Abstract:
Proc. Assoc. Advmt. Anim. Breed. Genet. Vol13 BENCHMARKING MATERNAL GENETICS IN THE LAMB INDUSTRY N. M. Fogarty', L. Cummins', J. Stafford3, G. Gaunt4 and R. Banks' `NSW Agriculture, Agricultural Institute, Orange, NSW 2800 *Agriculture Victoria, Pastoral & Veterinary Institute, Hamilton, Vic. 3300 3 PIRSA, Struan Research Centre, Naracoorte, SA 527 1 4Agriculture Victoria, Rutherglen, Vic. 3685 `LAMBPLAN, Department of Animal Science, University of New England, A&dale, NSW 235 1 SUMMARY The design and early results from the national central progeny test for maternal sires in the lamb industry are presented. Sires are mated to Merino ewes at 3 linked sites (Cowra, Hamilton and Struan/ Rutherglen) to produce >25 1stX ewe progeny. IstX wethers are slaughtered at heavy carcass weights and 1stX ewes are mated to terminal sires over 3 years. Sire EBVs for 1stX meat traits from the first 21 sires tested in 1997 showed large variation for weight (+4.1 to -7.5 kg), fat (-6.9 to +6.0 mm GR) and muscle (+I .8 to -1.0 cm2 eye muscle area). 1stX daughters of the 12 sires tested at Cowra in 1997 were mated to Poll Dorset rams at 7 months of age. The sire mean daughter performance varied from 4.6*3.2 to 32.9+3.7 kg for total weight of lamb weaned per ewe joined (P<O.Ol). Sires varied and rankings changed for the components, ewes lambing, litter size, lamb survival and weaning weight. These preliminary results show the large impact of maternal sire selection on lamb productivity. Keywords: EBVs, meat, lamb production, LAMBPLAN INTRODUCTION Central progeny tests have demonstrated a great range in performance of lambs from different terminal sires (Banks et at. 1995). The industry is benefiting from using LAMBPLAN (Banks and Kinghom 1997) and producers are paying more for high merit terminal sires (Ferguson and Fogarty 1997). Use of superior maternal genetics has the potential for even greater increases in lamb productivity and profitability. The maternal sire central progeny test (MCPT), provides genetic information to assist seedstock breeders and lamb producers to identify the best maternal genes that suit their production system. MCPT also encourages greater use of LAMBPLAN by the maternal sector of the industry. Progeny testing is a powerful tool identify superior sires demonstrate variation benchmark sires with l l l to: for breeding between sires for all traits affecting profitability others in the industry counts: their ability to produce crossbred lambs and and profitable for the producer. This paper outlines and carcass performance from crossbred wether daughters mated at 7 months of age. MCPT tests the merit of maternal sires where it ewes with superior productivity that are efficient the design of the MCPT and presents growth progeny and lambing performance from crossbred 78 hoc. Assoc. Advmt. Anim. Breed. Genet. Vol13 MATERIALS AND METHODS MCPT design. Top maternal sires are nominated by industry breeders and mated to Merino (and Corriedale at Hamilton) ewes to test the lamb performance of their crossbred progeny. Lamb production (lambing rate, 2ndX lamb growth and carcass) and wool production (fleece weight and fibre diameter) from the IstX ewe daughters of the maternal sires are measured, as well growth and carcass performance of their IstX wether progeny. The 1stX ewes are retained for mating to terminal sires over 3 years to assess lambing performance and other traits in a range of production systems. Matings of maternal sires are at 3 sites over 3 years (Cowra and Hamilton, Feb/Mar 1997-1999; Struan, Jan 1998-2000) and will involve progeny testing a total of about 90 sires. Link sires allow combined best