Productivity of Hereford, highgrade Simmental and Belmont Red beef herds in central Queensland, 4. Liveweight and age of heifers at puberty
1992
Burns, B.M. (Queensland Dept. of Primary Industries, Theodore (Australia)) | Howitt, C.J. | Webber, R.J. (Queensland Dept. of Primary Industries, Mareeba (Australia)) | Rudder, T.H. | Tierney, T.J. | O'Rourke, P.K. (Queensland Dept. of Primary Industries, Brisbane (Australia))
Liveweight and age at first and second oestrus of Hereford, highgrade Simmental, and Belmont Red heifers were measured over 4 cohorts born from 1979 to 1982. Hereford heifers demonstrated first and second oestrus at lower liveweights (277 and 203 kg) than Belmont Reds (293 and 319 kg), which were lighter than highgrade Simmentals (322 and 345 kg). Belmont Red heifers were younger at first oestrus (527 days) than either Hereford (565 days) or highgrade Simmental (550 days), which were not significantly different. There was a similar pattern for age at second oestrus, except that only Belmont Red (583 days) and Hereford (617 days) differed significantly. However, 13 percent of heifers did not record a second oestrus during the observation period, in addition to the 7 percent that failed to record first oestrus by the end of the experiment. Only 6 percent of Hereford, 19 percent of highgrade Simmental, and 16 percent of Belmont Red heifers had reached puberty in time for seasonal mating as yearlings (about 15 months), and 88 percent of these were from the 1982 cohort.
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