High Incidence of Twinning in Beef Cattle
USMARC cow with twin calves on Leo Cummins belongings Admetus
DURING times like this when the national beef herd is recovering after drought, cattle producers await on with envy at the sheep manufacture, where rates of twinning are common – and contributing heavily to the step of the rebuilding and restocking process.
But is it possible to select beef cattle for high rates of twinning?
A small but enthusiastic grouping of cattle producers in western Victoria have been exploring this topic for the by 16 years, with considerable success.
Retired Victorian research scientist Leo Cummins and his colleagues started selecting cattle for twinning performance in 2005.
Mr Cummins, who worked at the Pastoral and Veterinarian Establish at Hamilton, led a study into twinning in both sheep and cattle during his professional life, and has retained his passion for the topic since his retirement in 2002. At ane point he earned a Meat Enquiry Corporation scholarship to move to Armidale to work with UNE and CSIRO animal scientists looking at twinning functioning in Booroola sheep – regarded as the starting point in understanding ways to increase reproduction rates in sheep.
Former Beefiness CRC headDr Bernie Bindon, well known to many Beef Cardinal readers, was i of the main collaborators. Piece of work focused on both agreement the physiology likewise as the genetics behind the prolific- twinning Booroola sheep. The group discovered a major gene in the sheep that played a pregnant part in the process.
Encouraged somewhat by the results in the Booroola sheep project, a cattle twinning selection line was established at Armidale in the 1980s, based on diverse British breeds. The project advertised to purchase cows that had had twin calves, to establish the herd.
"In essence, they were mainly sheep researchers involved, simply while they were keen, and interested in the cattle, the cattle were actually a sideline," Mr Cummins said.
Around the same fourth dimension, the U.s. Department of Agriculture got interested in twinning functioning, establishing a breeding line called USMARC (United states Animal Research Middle), based out of Clay Centre, Nebraska.
The USMARC herd – a single-purpose research selection line, based on about a dozen breeds – was selected for around 25 years at Clay Centre, rising over that time from a 2pc twinning charge per unit to 160pc calving.
In the early 2000s, the projection was concluded, and Mr Cummins was presented with the opportunity to import some USMARC genetics to Commonwealth of australia, via embryos and semen. His first calves hit the basis in 2004.
He estimates there are currently around 100 USMARC descendent cattle in Commonwealth of australia, including around lx in his own herd on his property, Admetus, plus several smaller herds run by colleagues. The holding name Admetus was derived from Greek mythology, where a king'southward herd of cows all had twin calves after existence touched past the god, Apollo.
Cows with twin calves on Admetus
"Results have shown we can attain very high twin conception rates with the USMARC cattle we have bred," Mr Cummins said.
"But with college rates of twinning comes its own issues. Calving must be managed quite carefully," he said.
"They have very different reproductive capacity just they probably need more work to brand people interested. Information technology'southward not the sort of stuff that can be done in large, less intensively managed herds, or in herds exposed to poorer diet."
Mothering-up was another important factor later on twin births.
Set up out below is a summary of the March-to-May calving season performance recently completed at Admetus. The property regularly achieves 130pc calves built-in, and 120pc calves weaned each season. This would arguably be among the highest calving and weaning rates on any cattle property in Australia. In recent surveys, comparable Angus herds in the region average around 90pc weanings.
Equally the results below show, 53pc of mature cows on Admetus were sacanned for twins this year, and equally impressively, 33pc of starting time-calf heifers.
In comparing, the rate of twinning in conventional beef cattle varies from two-4pc.
While rates of dogie mortality in the herd may be relatively high, information technology is considerably less than lambs lost in high-twinning sheep flocks.
Weaners produced from Admetus herd with high rates of twinning preparing for sale
As the photos published here evidence, the USMARC descendent cattle in the Admetus herd are mixed colours, but predominantly reds and blacks (having obviously never been selected on coat colour.)
