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To achieve sustainable lamb production, it is crucial to determine the optimal slaughter age for maximum economic efficiency and have a comprehensive understanding of breed characteristics. This study focuses on evaluating different nonlinear models to determine the optimal slaughter age for Karacabey Merino and Kıvırcık lambs, renowned for their early development and superior meat quality, respectively. The dataset comprised age-related live weight data from 98 lambs, including 36 female and 15 male Kıvırcık lambs, as well as 33 female and 14 male Karacabey Merino lambs. Six models, namely, negative exponential, Brody, Gompertz, logistic, Bertalanffy, and Richards were utilized to analyze the data. The model parameters were estimated through an iterative process, and their goodness of fit was evaluated using various metrics. The adjusted coefficient of determination for male Kıvırcık lambs was 0.9755, while female Kıvırcık lambs exhibited a lower value of 0.8912. For Karacabey Merino lambs, males had an adjusted coefficient of determination of 0.9534, while females had a slightly lower value of 0.9044. The study concluded that the Brody model provided more accurate predictions for the growth curve of these sheep breeds compared to the other models. [ABSTRACT FROM AUTHOR]

This study is set out to evaluate the effects of callipyge (CLPG) gene, attributed to sheep affecting growth and meat quality, on carcass and sensory trait of most preferred meat-type lamb (Kıvırcık, Karacabey Merino, Ramlıç, German Black-Head Mutton x Kıvırcık, Hampshire Down x Merino) in the western part of Turkey. Two datasets were used: (i) 177 lambs (66 males, 111 females) to determine genotype and allele frequencies; (ii) 48 genotypically identified male lambs for the assessment of carcass and meat sensory quality. It was found that homozygous (NN) and heterozygous (MN) conditions of the CLPG gene were observed in all sheep breeds, except Ramlıç which exhibits only NN. No significant differences were observed in CLPG genotypes for slaughter weight, cold carcass weight, and cold dressing percentage (p > 0.05). On the other hand, the effect of genotype on neck percentage was significant (p < 0.01), and lambs expressing CLPG genotype (MN) had a higher neck percentage. Not significantly, but numerically the MN genotype had a higher percentage of the shoulder, rack, and leg than the NN genotype, while the NN genotype had a higher percentage of loin (p > 0.05). Similarly, the effect of genotype on meat quality assessment was not significant (p > 0.05); however, shear force, water holding capacity, and cooking loss of the NN genotype were higher than the MN genotype. Indeed, no interaction between genotype and time was observed on the color parameter of the Longissimus thoracis et lumborum muscle at various storage periods (p > 0.05). The findings suggest that all meat-type sheep breeds (except Ramlıç) were polymorphic, suggesting that heterozygous individuals who received the CLPG mutation from the sire should be adopted in selection programs to improve carcass traits. [ABSTRACT FROM AUTHOR]

This study aimed to determine the slaughter and carcass characteristics of five different meat-type lambs reared under intensive husbandry conditions. For this purpose, a total of 202 lambs--Kıvırcık (K, n = 51), Karacabey Merino (KM, n = 47), Ramlıç (R, n = 28), German Black-Head Mutton × Kıvırcık (GBK, n = 49), and Hampshire Down × Merino crossbreed (HM, n = 27)--were used to evaluate rearing performance. At the end of the rearing period, 10 male lambs of each breed were randomly selected to investigate slaughter and carcass characteristics. All lambs were housed in a single flock until the slaughtering period. An average of 600 g/lamb of concentrate feed, 100 g/lamb of alfalfa hay, and 300 g/lamb of vetches-wheat mixtures hay per day were given with ad libitum fresh water. While the average daily gain (ADG) of female K, KM, R, GBK, and HM lambs was 94.4, 165.2, 142.2, 109.0, and 160.0 g (P < 0.001); the male lambs' ADG was 167.3, 240.4, 180.5, 176.0, and 246.6 g, respectively (P < 0.001). Cold carcass weights of lambs in breeds were 19.12, 21.76, 16.80, 20.71, and 20.80 kg (P < 0.001); cold dressing percentages (CDP) were 47.39%, 47.55%, 44.86%, 47.41%, and 45.61% in K, KM, R, GBK, and HM, respectively (P < 0.01). It is concluded that Merino crossbreeds (KM and HM) had significantly more ADG and total weight gain when compared to K, R, and GBK. On the other hand, KM and GBK had higher CDP value while HM came forward for the loin eye area. [ABSTRACT FROM AUTHOR]