Selection for lean growth rate and correlated responses in litter traits in a synthetic line of Yorkshire-Meishan pigs

2001 ◽  
Vol 81 (2) ◽  
pp. 205-214 ◽  
Author(s):  
P. Chen ◽  
T. J. Baas ◽  
J. C. M. Dekkers ◽  
L. L. Christian
Keyword(s):  
Growth Rate ◽  
Regression Coefficients ◽  
Correlated Response ◽  
Selection Line ◽  
Control Line ◽  
Correlated Responses ◽  
Lean Growth ◽  
Litter Traits ◽  
Selection For ◽  
Synthetic Line

Selection for lean growth rate (LGR) was conducted for four generations in a synthetic line of Yorkshire-Meishan pigs to study the effectiveness of selection for LGR and correlated responses in litter traits. Lean growth rate was estimated from ultrasound measurements of 10th-rib backfat thickness and longissimus muscle area. In the selection line, 7 boars and 20 gilts with the highest LGR were selected to produce the next generation. The generation interval was 13 mo and the average selection differential per generation was 1.1 phenotypic standard deviation units. A contemporaneous control line was maintained by randomly selecting 5 boars and 15 gilts. Data from a total of 1057 pigs sired by 58 boars and out of 133 sows were available from the two lines. Selection responses were estimated from deviations of the selection line from the control line using least squares (LS) and by multiple trait derivative-free restricted maximum likelihood analysis using an animal model (AM). The estimate of response to selection per generation using LS was 9.4 ± 0.95 g d–1 for LGR. The corresponding estimate from the AM was 9.8 ± 0.51 g d–1. Correlated responses in litter traits were regressed on generation. For the LS method, regression coefficients were negative but not significant (P > 0.05) for total number born, number born alive, and number at 21 d and at 42 d. Significant, positive correlated responses occurred in 42-d litter weight and 21-d piglet weight (P < 0.05). For the AM method, the regression coefficients were also negative, but were not significant (P > 0.05) for numberalive at birth, at 21 d, and at 42 d. A significant positive correlated response occurred only for 42-d litter weight (P < 0.05). Although results are based on a population of limited size, it can be concluded that selection for LGR in a synthetic line is effective and should have little effect on litter traits. Key words: Pigs, selection, lean growth rate, correlated response

Selection for components of efficient lean growth rate in pigs 2. Selection pressure applied and direct responses in a Landrace herd

1994 ◽  
Vol 59 (2) ◽  
pp. 263-269 ◽  
Author(s):  
N. D. Cameron ◽  
M. K. Curran
Keyword(s):  
Growth Rate ◽  
Genetic Correlations ◽  
Correlated Response ◽  
Selection Line ◽  
Control Line ◽  
Direct Response ◽  
Lean Growth ◽  
Ad Libitum ◽  
Selection For ◽  
Ad Libitum Feeding

AbstractResponses to divergent selection for lean growth rate with ad-libitum feeding (LGA), for lean food conversion (LFC) and for daily food intake (DFI) in Landrace pigs were studied. Selection was practised for four generations with a generation interval ofl year. A total of 2642 pigs were performance tested in the high, low and control lines, with an average of 37 boars and 39 gilts performance tested per selection line in each generation. The average within-line inbreeding coefficient at generation four was equal to 0·04. There was one control line for the DFI and LFC selection groups and another control line for the LGA selection group. Animals were performance tested in individual pens with mean starting and finishing weights of 30 kg and 85 kg respectively with ad-libitum feeding. The selection criteria had phenotypic s.d. of 32, 29 and 274 units, for LGA, LFC and DFI, respectively, and results are presented in phenotypic s.d.Cumulative selection differentials (CSD) were 5·1, 4·5 and 5·5 phenotypic s.d. for LGA, LFC and DFI, respectively. Direct responses to selection were 1·4,1·1 and 0·9 (s.e. 0·20) for LGA, LFC and DFI. In each of the three selection groups, the CSD and direct responses to selection were symmetric about the control lines. The correlated response in LFC (1·1, s.e. 0·19) with selection on LGA was equal to the direct response in LFC. In contrast, the direct response in LGA was greater than the correlated response (0·7, s.e. 0·18) with selection on LFC. There was a negative correlated response in DFI (-0·6, s.e. 0·18) with selection on LFC, but the response with selection on LGA was not significant (0·2, s.e. 0·16).Heritabilities for LGA, LFC and DFI ivere 0·25, 0·25 and 0·18 (s.e. 0·03), when estimated by residual maximum likelihood, with common environmental effects of 0·12 (s.e. 0·02). Genetic correlations for LFC with LGA and DFI were respectively positive (0·87, s.e. 0·02) and negative (-0·36, s.e. 0·09), while the genetic correlation between DFI and LGA was not statistically different from zero, 0·13 (s.e. 0·10). Selection on components of efficient lean growth has identified LGA as an effective selection objective for improving both LGA and LFC, without a reduction in DFI.

