368 McLean et al. – SHEEP MEAT GENETICS - CPT

An evaluation of sheep meat genetics in New Zealand: The central progeny test (CPT)

N.J. MCLEAN1, N.B. JOPSON2, A.W. CAMPBELL1, K. KNOWLER1, M. BEHRENT3, G. CRUICKSHANK4, C.M. LOGAN5, P.D. MUIR6, T. WILSON1 AND J.C. MCEWAN1

1AgResearch, Invermay Agricultural Centre, Private Bag 50034, Mosgiel, New Zealand

ABSTRACT

The New Zealand Central Progeny Test (CPT) was first established in 2001 with the aims of improving the carcass dollar value of sires and establishing genetic links among sire referencing schemes. Over the past three seasons, a total of 72 sires from both terminal and dual purpose breeds have been evaluated for meat genetics at the AgResearch Woodlands farm and the Lincoln University Ashley Dene farm. All progeny, except the 2004 born ewe progeny from the dual purpose sires, were slaughtered at monthly intervals from December to March each year through two Alliance plants, at threshold liveweights of 34kg. Carcass measurements included cut yield (measured by ViaScan grading) eye muscle area, GR, meat pH, meat and fat colour and days to reach an 18kg carcass weight. These measurements were used to calculate three key indices; days to kill, meat value and a combined meat and growth index, as well as individual breeding values. Results showed significant variation among sires for all key traits and that no single ram or breed dominated the top of the indices or breeding values. The range of economic value was approximately $10 across the terminal and dual purpose sires evaluated, demonstrating that considerable potential exists to identify and select better terminal sires. The CPT is now commencing maternal evaluation, using the retained ewe lambs produced from the dual purpose sires.

Keywords: Ovis aries; progeny test; meat evaluation; breeding values.

INTRODUCTION Ltd. In 2004, the Meat Board also contributed and have been the majority investor since October National progeny testing schemes have 2005. Despite changes in investment, the overall become important components of national sheep aims of the CPT remain constant: to genetically genetic improvement programmes in Australia, improve lamb within New Zealand and to increase France, and New Zealand (Fogarty et al., 2005; the number of genetic linkages between various Bibé et al., 2002; Campbell et al., 2005). National breeds and strains of sheep in the New Zealand progeny test schemes provide four major benefits sheep industry. For the first three years, the CPT as follows: has targeted improvement of meat production and associated traits. A key facet of this work has been 1) Fostering genetic links across breeds the estimation of genetic parameters for carcass allowing national across breed evaluations cuts measured both by dissection and Viascan 2) Identification of leading sires (Campbell et al., 2005) and the creation of 3) Enabling the investigation of new and economic indices suitable for use in New Zealand. difficult to measure traits in an industry This paper presents the results in the form of setting indices and individual breeding values (BVs) from 4) Providing a central and easily demonstrated sires used in the first three years of the CPT. example of the benefits of genetic selection. MATERIALS AND METHODS The New Zealand national progeny test scheme, known as the Central Progeny Test (CPT), The first mating was carried out at was established in 2001. The CPT has undergone AgResearch’s Woodlands Research Farm (WDL) some changes since inception. For the first three in 2002, this was expanded in 2003 to include years the CPT was underwritten by Alliance Group animals at Lincoln University’s Ashley Dene

2Abacus Biotech Limited, PO Box 5585, Dunedin, New Zealand 3Alliance Group Limited, 51 Don St, Invercargill, New Zealand 4Sheep Improvement Limited, PO Box 12146, Ahuriri, Napier, New Zealand (current address Genequest Limited, RD 12, Havelock North, New Zealand) 5Lincoln University, PO Box 84, Lincoln University, New Zealand 6On-Farm Research Ltd, PO Box 1142, Hastings, New Zealand Proceedings of the New Zealand Society of Animal Production 2006, Vol 66 369

