Mackinnon Project: Ewe nutrition a key to fertility

EWE nutrition at joining can have potentially the biggest single effect on ewe conception rates, research by the Mackinnon Project has found.

EWE nutrition at joining can have potentially the biggest single effect on ewe conception rates, recent research by the Mackinnon Project has found.

Elsa Glanville studied nutrition, protein flushing and pharmaceuticals Regulin and Ovastim to see which methods could improve reproductive performance.

Speaking at an Investment in Agriculture seminar, hosted by the Mackinnon Project, Dr Glanville said farmers needed to ask what was driving the desire to increase the flock’s reproductive performance.

“Is it profit or is there a problem to be fixed?” she said.

Dr Glanville said the threshold weight for joining ewes was usually regarded as about 75-80 per cent of the flock’s mature ewe weight.

Below the threshold weight ovulation could decrease, with it dropping further as the weight declines.

An analysis of data from mobs the Mackinnon Group has been involved with for the past two reproductive seasons was used to estimate the marginal return of investment in feeding maiden Merino ewes to reach the target weight.

Dr Glanville said the analysis found that feeding to gain weight to reach the threshold gave a return on investment, in the current economic climate of 98 per cent for the modelled mob.

“This suggests it can pay to weigh young ewes with enough time before joining that you can increase the weight of those below the critical threshold,” she said.

Dr Glanville said the weighing might be eight weeks before joining.

She said a second set of analyses, this time of mature ewes in a prime lamb system, showed the old adage of “it pays to feed to maintain, but not gain weight” was true.

She said the analysis showed it did not pay to feed ewes to gain weight above a target condition score of three.

“It highlights the importance of checking ewe condition and feed availability before joining,” Dr Glanville said