Genetic selection has played an important role in halting the downward trend in Australian dairy herd reproductive performance.
An analysis by Dr John Morton confirmed that the Daughter Fertility Australian Breeding Value (ABV) has given dairy farmers an effective tool to breed for improved herd reproductive performance.
His analysis, found that the daughters of sires with higher ABVs for daughter fertility have markedly better reproductive performance than daughters of sires with lower Daughter Fertility ABVs.
He concluded that continual selection of sires with a high Balanced Performance Index (BPI) would result in small but ongoing improvements in herd reproductive performance.
“This is significant because genetic improvement is both permanent and cumulative. Some farmers may choose to use the Health Weighted Index (HWI) which puts more emphasis on daughter fertility than the BPI,” John said.
“However, to maximise genetic gain for herd fertility, select high BPI/HWI sires from the Good Bulls Guide that have high ABVs for daughter fertility.”
Michelle Axford from the Australian Dairy Herd Improvement Scheme (ADHIS) said farmers could expect continued improvements in herd fertility, as more cows with better genes for fertility enter the milking herd.
“Farmers have more choice than in the past, with the number of high BPI bulls with a Daughter Fertility ABV of at least 105 increasing from 16 in 2011 to 478 in 2016 in the Good Bulls guide/App,” she said.
As well as this, the reliability of the Daughter Fertility ABV has improved. In 2003 only 10 of the top 50 Holstein bulls and eight of the top 20 Jersey Bulls had a Daughter Fertility ABV. Now, with improvements to the genetic evaluation model and increased reliability, every Holstein and Jersey Bull listed in the Good Bulls Guide has a Daughter Fertility ABV. Similar improvements have been achieved in other dairy breeds. This improvement provides dairy farmers with even more power to breed for better reproduction.
“Of course, genetics complements other management strategies used by dairy farmers to improve herd fertility, including nutrition, heat detection, AI practices and bull management,” she said.
The study drew upon data from 74 seasonal and split calving commercial herds with high quality reproductive data, covering more than 60,000 lactations from Holstein cows and almost 3,000 Jersey cow lactations.
ADHIS is an initiative of Australian Dairy Farmers Ltd, that receives the majority of its funding from Dairy Australia through the Dairy Services Levy.