Pastoral Systems Research Farm (AD). Sires for with a heritability of 0.30), based on expected mating are selected by contacting various breeding success rates at each of the sites. Single bearing groups and breeding companies and asking them to ewes were run separately from multiple bearing nominate rams for either artificial insemination ewes prior to lambing. The smallest of the triplet (AI) or for natural mating. Final rams selected are lambs were mothered onto single bearing ewes at based on performance and linkage to industry. The WDL while at AD the triplets were all left on their rams used between 2002 and 2005 are listed in maternal dam. Ram lambs at WDL were made Table 1. The ewe flocks are made up of cryptorchids while the ram lambs at AD were kept predominately Coopworth ewes, with a small entire. Lambs were weaned and weighted at 12 – number of ¼ East Fresian x Coopworth ewes at 14 weeks of age in mid to early December. A WDL. In 2004 the ewe progeny produced from the sample of lambs (15/sire) had faecal egg counts dual purpose sires were retained to evaluate recorded after approximately 6-8 weeks from the maternal traits (data not yet available). last drench. All remaining lambs were weighed drafted for slaughter at monthly intervals with the Farm Management first draft at weaning. A target of at least 34kg All ewes were synchronised using CIDRs liveweight was set for each draft, with three to four (for both naturally mated and AI ewes). The ewes drafts per site per year. All remaining lambs after which were mated naturally were single sire mated the third draft go to the last slaughter. over a period of one week to ten days. Ewes were allocated to sires to obtain a minimum of 20 lambs per sire (accuracy of selection of 0.79 for a trait

TABLE 1: A list of the sires used in the CPT (Bold italics indicates link sires)

Terminal sires used in the CPT Dual purpose sires used in the CPT

Flock Breed Sites TAG Progeny Flock Breed Sites TAG Progeny Wharetoa Composite A03 T369/02 27 Raywell Borderdale A03 A04 97/02 50 Wharetoa Composite W02 W03 T533/01 56 Little River Cheviot A03 W03 11/01 60 Turnberry Composite W02 140/00 21 Kelso Composite W03 132/01 31 Darenal Dorset Down A03 767/99 13 Kelso Composite W02 435/98 31 Trackly Dorset Down W02 51/00 25 Edale Composite A03 138/01 35 Lincoln Dorset Down W04 78/02 30 Wharetoa Coopworth W03 531/98 27 Glendhu Dorset Down W03 120/00 33 Tahakita Coopworth W04 A04 85/00 75 Lincoln Dorset Down A03 26/00 29 Lincoln Coopworth A03 W03 A04 706/00 76 Douglas Downs Dorset Horn W02 W04 77/95 75 Blackdale Coopworth W03 211/99 27 Bilberry Oaks Hampshire W02 W03 4012/99 49 Valley Coopworth W04 313/01 36 Glenaven Hampshire W04 25/02 40 Strathblane Corriedale A03 107/97 14 Teviotdale Hampshire W02 1144/99 34 Wattle Bank Corriedale A04 422/00 25 Sheepac Oxford W03 X0050/87 27 Strathblane Corriedale A04 1235/00 30 Oringi Oxford Down A04 61/97 38 Rosedale Growbulk W03 2135/99 30 Ohio Poll Dorset A04 299/01 35 Newhaven Perendale W04 1035/02 32 Linton Poll Dorset W04 514/00 46 Mt Guardian Perendale W03 426/99 21 Ohio Poll Dorset W02 106/99 46 Hazeldale Perendale W03 493/00 23 Glengarry Poll Dorset A03 W03 35/01 38 Flockton Perendale A04 774/02 37 Kurralea Poll Dorset W02 211/98 28 Glen Rannoch Perendale A04 172/02 33 Ivadene Poll Dorset W02 154/99 27 Hillcrest Perendale W03 850/00 30 RBL Rissington Primera W04 33/02 27 TRIGG - Hiwinui Romney W03 232/01 21 Craig Annat South Suffolk W02 929/00 33 Shoreford Romney W03 781/00 29 Pahiwi South Suffolk W02 125/98 28 Awareka Romney W03 1127/95 19 Logan South Suffolk A03 226/00 29 Meadowslea Romney A03 5093/99 21 Tasvic Downs Southdown W02 41/00 46 View Hill Romney W03 458/01 29 Mapua Southdown A04 R77/02 52 Wairere Romney W02 W03 A04 2165/97 86 Charleston Southdown W02 c57/99 21 Awareka Romney W04 A04 1832/02 75 Punchbowl Suffolk W03 *128/97 38 Waihora Romney W04 5828/02 51 Punchbowl Suffolk W02 *419/96 12 Waihora Romney W04 4014/96 22 Tyanee Suffolk A04 25/99 41 ARDG Elite Romney W03 664/98 16 Torresdale Suffolk W02 165/00 30 Twin Farm TEFRom W03 34/01 30 Mornish Suffolk W02 u33/97 16 Waikite Texel W02 W03 299/00 59 Brandes Burton Texel W02 W04 400/00 63 Murray Downs Texel W03 911/99 31 The Burn Texel W02 xa2/99 23 Broken Hut Texel A03 21/01 30 MEBA Texel W04 167/02 51 Mt Linton Texel W03 5258/01 29 Mt Linton Texel Cross A04 2002/02 34 Mt Linton Texel Cross W02 2855/00 39

The sites column shows which site the ram was used at and which year, i.e. W02, W03 and W04 stands for Woodlands 2002, 2003 and 2004 respectively and A02, A03, A04 stands for Ashley Dene 2002, 2003 and 2004 respectively.

