@conference {69505,
	title = {Correlated responses following genetic selection to change age at puberty in Angus cattle},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {70},
	year = {2010},
	month = {Jun},
	pages = {202-205},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {Direct and correlated responses in a 23-year selection experiment to change puberty in heifers are reviewed. Selection was for age at first oestrus (AFO). It was applied in both sexes, using the genetic correlation (-0.25 {\textpm} 0.09) between scrotal circumference in juvenile males and AFO in female relatives. The main breeding lines were those selected for early AFO (AGE-), late AFO (AGE+), or unselected (Control). A 69-day difference (19\% of the herd mean) was achieved between the two AGE lines, with a 3.0 cm (9.9\%) difference in scrotal circumference. Relative to the AGE+ line, the AGE- line means were +10.8 {\textpm} 3.1 kg (3.9\%) in yearling weight, -6.0 {\textpm} 3.0 kg (1.3\%) in cow mature weight, -47 {\textpm} 6 kg (16\%) in heifer weight at first oestrus, and +3.7 {\textpm} 1.5 percentage points for mixed-aged cow pregnancy rate. There were significantly fewer sub-fertile yearling bulls in the AGE- line (P <0.001), and maternal effects on autumn and winter weights on calves of this line were positive. For carcass composition, only depot fat differed significantly between lines (AGE- mean < AGE+ mean). No major unfavourable traits were observed in the AGE- line in this study.},
	issn = {1176-5283},
	author = {Morris CA and Amyes NC}
}
