The objective of the present study was to use electrical bioimpedance analysis (BIA) as an alternative method of evaluating the quality of bovine raw milk. Fourteen lactating purebred Dutch cows were used. For the analyses of milk quality and electrical bioimpedance, 140 ml milk per mammary quarter and a homogeneous sample of each animal were collected, totalling 70 samples. The criteria used to evaluate milk quality consisted of somatic cell count (CCS), total bacterial count (CBT), fat, protein, lactose, total solids (ST) and non-greasy solids (SNG) as required by IN No 62/2011. A monofrequential 50 kHz and 800 μA alternating current generator was used for electrical BIAs. The temperature of the raw milk was 5 °C for all samples. Primary resistance and reactance readings were obtained. From these values, the values of impedance, conductance and phase angle were obtained. Correlation analyses were performed to determine the variables used by the regression analyses. The regression analysis was performed using raw milk components as dependent variables and BIA measurements as independent variables. Lactose, ST and SNG were the components of milk that correlated best and presented moderate prediction equations in relation to BIA variables. The prediction equations using resistance showed R2 of 0.42 and 0.45 for ST and SNG, respectively. In the prediction equation for ST and SNG, the conductance resulted in R2 of 0.45, and 0.45, respectively. Regarding impedance, the R2 of 0.42 and 0.45 were obtained for the predicted equations ST and SNG, respectively. Thus, it can be concluded that BIA has the potential to estimate the composition and quality of bovine raw milk.
In this study, we evaluated the tissue composition, the ratios between different issues, and the allometric growth of tissues from the commercial cuts neck, shoulder, rib, and leg, and of the carcass of Texel lambs. Thirty uncastrated male lambs born from single calvings were used in this experiment. Lambs were weaned, confined individually, and distributed into five treatments with six replications. Each treatment consisted of a predefined slaughter weight (T23 -initial slaughter, T25, T30, T35, and T40). The proportion of bone decreased linearly in the shoulder, rib, and legs, but remained constant in the neck. The proportion of muscle decreased in the rib, whereas in the other cuts it remained constant. The percentage of fat increased as the slaughter weight of the lambs was increased, for all cuts. In all cuts and in the carcass, bone and muscle showed early growth (b<1), whereas fat displayed late growth (b>1). The proportion of bone decreased and fat increased linearly in the carcass, and the proportion of muscle was not influenced by the slaughter weight of the lambs. The muscle/fat ratio decreased in all cuts, and consequently in the half-carcass, as the slaughter weight was increased. The muscle/ bone ratio increased in the shoulder, rib, leg, and half-carcass, but there was no significant effect on the neck. The bone and muscle tissues showed early growth, whereas the fat had late growth in the different commercial cuts and carcass of Texel lambs. The tissue growth pattern of the shoulder may be representative of the allometric growth of the different carcass tissues. An increase in the slaughter weight of Texel lambs leads to a reduction of the muscle/fat ratio, due to the higher deposition of fat in the carcass of these animals. ResumoAvaliou-se a composição tecidual, a relação existente entre os diferentes tecidos e o crescimento alométrico dos tecidos dos cortes comerciais pescoço, paleta, costilhar e perna e da carcaça de cordeiros da raça Texel. Foram utilizados 30 cordeiros machos, não castrados e nascidos de parto simples. Os cordeiros foram desmamados, confinados individualmente e distribuídos em cinco tratamentos com seis repetições, sendo cada tratamento um peso pré-estabelecido de abate (T23 -abate inicial, T25, T30, T35 e T40). A proporção de osso diminuiu linearmente na paleta, no costilhar e na perna e se manteve constante no pescoço. A proporção de músculo diminuiu apenas no costilhar, enquanto que nos demais cortes se manteve constante. A porcentagem de gordura aumentou com a elevação do peso de abate dos cordeiros, em todos os cortes realizados. Em todos os cortes e na carcaça, o osso e o músculo apresentaram crescimento precoce (b<1), enquanto que a gordura apresentou crescimento tardio (b>1). A proporção de osso diminuiu e a de gordura aumentou linearmente na carcaça, enquanto que a proporção de músculo não foi influenciada pelo peso de abate dos cordeiros. A relação músculo/gordura diminuiu em todos os cortes e, consequentemente, na meia carcaça com o aumento no peso de ab...
The objective of this study was to evaluate the potential of in vivo bioimpedance analysis (BIA) as a method to estimate body composition in lambs. Thirty-one Texel x Ile de France crossbreed ram lambs were slaughtered at pre-determined intervals of average weights of 20, 26, 32, and 38 kg. Before the slaughter of the animals, their body weight (BW) and body length (BL) were measured. The values for resistance (Rs) and reactance (Xc) were collected using a single-frequency BIA equipment (Model RJL Quantum II Bioelectrical Body Composition Analyzer). The BIA main variables such as body bioelectrical volume (V), phase angle (PA), resistive density (RsD), and reactive density (XcD) were then 2 calculated. The soft tissue mass of the right-half cold carcass was analyzed in order to determine its chemical composition. Multiple regression analyses were performed using the lamb body composition as dependent variables and the measurements related to bioimpedance as independent variables. The best regression models were evaluated by cross-validation. The predictive model of moisture mass, which was developed by using XcD and V, accounted for 84% of its variation. Resulting models of percentage moisture (R 2 = 0.79), percentage lean mass (R 2 = 0.79), percentage fat (R 2 = 0.79), and fat mass (R 2 = 0.87) were obtained using RsD and V. Furthermore, the values of RsD regarding V, and PA in the prediction models accounted for 91% and 89% of variation in protein mass and lean mass, respectively. Bioimpedance analysis proved to be an efficient method to estimate the body composition of lambs slaughtered at different body mass stages.
