The liveweight, carcasses and meat quality of intact and castrated male lambs reared under a pasture-fed Australian production system
Shawn R. McGrath
A B , M. Bruce Allworth A B , James Stephens C , Michelle L. E. Henry D and Benjamin W. B. Holman E *
A
B
C
D
E
Abstract
Intact male (ram) lambs are often discounted by meat processors because of their perceived defective meat quality.
This study quantified the effects of castration on the liveweight, growth, carcass parameters and the meat quality of male lambs.
Liveweight, growth and carcass data were collected from 133 ram and 132 castrated (wether) lambs reared under a pasture-fed production system. A total of 50 lambs were subsequently selected, balanced by final curfew liveweight and castration status, to investigate additional carcass, meat quality, consumer sensory panel scores and colour stability parameters.
It was found that total average daily gains for ram lambs were highest (242.9 ± 5.2 g/day; P = 0.002), resulting from their higher pre-weaning growth rate of 327.7 ± 9.7 g/day (P < 0.001). Wethers were fattier, having higher estimated intramuscular fat (3.9 vs 3.3 ± 0.1%, respectively) and subcutaneous fat depth (14.7 vs 13.5 ± 0.4 mm, respectively) than ram lambs. Purge loss (P < 0.030) and ultimate pH (P < 0.035) were higher for the meat of wether lambs, but only after 32 days of wet ageing. Consumers scored the meat of wether lambs as significantly more tender (61.0 vs 54.6 ± 2.3%; P = 0.005) and of greater overall liking (65.1 vs 61.1 ± 2.0%; P = 0.044) than that of ram lambs. These, and a comparison of shear force, near infrared spectroscopy for intramuscular fat content and retail colour with consumer thresholds, suggest a general satisfaction with ram and wether lamb meat quality.
Collectively, there seems to be few tangible performance and meat quality advantages to the castration of male lambs.
Prime lamb producers must consider flock management and market preference when deciding on best practice.
Keywords: animal performance, carcass properties, consumer sensory panel, intact ram lambs, lean tissue yield, meat shelf-life, wet ageing period, wethers.
References
Animal Health Australia (2016) The Australian animal welfare standards and guidelines for sheep. Animal Health Australia. Available at www.animalwelfarestandards.net.au
Arnold AM, Peralta JM, Thonney ML (1997) Effect of testosterone on differential muscle growth and on protein and nucleic acid concentrations in muscles of growing lambs. Journal of Animal Science 75(6), 1495-1503.
| Crossref | Google Scholar | PubMed |
Bailes KL, Meyer RG, Piltz JW (2022) Prediction of the intramuscular fat and protein content of freeze-dried ground meat from cattle and sheep using near-infrared spectroscopy (NIRS). International Journal of Food Science & Technology 57(4), 2249-2256.
| Crossref | Google Scholar |
Bates AL, McGrath SR, Allworth MB, Robertson SM, Refshauge G (2023) A cross-sectional study of commercial ewe management practices for different sheep breeds across Southern Australia. Animals 13(3), 388.
| Crossref | Google Scholar | PubMed |
Bhatti MA, Williams T, Hopkins DL, Asheim LJ, Steinheim G, Campbell M, Eik LO, Wynn PC, Ådnøy T (2019) Adapting seasonal sheep production to year-round fresh meat and halal market in Norway. Sustainability 11(6), 1554.
| Crossref | Google Scholar |
Bouton PE, Carrol FD, Harris PV, Shorthose WR (1973) Influence of pH and fiber contraction state upon factors affecting the tenderness of bovine muscle. Journal of Food Science 38(3), 404-407.
| Crossref | Google Scholar |
Calnan H, Jacob RH, Pethick DW, Gardner GE (2016) Production factors influence fresh lamb longissimus colour more than muscle traits such as myoglobin concentration and pH. Meat Science 119, 41-50.
| Crossref | Google Scholar | PubMed |
Champness MR, McCormick JI, Bhanugopan MS, McGrath SR (2021) Sodium deficiency in lucerne (Medicago sativa) forage in southern Australia and the effect of sodium and barley supplementation on the growth rate of lambs grazing lucerne. Animal Production Science 61(11), 1170-1180.
| Crossref | Google Scholar |
CIE (1977) CIE recommendations on uniform color spaces, color-difference equations, and metric color terms. Color Research & Application 2(1), 5-6.
