1st March 2013

Bull Fertility Tops Agenda at Clyde Monitor Farm

Percentage of calves weaned was one of the main topics at the recent Clyde monitor farm meeting, hosted by monitor farmer Andrew Baillie of Carstairs Mains near Lanark.

Mr Baillie runs a Johne’s Accredited, spring calving suckler herd of 75 breeding females on his 650 acre mixed unit, which is one of the network of Quality Meat Scotland (QMS) monitor farms throughout Scotland.

Heifers which are not retained are sold store and bull calves are kept entire and finished, along with approximately 120 dairy bull calves purchased annually from two local farms.

Recent pregnancy diagnosis testing had shown 90% of the breeding herd is in calf, promising a much improved calving compared with last year. In 2012 the  calving figure was 60%, the result of a working, but sub-fertile Limousin bull and well back on the 96% calving in 2011.

At the meeting, farm vet Charles Marwood of the Clyde Vet Group outlined the key areas to help maximise herd fertility and production. This included ensuring bulls are fertile, control of infectious diseases and good nutrition to achieve target body condition score. He also emphasised the need to avoid difficult calvings.

With calves born in the first cycle weighing significantly more at weaning than calves born in later cycles, Mr Marwood also highlighted the value of females being clean and cycling, before the bull is introduced.

One infertile cow is one less calf. However, one bull of poor fertility can result, as Mr Baillie discovered to his cost with his 2012 calving, in a disappointing and costly drop in conception rate.

Mr Marwood told the group that bull sub-fertility is not uncommon. “Last year we tested 150 bulls in the practice and found one in five to be sub-fertile.”

He encouraged the community group to semen test and examine all breeding bulls a month before use. “Even if a bull has worked well previously, it’s no guarantee that he is still fertile – things like a testicle infection, temporary fever or lameness, could affect fertility.”

Mr Marwood also explained that over-thin females may prove difficult to get in calf as they may not be cycling.

“If you are concerned that you’ve fed your cows well  but they’re still thinner than they should be, tests should be done to help establish the reason why.

“On the other hand, over-fat cows have not only eaten too much costly feed, but will also pose an increased risk of difficult calvings.”

A number of infectious diseases can reduce fertility. Some of the most common include Bovine Viral Diarrhoea (BVD), Leptospirosis, Infectious Bovine Rhinotracheitis (IBR), Johne’s and Neospora.

Mr Marwood told the group that correct vaccination can protect breeding cattle against BVD, Leptospirosis and IBR, but Johne’s is more difficult to control. If breeding females are identified as being infected, the advice is to cull them and not retain progeny for future breeding.

To help avoid difficult calvings, Mr Marwood recommended that the group consider a number of bull factors.

“Breed certainly does have effect, with some breeds acknowledged as being more challenging for calving.

“Try to avoid bulls with long gestation periods. Native breeds, although later maturing, generally have shorter gestation periods.

“Look at the Estimated Breeding Values (EBVs) for Calving Ease Direct, while also checking the percentage of accuracy for this figure.”

Monitor farmer Andrew Baillie selects his herd replacements from his annual heifer calf crop. “I aim for early-born, well-grown heifers out of cows which are problem-free, and that includes temperament.

“I particularly like to keep heifers out of the 20 or so cows which go back to Hereford cross Friesians I bought several years ago – their daughters are easy calving, milky, great to handle and their calves, particularly the bulls, are easy fleshing.”

For farmers who buy in their breeding females, Mr Marwood emphasised the importance of quarantining and health testing purchased animals before incorporating with the main herd.

“Particular care should be given to purchased, in-calf females, as they may be carrying a BVD Persistently Infective (PI) calf. Calves born to such females should be tested for the BVD virus as soon as possible after birth.”

The next Clyde Monitor Farm meeting will be towards the end of May.


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