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Where are my weaners? Flock and herd infertility

25 July 2019

By Scott Ison
District Veterinarian 

A group of lambsWe’ve seen and heard of a few nasty surprises this year when it comes to breeder performance. Some people had scanning percentages well below par, and others drove into their paddocks to find huge shortages of lambs or calves.

We are learning new things about livestock reproduction all the time, and we may never know what has gone wrong in some of these mobs. Having said that, here are a few proven methods to reduce reproductive wastage and get more weaners.

Body condition

This is at the top of the list because reproductive performance is closely correlated to body condition. Peak reproductive efficiency starts at condition score 3 and up (cows and ewes).

Nutrition needs to be planned, monitored and managed, especially in the tough years, which is why regular condition scoring needs to part of everyone’s routine.

In maidens, the focus should be on growth rate without too much fat. Targets are available for different breeds, indicating the ideal weight for maximum pregnancy rates.

Biosecurity and animal health

There are a number of diseases that can have devastating effects on reproduction. Thankfully, good biosecurity and vaccinations can prevent most of them. For cattle, these include vibriosis, pestivirus, trichomoniasis and leptospirosis. In sheep, brucellosis and campylobacter occur commonly, while other infectious causes include listeria, toxoplasma and Q fever.

There are many other diseases that can also cause infertility. When a pregnant female has a high temperature, she is at risk of losing the foetus, especially in the first trimester. When a male has a temperature, it can kill of all sperm and take two months for viable sperm to be produced again. A number of conditions can lead to a raised temperature, including feed contaminants.

Examine and cull

If your focus is to maximise breeding efficiency - and it should be - then you need to check each animal and make sure it is producing for you.

There are some key times to do this. Bulls and rams should be checked before joining, leaving you enough time to find replacements. Rams can usually be checked by an experienced sheep person, but you probably need a vet to fully examine a bull, including reproductive health and semen quality.

Scanning ewes for twins and singles, and separating them for tailored management, has been an important industry recommendation for many years. Empties should be culled.

Cows should also be pregnancy tested so that empties can be culled.

Dry cows and ewes should be identified at marking or weaning and culled, as they can be the most expensive animals. Cows can be very expensive to carry through to the next calving season, and ewes have been shown to be repeat offenders. The ewe that doesn’t wean a lamb this year is likely to be dry again next year.

Get professional advice

If you have poor pregnancy, marking or weaning rates, talk to your local private vet or call Local Land Services on 1300 795 299 to speak to a district vet.