The use of ultrasound measurements for monitoring subcutaneous fat and muscle depths of Churra
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Data
2009
Autores
Silva, Severiano
Santos, Virgínia
Azevedo, Jorge Manuel Teixeira de
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Resumo
Throughout the Northeast of Portugal most sheep are raised under extensive production systems with
seasonality of feed resource availability. Depending on the severity and length of the scarcity, the ewes
use their body reserves, which results in significant variations of body weight (BW) and body condition.
Objective techniques, such as real time ultrasonography (RTU), are able to monitor body reserves during
food shortage periods. Our aim was to monitor subcutaneous fat (SF) and Longissimus thoracis et lumborum
muscle (LM) depletion using RTU. Eighteen non-lactating and non-pregnant Churra da Terra Quente ewes
were fed restricted diets to lose BW (49±5 to 37±1kg) during 42 weeks and were scanned biweekly using
an AlokaSSD500V with a 7.5 MHz probe. The probe was placed over the 13th thoracic (13T) and between
the 3rd and the 4th (34L) vertebrae. At these sites SF depth (SFD) and LM depth (LMD) were measured by
image analysis using ImageJ software on digitised ultrasound images. Relationships between BW and RTU
measurements and the relative growth of SFD and LMD were analysed by regression. The SFD growth
relative to BW was obtained after log transformation of Huxley allometric equation. Both SFD and LMD
were depleted (SFD: 7 to 3mm; LMD: 22 to 14mm). The decrease of 1mm on SFD and LMD represented
2.4 and 1.4kg of BW loss, respectively. The relative growth of SFD (SFD13T: b=1.73; SFD34L: b=1.62,
both b>1, P<0.01) confirmed that subcutaneous fat varies highly with body condition. Results suggest
that RTU can be used to monitor SFD and LMD depletion. It can also be concluded that RTU is useful to
evaluate the relative growth of subcutaneous fat in different body regions.