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 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

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.

Influence of the correlation between growth rate and backfat on selection response in pigs

1990 ◽  
Vol 1990 ◽  
pp. 84-84
Author(s):  
P. R. Bampton ◽  
A. J. Webb
Keyword(s):  
Growth Rate ◽  
Performance Test ◽  
Performance Testing ◽  
Selection Response ◽  
Economic Traits ◽  
Lean Growth ◽  
Genetic And Phenotypic Correlations ◽  
Ad Libitum ◽  
Selection For ◽  
Ad Libitum Feeding

Backfat levels in pigs have declined rapidly in the last decade and are approaching an economic optimum. As optimal levels of backfat are achieved this has two important implications for selection objectives. First, the relative emphasis of selection will shift to other traits, particularly lean growth rate. Second, there will also be a move towards ad libitum feeding on performance test to allow expression of appetite and to increase response to selection for lean growth rate. The effect of very lean pigs coupled with ad libitum feeding may result in changes in the genetic and phenotypic relationship between growth rate and fat depths. Reported genetic and phenotypic correlations between growth rate and backfat range from +0.3 on ad libitum feeding to -0.3 on restricted feeding. In most performance testing regimes the key relationship is between growth rate and ultrasonic fat depths which in contrast to other economic traits are often unfavourably correlated.

Genetics of food intake in the pig

1989 ◽  
Vol 13 ◽  
pp. 41-50 ◽  
Author(s):  
A. J. Webb
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Genetic Correlations ◽  
Live Weight ◽  
Selection Strategy ◽  
Selection Regime ◽  
Lean Growth ◽  
Optimum Selection ◽  
Ad Libitum ◽  
Selection For

AbstractThe rôle of voluntary food intake, measured as daily food consumption on ad libitum feeding from 30 to 90 kg live weight, in future selection strategy is reviewed. Intake shows a heritability of 0.3, and genetic correlations of 0.6 with growth rate and –0.4 with leanness. Low genetic correlations between test station and commercial farm performance are reported for growth rate (0.27) and backfat (0.41) which arise either from genotype × feeding level interactions, or from individual feeding at stations. Selection for rate of lean growth appears to lead to a primary increase in rate of protein deposition, whereas selection for efficiency of lean growth appears to lead to a reduction in rate of fat deposition via a decline in intake. Continued reduction in intake may limit further improvement in lean growth rate and sow productivity. As optimum fatness is approached, the selection emphasis is expected to swing towards rate of lean growth to reduce total food used for maintenance. To determine the optimum selection regime, a knowledge is required of the genetic relationship between intake and lean growth rate. Meanwhile, the optimum selection regime may involve ad libitum group feeding with electronic recording of individual food intake. In the long term, exogenous or endogenous growth promoters could remove the need for selection against backfat, and necessitate a radical genetic increase in intake.

Reproductive performance of pigs selected for components of efficient lean growth

1995 ◽  
Vol 60 (2) ◽  
pp. 281-290 ◽  
Author(s):  
J. C. Kerr ◽  
N. D. Cameron
Keyword(s):  
Growth Rate ◽  
Litter Size ◽  
Reproductive Performance ◽  
Selection Line ◽  
Food Conversion ◽  
Daily Food Intake ◽  
Lean Growth ◽  
Daily Food ◽  
Ad Libitum ◽  
Selection For

AbstractCorrelated responses in reproductive performance to five generations of divergent selection for daily food intake (DFI), lean food conversion (LFC), lean growth rate on ad–libitum feeding (LGA), and lean growth rate on scale feeding (LGS) were studied. Litter traits were measured on 1220 Large White gilts. Mean litter weights at birth and weaning were 12·9 kg and 63·5 kg, with average litter sizes of 10·3 and 7·9. Responses to selection in the high and low lines for litter size in the DFI and LFC selection groups were 1·9 and –1·5 (s.e.d. VI) at birth and 0·9 and –1·8 (s.e.d. 1·2) at weaning. Responses in litter birth weights were respectively positive and negative for DFI and LFC (3·0 and –2·8 (s.e.d. 1·4) kg) and the response in LGS (3 kg) was greater than in LGA (–0·1 kg). Selection line differences in litter weaning weight followed a similar pattern to birth weight for DFI and LFC (17·5 and –17·3 (s.e.d. 10·1) kg). Responses in litter weights were a result of selection line differences in both litter sizes and piglet weights. The relationships between litter size, litter weights and piglet weights at birth and weaning were essentially linear. An extra piglet at birth and weaning corresponded to an increase of 1·0 (s.e. 0·02) kg and 6·9 (s.e. 0·1) kg in litter weights. Piglet birth and weaning weights were decreased by 0·03 (s.e. 0·003) kg and 0·19 (s.e. 0·02) kg. A uterine constraint on piglet growth was implied, but there was no evidence for a limit to uterine capacity. Heritabilities for litter size, weight and piglet weight at birth of 0·06, 0·11 (s.e. 0·04) and 0·16 (s.e. 0·02) respectively were similar to those at weaning. Common environmental effects on piglet weights at birth and weaning were substantially higher than the heritabilities (0·38 and 0·45, s.e. 0·01). The study indicated that selection for lean growth on either an ad–libitum or restricted feeding regime did not significantly affect reproductive performance, but the high lean food conversion ratio and low daily food intake selection lines had impaired reproductive performance.

