Genotype with feeding regime interaction in pigs

1994 ◽  
Vol 1994 ◽  
pp. 13-13
Author(s):  
N.D. Cameron ◽  
M.K. Curran
Keyword(s):  
Performance Test ◽  
Performance Testing ◽  
High Energy ◽  
Restricted Feeding ◽  
Large White ◽  
Feeding Regime ◽  
Lean Growth ◽  
Fixed Weight ◽  
Ad Libitum ◽  
Alternative Feeding

This paper examined a genotype with feeding regime interaction by performance testing pigs, selected for lean growth on ad-libitum or restricted feeding, on both the normal and the alternative feeding regime.Large White (LW) and Landrace (LR) pigs from divergent selection lines were for four generations for lean growth either on an ad-libitum (LGA) or a restricted (LGS) feeding regime. In each selection group, there were high, low and control lines, which consisted of 10 sires and 20 dams. On average, 3 boars and 3 gilts were tested per litter, with one boar and one gilt per litter tested on the alternative feeding regime. On ad-libitum feeding, there were 181 LGA and 94 LGS LW pigs and 162 LGA and 67 LGS LR pigs. On restricted feeding, 92 LGA and 212 LGS LW and 53 LGA and 135 LGS LR pigs were tested.Performance test. The performance test was over a fixed weight range of 30±3 kg to 85±5 kg for ad-libitum fed pigs and for a fixed time of 84 days for restricted fed pigs. Restricted feeding was equal to 0.75 g/g of daily food intake of ad-libitum fed pigs. All pigs were individually penned and fed a high energy (13.8 MJ DE/kg DM) and high protein (210 g/kg DM crude protein) pelleted ration.

Selection for lean growth in pigs with a restricted feeding regime

1994 ◽  
Vol 1994 ◽  
pp. 12-12
Author(s):  
M.K. Curran ◽  
N.D. Cameron ◽  
J.C. Kerr
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Restricted Feeding ◽  
Correlated Responses ◽  
Large White ◽  
Daily Food Intake ◽  
Feeding Regime ◽  
Lean Growth ◽  
Daily Food ◽  
Ad Libitum

Divergent selection lines for lean growth on a restricted feeding regime, in Large White and Landrace pigs, were established to complement the lean growth selection lines on ad-libitum feeding. This study estimated the direct and correlated responses after four generations of selection and the corresponding genetic and phenotypic parameters.The selection objective for lean growth on restricted or scale (LGS) feeding was to obtain equal correlated responses in growth rate and carcass lean content, measured in phenotypic s.d. The selection criterion included measurements of growth rate and ultrasonic backfat depth.Large White (LW) and Landrace (LR) 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 populations consisted of 31 LW and 19 LR sires and 57 LW and 67 LR dams. Within each population, there were high and low selection lines with a control line, each consisting of 10 boars and 20 gilts, with a generation interval of 13.5 and 12 months for LW and LR pigs. Animals were performance tested in individual pens from 30±3 kg for a period of 84 days and fed a high energy (13.8 MJ DE/kg DM) and high protein (210 g/kg DM crude protein) pelleted ration. Daily food intake was equal to 0.75 g/g of the daily food intake for ad-libitum fed pigs and the total food intake was 134 kg for LW pigs and 150 kg for LR pigs. On average, 3 boars and 3 gilts were tested per litter. The total number of pigs tested per line and average inbreeding coefficients at generation four, by population are given below.

Responses in performance test traits to selection on components of efficient lean growth

1994 ◽  
Vol 1994 ◽  
pp. 11-11
Author(s):  
N.D. Cameron ◽  
M.K. Curran
Keyword(s):  
Performance Test ◽  
High Energy ◽  
Selection Line ◽  
Control Line ◽  
Large White ◽  
Lean Growth ◽  
Fixed Weight ◽  
Daily Food ◽  
Derivative Free ◽  
Line Breeding

This study determined the responses in performance test traits after four generations of divergent selection for lean growth rate (LGA), lean food conversion ratio (LFC) and daily food intake (DFI) in Large White and Landrace pigs.Within each of the three selection groups, there were high and low selection lines with a control line, each consisting of 10 sires and 20 dams, with an average of 3 boars and 3 gilts tested per litter. A total of 3537 Large White and 2642 Landrace pigs were performance tested in Edinburgh and Wye, respectively. The performance test was over a fixed weight range of 30±3 kg to 85±5 kg. All pigs were individually penned, with ad-libitum feeding of a high energy (13.8 MJ DE/kg DM) and high protein (210 g/kg DM crude protein) pelleted ration.Correlated responses in performance test traits to selection on LGA, LFC and DFI were estimated from the mean within-generation selection line breeding values for each trait, determined with the additive genetic and common environmental (co)variances for performance test traits, which were estimated using multivariate derivative-free residual maximum likelihood analyses.

