Robust herd benefits from new insights

Darcy Bateman and his father Chris have a tried and tested approach which achieved strong fertility and productivity outcomes in their south-east SA mixed enterprise – but they’re open to new ideas.

Their involvement in a local Producer Demonstration Site (PDS) project looking at reproductive health and management practices for beef heifers (see Hot tips for top heifers), informed some potentially profitable tweaks to their breeding strategy.

PDS a timely refresher

Darcy, who recently returned home after almost a decade studying and working as a project manager in the construction industry, was keen to join the PDS to brush up on his skills.

He said hearing from other producers about their different management styles and production systems was valuable.

“We also had access to a range of presenters who spoke about economic modelling of different herd compositions and reproductive and metabolic diseases,” Darcy said.

For example, veterinarian Sean McGrath facilitated animal health testing to investigate possible contributors to some animal health issues in their herd – blood tests taken from heifers with lower condition scores revealed markers pointing to kidney damage resulting from plant toxicity.

“We gave the heifers a drench and improved their nutrition – we moved them to a paddock with more food on offer which was of better quality,” Darcy said.

Breeding strategy

The Batemans run a self-replacing herd of Hereford/Simmental-cross and Angus/Black Simmental cows. They use Angus bulls in the top 30% for the Calving Ease estimated breeding value (EBV) over heifers, while Hereford and Simmental bulls are used over mature breeders.

Their established crossbreeding approach to derive hybrid vigour (heterosis) has yielded strong results, with progeny exhibiting greater size, growth rates and fertility than their parents.

“It’s interesting to see bull EBVs translate into our bullock carcase data – our Simmental-cross bullocks consistently achieve higher Eye Muscle Area (EMA) values, while our Hereford-cross and Black Simmental-Angus bullocks achieve better marbling scores,” Darcy said.

The Batemans grow bullocks out to target 340kg dressed weight to meet Grasslands/PCAS specifications at 18–21 months. One of their bullocks recently won reserve grand champion carcase at the annual Southern Grassfed Carcase Classic at Lucindale.

Stringent standards

The Batemans wean in December.

Heifer weaners are generally run on perennial pastures and receive supplementation (such as ryegrass/clover hay) through autumn until after mating.

Heifers are joined at 14–15 months, and the Batemans’ management has resulted in a long-term average pregnancy tested in calf (PTIC) rate of 85%.

“We pay stringent attention to any structural or temperament issues and meticulously cull heifers after preg-testing if they don’t meet required standards,” Darcy said.

Trialling new management

Previously, they used a six-week joining. However, Darcy aims to adjust his joining schedule this year – moving to a split joining of four weeks, with a one to two-week break followed by another three-week joining – resulting in two calving periods.

“Our mob sizes vary a bit at joining, but bulls are generally run at approximately 3–4% in cows and 2.5–3% in heifers. The ratio will remain unchanged at this stage.

“We trialled this in 2022 in a different mob sold as PTIC every year and found that 65% of retained heifers from the second joining had calved within the first week of the due date.

“Providing we get a favourable preg-scanning result, we’ll retain as many heifers in the first calving cycle as possible to tighten up the spread in calf phenotypes as they’re marketed,” Darcy said.

Rethinking EBVs

Throughout the PDS, Darcy has followed a ‘monitor mob’ of heifers, from weaning age to turning off their second calf. Body condition score (BCS) and weight were recorded during different periods to determine what relationship exists between BCS and conception rates.

“It’s been interesting reviewing scanning results and identifying their relationship to BCS and percentage of mature cow weight (MCW) at joining,” Darcy said.

The PDS learnings have seen Darcy branch out from initially prioritising Calving Ease and Scrotal Size EBVs when considering fertility in bulls. He now also considers Days to Calving – rather than lower birth weights – to ensure calves’ eventual size at maturity is not compromised.

He’s also drawing on the data generated by the PDS to investigate the heritability of conception rates, particularly out of leaner-type bulls.