GENETICS TROPICAL CATTLE The genetic pay off Imagine if someone told you Breeding objectives they were able to lift their Where did they start? The first step weaning rates by more than was to identify a breeding objective – one‑third, reduce breeder they wanted an early‑maturing, highly mortality to 0.5% and improve fertile Brahman herd whose progeny turn‑off weights by 15%. would comply with a broad range of markets. That’s exactly what Russell and Donna Their approach was simple – select for Lethbridge have done. reproduction and the rest will follow. And to further prove it’s not just “I breed to produce a marketable theory, the couple’s Werrington animal – one that is fleshy and early Cattle Company operates in a harsh maturing, will put muscle on bones at environment where any system is put any time after 12 months and will lay to the test. down fat before it’s three years old,” The herd operates at 20% above Russell said. the district average for reproduction To achieve this, Donna and Russell efficiency and its weaning rate is cull non‑productive females and 25% above the industry average only buy bulls with above‑average for northern Queensland. BREEDPLAN ‘days to calving’ The Lethbridges attribute the improved values and whose dams are proven performance of their enterprise to: reproductive performers. • investing in sires with above‑average“The reliability of the traits for reproduction from a performance‑recorded herd with mother is very important,” similar breeding objectives Russell said. • applying selection pressure on the breeder herd for reproductive “If she’s had nine calves in performance. 10 years, it’s her genetics challenging conditions.” Russell (pictured) said, in their region, breeder mortality rates are typically I want.” This approach means the 3,000 head high and reproduction rates are breeding herd is young, with about low. This is a result of native pasture All females are pregnancy tested after one‑third of the annual calf drop out of nutrition levels below that required a four‑month controlled‑mating period, maiden heifers. for animal maintenance for up to nine and all empties become part of the cull‑cow income stream. Recent benchmarking has shown months each year. these young heifers hold their own. The couple have proven that: Heifers, on the other hand, face their biggest fertility challenge first up – Choosing the right bulls • selecting for fertility is indirectly a 10‑week joining. “When they are selecting bulls, I think selecting for adaptability and people are too obsessed with growth ‘doing’ ability However, pregnancy test results traits and don’t pay enough attention • removing non‑performing females are regularly above 90%, a vast to fertility indicators such as moderate (for reproduction) improves entire improvement on the 40–50% rate the frame size, days to calving, calving herd performance Lethbridges accepted 25 years ago. ease and scrotal circumference,” • weaning rates can be lifted (in their“Where it really pays off is with the Russell said. case from 45% to 72%) first‑calvers,” Russell said. “Our most progressive move was • breeder mortality can be reduced “We know we can successfully finding a seedstock producer who had to 0.5%. rejoin about 75% on no rain and in the same commercial trait objectives 6