Selection for rate and efficiency of lean gain in Hereford cattle 1. Selection pressure applied and direct responses

1990 ◽  
Vol 51 (1) ◽  
pp. 23-34 ◽  
Author(s):  
R. A. Mrode ◽  
C. Smith ◽  
R. Thompson
Keyword(s):  
Genetic Parameters ◽  
Control Line ◽  
Correlated Responses ◽  
Direct Response ◽  
Lean Growth ◽  
Hereford Cattle ◽  
Frozen Semen ◽  
Phenotypic Standard Deviation ◽  
Selection For ◽  
Selection Of

ABSTRACTSelection of bulls for rate and efficiency of lean gain was studied in a herd of Hereford cattle. There were two selection lines, one selected for lean growth rate (LGR) from birth to 400 days and the other for lean food conversion ratio (LFCR) from 200 to 400 days of age, for a period of 8 years. A control line bred by frozen semen from foundation bulls was also maintained. Generation interval was about 2·4 years and average male selection differentials, per generation were 1·2 and — 1·1 phenotypic standard deviation units for LGR and LFCR respectively.Genetic parameters and responses to selection were estimated from the deviation of the selected lines from a control line and by restricted maximum likelihood (REML) techniques on the same material. Realized heritabilities were 0·40 (s.e. 0·12) for LGR and 0·40 (s.e. 0·13) for LFCR using the control line. Corresponding estimates from REML were 0·42 (s.e. 0·10) and 0·37 (s.e. 0·14). The estimate of the genetic correlation between LGR and LFCR was about — 0·69 (s.e. 0·12) using REML.The estimates of direct annual genetic change using deviations from the control were 3·6 (s.e. 1·3) g/day for LGR and — 0·14 (s.e. 0·07) kg food per kg lean gain for LFCR. Corrsponding estimates from REML were similar but more precisely estimated. The correlated responses for LFCR in the LGR line was higher than the direct response for LFCR.

Selection for components of efficient lean growth in Landrace pigs

1994 ◽  
Vol 1994 ◽  
pp. 10-10
Author(s):  
M.K. Curran ◽  
N.D. Cameron
Keyword(s):  
Growth Rate ◽  
Selection Criteria ◽  
Conversion Ratio ◽  
Control Line ◽  
Food Conversion ◽  
Lean Growth ◽  
Food Conversion Ratio ◽  
Daily Food ◽  
Selection For ◽  
One Year

To study responses to divergent selection for lean growth rate (LGA), lean food conversion ratio (LFC) and daily food intake (DFI), an experiment was started in 1984 at Edinburgh and Wye. This paper measured the selection pressure applied, the responses in the selection criteria and estimated the genetic and phenotypic relationships between the selection criteria with ad-libitum feeding of Landrace pigs after four generations of selection.The LGA (LFC) selection objective was to obtain equal correlated responses in growth rate (food conversion ratio) and carcass lean content, measured in phenotypic s.d. The LGA, LFC and DFI selection criteria had phenotypic s.d. of 32, 29 and 270 units and results are presented in s.d. units.Boars and gilts were purchased from eight British nucleus herds and boars from national artificial insemination centres in 1982. Homozygous or heterozygous halothane positive pigs were not included in the experiment. The base population consisted of 20 sires and 89 dams. Within each of the three selection groups, there were high and low selection lines with a control line, each consisting of 10 boars and 20 gilts, with a generation interval of one year. There were two control lines, one for LGA and one for LFC and DFI, as selection groups were arrowed continuously. The total number of pigs tested per line and average inbreeding coefficient at generation 4, within selection group are given below.

