McGovern Fiona Mary, McHugh Noirin, Fitzmaurice Shauna, Pabiou Thierry, McDermott Kevin, Wall Eamon, Fetherstone Nicola
Teagasc, Animal & Grassland Research and Innovation Centre, Mellows Campus, Athenry, Co. Galway, Ireland.
Teagasc, Animal & Grassland Research and Innovation Centre, Fermoy, Co. Cork, Ireland.
Transl Anim Sci. 2020 Nov 14;4(4):txaa206. doi: 10.1093/tas/txaa206. eCollection 2020 Oct.
Understanding the phenotypic factors that affect lamb live weight and carcass composition is imperative to generating accurate genetic evaluations and further enables implementation of functional management strategies. This study investigated phenotypic factors affecting live weight across the growing season and traits associated with carcass composition in lambs from a multibreed sheep population. Four live weight traits and two carcass composition traits were considered for analysis namely; birth, preweaning, weaning, and postweaning weight, and ultrasound muscle depth and fat depth. A total of 427,927 records from 159,492 lambs collected from 775 flocks between the years 2016 and 2019, inclusive were available from the Irish national sheep database. Factors associated with live weight and carcass composition were determined using linear mixed models. The heaviest birth, preweaning, and weaning weights were associated with single born lambs ( < 0.001), however by postweaning, there was no difference observed in the weights of single and twin born lambs ( > 0.01). Breed class affected lamb live weight and carcass composition with terminal lambs weighing heaviest and having greater muscle depth than all other breed classes investigated ( < 0.001). Lambs born to first parity dams were consistently lighter, regardless of time of weighing ( < 0.001), while dams lambing for the first time as ewe lambs produced lighter lambs than those lambing for the first time as hoggets ( < 0.001). Greater heterosis coefficients (i.e., >90% and ≤100%) resulted in heavier lambs at weaning compared with lambs with lower levels of heterosis coefficients ( < 0.001). A heterosis coefficient class <10% resulted in lambs with greater muscle depth while recombination loss of <10% increased ultrasound fat depth ( < 0.001). Results from this study highlight the impact of multiple animal level factors on lamb live weight and carcass composition which will enable more accurate bio-economic models and genetic evaluations going forward.
了解影响羔羊活体重量和胴体组成的表型因素对于进行准确的遗传评估至关重要，并且有助于进一步实施功能性管理策略。本研究调查了多品种绵羊群体中，整个生长季节影响羔羊活体重量的表型因素以及与胴体组成相关的性状。分析时考虑了四个活体重量性状和两个胴体组成性状，即出生重、断奶前体重、断奶体重和断奶后体重，以及超声测定的肌肉深度和脂肪深度。从爱尔兰国家绵羊数据库中获取了2016年至2019年（含）期间，来自775个羊群的159,492只羔羊的总共427,927条记录。使用线性混合模型确定与活体重量和胴体组成相关的因素。出生重、断奶前体重和断奶体重最重的是单胎羔羊（P<0.001），然而到断奶后，单胎和双胎羔羊的体重没有差异（P>0.01）。品种类别影响羔羊的活体重量和胴体组成，终端杂交羔羊体重最重，且肌肉深度比所研究的所有其他品种类别都大（P<0.001）。初产母羊所生的羔羊无论在何时称重都始终较轻（P<0.001），而首次产羔时为青年母羊的母羊所生的羔羊比首次产羔时为周岁母羊的母羊所生的羔羊体重更轻（P<0.001）。与杂种优势系数较低的羔羊相比，较高的杂种优势系数（即>90%且≤100%）导致断奶时羔羊体重更重（P<0.001）。杂种优势系数类别<10%导致羔羊肌肉深度更大，而重组损失<10%会增加超声测定的脂肪深度（P<0.001）。本研究结果突出了多种个体水平因素对羔羊活体重量和胴体组成的影响，这将有助于未来建立更准确的生物经济模型和遗传评估。
