection for growth rate must eventually exhaust the capacity of the support systems – digestive, respiratory, circulatory and excretory – to cope with the increased metabolic rate. Selection for increased yield of valuable parts will cause these problems to occur earlier. While it is possible to predict that these problems will occur it cannot be predicted when they will. Breeders need to be aware of these problems, and use all possible routes to help them in reducing their severity. Where the appropriate actions for fitness selection, and nutritional and environmental modifications, are taken the occurrence of the problems will be delayed.

scholarly journals Genetic mechanisms underlying feed utilization and implementation of genomic selection for improved feed efficiency in dairy cattle

2020 ◽  
Vol 100 (4) ◽  
pp. 587-604 ◽  
Author(s):  
Luiz F. Brito ◽  
Hinayah R. Oliveira ◽  
Kerry Houlahan ◽  
Pablo A.S. Fonseca ◽  
Stephanie Lam ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Genomic Selection ◽  
Feed Efficiency ◽  
Genetic Selection ◽  
Complex Trait ◽  
Feed Utilization ◽  
Successful Implementation ◽  
Genetic Progress ◽  
Selection For ◽  
Indicator Traits

The economic importance of genetically improving feed efficiency has been recognized by cattle producers worldwide. It has the potential to considerably reduce costs, minimize environmental impact, optimize land and resource use efficiency, and improve the overall cattle industry’s profitability. Feed efficiency is a genetically complex trait that can be described as units of product output (e.g., milk yield) per unit of feed input. The main objective of this review paper is to present an overview of the main genetic and physiological mechanisms underlying feed utilization in ruminants and the process towards implementation of genomic selection for feed efficiency in dairy cattle. In summary, feed efficiency can be improved via numerous metabolic pathways and biological mechanisms through genetic selection. Various studies have indicated that feed efficiency is heritable, and genomic selection can be successfully implemented in dairy cattle with a large enough training population. In this context, some organizations have worked collaboratively to do research and develop training populations for successful implementation of joint international genomic evaluations. The integration of “-omics” technologies, further investments in high-throughput phenotyping, and identification of novel indicator traits will also be paramount in maximizing the rates of genetic progress for feed efficiency in dairy cattle worldwide.

scholarly journals SELECTION FOR GROWTH RATE, FEED EFFICIENCY AND BODY COMPOSITION IN MICE

Genetics ◽  
1974 ◽  
Vol 78 (1) ◽  
pp. 525-540
Author(s):  
T M Sutherland ◽  
Patricia E Biondini ◽  
G M Ward
Keyword(s):  
Growth Rate ◽  
Body Composition ◽  
Feed Efficiency ◽  
Selection For

RELATIVE MERIT OF THREE SWINE SELECTION PROGRAMS FOR THE SIMULTANEOUS IMPROVEMENT OF GROWTH RATE AND FEED EFFICIENCY

1970 ◽  
Vol 50 (3) ◽  
pp. 663-670
Author(s):  
G. W. RAHNEFELD
Keyword(s):  
Growth Rate ◽  
Genetic Correlation ◽  
Feed Efficiency ◽  
Genetic Improvement ◽  
Relative Merit ◽  
Genetic Progress ◽  
Plan B ◽  
Primary Selection ◽  
Selection For

Hypothetical swine populations with selection programs designed to capitalize on the favorable genetic correlation between growth rate and feed efficiency, and their heritabilities, are considered. Three types of selection programs are evaluated: plan A—selection for growth rate alone; plan B—selection for feed efficiency alone; and plan C—primary selection among litters for feed efficiency, coupled with secondary selection for growth rate. In the three programs, approximately 5% of the available boars and 25% of the available gilts are retained for breeding purposes. With the parameters selected, plan A will produce more genetic progress in growth rate than plan B or C, and plan B generally more than plan C. In the case of feed efficiency, selection under plan B consistently produces more genetic progress than plan A or C, and plan A generally more than plan C. Selection under plan A and plan B results in a greater amount of simultaneous genetic progress in the two traits than does plan C. In general, there is little to choose between plan A and plan B in the simultaneous genetic improvement of the two traits. The advantage of plan A over plan B is that growth rate can be measured with ease, and accuracy and testing facilities costs can be kept to a minimum.

scholarly journals The Impact of Selection using Residual Average Daily Gain and Marbling EPDs on Growth Performance and Carcass Traits in Angus Steers

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
T. R. Krause ◽  
E. R. Moore ◽  
J. Duggin ◽  
J. R. Segers ◽  
T. D. Pringle
Keyword(s):  
Growth Performance ◽  
Feed Efficiency ◽  
Average Daily Gain ◽  
Backfat Thickness ◽  
Feeding Trial ◽  
Body Weights ◽  
Selection For ◽  
Carcass Merit ◽  
The Impact ◽  
Daily Gain

