Thursday, 16 November 2017 14:55

Quest to compare bulls with AI

Written by  Sudesh Kissun
Farm manager Ian Fraser says using all bulls for mating cows is going well. Farm manager Ian Fraser says using all bulls for mating cows is going well.

Reporoa farm manager Ian Fraser is using all bulls to get his cows into calf this season.

With a herd of 373 milking cows, Fraser says farm owner Matt Pepper is keen to see if using all bulls instead of artificial insemination (AI) is more profitable.

The farm has chosen 21 Hereford bulls -- 18 of them divided into teams of three. The first two teams were set loose among cows on October 9. One team is rested while the other two teams ‘work’.

A Smaller Milk and Supply Herds (SMASH) field day was held on the farm on October 31; about 50 farmers were on hand to find out how the first season with all bulls was going at the farm.

With the bulls out for nearly three weeks, Fraser says “on the whole things were going on very well”.

He says the bulls are colour coded to differentiate each team member. With the bulls having to walk around the paddock, lameness can be an issue but Fraser says any bulls showing early signs of lameness were taken out.

“One young bull had a badly damaged toe but it came right,” he says.

No cows have been tail painted to indicate which are on heat. Fraser says the plan is to “keep doing what we are doing”.

“We won’t know the results until we do the pregnancy tests later,” he says. Mating will continue on the farm until December 20. Fraser says using bulls for mating is much easier than AI; the bulls took 10 days to train.

“They have trained well and go towards the paddocks without much coaxing; all we are required to do is take the bulls out and keep them healthy.”

Working with young Hereford bulls has been easy, he says. “They are good bulls, really passive and a joy to work with.”

Having the extra bulls hasn’t put pressure on feed supply on the farm. PKE, winter crops and swedes have helped feed the animals.

Vets from Vetora were also on hand to talk about good bull management. They told farmers it is essential to get bulls onfarm at least two months before the start of mating and to have enough bulls so they could be split into teams.

Ideally a farm should have one bull for every 30 non-pregnant cows. However, when using yearling bulls with heifers, one bull per 15 - 20 cows is ideal. The vets say yearling bulls produce 25 - 50% of the semen of two-year-old bulls.

It’s essential to rotate bulls, allowing them time to eat, drink and rest; a bull can only serve two cows a day.

Keeping an eye out for lame or sick bulls is crucial. A bull with a high fever should be removed from the team for at least 60 days. It takes about 60 days for a bull’s sperm to reach optimum level. “If a bull’s temperature is raised by 1 - 2 degrees C, the sperm produced is compromised,” the vets say. “It takes on average two months for this compromised sperm to be replaced by healthy sperm.”

Working with bulls on-farm

- Manage bulls as though they are professionals

- Ensure two or more bulls are in the herd at all times

- Rotate and rest bulls

- Monitor bulls for lameness or sickness

- Observe bulls to ensure they are mounting and serving correctly; remove a bull if he is unable to serve correctly and replace

- Avoid feeding bulls entering yards

- Feed bulls well.


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