Allometric growth of body components in crossbred ewe lambs fed increasing dietary concentrate levels

Abstract

This study aimed to evaluate the growth of body components in crossbred ewe lambs fed increasing levels of dietary concentrate and to determine the optimum level of supplementation for finishing ewe production. Thirty crossbred (½ Pantaneira × ½ Texel) wool ewe lambs fed Tifton 85 hay (Cynodon spp.) and different dietary concentrate levels (20, 40, 60, and 80% DM basis) were selected for study. At the beginning of the study, six animals were slaughtered for determination of initial body composition. The remaining animals were slaughtered at approximately 48 kg live weight. The growth of body components in relation to body growth was estimated from the allometric model BC = a × (FBW) b , where BC is body component weight, a and b are growth equation parameters, and FBW is fasted body weight. Carcass, muscle, bone, and gastrointestinal tract were late maturing (b <1, P <0.01). Carcass and carcass fat growth was positively affected (linear, P <0.05) by concentrate level. Total fat weight increased with increasing concentrate level (P <0.05). The addition of up to 60% concentrate in growing ewe lamb diets is recommended for production of carcasses with early deposition of muscle and fat. The addition of 20% concentrate in ewe lab diets is sufficient for production of carcasses with maximum deposition of muscle and no excess fat. Key words: Allometric coefficient. Body composition. Lambs. ResumoObjetivou-se avaliar o crescimento dos componentes corporais de borregas mestiças alimentadas com níveis crescentes de concentrado na dieta e estabelecer o nível adequado de suplementação para produção de fêmeas para abate. Foram utilizadas 30 borregas lanadas, oriundas de cruzamentos com ovinos da raça Texel, alimentadas com feno de capim-Tifton 85 (Cynodon spp.) e quatro níveis de concentrado na dieta (20, 40, 60 e 80%). No início do experimento foi realizado abate para determinação da composição corporal de seis borregas. Os demais foram abatidos com aproximadamente 48 kg. Para o estudo do

Allometric growth of non-carcass components and hind limb tissue composition in Saanen goat kids reared under natural and artificial systems

“…These results might be attributed to the fact that liver growth is dependent on the dietary energy level, which is higher in artificial milk products. Supporting the current results, a rapid growth rate of liver in artificially reared lambs had been reported by Santos 26 and Oliviera et al 5 . Although not statistically significant, in this study, it was determined that the allometric growth coefficients for most of the non-carcass components decreased partially with increasing slaughter age.…”

“…b>1 indicates a faster growth rate of investigated non-carcass components and hind limb tissues to empty body or hind limb, while b<1 indicates a lower growth rate of the investigated dependent variable. 5,16 Both GLM and nonlinear regression analyses were performed using SPSS 21.0 Programme (SPSS Inc., IBM, NY, USA).…”

“…On the other hand, muscle and fat tissues are late maturing tissues, which make the slaughter weight and dietary components quite important. 5 Muscle tissue continue to develop even after 120 days of age, which represents that higher slaughter weights can be used for both natural and artificial reared Saanen kids.…”

“…4 In slaughtered farm animals, the percentages of non-carcass components (such as head, skin, feet, gastro-intestinal tract) and tissue composition in the carcass (proportions of meat, fat, bone) are the main criteria that determine the dressing percentage and the carcass quality, respectively. 5 On the other hand, the development of various non-carcass components and body tissues is not simultaneous. In order for the new-born to survive, bones and vital organs are well developed at birth and therefore develop slowly after birth.…”

“…In contrast, muscle and fat tissues, which are the main components of the carcass, mature later. 5,6 For differential growth of this kind, the term "allometry" has been generally recognised, which states that the rate of relative growth of an organ is a constant fraction of the relative growth of the total organism. 7,8 Besides, the allometric growth rates of each organ and tissue can vary according to management and feeding conditions.…”