LIVE PERFORMANCE AND CARCASS CHARACTERISTICS OF BEEF BULLS IN RELATION TO SELECTION FOR YEARLING WEIGHT

1970 ◽  
Vol 50 (3) ◽  
pp. 491-497 ◽  
Author(s):  
A. H. MARTIN ◽  
H. T. FREDEEN ◽  
J. A. NEWMAN
Keyword(s):  
Growth Rate ◽  
Live Weight ◽  
Direct Selection ◽  
Control Line ◽  
Live Performance ◽  
Carcass Yield ◽  
Yield And Quality ◽  
Lean Growth ◽  
Kidney Fat ◽  
Selection For

Data over two years on a total of 149 Shorthorn bulls from a closed herd under direct selection for yearling weight were used to examine line differences in carcass yield and quality and to evaluate relationships between live performance and carcass yield and quality. No significant differences [Formula: see text] in performance or carcass data between control and selected lines were apparent in 1967. However, in 1968 bulls from the selected line were heavier at slaughter (470.5 kg vs. 441.8 kg), their carcasses contained more kidney fat (9.14 kg vs. 8.46 kg), and they had larger loin eye area but smaller weight-adjusted loin eye area. Rate of gain was superior for the selected line whether examined as live-weight, carcass weight, trimmed primal cut weight or lean weight per day of age. There were no significant differences between lines for percent fat, lean or bone in primal cuts, or for rib fat thickness, percent trimmed prime cuts, percent seam fat, muscle/bone and hind/front ratios, or for chemical composition or tenderness evaluations of the longissimus dorsi. Averaged over the two years and at the same averaged slaughter weights (418 days), selected-line bulls produced a significantly greater quantity of total carcass, of trimmed primal cuts and of total lean than did the control-line bulls; selection for yearling weight appeared to have been effective in increasing rate of lean growth. Phenotypic correlations indicated that liveweight/day of age was more highly related to variation in lean growth rate than growth rate of fat. From 20 to 60% of the variation in wholesale cut weights was associated with differences in rate of gain. Distribution of the gains was little influenced by rate of gain. Tenderness evaluations were not related to live performance.

Meat quality of Large White pig genotypes selected for components of efficient lean growth rate

1999 ◽  
Vol 68 (1) ◽  
pp. 115-127 ◽  
Author(s):  
N. D. Cameron ◽  
G. R. Nute ◽  
S. N. Brown-a2 ◽  
M. Enser ◽  
J. D. Wood
Keyword(s):  
Growth Rate ◽  
Meat Quality ◽  
Shear Force ◽  
Carcass Composition ◽  
Selection Line ◽  
Quality Traits ◽  
Large White ◽  
Lean Growth ◽  
Ad Libitum ◽  
Selection For

AbstractResponses in carcass composition and meat quality after seven generations of selection for components of lean growth rate were examined in a population of Large White pigs. There were four selection groups in the study, with divergent selection for lean growth rate on ad libitum (LGA) or restricted (LGS) feeding regimes, lean food conversion ratio (LFC) and daily food intake (DFI). In generations six and seven, two offspring from each of 10 sires, within each selection line, were to be allocated for half-carcass dissection and measurement of meat quality. There were 320 animals in the study, with 40 animals from each of the high and low selection lines and, within each selection line, two offspring per sire.Responses in carcass composition were similar in the three selection groups given food ad libitum, but rates of lean and fat growth rate differed between selection lines. Intramuscular fat content was reduced with selection for high LGA and high LFC but was increased with selection for low DFI (-1·7 and -3·2 v. 2·7 (s.e.d. 0·7) mg/g), which was unexpected given the higher carcass fat content of the low DFI line, relative to the high line (249 v. 190 (s.e.d. 7) g/kg). Muscle colour was darker, as measured by trained sensory panel assessment, in selection lines which reduced the rate of fat deposition to achieve a leaner carcass (high LFC and low DFI) but there was no response in muscle colour with selection for LGA (0·4 and 0·3 v. 0·0 (s.e.d. 0·1)). Responses in muscle shear force (5·3 v. 4·4 (s.e.d. 0·4) kg) and flavour liking (4·0 v. 4·3 (s.e.d. 0·12)) were limited to the LGA and LFC selection groups, respectively. There were no significant responses in muscle moisture content, muscle pH or myofibrillar fragmentation index, nor were there any responses in meat quality with selection on LGS. Therefore, decreasing the rate of fat deposition was associated with darker meat and increasing the rate of lean growth was associated with higher shear force. There were selection strategy specific responses in the fatty acid composition of intramuscular fat, which may have contributed to the responses in eating quality.In general, responses in meat quality were small, such that incorporation of meat quality traits in selection objectives, which are primarily focused on increasing the efficiency of lean meat production, may not be necessary. However, it would be pertinent to evaluate periodically genotypes of breeding companies for muscle quality traits.

