TRIGG PROGENY TEST 2005/06

Dr Patricia Johnson and Clem Barton, Institute of Veterinary, Animal and Biomedical Sciences, Massey University

Introduction

Results and discussion of the 2005/2006 TRIGG progeny test. The lambs averaged 40.6kg at the time they were slaughtered.

In the following tables each trait has been adjusted to the same age, sex, birth rank, rearing rank and kill group to obtain adjusted means.  The average of each flock-adjusted mean was then subtracted from that of individual sires to obtain a deviation which was then multiplied by a weighting factor (b), to get the BV for each trait.

Table One: Ranking of TRIGG Sires 2005/2006 for Weaning Weight BV.

The range for weaning weight BV was 7.35kg.

The best sire (671) had a BV nearly 1kg greater than the next best sire (543).

Table Two: Ranking of TRIGG Sires 2005/2006 for Carcass Weight BV (kg)

The range in carcass weight BV was 3.43kg.

The carcass weight BV gives an indication of the growth of the lambs, and also includes dressing out percentage.  The top two sires for carcass weight BV are the same as those for the weaning weight BV.  However, the sire ranked 3rd for weaning weight BV (16) ranks considerably lower for carcass weight, this is due to it having a very poor dressing out percentage BV (see Table 5)

Table Three: Ranking of TRIGG Sires 2005/2006 for Carcass Value BV ($) (not adjusted for carcass weight)

Carcass value has been estimated based on the equation developed by Johnson et al. in 2002.  The weighting factors for the three cuts were rescaled in 2004/2005, to reflect prices at that time, however, they have not been rescaled for this year, which means that the overall values estimated here are likely to be an overestimate of their 2006 value with the lower prices being experienced this year.  However, this is only a relative scaling and sire rankings remain the same. This BV includes the effect of carcass weight, so sires with heavier progeny will be advantaged.  Sire 671 is again the top ranking sire.  Sire 263 has overtaken 543 which suggests that it has a better cut distribution.   Sire 16 jumps from 13th for CWBV to 5th for CVBV suggesting that its progeny have improved cut distribution relative to some other sires.  There is a $19 difference in CVBV between the top and bottom sires which is consistent with previous years progeny tests.

Table Four: Ranking of TRIGG Sires 2005/2006 for Carcass Value BV ($) (adjusted for carcass weight)

Adjusting the carcass value to a constant carcass weight allows the identification of sires which produce lambs with a better distribution of muscle in the more valuable cuts.  The range in BVs is now reduced to about $8.50.  Sire 671 continues to be the leading sire, which suggests that in addition to producing fast growing progeny, he is also producing progeny whose carcasses have improved cut distribution.  Sire 445 was below average carcass weight (ranked 7th), however, at the same carcass weight he has better cut distribution than most of the other sires.

Table Five: Ranking of TRIGG Sires 2005/2006 for Dressing out Percentage BV (%)

This is the first year that dressing out percentage has been analysed.  The BV for DO% explains why sire 15 dropped from 3rd for weaning weight BV to 13th for CWBV.  As can be seen in table six, sire 16 has the second to lowest BV for DO% BV.  There is a 3.6% range in DO% BV.

Overall Discussion:

Sire 671 was the top in all the analyses, except for dressing out percentage where it ranked 6th.

Sire 543 showed good growth and carcass weight.  However, he had a poorer cut distribution than other sires and so he was poorer for carcass value, when adjusted for carcass weight.

Sire 17 was 3rd for weaning weight, however, he had a very poor dressing out percentage breeding value, which resulted in poor carcass weight and unadjusted carcass value BVs. It did, however, show good cut distribution when carcass value was adjusted for carcass weight.

Finally, a reminder that best sires for the current carcass payment systems in New Zealand would be found at the top of table four, which lists the BVs for unadjusted carcass value.  However, TRIGG is committed to breeding better rams for 5 to 10 years into the future, when it is likely that farmers will be being paid on the basis of individual carcass cuts.  As a consequence, any sires to receive wide use amongst TRIGG flocks should be chosen from table five.  Fortunately, the top ram (671) for this year is the best ram in both tables, but care needs to be taken when choosing the next best sires.