| Crossref | Google Scholar |
Connaughton SL, Williams A, Anderson F, Kelman KR, Gardner GE (2020) Dual energy X-ray absorptiometry precisely and accurately predicts lamb carcass composition at abattoir chain speed across a range of phenotypic and genotypic variables. Animal 14(10), 2194-2202.
| Crossref | Google Scholar | PubMed |
Coombs CEO, Holman BWB, Collins D, Friend MA, Hopkins DL (2017a) Effects of chilled-then-frozen storage (up to 52 weeks) on lamb M. longissimus lumborum quality and safety parameters. Meat Science 134, 86-97.
| Crossref | Google Scholar | PubMed |
Coombs CEO, Holman BWB, Friend MA, Hopkins DL (2017b) Long-term red meat preservation using chilled and frozen storage combinations: a review. Meat Science 125, 84-94.
| Crossref | Google Scholar | PubMed |
Crouse JD, Busboom JR, Field RA, Ferrell CL (1981) The effects of breed, diet, sex, location and slaughter weight on lamb growth, carcass composition and meat flavor. Journal of Animal Science 53(2), 376-386.
| Crossref | Google Scholar |
De Brito GF, McGrath SR, Holman BWB, Friend MA, Fowler SM, van de Ven RJ, Hopkins DL (2016) The effect of forage type on lamb carcass traits, meat quality and sensory traits. Meat Science 119, 95-101.
| Crossref | Google Scholar | PubMed |
Dransfield E (1994) Optimisation of tenderisation, ageing and tenderness. Meat Science 36(1–2), 105-121.
| Crossref | Google Scholar | PubMed |
Dransfield E, Nute GR, Hogg BW, Walters BR (1990) Carcass and eating quality of ram, castrated ram and ewe lambs. Animal Science 50(2), 291-299.
| Crossref | Google Scholar |
Gardner GE, Williams A, Ball AJ, Jacob RH, Refshauge G, Hocking Edwards J, Behrendt R, Pethick DW (2015) Carcase weight and dressing percentage are increased using Australian sheep breeding values for increased weight and muscling and reduced fat depth. Meat Science 99, 89-98.
| Crossref | Google Scholar | PubMed |
Gkarane V, Allen P, Gravador RS, Diskin MG, Claffey NA, Fahey AG, Brunton NP, Farmer LJ, Moloney AP, Monahan FJ (2017) Effect of castration and age at slaughter on sensory perception of lamb meat. Small Ruminant Research 157, 65-74.
| Crossref | Google Scholar |
Gravador RS, Pace E, Mooney BR, Jaeger SR, Gkarane V, Fahey AG, Brunton NP, Claffey NA, Allen P, Diskin MG, Moloney AP, Farmer LJ, Monahan FJ (2018) A consumer study of the effect of castration and slaughter age of lambs on the sensory quality of meat. Small Ruminant Research 169, 148-153.
| Crossref | Google Scholar |
Hoffman LC, Claasen B, van der Merwe DA, Cloete SWP, Cloete JJE (2020) The effects of production system and sex on the sensory quality characteristics of dorper lamb. Foods 9(6), 725.
| Crossref | Google Scholar |
Holman BWB, Alvarenga TIRC, van de Ven RJ, Hopkins DL (2015a) A comparison of technical replicate (cuts) effect on lamb Warner–Bratzler shear force measurement precision. Meat Science 105, 93-95.
| Crossref | Google Scholar | PubMed |
Holman BWB, Ponnampalam EN, van de Ven RJ, Kerr MG, Hopkins DL (2015b) Lamb meat colour values (HunterLab CIE and reflectance) are influenced by aperture size (5mm v. 25mm). Meat Science 100, 202-208.
| Crossref | Google Scholar | PubMed |
Holman BWB, Alvarenga TIRC, Hopkins DL (2020a) The effect of fibre orientation, measurement interval and muscle on lamb meat drip loss values. Meat Science 161, 107959.
| Crossref | Google Scholar |
Holman BWB, Collins D, Kilgannon AK, Hopkins DL (2020b) Using shear force, sarcomere length, particle size, collagen content, and protein solubility metrics to predict consumer acceptance of aged beef tenderness. Journal of Texture Studies 51(4), 559-566.
| Crossref | Google Scholar | PubMed |
Holman BWB, Hayes RC, Newell MT, Refshauge G, McGrath SR, Fowler SM, Shanley AR, Hopkins DL (2021) The quality and mineral composition of the longissimus lumborum and semimembranosus muscles from lambs fed perennial or annual wheat forage with or without lucerne. Meat Science 180, 108564.
