2011-2012 LambPlan EBV Analysis

Good record keeping is essential to keeping track of animal production & performance.  Weighing and measuring animal are absolutes. They give us a quantitative description that is more accurate than a visual description. The terms “good mothering”, “fast-growing” are subjective, and may not tell the whole story.  Measured weights can be taken a step further and analyzed as an EBV, Estimated Breeding Value.  What are EBV’s ?  A computer program takes the weights and considers both parental influence and common relatives to demonstrate performance deviation (in weight) from the flock average.  Only similarly managed animals are compared called contemporary groups.  This minimizes bias to environmental influences.  Because related animals like brothers, sisters, aunts, uncles are considered by the computer program, the data is a more accurate tool.  One star ewe in a flock may hinder your production goals if her relatives are weak.  The star ewe’s overall superior genetic potential would be poor.   This is why it is difficult to just take individual raw weight data, calculate your own averages and determine performance with accuracy.  We should always remember though, that EBV’s are just another tool to aid in improving production in a herd and should NOT be exclusive to other traits that are not measured by a computer program.

WLF 016X (yearling mom) and newborn, unassisted, in the expanse of the yearling lambing yard

2011 is our first year of enrollment in the NSIP (National Sheep Imrovement Program).  All our data is run through LambPlan in Autralia.  We are attempting to simulate part of what Iceland does in testing their rams.  Because sample size is so crucial you will see accuracy ratings under the Carcase Plus category.  Any data with accuracy less than 75% could be argued.  The more data we submit in the future, the more accurate the data on related animals will be.  So come along with us and see what can be derived from all those weights we take throughout the year! Remember, too: This is In-Farm analysis for us to help cull inferior performance. Our animals are only compared to themselves within our mangament sytem and not to other farms…yet.

EBV Descriptions

The Maternal Weaning Weight (MWWT) EBV (kg) (not pounds!) estimates genetic merit for mothering ability. (since we are new, there is very limited MWWT data because some rams do not have daughters in production yet) This EBV mainly reflects genetic differences in ewe milk production, but other aspects of maternal behavior may also be involved (good mothering, internal parasite stress minimal). The Maternal Weaning Weight EBV is derived by evaluating if individual ewes produce lambs that are heavier or lighter than expected based on the weaning weight EBVs of the parents (hence why we have limited data here). Ewes whose lambs grow faster than predicted are assumed to be better milk producers, whereas ewes whose lambs grow more slowly than predicted are assumed to produce less milk. Selection for high maternal milk EBVs is expected to improve milk production and mothering ability and considered to be important for maternal breeds.

Unregistered purebred ewe 302 with 60 day old twins

The Weaning Weight (WWT) EBV (kg) provides an estimate of preweaning growth potential and will likely receive positive selection emphasis in most flocks. (parasite stress could be seen here) In extensively managed flocks with weaning at 90 to 150 days, the Weaning Weight EBV is commonly estimated from preweaning weights taken at 45 to 90 days of age. In such flocks, the true weaning weight is recorded as an early postweaning weight, with genetic differences reflected in the Postweaning Weight EBV.

The Postweaning Weight (PWWT) EBV (kg) combines information on preweaning and postweaning growth to predict genetic merit for postweaning weight at 120 days. Up to two postweaning weights can be recorded: an “early” postweaning weight at 90 to 150 days and a “late” postweaning weight at 150 to 305 days. Either or both can be recorded. These two postweaning weights are assumed to have a genetic correlation of 1.0 and contribute equally to the final Postweaning Weight EBV. In extensively managed flocks with weaning at 90 to 150 days, the weaning weight is commonly recorded as an early postweaning weight, and the Postweaning Weight EBV predicts genetic differences in body weight at typical weaning ages. Positive selection on Postweaning Weight EBV is expected to favor rapid growth to typical market ages.

Adult & 2year old ewes for 2012

Replacement Ewelambs for 2012

Breeder ram lambs used for 2012 Lamb Crop