Fat Deposition in a Broiler Sire Strain I. Phenotypic and Genetic Variation in, and Correlations Between, Abdominal Fat, Body Weight, and Feed Conversion

Abstract

Variability in body composition was examined weekly from 3 to 10 weeks of age in chickens from a broiler sire strain. Genetic aspects of body weight, quantity of abdominal fat, and feed conversion were examined in pedigree birds of the same strain at 6 weeks of age.Variability in abdominal fat relative to body weight (RAF), total percentage of carcass fat, and body weight (BW) was not influenced by sex or age. The phenotypic correlation (rp) between RAF and BW was generally positive, but low (between .20 and .68); that between RAF and total percentage of carcass fat was invariably positive and higher.The heritability estimated from sib analyses for body weight after ad libitum feeding was 0 (h 2 s ; res ) and 1 (h 2 d arns ), for RAF .41 (h 2^^) and 1 (h^ams). for feed conversion .39 (h 2 s i res ) and .53 (h 2 d ams ), and for body weight after restricted feeding .31 (h 2 s { res ) and .57 (h 2 <j ams ). The genetic correlations were estimated as correlation between mean performance of progeny of each sire (r s j res ) or dam (rd ams ). The correlation between family mean of RAF and BW was -.01 (r s i res ) or .04 (rd ams ), between RAF and feed conversion .19 (r s i res ) and .29 (rd ams ), and between RAF and body weight after restricted feeding -.12 (r s j res ) and -.24 (r<j arns ).The heritability indicates that selection against RAF is possible. The genetic correlations indicate that selection based on feed conversion or on body weight after restricted feeding could result in less fat deposition under ad libitum feeding conditions. (

Fat Deposition in a Broiler Sire Strain

“…Eitan et al (1982) and Leenstra et al (1986) found negative genetic correlations between body weight gain with restricted feeding and amount of abdominal fat deposited with ad libitum feeding. Eitan et al 1982) used individual housing, while Leenstra et al (1986) housed the chickens in groups. Selection for body weight among grouphoused chickens, which are fed restricted, can be applied easily to large numbers of chickens.…”

“…However, measurement of both characteristics is laborious and individual selection for feed conversion requires individual cages (Pym and James, 1979). Eitan et al (1982) and Leenstra et al (1986) found negative genetic correlations between body weight gain with restricted feeding and amount of abdominal fat deposited with ad libitum feeding. Eitan et al 1982) used individual housing, while Leenstra et al (1986) housed the chickens in groups.…”

Sources of shared variability of the carcass and non-carcass components in pekin ducklings

“…In broiler chickens, the correlation coefficient between live body weight and abdominal fat weight was 0.50 [26], and 0.49 and 0.53 for males and females, respectively [4]. Also, Leenstra et al [12] estimated the correlation between live body weight and abdominal fat weight as 0.46. Weight of carcass and non-carcass components were positively intercorrelated.…”

“…In a literature review by Leenstra [11] the coefficient of variation of the abdominal fat weight of broiler reared in the same environment varied from 24 to 47%. The large variability of this trait along with its high heritability offers favourable prospects for selection against this trait [12]. of the original 5 variables, leaving 27.1% to the 5 'special' factors (Tab.…”

Heterosis for growth related traits in White Plymouth Rock and Single Comb White Leghorn reciprocal crosses reared under two crude protein regimens

“…These two traits are commonly used in determining performance of both meat and egg-type birds. Further, these traits with an estimated correlation of +0.52 have been of both biological and economic significance towards genetic improvement through selection of faster growing and high producing birds (Chambers et al, 1984;Leenstra et al, 1986).…”