Pregnancy event may affect next generations

Massey University’s professor of animal science Hugh Blair is part of a team that launched a long-term trial in the past year researching the effects of nutrition during pregnancy.

01-06-2006 | Amy Bielski

Under nutrition during pregnancy could have greater consequences on future production than currently thought, a trial is seeking to confirm.

Massey University is following up on research related to humans that could have far reaching implications for sheep, beef and deer production.

It is well known that there is a birth and weaning weight effect on lambs from ewes that have been undernourished during pregnancy, but in humans it has been shown to also affect health later in life and in future generations.

Following the Second World War a professor found that events during pregnancy impacted on children up to 50 years later.

Pregnant women who had restricted food intake were found to have lighter birthweight babies and when checked up on years later the same was said for their children’s children.

From an agricultural perspective there was another piece of supporting information for this theory done by Massey PhD student Katrina Jenkinson. Her work showed mammary development in ewe lambs was not as comprehensive if the mother was undernourished during pregnancy.

To further investigate the influence of nutrition during pregnancy on future generations, funding has been secured from two streams; Meat & Wool New Zealand from the agricultural perspective and the National Centre for Research and Development for the human aspect.

“From a sheep, cattle and deer production perspective this has implications because typically ewes have been put under pressure at certain times of the year.

“But more importantly for female replacements because the connection could be affecting the life time performance of the flock.

“But at this point there are not any on-farm data to support this, there are no records to show if those born from a rough pregnancy are gone from the flock earlier than those ewes that have an easier pregnancy. We are assuming this would happen because farmers typically cull the lighter ewes,” says project leader Hugh Blair.

Blair believes they are now at a point where sufficient literature supports the transgenerational, meaning across generations, effects of an event during pregnancy. He is setting out to measure the size of the effects in sheep, under contract to Meat &Wool New Zealand.

The other key point in the research is foetal programming, the idea that a foetus is programmed during pregnancy for later in life.

To this end a trial was set up on Massey’s Riverside farm in 2005, 800 of 3000 mixed-age Romney-cross ewes were selected.

Of the 800 ewes, 400 were heavy and 400 were light. This added another aspect to the trial testing for ewe efficiency.

The 800 ewes were synchronised and then artificially inseminated to Suffolk rams.

At 21 days of pregnancy the ewes were cut into two groups, ad lib feeding and restricted. The restricted group grazed pasture less than 2cm long for the remainder of pregnancy to maintain their bodyweight, although it did increase with the weight of the foetus and placental tissues. In May, the pregnant ewes were moved to Massey’s Keeble farm.

The ewes lambed at the end of August 2005 and the difference between the heavy and light ewes was about 18kg (consistently from mating through until weaning).

The difference in ewe bodyweight between those fed ad lib and undernourished was 14kg.

The impact of this on lamb birthweight was minimal when comparing the heavy and light ewes. But by undernourishing ewes during pregnancy the lamb birthweights were 200g lighter than the ad lib fed ewes, which is significant especially from a lamb survival perspective.

The male progeny were slaughtered at the end of March. Ram lambsfrom the light ewes had carcase–weights about one and a half kg lighter than those from heavier ewes and those from undernourished ewes were about half a kg lighter than rams from ewes fed ad lib during pregnancy.

Farm system modelling is also to be completed to highlight the wider system effects of lighter weaning weights, perhaps a higher stocking rate.

Currently oestrus in the ewe lamb progeny is being monitored and they will be mated in 2007. Their progeny’s lamb birthweight and growth rate and the ewe’s milk production will be related back to their grandmother’s pregnancy.

The trial is to continue for at least another two years to identify any carry over effect in future generations from the mother’s pregnancy treatment.

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