Carcass composition in pigs selected for components of efficient lean growth

1994 ◽  
Vol 1994 ◽  
pp. 15-15
Author(s):  
E.A. Bruce ◽  
N. D. Cameron ◽  
M.K. Curran
Keyword(s):  
Growth Rate ◽  
Divergent Selection ◽  
Carcass Composition ◽  
Correlated Responses ◽  
Large White ◽  
Lean Growth ◽  
Selection For

This study determined the correlated responses in carcass composition after four generations of divergent selection for components of efficient lean growth rate in Large White (LW) and Landrace (LR) pigs.

Selection for components of efficient lean growth rate in pigs 1. Selection pressure applied and direct responses in a Large White herd

1994 ◽  
Vol 59 (2) ◽  
pp. 251-262 ◽  
Author(s):  
N. D. Cameron
Keyword(s):  
Growth Rate ◽  
Divergent Selection ◽  
Correlated Response ◽  
Food Conversion ◽  
Correlated Responses ◽  
Direct Response ◽  
Large White ◽  
Selection For ◽  
The Difference ◽  
And Control

AbstractResponses to four generations of divergent selection for lean groivth rate with ad-libitum feeding (LGA), for lean food conversion (LFC) and for daily food intake (DFI) in Large White pigs were studied. The LGA (LFC) selection criterion was designed to obtain equal correlated responses in growth rate (food conversion ratio) and carcass lean content, measured in phenotypic s.d. The selection criteria had phenotypic s.d. of 27, 29 and 253 units, respectively, and results are presented in s.d. units. There was a total of 3537 pigs, with an average of 40 boars and 40 gilts performance tested in each of the high, low and control lines per generation and the lines consisted of 10 sires and 20 dams. The generation interval was equal to 13·5 months. Animals were performance tested in individual pens with mean starting and finishing weights of 30 kg and 85 kg respectively.Cumulative selection differentials in the three selection groups were 5·8, 3·6 and 3·3 phenotypic s.d. for LGA, LFC and DFI respectively. Direct responses to divergent selection were 1·7, 1·3 and 1·2 (s.e. 0·17) for LGA, LFC and DFI. The correlated response in LFC (1·6 (s.e. 0·18)) with selection on LGA was greater than the direct response in LFC. Conversely, the direct response in LGA was greater than the correlated response (1·1 (s.e. 0·18)) with selection on LFC. The response in LFC (–1·1 (s.e. 0·17)) with selection on DFI was similar in size but opposite in sign to the direct response in LFC. Responses were asymmetric about the control, as the high LGA and LFC responses were proportionately smaller (0·74 and 0·58) than low line responses. In contrast, the difference between the high DFI and control was four times greater than the difference between low line and control.Heritabilities of LGA, LFC and DFI were 0·38, 0·35 and 0·29 (s.e. 0·03), when estimated by residual maximum likelihood, with common environmental effects of 0·09 (s.e. 0·02). Genetic correlations for LGA with LFC and DFI were positive, 0·76 (s.e. 0·03) and 0·23 (s.e. 0·07), but the genetic correlation between DFI and LFC was negative, –0·45 (s.e. 0·06). The experiment demonstrated that substantial responses to selection can be achieved in LGA, LFC and DFI. Selection on LGA resulted in larger direct and correlated responses than selection on LFC.

EFFECT OF SELECTION FOR LEAN GROWTH RATE UPON FEED UTILIZATION BY THE MARKET HOG

1978 ◽  
Vol 58 (2) ◽  
pp. 285-289 ◽  
Author(s):  
A. P. SATHER ◽  
H. T. FREDEEN
Keyword(s):  
Growth Rate ◽  
Correlated Response ◽  
Fixed Costs ◽  
Genetic Response ◽  
Lean Growth ◽  
Selection For ◽  
Carcass Performance ◽  
Feed Costs ◽  
Two Populations ◽  
Practical Implications

Results from an individual feeding trial comparing the feedlot and carcass performance of pigs from two populations, an index selected line and a genetic control, are described. The populations were initiated in 1961, the select line restructured in 1972, and the present evaluation made on progeny born in 1976. The index was based on two traits, growth rate and backfat. Feedlot data for 123 pigs indicated a direct genetic response of.94 standard deviation units (SDU) for rate of feedlot gain and correlated responses of −1.07 SDU for days on test, −1.22 SDU for total feed required and −1.07 SDU for feed/gain ratio. Carcass data for 96 pigs indicated a direct genetic response of −1.51 SDU for average backfat and a correlated response of 1.21 SDU for carcass index. In economic terms (1976 values), the improvement in carcass merit represented an increased revenue of $3.04 per pig, the increased growth rate was equivalent to a 10% reduction in the fixed costs and non-feed variable costs per pig, and the correlated response in feed requirements reduced feed costs by $3.13 per pig. Practical implications in respect of pig testing programs are discussed.

