Factors Influencing Cow Fertility

AUSTRALIA - While the latest findings are only preliminary, the MLA-funded Cash Cow or Northern Australian Beef Fertility project has identified the significant factors impacting on the likelihood of a cow becoming pregnant four months after calving.
calendar icon 6 August 2012
clock icon 3 minute read
Meat & Livestock Australia

Across the Cash Cow herds, preliminary analysis showed significant factors reducing the percentage of cows pregnant four months after calving were:

  • timing of previous calving – out-of-season calvers (April–June) were much less likely to be back in calf within four months of calving than those calving October–January;

  • wet season phosphorus deficiency – cows with evidence of low dietary P (as determined from faecal P levels) during the wet season were much less likely to be in-calf than those with adequate dietary P;

  • previous year’s reproductive performance – non-lactating cows that became pregnant were subsequently less likely to be in-calf than lactating cows that became pregnant;

  • body condition score at last year’s annual pregnancy test – cows in poor to fair condition were much less likely to be in-calf than cows in good condition.

Project leader Professor Michael McGowan from the University of Queensland (UQ), said that the Cash Cow data analysis team had completed the first round of multivariate analysis.

The analysis recognised that different factors collectively influence a breeding female’s performance, and that producers need to know the magnitude of each identified factor that affects performance. This will enable producers to make better management decisions and more effectively target resources.

Michael stressed results available at this stage were only preliminary, and that the findings of the final round of multivariate analysis would be available later in the year.

The Cash Cow data showed that all four regions of northern Australia (Downs, Brigalow, Southern Forest and Northern Forest experienced some high calf losses between pregnancy diagnosis and weaning. Some preliminary findings of factors increasing calf losses were:

  • timing of previous calving – out-of-season calvers (April–June) had higher losses;

  • low protein and energy consumption in last trimester – cows consuming pasture with less than 0.125cp:dmd (ratio of crude protein content to dry matter digestibility).

Dianne Joyner from UQ said Cash Cow benefited from the whole-hearted participation of its co-operating cattle producers and veterinarians.

She said the recent project meeting at Beef Australia 2012 in Rockhampton demonstrated a great camaraderie between participants and researchers and an invaluable industry network had been established.

Best practice approach to managing breeder herds

While industry-wide recommendatios based on the Cash Cow project can’t be made just yet, preliminary findings point toward a number of best practice approaches to managing breeder herds in northern Australia.

  • Implement foetal ageing at annual pregnancy test to enable identification and management of ‘out-of-season calving females’ and more appropriate timing of branding/ weaning musters.

  • Assess wet season pastures by using faecal P testing to determine P status of females.

  • Implement a heifer replacement program, and cull heifers that fail to conceive within three months of joining.

  • Assess body condition score of all cows at annual pregnancy test during first-round muster. Aim to have cows at body condition score 3 or better at time of calving.

  • Ensure weaning occurs before cows lose too much condition, and that cows have sufficient time and access to adequate quality pasture to recover condition prior to next calving.

  • Ensure pregnant cows are on a good plane of nutrition (protein and energy) in the last trimester of pregnancy. (This is another good reason to manage out-of-season calvers as a separate group, as it’s difficult to achieve this in the last months of the dry season).

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