ObjectivesProfitability in the beef industry has narrow margins regulated by revenue from output traits like growth and carcass merit, but profitability is also largely impacted by input expenses like feed costs. Selecting for improvements in feed efficiency during the finishing phase, one of the most feed intensive segments of the industry, can help to mitigate those input costs. This study compared growth performance, feed efficiency, body composition, and carcass characteristics in Angus steers (n = 321) from bulls divergently selected for feed efficiency and marbling.Materials and MethodsAngus sires were selected based on high (10th percentile or better) and low (85th percentile or worse) residual average daily gain (RADG) EPD as well as high (fifth percentile or better) and average (near 50th percentile) marbling (MARB) EPD. These criteria resulted in a 2 × 2 factorial design with four breeding lines: high RADG/high MARB, high RADG/average MARB, low RADG/high MARB, low RADG/average MARB. Data were analyzed using MIXED procedures of SAS with RADG and MARB as main effects. Significance was set at α = 0.05. Generation was also analyzed, where generation one (GEN1) steers were from a selected sire while generation two (GEN2) steers were from a selected sire and a selected dam.ResultsUltrasound and carcass data revealed no differences (P ≥ 0.12) in 12th rib backfat thickness from weaning through slaughter for the RADG EPD groups. Yield grade and dressing percent did not differ (P ≥ 0.56) across RADG or MARB groups. At the beginning and end of the feeding trial, the high RADG (P ≤ 0.02) group had larger ultrasound ribeye area (REA) than the low RADG group. Carcass REA tended (P = 0.08) to be larger in the high versus low RADG steers. During the feedlot trial and through slaughter, body weight was heavier (P ≤ 0.006) for the high versus low RADG steers but did not differ (P ≥ 0.44) across MARB EPD. Feed efficiency measures did not differ (P ≥ 0.32) across RADG or MARB groups apart from the tendency (P = 0.08) for residual feed intake to be lower in the high versus low RADG steers. Marbling scores differed (P ≤ 0.04) across RADG and MARB groups with the low RADG steers and the high MARB steers having improved marbling. The quality grade distribution across MARB EPD revealed that the average MARB steers graded 73% Choice and 25% Prime while the high MARB steers graded 56% and 42%, respectively. Slice shear force did not differ (P ≥ 0.32) across RADG or MARB EPD. Body weights tended (P = 0.06) to be heavier at the start of the feeding trial for GEN1 versus GEN2 steers. Total gain, average daily gain, and feed to gain (F:G) differed by generation (P ≤ 0.007) with increased rates of gain and reduced F:G in the GEN2 versus GEN1 steers. Body weights did not differ (P = 0.72) across GEN at the end of the feeding trial. Backfat thickness at the start and end of the feedlot phase was less (P ≤ 0.03) and marbling score was improved (P = 0.02) in the GEN2 versus GEN1 steers, respectively.ConclusionThese results suggest that selection using RADG EPD has negligible impacts on meat quality; and that progress in selection for efficiency can be achieved while advancing carcass quality and value. Furthermore, continued divergent selection for feed efficiency and marbling has the potential to improve feed efficiency through advancements in the rate of gain, while enhancing carcass merit through marbling.

Post-weaning growth rate effects on body composition of Nellore bulls

2020 ◽  
Vol 60 (6) ◽  
pp. 852
Author(s):  
Luiz H. P. Silva ◽  
Pedro V. R. Paulino ◽  
Pedro D. B. Benedeti ◽  
Mauricio M. Estrada ◽  
Lyvian C. Alves ◽  
...  
Keyword(s):  
Growth Rate ◽  
Body Composition ◽  
Feed Efficiency ◽  
Compensatory Growth ◽  
Average Daily Gain ◽  
High Growth ◽  
High Growth Rate ◽  
Carcass Weight ◽  
Apparent Digestibility ◽  
Rate Effects

Context Previously feed-restricted cattle may exhibit compensatory growth during the finishing phase. However, the efficiency in converting feed into carcass should be evaluated since cattle undergoing compensatory growth usually have high non-carcass weight gain. Aims The objective of this study was to evaluate the effect of growth rate throughout the post-weaning growing phase on subsequent feed efficiency, carcass gain, and gain composition. Methods Thirty-nine weaned young Nellore bulls averaging 230.4 ± 5.62 kg of bodyweight and 8.5 ± 0.25 months of age were used. Initially, five bulls were slaughtered as a reference initial group. The remaining bulls were randomly assigned to one of three nutritional plans to achieve Low (0 kg/day), Medium (0.6 kg/day) or High (1.2 kg/day) average daily gain (ADG) throughout the post-weaning growing phase, followed by high growth rate during the finishing phase. One-half of the bulls from each treatment were slaughtered at the end of the post-weaning growing phase, and the other one-half after the finishing phase. During both phases the feed intake, apparent digestibility, performance, and body composition were evaluated. Key results Throughout the post-weaning growing phase, High bulls had greater ADG and more efficiently converted feed into carcass, compared with other nutritional plans (P < 0.01). Throughout the finishing phase, Low bulls had greater ADG, carcass gain, and feed efficiency than High and Medium bulls (P < 0.01). Previous feed restriction did not affect (P > 0.05) apparent digestibility. During the finishing phase, previously restricted bulls fully compensated for the lost visceral organ weight, whereas the losses of bodyweight and carcass weight were only partially compensated. Throughout finishing, Low bulls had the greatest feed efficiency and profitability among nutritional plans. However, considering the overall experiment, Hight bulls converted feed into carcass more efficiently than Low bulls (P = 0.02), but did not differ from Medium (P > 0.05). Conclusions Although previously restricted bulls had greater performance and efficiency throughout finishing, the improvement was not enough to reach the same carcass weight at the same age of the unrestricted bulls. Implications Despite the greater profitability of previously restricted bulls throughout finishing, unrestricted bulls were more profitable considering both growing and finishing phases.

Effect of index selection for reduced backfat thickness and increased growth rate on sow weight changes through two parities in swine

1992 ◽  
Vol 72 (2) ◽  
pp. 403-408 ◽  
Author(s):  
R. M. McKay
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Selection Pressure ◽  
Backfat Thickness ◽  
Index Selection ◽  
Weight Changes ◽  
Selection For ◽  
The Impact

The impact of continued selection for reduced backfat thickness and improved growth rate on weight changes in Yorkshire and Hampshire sows, from breeding as gilts to weaning their second litter, was studied. Results suggest that some sow weight changes may have been influenced by selection pressure exerted. Key words: Sows, Canadian Yorkshire, Hampshire, liveweight change

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