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Browsing by Author "Honaker, Christa Ferst"

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    The Effects of Beak Trimming and Claw Reduction on Growing and Early Laying Parameters, Fearfulness, and Heterophil to Lymphocyte Ratios
    Honaker, Christa Ferst (Virginia Tech, 2003-05-26)
    Commercial equipment used by the turkey industry at hatch sterilizes the germinal tissue of the claw with microwave energy and the beak tissue with infrared energy. This effectively claw and beak trims the birds. To test this technique on chickens, one-half of two strains of 1,200 Leghorn chicks were each subjected to the claw reduction (RC) technique at hatch, while one-half retained intact claws (IC). The beaks of one-third of these treatments were reduced at hatch using the infrared technique (1-day), one-third were precision trimmed at 7 d of age (7-day), and one-third were not trimmed (IB). Body weight, weight gain, feed intake, feed conversion, mortality, and fearfulness were measured. Rearing followed standard commercial feeding and husbandry procedures. During the preliminary experiment, heterophil to lymphocyte ratios did not consistently differ significantly between treatments. The RC birds had significantly lower body weight, except from 3 to 6 wk and had significantly lower feed consumption from 8 to 18 wk. The 1-day beak trimmed (BT) birds had significantly lower body weight from 3 to 14 wk and ate less total feed by 4 wk. Subjective evaluation showed that the RC birds exhibited less fearfulness during the growing period than the IC birds. Throughout lay, the body weight of RC and BT birds was significantly affected. Feed consumption was not lessened for RC birds, but was for BT birds throughout lay. Egg production, egg quality, and mortality were not affected by either treatment.
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    Selection for Body Weight in Chickens: Resource Allocations and Scaling
    Jambui, Michelle (Virginia Tech, 2016-06-08)
    Evaluated were correlated responses to 54-generations of divergent selection for 8-week body weight (BW) and of BW at other ages and reproductive traits. Evaluated first was the influence of scaling on phenotypic responses to selection, phenotypic correlations of means and standard deviations, and unadjusted vs. standardized responses. Measured was BW at 4 (BW4), 8 (BW8), 24 (BW24), and 38 (BW38) weeks of age. Correlations between means and standard deviations were positive and greater in the LWS than HWS. Scaling masked the degree more than the pattern of response and was line specific with the magnitude of response greater in the LWS than HWS. While BW ratios across ages were not influenced by scaling in LWS, they were evident in HWS. Also measured were correlated responses of reproductive traits in selected and relaxed lines. Traits were age at first egg (AFE), body weight at first egg (WFE), their ratio (WAFE), and hen-day normal egg production (HDP). Although sexual maturity was delayed, the effect was more pronounced in the low than high weight lines. Selection for low BW decreased WFE, WAFE and HDP. Selection for high BW resulted in lower HDP, while WFE and WAFE were generally higher. Minimum AFE, WFE and WAFE in relation to sexual maturity were line specific. Opposition between relaxed and artificial selection resulted in a higher reproductive performance and fitness with relaxed than artificial selection. Overall, results demonstrate that correlated responses to long-term divergent selection were masked by scaling and negative correlated reproductive responses.