食物类型对平胸龟幼体摄食和消化影响的初步研究

Effects of Food Type on Food Intake and Digestion of Juvenile Big-headed Turtles(Platysternon megacephalum)

在(25±1)℃水温下,以鱼肉、猪肉和配合饲料3种食物投喂平胸龟(Platysternon megacephalum)幼体,测定食物类型对其摄食、消化及饵料湿重转化率的影响。结果显示:食物种类不影响平胸龟幼体的摄入能,平均为139.3 J/(d.g),但显著影响幼龟的表观消化率、蛋白质和脂肪消化率以及饵料湿重转化率。其中,摄食配合饲料的表观消化率(91.9%)低于鱼肉(94.1%)和猪肉(94.7%),蛋白质消化率亦为配合饲料<鱼肉<猪肉,但配合饲料的脂肪消化率和饵料湿重转化率则显著高于鱼肉和猪肉。因此,从饵料湿重转化率及养殖效益考虑,配合饲料优于鱼肉和猪肉。

Husbandry is one of important measures that may protect the wild populations under threaten effectively. Bigheaded turtles（Platysternon megacephalum）, which is distributed in creeks of mountain area in southern China, Myanmar, Thailand and Vietnam, is one of the species currently suffering over-hunting and uncontrolled trade. Here we present information on digestive physiology of this turtle to provide important implication for its artificial culture. We collected juvenile big-headed turtles（mean mass, 103.5 g）from Quzhou, Zhejiang, China to determine the effect of food type on food assimilation of these turtles. The juvenile P. megacephalum had been raised at temperature a controlled room （ 25 ± 1 ）℃ with a light cycle of 14： 10（ L： D）at least two months before the experiments were carried out. The experimental animals were divided into three groups in which they were individually kept in 30 （diameter） × 50 （height）cm buckets with 100 mL water, and fed with fish, pork, and compound feed, respectively. After the turtles were starved for three days to ensure uniform post-absorptive states, they were provided with pre-weighed food at 9：00 throughout the 15 days of trail. The residual food was collected two hours later, and the feces were collected every two hours from 08：00 to 22：00, and extracted by a centrifuge from the water as well. The food and feces were oven dried at 65 ℃ for 24 h and weighed. Energy density of food and feces were determined by burning them in a GR-3500S adiabatic calorimeter（ Changsha Instruments）. Non-polar lipids were extracted from dried samples in a Soxhlet apparatus for a minimum of 5.5 h using absolute ether as solvent. Protein contents were determined using a Kjeltec 2300（GB/T6432-1994）. Our results indicated that food type did not affect food intake with a mean of 139.3 J/（ d · g）, but significantly influenced apparent digestive coefficient （ ADC）, digestive efficiencies of lipid （DEL） and protein （ DEP）, and conversion efficiency of food （CEF）. The ADC was significantly lower in compound feed group （91.9% ）than in fish （94. 1% ）and pork （94. 7% ）groups. A similar pattern was also found in DEP among different foods. By contrast,the CEF was substantially higher in compound feed group than in fish and pork groups. On the basis of CEF and the cost of food, compound feed is better than fish and pork in aquaculture.