Allometric Growth of Non-Carcass Components, Carcass Cuts and Hind Limb Tissues in Kivircik Lambs Finished Under Concentrate- and Pasture-Based Systems.

Background: Obtaining information about the growth rates of animals' organs and tissues can help understand their meat production potential and determine the ideal slaughter weight (SW).

Objectives: This study aimed to determine the effects of production system and SW on the allometric growth of the non-carcass components, carcass cuts, and hind limb tissues of Kivircik lambs.

Methods: A total of 54 single-born male lambs were randomly allocated into production systems (concentrate- and pasture-based) and SW groups: 25-26 kg (LOW), 30-31 kg (MEDIUM), and 35-36 kg (HIGH). The data for weights of non-carcass components, carcass cuts and hind limb tissues were analysed using General Linear Model (GLM). The allometric growth of non-carcass components, carcass cuts and hind limb tissues was estimated using the nonlinear allometric equation (Y = aX).

Results: The mean of carcass components increased linearly with SW (p < 0.05). Similar omental-mesenteric fat, kidney knob and channel fat (KKCF), back fat thickness, subcutaneous fat, intermuscular fat and total fat levels were observed in the different SW groups in a pasture-based system (p > 0.05). Carcass cuts and hind limb fat tissues show late development (b > 1) in the concentrated system. Development of subcutaneous fat and total fat was late maturing (b > 1) in the pasture-based system. Allometric growth of KKCF, subcutaneous fat and total fat was rapid.

Conclusion: If more carcass weight is desired from Kivircik lambs in the concentrated production system, they should be slaughtered at higher weights than the HIGH group. Continuing to fatten pasture-based lambs after 30-31 kg may result in fatty carcasses.