| Crossref | Google Scholar |
Holman BWB, Refshauge G, Newell MT, Hopkins DL, Hayes RC (2024) The carcass characteristics and quality of meat from lambs grazing perennial wheat with different companion legumes (clover, serradella, lucerne) or a mineral supplement. Meat Science 216, 109549.
| Crossref | Google Scholar | PubMed |
Hopkins DL, Thompson JM (2001) The relationship between tenderness, proteolysis, muscle contraction and dissociation of actomyosin. Meat Science 57(1), 1-12.
| Crossref | Google Scholar | PubMed |
Hopkins DL, Gilbert KD, Pirlot KL, Roberts AHK (1992a) Elliotdale and crossbred lambs: growth rate, wool production, fat depth, saleable meat yield, carcass composition and muscle content of selected cuts. Australian Journal of Experimental Agriculture 32(4), 429-434.
| Crossref | Google Scholar |
Hopkins DL, Jackson RB, Roberts AHK (1992b) Comparison of a modified cryptorchid treatment and castration: effect on growth, wool production, posthitis, testosterone production and development of masculine characteristics. Australian Journal of Experimental Agriculture 32(4), 443-446.
| Crossref | Google Scholar |
Huff-Lonergan E, Lonergan SM (2005) Mechanisms of water-holding capacity of meat: the role of postmortem biochemical and structural changes. Meat Science 71(1), 194-204.
| Crossref | Google Scholar | PubMed |
Kelman KR, Alston-Knox C, Pethick DW, Gardner GE (2022) Sire breed, litter size, and environment influence genetic potential for lamb growth when using sire breeding values. Animals 12(4), 501.
| Crossref | Google Scholar |
Kemp JD, Shelley JM, Jr, Ely DG, Moody WG (1972) Effects of castration and slaughter weight on fatness, cooking losses and palatability of lamb. Journal of Animal Science 34(4), 560-562.
| Crossref | Google Scholar |
Khliji S, van de Ven R, Lamb TA, Lanza M, Hopkins DL (2010) Relationship between consumer ranking of lamb colour and objective measures of colour. Meat Science 85(2), 224-229.
| Crossref | Google Scholar | PubMed |
Lee GJ, Harris DC, Ferguson BD, Jelbart RA (1990) Growth and carcass fatness of ewe, wether, ram and cryptorchid crossbred lambs reared at pasture: effects of weaning age. Australian Journal of Experimental Agriculture 30(6), 743-747.
| Crossref | Google Scholar |
Mahgoub O, Lodge GA (1994) Growth and body composition of Omani local sheep 1. Live-weight growth and carcass and non-carcass characteristics. Animal Science 58(3), 365-372.
| Crossref | Google Scholar |
Miller LF, Judge MD, Diekman MA, Hudgens RE, Aberle ED (1989) Relationships among intramuscular collagen, serum hydroxyproline and serum testosterone in growing rams and wethers. Journal of Animal Science 67(3), 698-703.
| Crossref | Google Scholar | PubMed |
Mills J, Donnison A, Brightwell G (2014) Factors affecting microbial spoilage and shelf-life of chilled vacuum-packed lamb transported to distant markets: a review. Meat Science 98(1), 71-80.
| Crossref | Google Scholar | PubMed |
Mortimer SI, Van Der Werf JHJ, Jacob RH, Pethick DW, Pearce KL, Warner RD, Geesink GH, Hocking Edwards JE, Gardner GE, Ponnampalam EN, Kitessa SM, Ball AJ, Hopkins DL (2010) Preliminary estimates of genetic parameters for carcass and meat quality traits in Australian sheep. Animal Production Science 50(12), 1135-1144.
| Crossref | Google Scholar |
Nemati Z, Amirdahri S, Asgari A, Taghizadeh A, Siddiqui SA, Besharati M, Alirezalu K, Holman BWB (2024) Feeding pomegranate pulp to Ghezel lambs for enhanced productivity and meat quality. Veterinary and Animal Science 24, 100356.
| Crossref | Google Scholar | PubMed |
O’Reilly RA, Pannier L, Gardner GE, Garmyn AJ, Luo H, Meng Q, Miller MF, Pethick DW (2020) Influence of demographic factors on sheepmeat sensory scores of American, Australian and Chinese consumers. Foods 9(4), 529.
| Crossref | Google Scholar |
Pannier L, Gardner GE, O’Reilly RA, Pethick DW (2018) Factors affecting lamb eating quality and the potential for their integration into an MSA sheepmeat grading model. Meat Science 144, 43-52.
