SELECTION FOR GROWTH RATE OR FOR FEED EFFICIENCY IN MEAT-TYPE CHICKENS ALTERS THE PULSATILE GROWTH HORMONE SECRETORY PATTERN

1991 ◽  
pp. 205
Author(s):  
J. Buyse ◽  
E. Decuypere ◽  
F.R. Leenstra ◽  
G. Beuving ◽  
L. Berghman
Keyword(s):  
Growth Hormone ◽  
Growth Rate ◽  
Feed Efficiency ◽  
Selection For ◽  
Secretory Pattern ◽  
Meat Type

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.

Insulin, growth hormone, glucose, and fatty acids in gilts selected for rapid vs. slow growth rate

1989 ◽  
Vol 257 (4) ◽  
pp. E554-E560
Author(s):  
S. A. Norton ◽  
M. T. Zavy ◽  
C. V. Maxwell ◽  
D. S. Buchanan ◽  
J. E. Breazile
Keyword(s):  
Fatty Acids ◽  
Growth Hormone ◽  
Growth Rate ◽  
Slow Growth ◽  
Insulin Level ◽  
Growth Line ◽  
Slow Growth Rate ◽  
Selection For ◽  
Plasma Gh ◽  
Profile Area

Twelve-hour plasma profiles of growth hormone (GH), insulin, glucose, and nonesterified free fatty acids (NEFA), as well as GH, insulin, and glucose responses to saline, glucose, arginine, and human pancreatic growth hormone-releasing factor (GRF) infusion were examined in 15 crossbred gilts, selected for rapid vs. slow growth. For experiment 1 GH and insulin patterns differed (P less than 0.05) between the rapid growth line (RGL) and slow growth line (SGL). Mean GH concentrations in SGL and RGL gilts were 4.1 and 3.2 ng/ml, respectively (P less than 0.05). Plasma GH profile area was greater (P less than 0.08) for SGL than RGL gilts. Glucose level, glucose area, and insulin level were higher (P less than 0.05) for RGL than SGL gilts. Plasma NEFA levels and area were greater (P less than 0.05) for SGL gilts. In experiment 2 responses of GH, insulin, and glucose to saline, glucose, arginine, and GRF infusions varied (P less than 0.05) between and within lines relative to control values. These results indicate that selection for growth rate results in concomitant changes in endocrine and metabolic status.

scholarly journals The performance testing of boars II. Phenotypic and genetic correlations

1971 ◽  
Vol 43 (2) ◽  
pp. 103-110
Author(s):  
Elsi Ettala
Keyword(s):  
Growth Rate ◽  
Total Variation ◽  
Feed Efficiency ◽  
Genetic Correlations ◽  
Performance Testing ◽  
Stepwise Multiple Regression ◽  
Daily Growth ◽  
Fat Thickness ◽  
Selection For ◽  
Different Characteristics

In this study the interrelationships between the various characteristics for the boar material described in the first part were analysed. For this purpose the phenotypic, genetic and intra-sire correlation matrix as well as stepwise multiple regression analyses were calculated by computer for the material of 138 boars. The results showed that there was a very strong correlation between fat thickness and testing score (rG = —0.95***, rP = —0.88***). Of the total variation in the testing score 85.2 % was accounted for by the variation in fat thickness. Although the testing score is made up of the points for fat thickness and growth, the latter accounted for only 9.2 % of the variation in the score. Daily growth was positively associated with the testing score and negatively with the amount of feed units required per growth kilogram, but significantly so only for the intra-sire correlations; the genetic correlations being even, contrary to expectation. The association between growth rate and fat thickness was positive (rG = 0.47***). Of the total variation in feed efficiency the testing score accounted for 35.6 %. A high testing score was associated with a favourable feed efficiency (rg = —0.63***). By correlation studies attempts were also made to find out whether it would be possible to shorten the testing period without decreasing the accuracy. The correlations show that the growth rate can be predicted with an appreciable degree of accuracy already from the weight at the 8th testing week. The correlations between the above weight and growth rates were; rG = 0.84***, rP = 0.82***. From the associations between different characteristics one can decide on the suitability of testing and the consequences of selection for particular traits.

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.

BREEDING FOR FEED EFFICIENCY: SWINE AND DAIRY CATTLE

1984 ◽  
Vol 64 (3) ◽  
pp. 505-512 ◽  
Author(s):  
B. W. KENNEDY
Keyword(s):  
Growth Rate ◽  
Dairy Cattle ◽  
Feed Efficiency ◽  
Large Scale ◽  
Experimental Studies ◽  
Direct Selection ◽  
Correlated Response ◽  
Selection For ◽  
Potential Improvement ◽  
Current Selection

Feed efficiency in dairy cattle is moderately heritable and selection for its improvement theoretically would be effective. Despite this, direct selection for feed efficiency is not practiced in dairy cattle. Growth of milk recording programs which monitor feeding information has made selection for feed efficiency, or at least efficiency of concentrate conversion, possible on a large scale. However, it has been estimated that correlated response to direct selection for increased milk yield probably results in 70–95% of the potential improvement in feed efficiency that could be achieved through direct selection for feed efficiency. Current selection practices for increased body size may be detrimental to feed efficiency. In swine also, little direct selection for improved feed efficiency is practiced. Experimental studies for selection for feed efficiency have been less successful than expected. Correlated response from selection for an index that combines growth rate and backfat seems to be as effective in improving feed efficiency as direct selection. Development of automated feeding devices which allow measurement of individual feed intake under group penning will facilitate monitoring of and selection for improved feed efficiency. Key words: Selection, feed efficiency, swine, dairy cattle

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