Comparison of Bone and Muscle Growth in Turkey Lines Selected for Increased Body Weight and Increased Shank Width

Nestor, Karl E.; Bacon, Wayne L.; Moorhead, P. D.; Ym, Saif; Havenstein, G. B.; Renner, Philip A.

doi:10.3382/ps.0661421

Cited by 48 publications

(23 citation statements)

References 22 publications

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“…This confirms previous work (e.g. BACON et al, 1986;NESTOR et al, 1987) indicating that as total body weight increased a decline occurs in leg bones and skeleton in general. Heritabilities.…”

Section: Resultssupporting

confidence: 81%

“…Practically no attention might possibly be paid to the grade ofthe marketed birds. However, it is well established (especially in turkeys and broilers) that selection for increased body weight is accompanied by biologically incompatible reduction in relative weight of skeleton (the leg bones in particular) which would at the producer level, magnify the severity of cvcntual leg problems (MERCER and HILL, 1984;NESTOR et al, 1987;L1LBURN, 1994). To the authors' knowledge, no selection indexes are available to select for increased body weight while limiting reduction in body bone percentage, The development of such indexes are discussed in this paper with special reference to expected genetic changes on body weight, body bone percentage and the related meat production attributes.…”

Section: Introductionmentioning

confidence: 99%

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Selection index alternatives for increased marketing body weight with minimum concomitant reduction in body bone percentagerecourse to tissue dissection on Japanese quail

et al. 2000

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SummaryLive body weight, shank length, keel length and carcass dissection data taken at 6 weeks of age were available on 103 quails from 33 sires. In a principal factor analysis, the first varimax rotated factor explaining 46.1% of the total Variation, revealed that body weight had negative loading and all bone percentages positive. The implied contrast was confirmed by the finding that body weight (h 2 = 0.61) was genetically correlated negatively with weight of total bone relative to body weight (-0.23) and to carcass weight (-0.58). Noticeably, shank length (SL) had large positive genetic correlation with body weight (0.90) and practically independent relationship with body bone percentage (-0.04). Selection indexes for meat production capacity were construeted. The breeding goal was defined as body weight (BW) and body bone percentage (BBP). The descending order ofthe unrestricted indexes with respect to the correlation between the index and genetic worth was: the füll index utilising body weight, shank length and keel length (0.95), indexes based on body weight and one length measurement (0.86), body weight alone (0.78). The accuracy was reduced by 17-35% upon restraining changes in BBP to zero. This study indicated that an index of considerable accuracy and remarkable usefulness would be I 3 = 4.56 BW + 244.87 SL. Use of this index should result in developing birds with higher body weight and more advantageous carcass attributes than selecting for body weight alone (L) or on the restricted füll index (II(BBP)). Such three indexes were most efficient in limiting reduction in BBP.

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Section: Resultssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Selection index alternatives for increased marketing body weight with minimum concomitant reduction in body bone percentagerecourse to tissue dissection on Japanese quail

et al. 2000

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“…The volume of the tibiotarsi and size of their cross-section (area or diameter) are often in close relationship with body weight whatever the genetic origin of chickens (Abourachid, 1990;Leterrier and Nys, 1992b;Wyers et al, 1993). Genetic selection modi es bone diameter only when bone characteristics are used as selected traits, such as shank width in turkeys (Nestor et al, 1987).…”

Section: Discussionmentioning

confidence: 99%

“…Other components of the locomotor apparatus can be modi ed by reduced growth rate: selection for increased growth rate increases muscle cross-section (Nestor et al, 1987;Abourachid 1990) and conformation may also change in birds fed on a high energy diet. These changes could greatly increase the stresses applied to the tarsal joint (Abourachid, 1993) and therefore explain the difference we observed in leg weakness.…”

Section: Discussionmentioning

confidence: 99%

Reducing growth rate of broiler chickens with a low energy diet does not improve cortical bone quality

