Onset of puberty and early-life reproduction in Angus females divergently selected for post-weaning residual feed intake

• DOI: 10.1071/an10097
• Publication Date: 2011-03-08T03:53:30Z
• Authors: K. A. Donoghue; P. F. Arthur; J. F. Wilkins; R. M. Herd
• Keywords: Residual feed intake

Angus cattle that had been divergently selected for Low and High post-weaning residual feed intake (RFI) were used in two projects to evaluate early-life reproductive performance onset of puberty females. In the first project, data on 1999-born females (n = 64) evaluated weight, subcutaneous fat (P8 depth) over breeding cycles. These result 1.0–2.5 (mean 1.8) generations selection, mean (±s.e.) RFI –0.82 ± 0.19 kg/day 0.57 0.18 selection lines, respectively. second ultrasonography was scan ovaries 2008-born heifers 121) four occasions following weaning. these presence corpus luteum provided evidence ovulation, hence commencement puberty. The average estimated value (EBV) parents line –0.72 0.05 0.37 0.03 kg/day, no significant differences evident age at mating, pregnancy calving rates (percentage pregnant, or percentage calved out total number mating), calf birthweight weight born per female exposed bull. Females from significantly (P < 0.05) lower P8 depth relative their contemporaries most measurement dates (e.g. 9.2 0.5 versus 12.0 mm start mating). also later season than (35.7 3.0 27.6 2.4 days). results indicate there is a delayed date during mating leading heifers. then maintained subsequent calving. calving, however, did not impact rates. it observed irrespective line, attained greater those not. Hence expectation that, heifers, with fat, will attain slightly older age. This expected trend but difference significant, further investigations are recommended.