linear unbiased prediction (BLUP) analysis across sites and years. The matings aim to produce >25 1stX ewes per sire. 1stX ewes produced at Struan will be evaluated at Rutherglen. The production systems for evaluation of the 1stX ewes are as follows: Cowra - ewes split to autumn and spring joining systems, with first joining occurring at 7 and 14 months of age respectively; Hamilton - ewes joined in autumn, with first joining occurring at 7 months of age; Rutherglen - ewes joined in spring/summer, with first joining occurring at 17 months of age. Management. In March 1997, 21 sires (including 3 links) were mated at Cowra and Hamilton using thawed frozen semen and laparoscopic Al. The sires were from the range of maternal sire breeds now available to the sheepmeat industry (Table I). The 1stX progeny were weaned at about 12 weeks of age and weighed postweaning at about 7 months. IstX wethers at each site were randomly allocated within sire to 2 slaughters at average carcass weights of 21 kg and 24 kg. Hot carcass weight, fat depth (GR and C sites), eye muscle depth, width and area (depth x width x 0.8) at the 12'' rib were recorded. The Cowra IstX ewe progeny were randomly allocated within sire to autumn and spring mating groups. The autumn group was mated to Poll Dorset rams for 6 weeks from mid-February 1998. Their 2ndX progeny were weaned at approximately 12 weeks of age in November 1998. Statistical analysis. Sire estimated breeding values (EBVs) arc based on IstX progeny performance using BLUP procedures in BVEST (Gilmour and Banks 1992) modified from LAMBPLAN. EBVs for weight (postweaning) used birth, weaning and postweaning weights of ewes and wethers and carcass weight of wethers, with adjustment for age and type of birth and rearing. EBVs for fat (carcass CR) used carcass fat depth at the CR and C sites, adjusted for carcass weight. EBVs for eye muscle area used carcass measurements for area (depth x width x O.OOS),adjusted for carcass weight. RESULTS AND DISCUSSION EBVs for weight, fat and muscle for the 2 1 sires tested at Cowra and Hamilton in 1997 (Table I) are based on 1,570 ewe and wether progeny with postweaning records and 8 1I wethers slaughtered with carcass records. The range in EBVs amongst the sires was 11.5 kg for weight, 12.9 mm GR for fat and 3.8 cm' for eye muscle area. The ranges for weight and fat in particular are considerable and provide great scope for selection in maternal sheep breeds. The variation in fat EBVs is more than twice that found in terminal sire progeny tests (Banks rt ol. 1995). This is probably because terminal sire breeders have put more emphasis on leanness in their breeding programs for several years. 79 Proc. Assoc. Advmt. Anim. Breed. Genet. Vol I3 Table 1. EBVs for weight, fat and muscle for 21 sires tested in 1997 Sire codeA BLl BL2 Fi3 04 cp5* EF6 Fi7* BL8 Fi9 WSlO Crl 1 BL12* BL13 Ro14 BLl5 Cp16 Fi17 Cp18 EF19 Cr20 Fi2 1 Booroola Leicester Border Leicester Finnsheep Corriedale Coopworth East Friesian Finnsheep Border Leicester Finnsheep White Suffolk Corriedale Border Leicester Border Leicester Romney Booroola Leicester Coopworth Finnsheep Coopworth East Friesian Corriedale Finnsheep Breed Stud Tag 922047 950137 940001 940364 940449 940B2 930057 950181 935010 910058 930097 943291 950246 930146 924287 930069 950054 92042 940B26 880491 960002 Weight (kg) Fat GR Ema (cm*) -0.63 -0.28 0.02 1.74 0.07 0.49 -0.30 -0.99 -0.74 1.78 -0.14 -0.25 -0.39 -0.26 0.3 1 0.89 0.28 0.26 -0.99 -0.13 -0.73 Struan Johnos Yamba Maluka Oaklea Silverstream Warrayure Inverbrackie Warrayure Leachim Coora Kelso lnverbrackie Claymour Struan Narrambla Gippfinn Oaklea Silverstream Stanbury UNSW (mm) 3.89 -0.92 -1.60 -4.64 1.04 -6.91 0.06 6.01 0.38 -0.87 -0.10 1.85 6.77 -2.00 4.57 1.74 3.58 -0.29 -6.13 0.33 1 -0.37 4.00 1.62 -1.31 3.25 -7.49 4.05 1.16 -1.10 0.87 -0.43 1.84 1.oo 0.60 0.29 -6.83 -1.48 -1.09 I -4.29 3.96 -5.67 0.27 %.ires 1- 12 at Cowra, sires 13-2 1+ *link sires at Hamilton; Bold EBV is top for each trait Overall maternal performance of the 1stX daughters is assessed as total weight of lamb weaned per ewe joined. There was considerable variation in lamb production from daughters of the 12 sires tested at Cowra (P<O.Ol), when they were mated to Poll Dorset rams at 7 months of age in autumn 1998 (Figure 1). The only adjustment to results in Figure 1, is for sex of the 2ndX lambs (1.4 kg added to ewe lambs), so they include the weight advantage of older lambs for those ewes that lambed early and reared twins. The sire mean daughter performance ranged from 4.6%3.2 to 32.9*3.7 kg for total weight of lamb weaned per ewe joined. Weight of lamb weaned is a composite trait, combining the proportion of ewes lambing, litter size, lamb survival, lamb growth and time of lambing. The range in performance amongst the 12 sire groups was 17-94 % for ewes lambing, 1.0-2.1 for litter size, 44-90 % for lamb survival and 29.4-37.2 kg for weaning weight, adjusted for age (90d), sex and rearing, so the maternal environments provided by the ewes are comparable. These lambing results are based on half the ewe progeny (mean 17.8 per sire group), joined at 7 months of age. Similar numbers of ewes from each sire were joined for the first time in spring 1998. Evaluation of the sires will also include the results from this mating and another 2 lambings from 80 Proc. Assoc. Advmt. Anim. Breed. Genet. Vol13 both groups, combined with results from other sites and intakes of sires. However these early results show very large differences in lambing performance of 1stX ewes sired by different rams. BL2 BL8 BLI 2 BoLl 04 Crl 1 QS Fl3 Fi7 Fig E=6 WslO SireofIsKdam Figure 1. Total weight of lamb weaned per ewe joined at 7 months. The final evaluation of the maternal sires will include growth and carcass merit of 2ndX progeny, and wool production as well as lambing performance of their 1stX results have already highlighted the varying performance of sires for different traits. were trait leaders for growth, fat and muscle amongst the 1stX meat EBVs. Sires also ranking for component traits of 1stX lambing performance. This highlights the producers to carefully consider the production traits that have the greatest impact on profitability and ensure that the sires of their dams have high genetic merit for these important for lamb producers to exert greater control over the selection of sires (and lamb dam flock. Contract mating using selected sires is an avenue to achieve this, their 1stX and daughters. The Different sires varied in their need for lamb their enterprise traits. It is also dams) of their ACKNOWLEDGEMENTS The MCPT is run at Cowra, Hamilton and Struan/Rutherglen by NSW Agriculture, Agriculture Victoria and Primary Industries and Resources SA, with support from Meat and Livestock Australia. The support of breeders who entered sires and provided semen is appreciated. Jayce Morgan and Kelly Lees provided considerable technical assistance. REFERENCES Banks, R. G. and Kinghom, B. P. (1997) Proc. Assoc. Advmt. Anim. Breed. Genet. 12,20 Banks, R. G., Shands, C., Stafford, J. and Kenney, P. (1995) 'LAMBPLAN Superior Sires' Meat Research Corporation, Sydney Gilmour, A. R. and Banks, R. G. (1992) Proc. Aust. Assoc. Anim. Breed. Genet. 10543 Ferguson, B. D. and Fogarty, N. M. (1997) Proc. Assoc. Advmt. Anim. Breed. Genet. 12:360 81