scholarly journals Genetic Parameters and Responses in Growth and Body Composition Traits of Pigs Measured under Group Housing and Ad libitum Feeding from Lines Selected for Growth Rate on a Fixed Ration

2005 ◽  
Vol 18 (8) ◽  
pp. 1075-1079
Author(s):  
N. H. Nguyen ◽  
C. P. McPhee
Keyword(s):  
Growth Rate ◽  
Body Composition ◽  
Genetic Parameters ◽  
Group Housing ◽  
Ad Libitum ◽  
Ad Libitum Feeding

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.

Fibre diameter and staple strength of sheep selected for divergent clean fleece weight when subjected to an increase in intake or an increase in intake and diet change

2005 ◽  
Vol 56 (2) ◽  
pp. 195 ◽  
Author(s):  
M. A. Friend ◽  
G. E. Robards
Keyword(s):  
Growth Rate ◽  
Stepwise Regression ◽  
Fibre Diameter ◽  
Dietary Treatment ◽  
Diet Change ◽  
Wool Growth ◽  
Ad Libitum ◽  
Staple Strength ◽  
Fleece Weight ◽  
Ad Libitum Feeding

Merino wethers with a high (fleece plus, Fl+) or low (fleece minus, Fl–) potential for wool growth were offered a restricted intake of either oat grain or lucerne chaff for 8 weeks followed by ad libitum lucerne chaff for 4 weeks. The Fl– sheep that were fed oats then lucerne had a lower (P < 0.05) intake during the first 2 weeks of ad libitum feeding than all other groups. Staple strength of Fl+ sheep (37.5 ± 2.2 N/ktex) was less (P < 0.05) than that of Fl– sheep (44.5 ± 2.4 N/ktex), and dietary treatment did not significantly affect staple strength. Wool growth rate was unaffected by dietary treatment, but was greater (P < 0.001) for Fl+ (6.4 ± 0.2 µg/mm2.day) than for Fl– (4.0 ± 0.2 µg/mm2.day) sheep. Along-fibre variation in diameter was greater (P < 0.001) in Fl+ (15.6 ± 0.5%) than in Fl– (9.9 ± 0.5%) sheep. Between-fibre variation in diameter was greater (P < 0.001) in Fl+ (16.5 ± 0.5%) than in Fl– (13.2 ± 0.5%) sheep, and between-fibre variation in diameter was affected (P < 0.05) by dietary treatment in Fl+ sheep. Staple strength was significantly correlated (P < 0.05) with along-fibre variation in diameter (r = –0.48), and stepwise regression analysis indicated that along-fibre variation in diameter, wool growth rate during early restricted feeding, and minimum fibre diameter explained 63% of the variance in staple strength. The results are discussed in relation to the lower staple strength of Fl+ sheep.

Estimation of body composition changes during weight cycling by bioelectrical impedance analysis in rats

1993 ◽  
Vol 74 (5) ◽  
pp. 2092-2098 ◽  
Author(s):  
J. Ilagan ◽  
V. Bhutani ◽  
P. Archer ◽  
P. K. Lin ◽  
K. L. Jen
Keyword(s):  
Body Composition ◽  
Body Weight ◽  
Bioelectrical Impedance Analysis ◽  
Subcutaneous Fat ◽  
Bioelectrical Impedance ◽  
Impedance Analysis ◽  
Weight Cycling ◽  
High Fat ◽  
Ad Libitum ◽  
Ad Libitum Feeding

The effects of body weight cycling (WC) in rats on body composition (BC) and feeding efficiency were studied. The usefulness of estimating BC by bioelectrical impedance analysis (BIA) was also examined. Female Sprague-Dawley rats were divided into high-fat ad libitum feeding, either noncycling or cycling, or restricted feeding (75% of control feed) cycling groups. Control rats were fed a regular laboratory ad libitum diet and did not cycle. All rats were killed at the end of week 61. A BIA unit was used at each stage of WC to obtain resistance and reactance readings. Final BC was determined by chemical analysis. On the basis of the final chemical analysis and BIA measurements, an equation was established and applied to estimate BC at each stage of WC: fat-free mass (g) = 0.38 x body wt (g) + 13.8 x [length (cm)2/resistance] + 70.9 (r = 0.95, P < 0.001). High-fat ad libitum feeding induced rapid body weight and fat gains as well as an elevated feeding efficiency and an internal fat-to-subcutaneous fat ratio, regardless of whether the rats cycled. This change in fat mass was clearly detected by the BIA. Although rats fed restricted diets had similar body weights as did control rats, they had a significantly higher internal fat-to-subcutaneous fat ratio. Thus, not only the amount of food but also the composition of the diet is important for proper weight management. The BIA method is capable of detecting the body fat mass change during WC.

