Selection for fertility traits in Brahmans increases heifer pregnancy rates from yearling mating
T. J. Schatz A C , G. A. Jayawardhana A B , R. Golding A and M. N. Hearnden AA Department of Regional Development Primary Industry Fisheries and Resources, PO Box 3000, Darwin, NT 0801, Australia.
B Telac Enterprises, 44 Murrabibbi Street, Leanyer, NT 0812, Australia.
C Corresponding author. Email: tim.schatz@nt.gov.au
Animal Production Science 50(6) 345-348 https://doi.org/10.1071/AN09165
Submitted: 30 November 2009 Accepted: 1 February 2010 Published: 11 June 2010
Abstract
The performance of heifers from a Brahman herd that was selected for fertility was compared with Brahman heifers sourced from commercial properties using three year-groups of heifers. Each year, conception rates from yearling mating were significantly higher in heifers from the selected herd (SEL) than in heifers sourced from commercial properties (COM), despite the average joining weight of the SEL heifers being lower each year. The pregnancy rate in SEL heifers was 24% higher (P = 0.008) in the first year, 36% higher (P = 0.005) in the second year and 45% higher (P < 0.001) in the third year. Over the 3 years of the study, the conception rate was 35% higher (P = 0.009) in SEL heifers than in COM heifers. Joining weight also affected pregnancy rates. When heifers were split into weight ranges according to their pre-joining weight, pregnancy rates were significantly higher (P = 0.018) in the heavier weight range than the lighter one. The results indicate that selection for fertility has been successful in improving conception rates from yearling mating in SEL heifers.
Acknowledgements
The authors gratefully acknowledge the assistance of the manager and staff of DDRF for assistance with cattle management and data collection.
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