Selection for efficient lean growth in a pig herd

1981 ◽  
Vol 32 (4) ◽  
pp. 681 ◽  
Author(s):  
CP McPhee
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Performance Test ◽  
Subcutaneous Fat ◽  
Performance Testing ◽  
Restricted Feeding ◽  
Food Conversion ◽  
Muscle Area ◽  
Eye Muscle ◽  
Lean Growth

A pig herd was selected for 6 years by using an economic index combining growth rate, food conversion efficiency and carcass leanness. These three traits were all measured in a performance test which permitted appetite variation between pigs to be expressed. Boars selected with an intensity of 118 were used for 6 months, and sows with an intensity of 114 were kept for two farrowings. An unselected control herd was maintained concurrently. To measure selection response, selected (S) and control (C) pigs were compared as they grew from 25 to 90 kg liveweight on ad lib. and restricted feeding during the last 2 years of selection. The following significant (P < 0.05) responses occurred in the selection herd: (i) A slight increase in growth rate on restricted feed, balanced by a similar decrease on ad lib, feeding. (ii) A decline in food conversion ratio of 5 % (C, 2.79; S, 2.65) due mainly to a reduction in appetite. (On ad lib. feeding, food intake per day declined by 6 % (C, 2.30 kg/d; S, 2.16 kg/d.)). (iii) A decline in average subcutaneous fat depth by 11 % (C, 27.8 mm; S, 24.7 mm) and in fat dissected from the ham by 7 % (C, 2.80 kg; S, 2.61 kg). (iv) An increase in estimated lean in the carcass by 2% (C, 30.3 kg; S, 31.0 kg). (v) A decline in dressing percentage of the carcass by 1 % (C, 77.1 %; S, 76.2 %). There was no change in eye muscle area or carcass length. The results are discussed in terms of changes in the ratio of food intake to lean growth. In the group fed ad lib., this ratio declined by 7 %, mainly because of a decline in food intake. On restricted feeding it fell by 6 %, mainly owing to an increase in lean growth. That portion of the selection effort absorbed in reducing food intake may have been more profitably directed to increasing lean growth by suppressing appetite variation during performance testing, rather than allowing it to be expressed.

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.

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.

Selection for lean growth and food intake leads to correlated changes in innate immune traits in Large White pigs

2006 ◽  
Vol 82 (6) ◽  
pp. 867-876 ◽  
Author(s):  
M. Clapperton ◽  
S.C. Bishop ◽  
E.J. Glass
Keyword(s):  
T Cells ◽  
Food Intake ◽  
Γδ T Cells ◽  
Restricted Feeding ◽  
Large White ◽  
Lean Growth ◽  
High Line ◽  
Immune Traits ◽  
Ad Libitum ◽  
Selection For

Genetic selection is well established as a means of improving productivity in pigs, but the effects of continued selection for increased performance on immunity are not well understood, nor are genetic relationships between performance and immunity. This study compared differences in the levels of a range of immune traits between lines of Large White pigs divergently selected for a number of productivity traits. Selection lines compared were highv. low lean growth under restricted feeding (31 high linev. 10 controlv. 38 low line pigs), high v. low lean growth underad libitumfeeding (18 high line v. 10 controlv. 19 low line pigs), and highv. low food intake (24 high linev. 26 low line pigs). Immune traits measured were total white blood cell numbers (WBC), and the numbers of leukocyte subsets: neutrophils, monocytes, eosinophils, lymphocytes, CD4+cells, CD8α+cells, B cells, γδ T cells and CD11R1+Natural killer (NK) cells. CD4+, γδ T cells and CD11R1+cells were subdivided into subpopulations that were positive or negative for the CD8α marker, and conventional CD8αhigh+cytotoxic T cells were also determined. Pigs were tested underad libitumfeeding conditions from 14 to 24 weeks, and immune traits were assessed at ages 18 and 24 weeks. Line differences were estimated using residual maximum likelihood techniques. Consistent differences in immune trait levels were evident between pigs previously selected for high and low lean growth under restricted feeding: at age 24 weeks, high line pigs had higher basal levels of WBC (39·6v. 27·8×106cells per ml, s.e.d. 2·09, for highv. low line pigs) mainly explained by higher levels of lymphocytes (25·5v. 17·3×106cells per ml, s.e.d. 1·54, for highv. low line pigs) with increased numbers of CD8α+cells (8·19v. 5·15×106cells per ml, s.e.d. 0·14) and CD11R1+cells (5·23v. 2·46×106cells per ml, s.e.d. 0·43), predominantly the CD11R1+CD8α?subpopulation ((3·20v. 1·64×106cells per ml, s.e.d. 0·11). High line pigs also had increased numbers of monocytes (2·64v. 1·83×106cells per ml, s.e.d. 0·35). Similar results were obtained at age 18 weeks. There were no consistent differences between divergent lines in pigs selected for lean growth underad libitumfeeding or food intake. This is the first report to demonstrate that selection for some aspects of performance can influence WBC and leukocyte subset numbers in pigs.

