How to Make More From the Females in the Herd05 November 2013
Farmers are being advised to consider condition of older cows and maiden heifers after new research has linked female condition to both profitability and performance.
The Billabo Beef Group has announced the importance of heifer weights after an investigation, started in 2009 to look at the impact of reproductive disease in cattle on profitability.
The weight of maiden heifers and the condition of older cows are critical to reproductive performance and profitability, according to early findings from a Central Queensland Producer Demonstration Site (PDS), write Meat and Livestock Australia (MLA) experts.
The Billaboo CQ Beef Group members established an MLA-funded PDS in 2009 to investigate the impact of reproductive diseases in cattle on profitability.
MLA analysts write that, supported by staff from FutureBeef, group members have collected and recorded performance and disease data since 2010. Data includes body condition scores, pregnancy rates and losses from pregnancy test to weaning.
Project coordinator, Laura Devlin, said the producers wanted to identify where losses were occurring, determine the risk of reproductive diseases on their properties, and implement the most cost-effective strategies for managing the diseases.
The PDS discovered that all herds in the project had been exposed to pestivirus (BVDV) and so also undertook a cost-benefit analysis of vaccination.
Breeder Weight and Condition Score
“The PDS results have highlighted the importance of managing breeder body condition in achieving good reproductive performance,” Laura said.
“Cows in poor condition at calving take longer to ovulate after calving and may not ovulate until weaning. Ideally, cows should be in body condition score three or better at calving.”
The first year’s records also revealed the significance of weight at joining for maiden heifers. Across the group’s herds, heifers above 440kg achieved an average 87 per cent conception, compared to just 51 per cent for heifers below 360kg at pregnancy testing.
A critical consideration for the group is managing the key diseases that can cause reproductive losses: vibriosis, leptospirosis and pestivirus.
Vibriosis can be controlled in most situations with a bull vaccination program. Other important measures include culling bulls at seven years and culling empty cows.
Leptospirosis can be managed by vaccinating breeders and bulls. Vaccination also reduces the risk to humans.
Pestivirus outbreaks in Central Queensland have been known to cause foetal and neonatal calf losses of 25–50 per cent. Blood tests taken in the first year of the project revealed all herds had been exposed to pestivirus. Reproductive losses from the virus are minimised if exposure occurs prior to mating.
A vaccine is available but, once a vaccination program is started, it needs to continue, as the herd will lose all natural immunity. The two initial doses of the vaccine cost $8.24/head, and the annual booster $4.12/head.
Analysis of the cost/benefits of pestivirus vaccination using Breedcow/Dynama software showed that a 2 per cent reduction in foetal and calf losses from pregnancy test to weaning would pay for a whole herd vaccination strategy.
University of Queensland veterinarian Professor Michael McGowan analysed the findings, emphasising that vaccination couldn’t be undertaken in isolation.
"Prof McGowan said there would be little point in vaccinating the older cows because they already showed significant levels of disease exposure and therefore had acquired a natural immunity,” Laura said.
“He suggested a whole herd vaccination strategy could start with the heifers, eventually building up to the whole breeder herd.
“However, biosecurity measures must be put in place, such as keeping new cattle away from the breeding herd, especially if they’re in early pregnancy.”
An important outcome of the PDS has been the implementation of record keeping, which enables producers to better monitor reproductive performance. This is critical for the identification and management of reproductive losses.