Leterrier¹,

Rose²,

Constantin³

et al. 1998

British Poultry Science

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1. Reducing growth rate is often supposed to allow better skeletal development and improve bone quality. In order to test this assumption, flocks of broiler chickens fed on a diet containing 13.31 MJ ME/kg (H) were compared with flocks in which the growth rate was reduced by feeding birds with a low energy diet (L, 9.62 MJ ME/kg). 2. Bone growth was studied in 2 experiments in order to identify any changes in bone tissue of slow-growing chickens that might explain why they are less predisposed to varus-valgus deformities (3.1% vs 19.9%). 3. In experiment 1, the morphology, composition and histomorphometry of the tibiotarsi were analysed in both groups at 1, 12, 26, 42 and 46 d of age. Tibial variables (weight, volume, length, cortex size and structure, dry content and ash percentage) were always reduced in slow-growing birds except at 42 d of age, when tibial weight and cortex areas were similar in both groups. 4. Every variable was similar in both groups, or even higher in H birds, when chickens were compared at similar body weight, suggesting that the low growth rate did not improve bone quantity or quality of the tibiae. 5. In experiment 2, the composition of the tibiotarsi was compared every 2 days during the first week and twice a week until 36 d of age, in H and L birds. Weight and composition of the tibiotarsi did not differ between groups when compared at equal body weight, as also shown in experiment 1. 6. The reduced occurrence of varus-valgus deformities in slow-growing chicks cannot be related to an improvement in the structure and the composition of their bone tissue.

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“…A genetic basis for skeletal problems in meattype poultry has been clearly documented by studies showing that: 1) leg problems in broilers are moderately to highly heritable (Sheridan et al, 1974(Sheridan et al, , 1978Burton et al, 1981;Mercer and Hill, 1984); 2) different broiler and turkey strains differ considerably in their levels of leg problems (Haye and Simons, 1978;Veltman and Jensen, 1981;Nestor, 1984;Nestor et al, 1985Nestor et al, , 1987; 3) broilers respond to selection for a decreased incidence of leg abnormalities (Serfontein and Payne, 1934;Nesheim, 1965, 1972;Riddell, 1976); 4) selection for increased 16-wk body weight increased the number of leg problems in turkeys (Nestor, 1984); and 5) selection for increased shank width reduced the number of leg abnormalities and improved walking ability in turkeys (Nestor et al, 1985(Nestor et al, , 1987. Nestor et al (1985) hypothesized that direct selection for increased amount of breast muscles as well as for greater total body weight had caused total body weight and breast muscles to increase at a faster rate than the muscles and bones of the legs, and that this disproportionate change had caused an inherent weakness in the bird, which results in leg problems.…”

Section: Introductionmentioning

confidence: 97%

Estimates of Genetic Parameters in Turkeys.

et al. 1988

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Heritabilities (h2) of and genetic (rG) correlations among body weight and a number of skeletal characteristics were estimated from data on 1,088 pedigree turkeys (504 females and 584 males) of a randombred control line. All measurements were made at 16 wk of age. The h2 estimates (sire component) obtained from females (F) and males (M), respectively, were: BW .23, .60; shank width (SW) .54, .47; shank length (SL) .43, .54; drum length .66, .60; rough-cleaned weights of the thigh (nonestimable, .60), drum .09, .57, and shank .28, .69; cleaned weights of the drum .37, .71, and shank .30, .40; fat-free weights of the drum .44, .93, and shank, .45, .82; bone density measured at 40 and 60% of the length from the proximal end of the drum .68, .80 and .34, .92, respectively, and shank .28, .69 and .31, .55. Genetic correlations (rG) among the various bone weights were all above .66, with most above .85. The rG between BW and SW were .33 from M and .47 from F. These correlations suggest there is a relatively weak relationship, indicating that selection for BW alone might not cause a large enough increase in SW to support the increase brought about in BW. Shank width also had relatively low correlations with bone weight measurements, ranging from .27 to .53 from M and .17 to .56 from F. The h2 of walking ability score (WA) was .06 and the rG of WA with BW was -.73, which indicated that the low body weight families tended to have poor WA (i.e., higher scores). This may be a spurious rG, because poor walking ability scores tended to be grouped in families. Birds with poor walking ability would have difficulty eating, and would, therefore, tend to have low BW. The rG between SW:WA (-.09) and SL:WA (.03) indicated little relationship between those traits. The WA and the bone density readings had high negative rG (range -.75 to -1.47), indicating that families with poor WA ratings also had low bone density scores.

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Comparison of Bone and Muscle Growth in Turkey Lines Selected for Increased Body Weight and Increased Shank Width

Cited by 48 publications

References 22 publications

Selection index alternatives for increased marketing body weight with minimum concomitant reduction in body bone percentagerecourse to tissue dissection on Japanese quail

Selection index alternatives for increased marketing body weight with minimum concomitant reduction in body bone percentagerecourse to tissue dissection on Japanese quail

Reducing growth rate of broiler chickens with a low energy diet does not improve cortical bone quality

Estimates of Genetic Parameters in Turkeys.

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