370 McLean et al. – SHEEP MEAT GENETICS - CPT

Slaughter procedure meat values were weighted at a ratio of 1:2:4. An There were three to four slaughters per economic value of $0.15/day was used for the days year at each site. Processing procedures and times to slaughter index. The combined meat and growth were kept the same for each slaughter. On the day index was weighted 1:1.22. of slaughter, GR measurements were collected along with carcass length, leg length, hot carcass RESULTS weight as well as yield grades (ViaScan and the Meat Board National Grading system). ViaScan From 2002-2005, three full cycles of was used to predict the weights of lean in the progeny evaluations have been completed. A total hindleg, loin and shoulder. The following day at of 72 sires and 1500 progeny have been evaluated 24hrs post slaughter, fat colour was measured and for meat and growth traits, comprising 41 terminal pH measurements taken on the longissimus dorsi sires and 31 dual purpose sires. These sires are muscle, (taken in the chiller prior to boning out). from 19 different breeds. The results from the In the boning room, eye muscle area (EMA) and three years of evaluation and the two sites can be eye muscle colour (after allowing the cut surface to directly compared because two link sires have been bloom for 30min) were measured. All colour used across sites and years (link sires are measurements were taken using a Minolta highlighted in italics in Table 1). Results from the Chromometer, measuring the variables L*, a* and CPT are presented as indices (days to kill index, b*. meat value index and overall net value index) and individual BVs (eye muscle area (EMA), dressing Data analysis percent (DP%), meat colour, meat pH and Analysis of data was carried out as in wormFEC) (Tables 2 and 3). There were Campbell et al. (2005). The main points are as significant differences amongst sires for all traits follows: variance components were estimated from measured (Tables 2 and 3). The meat and growth the CPT data using a mixed model in ASReml. index for the terminal sires ranged from $66.14 - Multivariate “empirical” BLUP breeding values $76.13, giving an approximately $5.00 difference (BVs) were derived using a sire model in in progeny returns per sire. The dual purpose sires ASREML. The direct genetic effects were fitted as ranged from $60.48 - $70.72 for the meat and a random effect in all models. Breed was not fitted growth index, also giving an approximately $5.00 in any model as there were insufficient sires in each progeny return in sire difference between the top breed to be considered representative. For the meat and bottom ranked sires. value index, the ViaScan shoulder, hindleg and loin

TABLE 2: The top 15 dual purpose rams for meat and growth EMA Meat & Meat Days to BV Meat Colour Dressing WormFEC TAG Flock Breed Sites Growth ($) Rank Value ($) Rank kill ($) Rank (cm2) BV (a*) pH BV % BV BV 232/01 TRIGG - Hiwinui Romney W03 70.74 1 68.62 19 2.12 1 10.42 20.46 5.58 44 11.75 781/00 Shoreford Romney W03 70.12 2 70.60 3 -0.48 9 11.85 21.07 5.59 43 23.35 1127/95 Awareka Romney W03 69.80 3 69.55 13 0.26 3 12.58 21.24 5.56 44 -39.83 132/01 Kelso Composite W03 69.80 4 70.86 2 -1.06 13 11.37 19.44 5.60 47 -22.85 34/01 Twin Farm TEFRom W03 69.52 5 70.93 1 -1.42 16 10.82 19.77 5.60 45 6.11 97/02 Raywell Borderdale A03 A04 69.32 6 69.76 10 -0.44 8 10.77 20.47 5.60 44 3.13 1035/02 Newhaven Perendale W04 69.26 7 69.74 11 -0.48 10 10.66 20.82 5.63 46 -23.52 531/98 Wharetoa Coopworth W03 69.23 8 69.51 14 -0.28 7 11.52 20.62 5.59 44 80.54 107/97 Strathblane Corriedale A03 69.15 9 70.01 9 -0.87 12 12.55 21.08 5.56 43 9.98 5093/99 Meadowslea Romney A03 69.10 10 68.58 20 0.53 2 10.25 19.92 5.64 44 -21.19 435/98 Kelso Composite W02 68.95 11 70.49 6 -1.54 17 12.19 19.72 5.62 45 -17.88 138/01 Edale Composite A03 68.73 12 70.45 7 -1.72 20 13.08 19.02 5.57 46 55.4 85/00 Tahakita Coopworth W04 A04 68.42 13 70.24 8 -1.82 21 12.18 20.31 5.64 45 16.25 11/01 Little River Cheviot A03 W03 68.35 14 70.49 5 -2.14 26 12.01 20.31 5.65 46 -2.17 706/00 Lincoln Coopworth A03 W03 A04 68.20 15 69.31 15 -1.11 15 11.32 19.30 5.66 45 -11.74

