Métodos indiretos para estimar a composição corporal de cabras saanen e ovelhas sarda lactantes.

• Autor(a) principal: Knupp, Leonardo Sidney
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFPB
• Texto Completo: https://repositorio.ufpb.br/jspui/handle/123456789/18981
• topic: Zootecnia.; Composição da carcaça.; Escore de condição corporal.; Medidas corporais.; Peso corporal.; Ultrassom.; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

The energetic efficiency of goats and sheep during alternate periods of undernutrition and recovery can be assessed only if the accompanying changes in body composition are known. Changes in body composition can be estimated based on variations in body chemical content (lipids, protein, water and minerals) or energetic content. This work aimed to compare pre- and post-slaughter methodologies to estimate fat reserves and to compare indirect methodologies to estimate the chemical body composition in lactating dairy goats and ewes. Saanen goats (n = 26; BW 56.4 ± 6.8 kg, mean ± SD) and Sarda ewes (n = 26; BW 46.8 ± 6.9 kg, mean ± SD) were used. Fifteen pre-slaughter measurement and four post-slaughter measurement values were used to estimate the weight of fat in the omental (OM), mesenteric (MES), perirenal (PR), organ (ORG), carcass (CARC), non-carcass components (NC) and total depots (TOT, calculated as the sum of CARC and NC). The pre-slaughter measurements were: withers height; rump height; rump length; pelvis width; chest depth; shoulder width; heart girth; body length; sternum height; body weight (BW); BCS assessed in the lumbar (BCSl), sternal (BCSs – in goats) and tail (BCSt – in ewes) regions; fat thickness measured by ultrasound in the lumbar (FTUSl), sternal (FTUSs – in goats), tail (FTUSt – in ewes) and perirenal (FTUSpr) regions. The post-slaughter measurements were: hot carcass weight (HCW); empty body weight (EBW); fat thickness measured by digital caliper in the lumbar (FTDCl), sternal (FTDCs – in goats) and tail (FTDCt – in ewes) regions. Linear and multiple regressions were fit to data collected. In lactating Sannen goats, the BW, BCS (from lumbar and sternal regions), all somatic measurements and fat thickness measured by ultrasound in the lumbar and sternal regions were not adequate to estimate the weight of total fat (R2 ≤ 0.55). The best pre-slaughter and post-slaughter estimators of OM, MES, PR, ORG, NC and TOT fat were FTUSpr and EBW, respectively. Among pre- and post-slaughter measurements, BCSl (R2 = 0.63) and HCW (R2 = 0.82) gave the most accurate predictions of CARC fat, respectively. Multiple regression using the pre-slaughter variables FTUSpr, BW and BCSl yielded estimates of TOT fat with an R2 = 0.92. On the other hand, TOT fat predicted using the post-slaughter variables HCW and FTDCs had an R2 = 0.83. In Sarda ewes, the BCSt and HCW gave the most accurate predictions of the total fat among variables pre- and post-slaughter respectively (R2 = 0.84 and 0.92, respectively). Multiple regressions predicted total fat from the pre-slaughter variables FTUSpr, BCSt, FTUSl and BW with an R2 value of 0.96 (RSD = 0.96). Goats presented lower BCS from lumbar region than sheep (2.64 vs 3.01, respectively) accompanied also by lower FTUSl (mean of 2.3 vs 5.3 mm, respectively). Non-carcass components from Saanen goats were 18% heavier than that from Sarda ewes. However, just little difference was observed when components were compared in relation to empty body weight. Sarda ewes showed significantly lower content of water and ash in carcass, non-carcass and empty body mass than Saanen goats. In contrast, when the components were expressed as proportions of total in carcass, protein, fat and energy were higher in ewes than in goats. These same patterns of results repeated when evaluating empty body composition. Among all somatic measurements taken, heart girth was the most correlated variable with empty body chemical composition. In goats, the FTUSpr explained the largest amount of variation in total protein content (R2 = 0.67), fat (R2 = 0.64), energy (R2 = 0.65), protein proportion (R2 = 0.68), fat proportion (R2 = 0.64) and energy proportion (R2 = 0.68). In ewes, the BCSt was the best predictor of protein, fat and energy amount and proportion explaining more than 80% of the variation. Multiple regression equations were more accurate in ewes than in goats with R2 varying from 0.69 to 0.97 for the amount of ash and energy, respectively in Sarda ewes and from 0.66 to 0.95 for ash and water, respectively in Saanen goats. These results confirm that fat reserves and body composition can be predicted in lactating Saanen goats and Sarda ewes with high precision using multiple regression equations combining in vivo measurements.