CONICET | Buscador de Institutos y Recursos Humanos

Measurement of the spacing between the pelvic (pin) bones is used to determine the state of sexual development of female broiler breeders. Herein, we examined pubic spread (PS) at selected intervals before, during and after puberty in Coturnix, an avian species often used for extrapolation of data to more valuable poultry stocks. PS was determined by .rst constructing di.erent sets of wooden applicator sticks joined together to represent .xed gauges of increasing widths. The stick sets used an appropriate number of applicators that, when glued together, represented increasing one stick (～2.2 mm) incremental distances from 4 (～ 8.8 mm) to 13 (～ 28.6 mm) sticks. These stick gauges were then placed between the pin bones until the best .t was detected. Within a bird (n = 80), PS measurements were made at 15 di.erent ages (beginning at 21 and ending at 84 d of age). PS measures were regressed with age at .rst egg lay (FIRST) to determine the age when measurement of PS best predicts the initiation of oviposition. A cubic relationship (PS = 22.4 - 0.99 d + 0.03 d2 - 0.0002 d3; r = 0.98, P < 0.0001) was found to exist between age and PS. The sigmoid best-.t curve of this relationship showed that: 1) little development in PS was evident between 21 to 38 d (prepubescence), 2) rapid and increasing development occurred between 42 to 59 d, and 3) no further development occurred thereafter (from 63 to 84 d of age; postpubescence). Regressions of PS with FIRST showed that the optimum age range to make a PS measurement to predict the onset of egg lay was sometime during 49 to 52 d of age (FIRST (d) = 89.64 - 1.63*(PS, mm), r = .69, P < 0.00001 and FIRST (d) = 97.98 - 1.93*(PS, mm), r = .71, P < 0.00001, respectively). The data demonstrate the usefulness of making pubic measurements in Japanese quail to predict sexual development and the initiation of egg lay.

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