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.

Tolerance of growing pigs to lupin alkaloids

1985 ◽  
Vol 25 (4) ◽  
pp. 791 ◽  
Author(s):  
NW Godfrey ◽  
AR Mercy ◽  
Y Emms ◽  
HG Payne
Keyword(s):  
Growth Rate ◽  
Feed Intake ◽  
Growing Pigs ◽  
Progressive Decline ◽  
Young Pigs ◽  
Ad Libitum ◽  
Ad Libitum Feeding

In two experiments with a total of 93 young pigs, we measured responses in growth rate and feed intake to dietary lupin alkaloid concentrations which ranged from 0.05 to 0.52 g/kg. In the first experiment increasing the alkaloid levels from 0.12 to 0.52 g/kg in increments of 0.08 g/kg produced a progressive decline in growth rate and feed intake. In the second experiment, pig productivity was unaffected by increasing dietary alkaloids from 0.05 to 0.20 g/kg, but was depressed when the alkaloid level reached 0.35 g/kg. It was concluded that, with ad libitum feeding, growing pigs could tolerate up to 0.20 g/kg of dietary lupin alkaloids.

Genetic and phenotypic relationships between performance test and reproduction traits in Large White pigs

1996 ◽  
Vol 62 (3) ◽  
pp. 531-540 ◽  
Author(s):  
J. C. Kerr ◽  
N. D. Cameron
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Performance Test ◽  
Genetic Correlations ◽  
Restricted Feeding ◽  
Daily Food Intake ◽  
Daily Food ◽  
Reproduction Traits ◽  
Ad Libitum ◽  
Ad Libitum Feeding

AbstractGenetic and phenotypic relationships between performance test and reproduction traits were estimated, after five generations of divergent selection for components of efficient lean growth, in a population of Large Wltite pigs. On ad-libitum feeding, a total of 4334 pigs were performance tested, of which 884 selected gilts had measurements of reproduction traits. On a restricted feeding regime, 1558 pigs were tested, which included 336 selected gilts with reproduction records. For pigs given food ad libitum, genetic correlations between litter weights at birth and weaning with daily food intake (0·48 and 0·42, s.e. 0·16) and with growth rate on test (0·65 and 0·52) were positive, but correlations with backfat depths were not significantly different from zero. For pigs given food at a restricted level, litter birth weight was positively genetically correlated with growth rate (0·50, s.e. 0·18) and negatively correlated with backfat depths (-0·48, s.e. 0·16). Phenotypic and environmental correlations between performance test and reproduction traits were all less than 0·10 in magnitude, for pigs tested on either feeding regime. The variation in backfat depth enabled detection of a non-linear relationship between predicted breeding values for litter weight at birth with predicted breeding values for average backfat depth of farrowing gilts performance tested on ad-libitum feeding, but not for gilts tested on restricted feeding. The positive genetic correlations between growth rate and daily food intake with litter traits suggested that selection strategies which change growth and daily food intake may result in relatively greater genetic changes in piglet growth rate than in litter size.

Ad libitum feeding of group housed Meishan synthetic sows during pregnancy

1995 ◽  
Vol 1995 ◽  
pp. 180-180
Author(s):  
R J Berry ◽  
S A Edwards ◽  
A McCartney
Keyword(s):  
Lower Energy ◽  
Energy Requirements ◽  
Group Housing ◽  
Feed System ◽  
Housing Systems ◽  
Feeding Motivation ◽  
High Fibre ◽  
Beet Pulp ◽  
Ad Libitum ◽  
Ad Libitum Feeding

The future abolition of stall and tether systems has meant that, increasingly, producers are opting for group housing systems. Generally sows are fed a restricted concentrate ration during pregnancy at levels which do not induce satiety, leading to increased feeding motivation and competition between penmates for food. Feed competition can lead to compromised production in less dominant individuals. A possible solution would be to feed ad libituma lower energy diet which would restrict voluntary food intake (VFI) so that large undesirable weight gains would not be encountered. Brouns.(1993) found that diets containing 60% unmolassed sugar beet pulp (SBP) were capable of restricting intake to match energy requirements. Recently there has been heightened interest in the use of prolific strains of Chinese pigs such as the Meishan to develop commercial crossbreeds. Chinese breeds are reported to be capable of utilising dietary fibre to a greater extent than European breeds which would make the Meishan a more suitable option for an ad libhigh fibre feed system.

Sign in / Sign up

Export Citation Format

Share Document