The effects of selection for lean growth in Suffolk sires on the saleable meat yield of their crossbred progeny

1996 ◽  
Vol 62 (2) ◽  
pp. 255-263 ◽  
Author(s):  
G. Simm ◽  
S. V. Murphy
Keyword(s):  
Subcutaneous Fat ◽  
Live Weight ◽  
Carcass Weight ◽  
Selection Line ◽  
Control Line ◽  
Breeding Scheme ◽  
Lean Growth ◽  
Agricultural College ◽  
Selection For ◽  
Similar Growth

AbstractThis experiment involved a commercial evaluation of carcasses of extensively reared crossbred lambs. These were sired by Suffolk rams from either a selection line or a control line of a Scottish Agricultural College (SAC) selection experiment, in which selection wasfor lean growth, or by Suffolk ‘reference sires’ from an industry co-operative breeding scheme (SSRS). The lambs were slaughtered at a target live weight of 42 kg between June and October 1992. In total, 421 lamb carcasses were included in the evaluation, 173 from six selection-line rams, 193 from six control-line rams and 55from three SSRS rams. Each of the carcasses was visually appraised for estimated subcutaneous fat proportion and for conformation of the shoulder, loin and leg, as well as being classified using conventional Meat and Livestock Commission (MLC) scales for fat and conformation. Animals were slaughtered at an average age of 139·5 (s.d. 25·6) days and achieved an average cold carcass weight of 20·04 (s.d. 0·96) kg. Carcasses had an average estimated subcutaneous fat proportion of 122·3 (s.d. 22·4) g/kg — equivalent to MLC fat class 3L to 3H. Overall conformation scores, on a 15-point scale, averaged 8·63 (s.d. 1·80) points. Carcasses were cut into joints according to a leading supermarket specification. The weights of pairs of shoulder, flank, loin and leg joints were obtained for each carcass, as well as weights of bone and fat removed during jointing. Saleable meat weights and proportions averaged 15·31 (s.d. 0·76) kg and 765·9 (s.d. 10·0) g/kg respectively. At a constant carcass weight, the SAC selection-line progeny were significantly younger (-11 days), had a significantly higher carcass value (+£1·50), a significantly lower estimated subcutaneous fat proportion (-13 g/kg), and a significantly higher weight of saleable meat (+0·1 kg) and higher proportion ofsaleable meat (+4 glkg) than control-line progeny, but had lower conformation scores. SSRS progeny had similar growth and fatness to selection-line lambs, but had poorer conformation, and significantly more bone in the carcass than either of the SAC lines. When comparisons were made at a constant estimated subcutaneous fat proportion, all differences in conformation between SAC lines disappeared. However, SSRS progeny remained poorer in conformation. The SSRS rams werefrom afoundation generation of the scheme, and were not expected to be markedly superior for carcass characteristics. Carcass weight was byfar the most important predictor of weight of saleable meat, or leg and loin joint weights. Conformation and estimated fat proportion made only marginal improvements, if any, to the precision of prediction, with fat proportion being the more important of the two predictors.

Selection for components of efficient lean growth in Large White pigs

1994 ◽  
Vol 1994 ◽  
pp. 9-9
Author(s):  
N.D. Cameron
Keyword(s):  
Growth Rate ◽  
Selection Criteria ◽  
Conversion Ratio ◽  
Food Conversion ◽  
Correlated Responses ◽  
Large White ◽  
Lean Growth ◽  
Food Conversion Ratio ◽  
Daily Food ◽  
Selection For

An experiment was started in 1984 at Edinburgh and Wye to study responses to divergent selection for lean growth rate (LGA), lean food conversion ratio (LFC) and daily food intake (DFI). This paper measured the selection pressure applied, the responses in the selection criteria and estimated the genetic and phenotypic relationships between the selection criteria with ad-libitum feeding of Large White pigs after four generations of selection.Selection objectives and criteria. The LGA (LFC) selection objective was to obtain equal correlated responses in growth rate (food conversion ratio) and carcass lean content, measured in phenotypic s.d. The LGA, LFC and DFI selection criteria had phenotypic s.d. of 27, 29 and 250 units and results are presented in s.d. units.

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