WITH A 700 ha broadacre cropping farm in a 350 mm annual rainfall zone 155 km north of Adelaide, you might forgive the Zweck family for not scrutinising the performance of their Holstein herd.
However, Gary and Ros Zweck, and their son Justin, have embraced genomics to help them benchmark their herd, and gain further improvements in production.
About 30 dairy farmers visited South Australia’s northern most dairy farm at Blyth, just west of Clare, through DairySA last month.
The Zweck family has farmed in the Blyth area for more than 120 years with Gary’s parents Don and Elva farming on the current block from 1962 and establishing their Donava
Holstein prefix in 1970.
The Zwecks milk 230 registered Holstein cows in a split-calving herd at Blyth. The herd is fed a total mixed ration (TMR) on a feed pad.
They grow mainly wheat and barley and cut oaten and vetch hay and silage.
“We grow all our own grain for the cows and keep about 600t of grain stored on farm,” Mr Zweck said.
“Our milking herd gets 3 kg/cow/day of grain in the dairy at milking and is fed a TMR, while we graze our heifers on stubble from November to January.”
They milk up to 230 cows a year with 60 per cent of the herd calving between February and May, and 40 per cent calving between August and October. They employ two full-time staff.
“Not farming in a typical dairy area can create a few challenges because it’s not as easy to chat to people about new technology and ideas in dairying,” Mr Zweck said.
The Zwecks’ farm was one of 27 dairy farms across Australia that recently underwent detailed analysis by the ImProving Herds project to investigate the contribution of genetics to dairy businesses.
Mr Zweck said it was particularly appealing to be involved because of the opportunity to gain access to a wider dairy community.
“Having the opportunity to take part in the ImProving Herds project was a great opportunity to learn.”
Under the ImProving Herds program, the top and bottom 25 per cent of each participating herd was ranked based on the Balanced Performance Index (BPI), the genetic index for profit used by the Australian dairy industry.
Ten years of historical performance data, plus recent farm financial data from the Zwecks’ herd records were also analysed.
The Zwecks have maintained good records on their herd, herd test every five weeks and began genomically testing their heifer calves in 2014.
The study found the top 25 per cent of the Zwecks’ herd produced 876 more litres of milk per cow per year, 57 more kilograms of fat and 42 more kilograms of protein than the bottom 25 per cent.
The extra milk production from the top 25 per cent of cows ranked on BPI resulted in $532 more income per cow per year, after feed and herd costs, compared with the bottom 25 per cent of the herd.
On average, the top 25 per cent of the Zwecks’ cows also lasted in the herd eight months longer than the bottom 25 per cent.
Gary, Justin and Gary’s father before him, undertook AI courses so they could run their own AI programs as their location means they do not have access to AI technicians.
“Our bull selection has always looked at production and for cows that will last in our environment,” Mr Zweck said.
“We’ve been genomically testing our replacement heifers since 2014, which has given us a much broader understanding of our herd and its genetic merit.
“As a result, we are now looking for bulls which are strong for kilograms of protein, fertility and teat placement, which is a trait we want to include so we can have the option of robotic milking in the future.
“One of the other advantages of genomic testing is the parent verification of the calves. In our experience it shows we were not as good as picking the dams of calves as we thought we were!”
All cows in the herd are Metrichecked after calving then undergo two rounds of AI with conventional semen followed by mop-up bulls which have been genomically tested so they have a known BPI.
“We’ve been using conventional semen in the cows but will be looking to use sexed semen in the cows in the future as conception rates are improving.”
All heifer calves are genomically tested using ear punch samples at 10 weeks of age; last Year 110 samples were sent for testing.
When the results come back the heifers are ranked on BPI and type with the bottom 10 per cent sold for export when they reach the required export weights.
The top 80 per cent based on BPI and type are joined to sexed semen and the next 10 per cent are joined to Wagyu or beef semen so their progeny don’t go into the herd.
Mr Zweck said they had seen significant changes since they started genomically testing replacement heifers and using sexed semen on the top heifers.
“Last year, we had 61 per cent female calves and 39 per cent male calves, which included AI and mop-up sires.
“Having more female calves to choose from, combined with genomic testing to identify the better heifers, is certainly allowing us to improve the rate of genetic progress in the herd.
“We are seeing increased production as more of these genomically tested heifers come into the herd, and in turn have their own calves; the performance of the next generation of heifers keeps going up year after year.
“As more of these heifers come through the herd, the more selection pressure we can put on BPI in the future.”