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.

Responses in gilt post-farrowing traits and pre-weaning piglet growth to divergent selection for components of efficient lean growth rate

1996 ◽  
Vol 1996 ◽  
pp. 17-17
Author(s):  
J. C. Kerr ◽  
N. D. Cameron
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Fixed Time ◽  
Divergent Selection ◽  
Large White ◽  
Lean Growth ◽  
Fixed Weight ◽  
Ad Libitum ◽  
Selection For ◽  
Piglet Growth

Responses in sow traits at farrowing and during lactation and in pre-weaning piglet growth rate were determined in a population of Large White pigs, after seven generations of divergent selection for components of efficient lean growth rate. Information on the factors influencing preweaning piglet growth rate is required for a comprehensive evaluation of alternative selection strategies.There were four selection groups: daily food intake (DFI), lean food conversion (LFC), lean growth rate (LGA) on ad-libitum feeding and lean growth rate on scale feeding (LGS). There were 242 gilts in the study, with 20 gilts in the high, low and control lines of each selection group. Pigs in the ad-libitum selection groups were performance tested over a fixed weight range of 30 to 85 kg. Pigs fed on scale feeding were performance tested for a fixed time period of 84 days from 30 kg with food intake equal to 0.75 g/g of daily ad-libitum food intake. Matings were unsupervised and took place in outside paddocks.

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.

Physiological responses to divergent selection for daily food intake or lean growth rate in pigs

2003 ◽  
Vol 76 (1) ◽  
pp. 27-34 ◽  
Author(s):  
N.D. Cameron ◽  
E. McCullough ◽  
K. Troup ◽  
J.C. Penman
Keyword(s):  
Serum Creatinine ◽  
Divergent Selection ◽  
Serum Creatinine Concentration ◽  
Creatinine Concentration ◽  
Protein Deposition ◽  
Lean Growth ◽  
Daily Food ◽  
Ad Libitum ◽  
Selection For ◽  
Ad Libitum Feeding

AbstractCorrelated responses in physiological traits to divergent selection on components of efficient lean growth identified physiological traits for use as predictors of genetic merit and provided a biological explanation for the between-selection line differences in protein and lipid deposition. Responses (differences between high (H) and low (L) selection lines) in protein metabolism during ad-libitum feeding were associated with divergent selection for daily food intake (DFI) (reduced serum creatinine concentration (H = 1·30 v. L = 1·56, s.e.d. 0·08 mg/dl)) and for lean growth rate on an ad-libitum feeding regime (LGA) (increased serum urea (H = 48 v. L = 36, s.e.d. 4 mg/dl) and creatinine (H = 1·74 v. L = 1·45 mg/dl)) concentrations, but not with selection for lean growth on a restricted feeding regime (LGS). Following 24-h fasting, responses in lipid metabolism, in the form of higher serum non-esterified fatty acid concentrations, were detected with divergent selection for both LGA (399 v. 248, s.e.d. 66 µmol/l) and LGS (H = 361 v. L = 107 µmol/l). The high LGS line appeared to ‘preserve’ protein to a greater extent than the high LGA line and similarly there was greater maintenance of lipid depots by the low LGS line compared with the low LGA line. A tentative ranking of the two pairs of lean growth selection lines on the basis of ‘importance’ of protein deposition would be high LGS, high LGA, low LGA and low LGS.Coheritabilities for serum creatinine concentration with predicted lysine balance and lysine required for protein deposition (-0·17 and 0·17, s.e. 0·08) indicated that serum creatinine concentration may usefully be included in breeding value prediction for lysine requirement and protein deposition to increase the accuracy of predicted genetic merit.Fasting did not increase the coheritabilities for serum creatinine concentration, so inclusion of serum creatinine concentration in a selection criterion for dietary lysine requirement or protein deposition does not require withdrawal of food before blood sampling animals.

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