Growth performance and meat characteristics of the first filial Awassi Rambouillet callipyge ram lambs

Abstract

Aim: This study was designed to introduce the callipyge (CLPG) and 50% of Rambouillet sheep genes to improve meat quality and quantity of Awassi (AW) sheep. Materials and Methods: The CLPG mutation was introduced into the AW sheep through frozen semen of homozygous Rambouillet rams for the CLPG mutation. Four ram lambs from the first-generation Rambouillet callipyge Awassi (F1-RCA) and five from pure AW were recruited for a fattening trial conducted in individual pens using standard ration, following which ram lambs were slaughtered for carcass and meat evaluation. Results: Final body weight, dry matter intake, average daily gain, and feed conversion ratio were significantly higher in F1-RCA than AW. Hot and cold carcass weights and the other carcass cuts' weights, except for the fat tail, were heavier in F1-RCA than AW. There was no difference in dressing percentage between the two genetic groups (p>0.05). All non-carcass components' weights, except spleen, kidney, and testis, were higher in F1-RCA. Total lean, total bone, and intermuscular fat weight were greater in F1-RCA, but bone-to-lean ratio was lower in F1-RCA when compared with AW (p<0.01). No differences (p>0.05) were observed in all meat quality parameters for muscle longissimus with the exception of pH, redness color, and tenderness that were lower (p<0.05) in F1-RCA than AW. F1-RCA lambs had larger longissimus muscle area (30.9 vs. 16.9 cm2) and less leg fat depth (11.1 vs. 17.4 mm). Conclusion: The implications of this research show the potential of 50% of Rambouillet genes and the CLPG mutation to improve growth and meat characteristics in AW-Rambouillet crosses and can be used further to develop a meat-type AW with improved productivity and muscle mass.

Relationships between Hha1 Calpastatin Gene Polymorphism, Growth Performance, and Meat Characteristics of Awassi Sheep

“…At the end of the fattening period, all lambs were slaughtered for the evaluation of carcass traits and meat quality, as previously described [10,11,12]. Briefly, carcasses were divided into four parts, namely shoulder, rack, loin, and leg cuts, in addition to the fat tail and the rib-eye area, fat depth, tissue depth, rib fat depth, eye muscle width, eye muscle depth, eye muscle area, and leg fat depth, measured as previously described [10,12]. The right leg was dissected to determine muscle, bone, subcutaneous fat, and intermuscular fat components.…”

“…Longissimus muscles were excised from the right side of loin cuts, cleaned from all subcutaneous fat, vacuum-packaged, and frozen at −20 °C for meat quality measurements, as described [13]. Meat quality parameters were Warner–Bratzler shear force values for cooked meat samples, water holding capacity, cooking loss, and color coordinates (whiteness, redness, yellowness) [10,12,13].…”

Growth Performance and Meat Characteristics of the First Awassi–Rambouillet Callipyge Backcross

“…In this study, we expanded the findings from our previous work [7,8,14], where we introduced the CLPG in Awassi flocks and evaluated the effects of this CLPG in F1 (callipyge Awassi–Rambouillet lambs) to highlight the specific combined performance and meat characteristics traits of CLPG and 25% Rambouillet as compared to Awassi.…”

“…The callipyge mutation was introduced to the local Awassi sheep in 2011 by insemination with imported frozen semen of four Rambouillet homozygous rams for the CLPG gene from Utah University, USA. The first-generation callipyge Awassi rams (F1-CA, 50% Callipyge and 50% Awassi) characterized by Jawasreh et al [7,8], were used for mating the Awassi ewes to produce the first backcross of callipyge Awassi–Rambouillet lambs (CRAW), resulting in rams carrying 25% Rambouillet and 75% Awassi genes. Further, mating Awassi ewes with F1-CA sires heterozygous for the CLPG gene resulted in a Rambouillet–Awassi ram lambs without the CLPG gene (RAW), composed of 25% Rambouillet and 75% Awassi genes.…”

“…This study is part of a long program from the Jordan University of Science and Technology to develop a desirable Awassi phenotype with improved meat characteristics, including feed efficiency, meat growth, and tenderness by the introgression of the callipyge mutation into Awassi sheep [7]. To our knowledge, this the first study to investigate the effect of 25% Rambouillet genes and the CLPG mutation on Awassi growth and meat characteristics.…”