The relative growth and development of the carcass tissues of Merino and crossbred rams and wethers

Abstract

One hundred and twenty lambs were used to study the effects of breed (Merino or Dorset Horn x (Border Leicester x Merino)), sex (entire or castrate male) and liveweight (birth to 50 kg) on carcass conformation and composition. Merinos were lighter at birth and grew more slowly than crossbreds in both the pre- and post-weaning phases (P < 0.01). Rams grew significantly faster than wethers only after weaning (P < 0.01). Merinos exceeded crossbreds in height at withers and chest depth (P < 0.01), but the reverse was true for width at 'hooks' (P < 0.01) and length of pelvis (P < 0.05). Sex differences were confined to chest girth, which was greatest in wethers (P < 0.01). Eye muscle width and area were greater in crossbreds than Merinos (P < 0.01). Growth coefficients for bone and muscle calculated on the basis of both half-carcass weight and half-carcass muscle-plus-bone weight were comparable with reports in the literature. For fat, however, the coefficients were considerably higher than has been reported previously (1.938-2.010 and 2.364-2.563 for the half-carcass and the muscle-plus-bone bases respectively). When their values were averaged over the range of slaughter weights studied, crossbreds yielded more bone (P < 0.05), muscle and fat (P < 0.01) than Merinos. Rams yielded more bone (P < 0.05) and less fat (P < 0.01) than wethers. Variation in yields of muscle and fat were due largely to differences in tissue deposition in animals slaughtered at 40 and 50 kg liveweight. Partial correlation analysis indicated that changes in carcass composition were largely accounted for by differences in liveweight.

Growth and Body Conformation Responses of Genetically Divergent Australian Sheep to Spirulina (Arthrospira platensis) Supplementation

“…Based on these reports, it is evident that that nutrient demands, absorption and partitioning in ewes is different from those of wethers and results in the utilization of Spirulina for increasing liveweight and body conformation. Previous studies demonstrated that genetic variation between lambs influences nutrient partitioning and absorption despite the feeding of the same or identical rations Lewis et al, 2006;Oddy and Sainz, 2002;Cake et al, 2007;Wynn and Thwaites, 1981). …”

Genetic parameters for direct and maternal effects on post-weaning body measurements of Muzaffarnagari sheep in India

“…According to Salako (2006a), body measurement in addition to weight measurements describes more completely an individual or population than do the conventional methods of weighing and grading. Various studies showed that body dimensions could be used to study the interaction between heredity and environment (Dunlop 1963), and in assessing growth rate, feed utilizations and carcass characteristics in farm animals (Wynn and Thwaites 1981) and live body weight can be predicted from body measurements (Aziz and Sharaby 1993;Mohammed and Amin 1997;Varade and Ali 1999;Atta and El Khidir 2004). Besides, linear size measurements have been suggested as more objective measures of body conformation of animals (Janssens and Vandepitte 2004).…”

Crescimento alométrico de osso, músculo e gordura em cortes da carcaça de cordeiros Texel segundo os métodos de alimentação e peso de abate

“…WYNN & THWAITES (1981), trabalhando com cordeiros da raça Merina puros e cruzada (Border Leicester x Merina), observaram que os animais cruzados possuem maior quantidade de osso do que os animais puros quando comparados aos pesos de abate de 10; 40 e 50kg de peso vivo.…”