Heifers will need to play a major role in the Australian Beef Herd Re-Build. Calving Ease will need to be a priority amongst Beef producers breeding Maiden Heifers in larger numbers in order to replenish their depleted Breeding Herds.
To try and assist you with the challenging task of Selecting a Calving Ease Bull for your Maiden Heifers we have organised the Catalogue as follows:
- Lots 26 – 31 This set of six (6) bulls are 1) out of Maiden Heifers; 2) born early; 3) born unassisted and 4) by three (3) we have identified as Maiden Heifer safe. Note we have calved 43 heifers over the past two years to Knowla McCaw M20 for No Assists; we have calved 38 Maiden Heifers to Dulverton Montjeu M13 over the same two seasons for No Assists.
- Lots 32 – 51 This set of 20 bulls are by the four main bulls represented in the catalogue, including nine (9) by Boonaroo Gravity G013; five (5) by Spring Cove Gentleman Jack; four (4) by Esselmont Lotto L3, note dropped Lotto to four, just a bit worried about P129 being super easy calving due to limited knowledge of his dam, believe him (P129) to be amongst the top handful in the Sale all the same. There is one Dulverton Larry L154, D. Phar Lap P055.
- We did use Lot 1, P288 over heifers to ‘mop up’ after the heifer AI and believe him to be very safe.
We trust this arrangement is of some benefit and as always cannot give categoric recommendations remembering of course that many other factors, other than the sire’s ability to pass on Calving Ease genes, influence Calving Ease. Very happy to discuss this set of recommendations with you at your convenience.
HEIFER BULL BREEDING PHILOSOPHY
It’s long been our contention that CALVING EASE has to be built into the Beef Bull Breeding Enterprise, biologically and genetically engineered, if you like. To optimise Calving Ease in the Dulverton herd we continue to-:
- Rely upon data from years gone by that measured Pelvic Area in the retained heifers at joining and they had to measure 270 sq.cms.
- Set minimum weight requirements to ensure preferred skeletal development at calving – 320kg at joining & 460kg at calving
- Remove from the herd any female that has been assisted at calving.
- Never allow progeny of females that might have been assisted, entry to the breeding ranks—Male or Female.
- Select breeders-male and female with the preferred pelvic shape. That is, a pelvis with a slight roll from hip to pin bones while maintaining width through the thurls and pins. Note that natural selection for calving ease in the “wilds” has resulted in such a pelvic shape e.g. Zebras, Buffalo Wildebeests etc. The high tail settings which appear to be a lot more prevalent in Angus more recently are to be guarded against, they are a negative when it comes to Calving Ease. The correct shoulder set, that is, a “flat” shoulder well laid in with a 45° set and neck extension, are essential structural set ups not only to assist ease of calving but also to assist with mobility.
- Select heifer bulls from maiden first calving 2 year old’s, born early in the drop and definitely unassisted.
- Include gestation length in the selection criterion of Sires to be mated to the Yearling Heifers. Why? A bovine foetus grows at a rate in the order of 0.6 to 0.7kg/day during the last 5-6 weeks of the gestation, therefore Bulls such as Dulverton Pins P008 (-6.4), Dulverton Peter Pan P204 (-5.2), Dulverton Protectionist P117 (-7.5) and Dulverton Pierro P118 (-6.8) will sire calves with the genetic capability of being 2.5-3.5 kg lighter than the average of their calving group.
Notice we pay little to no attention to Birth Weight, we don’t measure it – if you can’t measure and record all calves then don’t pollute the data set by putting in incomplete sets. The Genetic Correlations developed by programmes such as Breedplan do make some very Valuable observations – the relationship Birthweight to Growth no doubt one of the best. As a General Rule the lighter the birth weight the-
- Greater the incidence of reduced Calf Survival rates-“ Dead Calves have Distressingly Poor Growth Rates”
- The lesser the Growth Rate and by implication the lighter the weaning weights the less the Dollar Value per head.
- The lesser the Growth Rate the lighter the heifer when she exhibits 1st Oestrus and the lighter she will be in October the preferred time of Joining. Heifers that aren’t 300-320kg at time of joining will struggle to be 460kg at the time of Calving. As a general rule heifers in the weight range 400- 440kg simply can’t have the necessary Skeletal Development to ensure a substantial enough Pelvic Area/ “Opening” to enable safe delivery, of a healthy live calf.