Recording replacements

[Joe]

I started recording my replacement ewe lambs this year, previous two years I'd colour tagged according to single, twin, and triplet. Last year I picked bunch of my perceived (start somewhere) best Mayo Mules and let them our with Lleyn rams. All lambs were EID tagged at birth including male lambs and all were recorded for ease of lambing, number of lambs, survival to 8 weeks, 8 week weight and weaning weight. My calcs for a homemade simple EBV was then worked out weightings as 25%, 10%, 25%, 25% & 15% for above categories.
Bit surprised with the results when calculated, starting with an EBV average of 100 have ewe lambs ranging from 35 to 150 on my scale majority are in 60 to 105 range though. Question is are my weightings and categories fair or slightly unbalanced and need to be adjusted? I would think the final numbers are irrelevant in difference as giving the best lambs and showing improvement is the aim??

slightly different note had a farm walk yesterday and gave my dwg figure for the above Lleyns at 280gms, others were surprised and said it would excellent for a terminal sired lamb. I would have thought 280gms would be ok for Lleyn cross mules but not for terminal sired lambs as they said?

 

[Woolless]

Interesting project, Joe.

As far as the balance of your index goes, I would be tempted to bump up the weighting for weaning weight. Global Ovine will tell you that days to slaughter decides 46% of the profit in a fat lamb enterprise. You just need to be careful that you're selecting the fastest growing/most efficent rather than just what will be the biggest sheep.

 

[Sandpit Farm]

Having weighed my lambs at 8wks, 10wks and 16-18wks, I have noticed a big difference in DWG for all these weigh dates. 280g compares well with what I've seen, though I would say it were on the low side if talking about a terminal X but I guess much depends on grazing quality etc. I think it is more useful to compare between sheep within a flock rather than between flocks.

As @Woolless says, I think that aiming for a good 8wk weight would be an excellent maternal indicator and leaves the lamb will little work to do to grow but I wonder if it would be better to look at Kgs of lamb weaned as that will give an input for no. lambs weaned too!! 2 slightly lighter lambs at weaning is better than one bloater.

 

[Sandpit Farm]

Sorry I missed 'number of lambs'. Ignore my post above.

 

[Joe]

Interesting project, Joe.

As far as the balance of your index goes, I would be tempted to bump up the weighting for weaning weight. Global Ovine will tell you that days to slaughter decides 46% of the profit in a fat lamb enterprise. You just need to be careful that you're selecting the fastest growing/most efficent rather than just what will be the biggest sheep.

Good point, I might be slightly high on ease of lambing and under on weaning weight....

 

[neilo]

Good point, I might be slightly high on ease of lambing and under on weaning weight....

If you just discount any that need assistance at lambing from being retained, you don't need to weight that trait at all. Obviously they'd have to be a long way down that road already to do that though, or you wouldn't have many to select from.

 

[neilo]

Having weighed my lambs at 8wks, 10wks and 16-18wks, I have noticed a big difference in DWG for all these weigh dates. 280g compares well with what I've seen, though I would say it were on the low side if talking about a terminal X but I guess much depends on grazing quality etc. I think it is more useful to compare between sheep within a flock rather than between flocks.

Absolutely right. One farm's nutrition/pasture quality, and the way that is managed, along with the parasite management, will be very different to another's. That's why we use Signet to do a BLUP run and produce ebvs. A lamb that is reared on very well fed ewes on fresh reseeds, who has access to the very best creep feed, wormed every 3 weeks and never receives a cocci challenge will grow faster than one that has been reared in a more challenging environment, but it isn't necessarily any better genetically (although it may well be, of course) even if it's growth rate is double.