Note; The sites column shows which site the ram was used at and which year, i.e. W02, W03 and W04 stands for Woodlands 2002, 2003 and 2004 respectively and A02, A03, A04 stands for Ashley Dene 2002, 2003 and 2004 respectively; WormFEC – worm faecal egg count, with negative values being more desirable; lower pH values and high colour values are more desirable. Ranges for Meat & Growth $60.48 to $70.74, Meat Value $66.86 to $70.94, Days to kill $66.86 to $70.94, EMA 9.64 to 13.08, Meat colour (a*) 19.0 to 21.5, pH 5.68 to 5.52, Dressing % 42.6 to 46.8 and WormFEC 80.5 to -42.0.

Proceedings of the New Zealand Society of Animal Production 2006, Vol 66 371

DISCUSSION production and maternal performance, or if there are some rams which perform well for both carcass There is significant variation among the traits and maternal traits. sires assessed in the CPT for all indices and BVs. The CPT has moved into a maternal The CPT demonstrates there is a definite economic evaluation phase. Thus far, 276 dual purpose ewe advantage in using some sires over others (Table 2 lambs were retained in 2004 and hogget mated in and 3) under a carcass cut evaluation system. April 2005. Maternal measurements relating to However, no one, breed or sire dominated across reproduction and lamb survival are being collected, all of the traits or indices. This shows it is as well as date of first oestrus, faecal egg count and important for commercial farmers to assess their gestation length. All terminal sire progeny and own farming situation before selecting a ram. For dual purpose male progeny will continue to be example, if a farmer was farming a drought prone involved in the carcass meat evaluation as part of area where it was important to get as many lambs the same project. off the farm prior to the Christmas period, they The CPT has generated considerable would need to balance their requirements for good industry interest and as a result more sire reference carcasses and good growth rate carefully. It may groups have been formed within breeds to take be that they select a ram which is not at the top in advantages of the genetic linkages provided. The either index, but is above average in both. formation of the Advanced Central Evaluation Both terminal and dual purpose rams have (ACE) (www.silace.co.nz), a national across flock been assessed for carcass traits (Tables 2 and 3 breeding analysis, has also been enabled because of respectively). The indices can be compared the increased across breed and national linkages directly because they are evaluated together and created from the CPT. The ACE involves 275 presented on the same basis. There are dual flocks and records from two million sheep and is a purpose rams that perform well for carcass traits. major initiative in the advancement of New For example, the top ranked ram for meat value in Zealand sheep genetics. the dual purpose rams is 34/01, a Twin Farm The CPT will continue to be an important TEFRom. TEFRom is a composite breed made up national project contributing to increased linkages of Texel, East Friesian and Romney. This ram has in ACE, showcasing top genetic performers in the the same meat value as the 33/02 Rissington New Zealand sheep industry and as such, providing Breedline Primera, ranked 17th for meat value in targets for genetic improvement across the the terminal sires. When we have information from industry. the maternal evaluations it will be of interest to establish if there is a trade off between meat