Phenotypically, they appear to be pretty good cattle, with reasonable bone and muscling. Weaners from the program are mostly sold in local shop sales each year, and in terms of size and growth, achieve results comparable with other mainstream breeds.
Freemartins
Some other factor universal with all sets of twin calves born to beef cattle is the fact that the majority of heifer calves built-in as mixed-sexual activity twins are sterile (freemartins). It does non impact heifers born as aforementioned-sex twin heifers.
While the condition does reduce the number of heifers bachelor to the herd as replacement breeders, the overall number of not-affected calves built-in – as either single calves, or heifer-heifer twins – offsets that. The internet result is effectively the aforementioned number of potential heifer breeder replacements as a conventional herd.
GHG considerations
Another potential gene in finding greater acceptance for the twinner cattle is in considerations surrounding greenhouse gas emissions, Mr Cummins believes.
"This is not a surprise but a reflection of the fact that we tin't afford to carry not-productive stock, and more productive stock are better (both from a greenhouse gas point of view more than obviously and importantly from a straight economical point of view).
2021 calving summary at Admetus
Calving at Admetus this year ran from 10 March to 1 May.
Grazing weather condition through autumn were reasonably tight but the very wet wintertime (273mm rain through May June and July – 73mm above average) – made the late winter very tight, say 700-1000kg/ha food on offer in mid-July / August with moderate pasture pugging. It has been as well moisture to leave and do any supplementary feeding since mid-July. The cows were generally a picayune low-cal but holding status for the start half of winter but have lost weight in the 2nd one-half.
Dr Ian McLeod did the pregnancy scanning on xix August. The cattle were torso status scored at that time. The bulls are still with the herd so conceptions in the last 2-3 weeks will exist recorded as not detectably significant. Therefore, potential end-date for calving is effectually 10 May 2022 (excluding any late conceptions).
Embryo transfer
Mating commenced with the embryo transfer program (Rob Pashen) on 5 June. 6 carryover empty cows received ane of Al joiner'southward embryos. A backup bull went with them from xv June. This was bull 912 till eight July so bull 2019. Preg testing on 19 August revealed 4 cows pregnant to the ET and two to the fill-in bull. Therefore, ET calves due near 7 March 2022.
Artificial insemination
The 20 heifers were ovary-scanned on 24 May and seven June and so 16 of them were detected on heat and AI'd to Paringa Fe Ore on 9/10 June. (Cloprostenol was given to all on 24/5 and 7/vi). 1 heifer not AI'd and not significant had no detected ovarian activity and a pocket-size uterus at scanning and was probably pre-pubic. The backup bull 2019 went with these heifers on 15 May and was replaced past 943 on viii July. AI calves due about 19 March for singles and 12 March for twins.
One heifer had calved 2 May (hard pull, dead at birth, seemed full term, therefore conception ~26 July 2020 at 4.v months of historic period) and is excluded from these figures.
Natural mating
The bulls arrived from Cashmore on 15 June and were put straight out. The lactating cows and first-calf heifers were run together and were in 2 groups, that is, some in paddocks 1 & ii and the residue in Paddocks 3 & 4. Bull 948 went into P1/2 and 943 went into P/4. Bull rotation occurred on 8 July.
"Overall, I am fairly happy with these results," Mr Cummins said. "The empty rate is a bit higher than I would hope for only near of the empty cows had had some issues (dystocia and/or getting sparse and requiring drenching, however some of the significant cows had these issues too).
"The twinning charge per unit is good considering the nutrition was a chip marginal," he said.
"At this stage we accept 57 pregnant with 84 foetuses on board."
- People interested in getting on lath with the twin breeding project tin contact Leo via Beef Cardinal. Transport an e-mail to jon@beefcentral.com and we will pass it on.
Source: https://www.beefcentral.com/genetics/is-it-possible-to-select-cattle-for-higher-rates-of-twins/
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