Estimation of sire with feeding regime interaction in pigs

1988 ◽  
Vol 46 (1) ◽  
pp. 87-95 ◽  
Author(s):  
N. D. Cameron ◽  
M. K. Curran ◽  
R. Thompson
Keyword(s):  
Average Daily Gain ◽  
Genetic Correlations ◽  
Restricted Feeding ◽  
Large White ◽  
Feeding Regime ◽  
Weighted Analysis ◽  
Feeding Regimes ◽  
Ad Libitum ◽  
Residual Variances ◽  
Daily Gain

ABSTRACTThe interaction of sire with feeding regime (ad libitum and restricted) was assessed in the first stage of a selection experiment. There were 79 sires (59 Large White (Edinburgh) and 20 British Landrace (Wye)) with 1549 progeny (745 at Edinburgh and 804 at Wye) in the study. Progeny within each litter were allocated at random to each feeding regime. Pigs started test at 30 (± 3) kg and finished test at 85 (± 5) kg for ad libitum fed pigs or after 84 days on test for restricted fed pigs. All pigs were individually penned. At the end of test, food intake, weight off test and ultrasonic backfat depths were recorded. Variance components were estimated using restricted maximum likelihood and a weighted analysis took account of the different residual variances between feeding regimes, within each breed.There were differences in some genetic parameters due to feeding regime within breeds. No evidence of a sire with feeding regime interaction for average daily gain or food conversion ratio was detected in Large White pigs (genetic correlations between ad libitum and restricted feeding were 1·21 (s.e. 0·17) and 0·89 (s.e. 0·19) respectively). Similar conclusions could not be made for the sample of British Landrace pigs due to the large standard errors of the genetic correlation estimates. For ultrasonic backfat depths, the negative estimates of sire variances under restricted feeding prevent calculation of the genetic correlations and conclusions to be made about the sire with feeding regime interaction.

Genotype with feeding regime interaction in pigs divergently selected for components of efficient lean growth rate

1995 ◽  
Vol 61 (1) ◽  
pp. 123-132 ◽  
Author(s):  
N. D. Cameron ◽  
M. K. Curran
Keyword(s):  
Growth Rate ◽  
Conversion Ratio ◽  
Restricted Feeding ◽  
Food Conversion ◽  
Feeding Regime ◽  
Lean Growth ◽  
Food Conversion Ratio ◽  
Daily Food ◽  
Feeding Regimes ◽  
Ad Libitum

AbstractThe genotype with feeding regime interaction was examined by testing pigs from four selection groups on both ad libitum and restricted feeding regimes. Within each selection group, there were high, low and control lines, which had been selected for lean food conversion ratio (LFC), daily food intake (DFI) or lean growth rate on ad libitum (LGA) or on restricted (LGS) feeding, in Large White-Edinburgh (LW) and Landrace-Wye (LR) populations. There were 1187 LW pigs and 768 LR pigs in the study, with 344 LW and 133 LR pigs tested on the alternative feeding regime.In the LW population, pigs in the high LGS line grew significantly faster than the high LGA and LFC lines with ad libitum feeding (919 v. 847 and 786 (s.e.d. 31) g/day), but had similar food conversion ratios and backfat depths. The high LGS and high DFI lines were similar for growth rate, daily food intake and food conversion ratio, but backfat depth was significantly lower in the high LGS line than in the high DFI line (12·0 v. 25·9 (s.e.d. 0·7) mm). On restricting feeding, the rankings of the selection lines for growth rate, food conversion ratio and mid-back fat depth were broadly similar to those with ad libitum feeding, except for the high LFC line. In the LR population, the high LGS, LGA and LFC lines did not differ significantly in growth rate, daily food intake, food conversion ratio and backfat depth within either the ad libitum or restricted feeding regimes. Growth rate of the high LGS line was similar to the high DFI line on ad libitum feeding (828 v. 836 (s.e.d. 40) g/day), but significantly higher on restricted feeding (704 v. 636 (s.e.d. 23) g/day). On both feeding regimes, food conversion ratio and backfat depth were significantly lower in the high LGS line compared with the high DFI line.In the LW population, the genetic correlation between feeding regimes for growth rate was significantly less than one (0·4 (s.e. 0·20)), but was not significantly different from unity (0·8 (s.e. 0·14)) for backfat depths. Based on the performance test results, selection for lean growth with testing on a restricted feeding regime may be preferable to testing animals on an ad libitum feeding regime.

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.

Selection for improved lean growth in Large White pigs can affect levels of total white blood cell counts, CD11R1+ leukocytes and alpha-1 acid glycoprotein

2005 ◽  
Vol 2005 ◽  
pp. 17-17
Author(s):  
M. Clapperton ◽  
S. C. Bishop ◽  
N. D. Cameron ◽  
E. J. Glass
Keyword(s):  
Immune Responses ◽  
Restricted Feeding ◽  
Large White ◽  
Acid Glycoprotein ◽  
Cell Counts ◽  
Lean Growth ◽  
Immune Traits ◽  
Selection For ◽  
White Blood Cell Counts ◽  
The Impact

Productivity in pigs can be improved by continued selection, however the impact of such selection on immune responses and resistance towards infectious challenges is not known. A risk is that this method may lead to a correlated reduction in the immune response and disease resistance. To estimate the effect of selection for performance traits upon immune responses, we compared levels of immune traits between divergent lines of Large White pigs selected for either lean growth under restricted feeding or feed intake.

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