RESUMO O objetivo desta pesquisa foi avaliar o efeito da suplementação privativa, com concentrado ou leguminosa, sobre as características da carcaça e dos componentes corporais de cordeiros lactentes mantidos em pastejo de azevém. Foram utilizados 27 cordeiros lactentes, distribuídos nos tratamentos que corresponderam aos sistemas de alimentação: cordeiros lactentes mantidos em pasto de azevém, cordeiros lactentes mantidos em pasto de azevém e suplementados com concentrado em comedouro privativo (creep feeding) e cordeiros lactentes mantidos em pasto de azevém e suplementados com leguminosa no pasto privativo (creep grazing). O concentrado era composto por milho, farelo de soja e calcário calcítico, e a leguminosa utilizada foi o trevo-branco. O delineamento experimental foi o inteiramente ao acaso. Os resultados foram submetidos à análise de variância, e as médias comparadas pelo teste de Tukey a 5% de significância. O conteúdo do trato gastrintestinal juntamente com bile e urina e a proporção de esôfago foram maiores (P<0,05) nos cordeiros mantidos em pasto de azevém. As proporções de fígado e intestino grosso foram maiores (P<0,05) nos cordeiros suplementados com concentrado. Os sistemas alimentares testados produzem carcaças com características semelhantes. A suplementação, com leguminosa ou concentrado, altera os componentes corporais de cordeiros lactentes mantidos em azevém.
The increase of sheep meat competitiveness in international markets can be attributed to the rise of the quantity and the improvement of the quality of the edible portion of sheep carcasses. Usually, carcass yield is established after the slaughter of the animals. Yet, when carcass yield is determined in vivo, it can be both a costly and subjective method. This study proposes models for predicting the physical characteristics of lamb carcass using bioimpedance analysis (BIA) in live animals. Thirty-one Texel × Ile de France crossbreed ram lambs were slaughtered at 20, 26, 32 or 38 kg of BW. Before the slaughter, values of resistance (Rs) and reactance (Xc) were collected using a single-frequency BIA equipment (Model RJL Quantum II Bioelectrical Body Composition Analyzer). Then, BIA main variables such as body bioelectrical volume (V), phase angle (PA), resistive density (RsD) and reactive density (XcD) were calculated. After slaughter, cold carcass weight (CCW), cold carcass yield (CCY), subcutaneous fat thickness (SFT), soft tissue weight (STW) and soft tissue yield (STY) were also measured. Multiple regression analyses were carried out using the physical characteristics as dependent variables and the bioimpedance values as independent variables. Predictive performance of the models was assessed using leave-one-out cross-validation. The prediction model of CCW was obtained using the V, PA and RsD (R2 = 0.97), STW through the V, RsD and XcD (R2 = 0.97), CCY by Rs, Z and XcD (R2 = 0.69), STY by V and XcD (R2 = 0.67), and SFT only for XcD (R2 = 0.84). The results indicated that BIA has the potential to predict carcass characteristics of lambs at different body masses.
RESUMOAvaliou-se o efeito de dietas contendo diferentes teores de borra de soja sobre o consumo de nutrientes, o ganho de peso, as características de carcaça e os componentes do peso vivo de cordeiros terminados em confinamento. Foram utilizados 25 cordeiros, machos, castrados, da raça Texel, distribuídos aleatoriamente em cinco tratamentos compostos por proporções de 0%, 2,89%, 5,77%, 8,65% ou 11,55% de borra de soja na matéria seca das dietas. Houve redução linear do consumo de nutrientes, com exceção do consumo de extrato etéreo, que aumentou linearmente. O peso vivo ao abate, o ganho de peso diário, os pesos e rendimentos de carcaça quente e fria, e os pesos de perna e de costilhar diminuíram linearmente, ao passo que as proporções de rúmen e do trato gastrintestinal, com conteúdo, bem como o conteúdo gastrointestinal, aumentaram linearmente com o aumento dos níveis de borra de soja nas dietas. A proporção de perna foi influenciada de forma quadrática. O aumento da participação de borra de soja na dieta de cordeiros em sistema de confinamento leva à diminuição do desempenho produtivo dos animais. Contudo, o lucro diário obtido por animal não é influenciado, podendo-se inferir que a inclusão de borra de soja até o nível de 11,55% da matéria seca total da dieta é uma alternativa viável para a terminação de cordeiros em confinamento. Palavras
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