TABLE 3: The top 15 terminal rams for meat and growth

EMA Meat & Meat Days to BV Meat Colour Dressing WormFec TAG Flock Breed Sites Growth ($) Rank Value ($) Rank kill ($) Rank (cm2) BV (a*) pH BV % BV BV *128/97 Punchbowl Suffolk W03 76.14 1 71.98 9 4.16 1 13.27 18.50 5.68 45 13.94 299/00 Waikite Texel W02 W03 76.05 2 75.12 1 0.94 20 15.54 19.87 5.60 47 -30.78 400/00 Brandes Burton Texel W02 W04 75.38 3 73.46 3 1.93 10 13.10 20.25 5.63 46 6.72 911/99 Murray Downs Texel W03 75.25 4 73.34 4 1.92 12 12.87 19.42 5.62 47 -5.63 33/02 RBL Rissington Primera W04 73.69 5 70.93 17 2.76 6 13.72 20.20 5.58 45 -1.81 xa2/99 The Burn Texel W02 73.61 6 73.67 2 -0.06 30 13.53 19.57 5.60 47 -21.13 299/01 Ohio Poll Dorset A04 73.47 7 73.21 5 0.26 27 15.06 19.94 5.59 46 48.83 X0050/87Sheepac Oxford W03 73.34 8 70.18 24 3.16 3 11.53 18.43 5.63 44 -19.73 77/95 Douglas Downs Dorset Horn W02 W04 73.32 9 71.99 8 1.33 17 13.57 18.95 5.57 45 -0.17 4012/99 Bilberry Oaks Hampshire W02 W03 73.02 10 70.00 26 3.02 4 11.39 18.16 5.59 45 77.64 T369/02 Wharetoa Composite A03 72.95 11 72.28 7 0.67 22 12.44 20.98 5.56 46 0.46 T533/01 Wharetoa Composite W02 W03 72.82 12 71.25 14 1.56 16 13.47 19.99 5.56 46 -10.17 514/00 Linton Poll Dorset W04 72.78 13 69.62 28 3.16 2 11.80 19.12 5.64 45 22.73 106/99 Ohio Poll Dorset W02 72.65 14 71.44 11 1.21 19 14.11 19.72 5.56 45 -13.5 21/01 Broken Hut Texel A03 72.56 15 72.41 6 0.15 28 13.77 20.44 5.56 45 7.11

Note; The sites column shows which site the ram was used at and which year, i.e. W02, W03 and W04 stands for Woodlands 2002, 2003 and 2004 respectively and A02, A03, A04 stands for Ashley Dene 2002, 2003 and 2004 respectively; WormFEC – Worm Faecal Egg Count, with negative values being more desirable; lower pH values and high colour values are more desirable. Ranges for Meat & Growth$66.14 to $76.13, Meat Value $66.96 to $75.18, Days to kill -$2.73 to $4.16, EMA 10.78 to 15.54, Meat colour (a*) 18.0 to 21.0, pH 5.73 to 5.55, Dressing % 43.6 to 47.9 and WormFEC 77.6 to -36.0.

372 McLean et al. – SHEEP MEAT GENETICS - CPT

SUMMARY many breeders who have made their rams available for the CPT. Without them the work would not The CPT is an important national progeny have been possible. testing scheme which is vital for the genetic REFERENCES improvement of New Zealand lamb. Within the New Zealand meat industry, meat companies are Bibé, B.; Brunel, J.C.; Bourdillon, Y.; Laradoux, D.; currently assessing yield based payment systems. Gordy, M.H.; Weisbecker, J.L.; Bouix, J. 2002: The CPT provides information which will enable Genetic parameters of growth and carcass quality of lambs at the French progeny-test breeders and commercial farmers to take full th advantage of these payment systems. Prior to the station Berrytest. Proceedings of the 7 World Congress on Genetics Applied to Livestock advent of the CPT, linkages between dispersed Production 31: 335-338 flocks in NZ were limited and mostly between Campbell, A.W.; Jopson, N.B.; McLean, N.J.; Knowler, breed. The CPT has enabled sire referencing .K; Behrent, M.; Wilson, T.; Cruickshank, G.; groups and sires to become better linked Logan, C. M.; Muir, P. D.; McEwan, J. C. genetically. This has allowed a national across 2005: The Alliance Central Progeny Test breed analysis to be undertaken. (CPT): an evaluation of sheep meat genetics in New Zealand. Proceedings of the 16th ACKNOWLEDGEMENTS conference for the Association for the Advancement of Animal Breeding and Genetics This work has been funded by the Alliance 16: 9-11 Fogarty, N.M.; Ingham, V.M.; Gilmour, A.R.; Group Ltd. In October 2005 Meat board took over Cummins, L.J.; Gaunt, G.M.; Stafford, J.; the funding for this project and are investing in it Edwards, J.E.H.; Banks, R.G. 2005: Genetic for the next three years. The authors would like to evaluation of crossbred lamb production. 1. thank G. Greer, S. Duncan, A. Pont, R. Wheeler, Breed and fixed effects for birth and weaning L. Hewitson, M. Colling, N. Wood, G. Anderson, weight of first-cross lambs, gestation length, J. Dunett, N. Jay and the late N.Lake for technical and reproduction of base ewes. Australian assistance. We also particularly want to thank the Journal of Agricultural Research, 56; 443-444.