| Crossref | Google Scholar | PubMed |
Pearce KL, Van De Ven R, Mudford C, Warner RD, Hocking-Edwards J, Jacob R, Pethick DW, Hopkins DL (2010) Case studies demonstrating the benefits on pH and temperature decline of optimising medium-voltage electrical stimulation of lamb carcasses. Animal Production Science 50(12), 1107-1114.
| Crossref | Google Scholar |
Pothakos V, Devlieghere F, Villani F, Björkroth J, Ercolini D (2015) Lactic acid bacteria and their controversial role in fresh meat spoilage. Meat Science 109, 66-74.
| Crossref | Google Scholar | PubMed |
Purchas RW (1978) Some effects of nutrition and castration on meat production from male Suffolk cross (border leicester-romney cross) lambs: I. growth and carcass quality. New Zealand Journal of Agricultural Research 21(3), 367-376.
| Crossref | Google Scholar |
Purchas RW, O’Brien LE, Pendleton CM (1979) Some effects of nutrition and castration on meat production from male Suffolk cross (border leicester-romney cross) lambs: II. Meat quality. New Zealand Journal of Agricultural Research 22(3), 375-383.
| Crossref | Google Scholar |
Ramanathan R, Hunt MC, Mancini RA, Nair MN, Denzer ML, Suman SP, Mafi GG (2020) Recent updates in meat color research: integrating traditional and high-throughput approaches. Meat and Muscle Biology 4(2), 1-24.
| Crossref | Google Scholar |
Sales J (2014) Quantification of the effects of castration on carcass and meat quality of sheep by meta-analysis. Meat Science 98(4), 858-868.
| Crossref | Google Scholar | PubMed |
Schanbacher BD, Crouse JD, Ferrell CL (1980) Testosterone influences on growth, performance, carcass characteristics and composition of young market lambs. Journal of Animal Science 51(3), 685-691.
| Crossref | Google Scholar | PubMed |
Seideman SC, Cross HR, Oltjen RR, Schanbacher BD (1982) Utilization of the intact male for red meat production: a review. Journal of Animal Science 55(4), 826-840.
| Crossref | Google Scholar |
Small AH, Jongman EC, Niemeyer D, Lee C, Colditz IG (2020) Efficacy of precisely injected single local bolus of lignocaine for alleviation of behavioural responses to pain during tail docking and castration of lambs with rubber rings. Research in Veterinary Science 133, 210-218.
| Crossref | Google Scholar | PubMed |
Smith GC, Dutson TR, Hostetler RL, Carpenter ZL (1976) Fatness, rate of chilling and tenderness of lamb. Journal of Food Science 41(4), 748-756.
| Crossref | Google Scholar |
Starkey CP, Geesink GH, Collins D, Hutton Oddy V, Hopkins DL (2016) Do sarcomere length, collagen content, pH, intramuscular fat and desmin degradation explain variation in the tenderness of three ovine muscles? Meat Science 113, 51-58.
| Crossref | Google Scholar | PubMed |
Suman SP, Joseph P (2013) Myoglobin chemistry and meat color. Annual Review of Food Science and Technology 4, 79-99.
| Crossref | Google Scholar | PubMed |
Thompson JM, Gee A, Hopkins DL, Pethick DW, Baud SR, O’Halloran WJ (2005a) Development of a sensory protocol for testing palatability of sheep meats. Australian Journal of Experimental Agriculture 45(5), 469-476.
| Crossref | Google Scholar |
Thompson JM, Pleasants AB, Pethick DW (2005b) The effect of design and demographic factors on consumer sensory scores. Australian Journal of Experimental Agriculture 45(5), 477-482.
| Crossref | Google Scholar |
Warner RD, Kearney G, Hopkins DL, Jacob RH (2017) Retail colour stability of lamb meat is influenced by breed type, muscle, packaging and iron concentration. Meat Science 129, 28-37.
| Crossref | Google Scholar | PubMed |
Wellington GH, Hogue DE, Foote RH (2003) Growth, carcass characteristics and androgen concentrations of gonad-altered ram lambs. Small Ruminant Research 48(1), 51-59.
| Crossref | Google Scholar |
Young OA, Lane GA, Podmore C, Fraser K, Agnew MJ, Cummings TL, Cox NR (2006) Changes in composition and quality characteristics of ovine meat and fat from castrates and rams aged to 2 years. New Zealand Journal of Agricultural Research 49(4), 419-430.
| Crossref | Google Scholar |
