The effects of protein restriction with subsequent re-alimentation on compensatory growth (CG) of juvenile soft-shelled turtles (Pelodiscus sinensis) were investigated. The turtles were fed five diets containing different crude protein content (T1: 29.24%, T2: 31.42%, T3: 34.19%, T4: 37.16%, C: 43.31%), while the energy content remained constant for 4 weeks (restriction period) and then re-fed a diet (43.31% crude protein) for 7 weeks (re-alimentation period). During the restriction period, feed conversion ratio (FCR) significantly increased in all protein-restricted groups (T1-T4) compared with the control group (C). At the end of the restriction period, body mass in groups T1 and T2 was significantly lower than that in the control group. During the re-alimentation phase, weekly body mass gain in group T1 was greater than that of the control from week 5 to week 10. FCR significantly decreased in group T1 compared with the control. No significant differences in final body mass between C and T1 groups were found at the end of the re-alimentation period. These results indicated that soft-shelled turtles receiving a diet in which protein was reduced from 43.31 to 29.24% (approximate 33% reduction) for 4 weeks achieved a 6 week complete CG response.

No abstract

To provide basic nutritional data and theoretical support for the processing and comprehensive utilization of the Chinese mitten crab, we performed a systematic study of the nutritional components of three edible parts, namely the hepatopancreas, gonads and abdominal muscle, of three groups of animals differing in body mass: 75.55 ± 1.56 g, 100.24 ± 2.04 g and 162.27 ± 3.44 g. The results showed that with a greater body mass, the water content was higher, the protein and ash contents were first higher and then lower, and the fat content was first lower and then higher. Amino acids (AAs), essential AAs (EAAs) and the EAA/AA ratio were first higher and then lower, all reaching the standard for high‐quality protein. The most limiting AA was valine. The EAA index was greater than 97 for all three edible parts of the medium‐sized crabs, indicating that crabs in this size group had very high nutritional value. The numbers of detected fatty acids were the same among the edible parts and the three size groups of the river crabs. Among the mineral elements measured, Ca, K and Na were the most abundant and showed a trend of first being higher and then being lower with a larger crab size. Although heavy metals were detected, the Cr, Pb and Cd levels were all within the permissible limits. Therefore, the nutritional quality of the three edible parts was greater for medium‐sized river crabs than for small and large mitten crabs.

The nutritional quality of muscle and skin tissues of hybrid sturgeon of different sizes, 1500.05 ± 1.50 g, 3002.25 ± 2.55 g and 4505.25 ± 4.15 g, were systematically studied to provide basic data for the processing and efficient use of hybrid sturgeon. The results showed that in hybrid sturgeon weighing 3002.25 ± 2.55 g, the muscle and skin accounted for the highest proportion of body weight. With increasing body mass, essential amino acids (EAAs), umami amino acids (UAAs) and total amino acids in each group first increased and then decreased, with the middle‐sized hybrid sturgeon showing the highest levels. The concentrations of fatty acids detected from the muscle and skin were the same among hybrid sturgeon of different weights, linolenic acid, DHA and linoleic acid were the top three polyunsaturated fatty acids in muscle and skin. In the muscle tissue of the three weight classes of hybrid sturgeon, the contents of Na, Mg and K ranked as the top three essential mineral elements, and the measured essential mineral elements all first increased and then decreased with increasing body mass. The mineral elements with the highest content in skin were Mg, Na and K. The content of mineral elements in skin was higher than that in muscle. The contents of Cr, Pb and Cd in the muscles and skin of the three weight classes of hybrid sturgeon were within the national standards. The results showed that the muscle nutritional quality of the medium‐sized hybrid sturgeon was the best.

We investigated the effect of the feeding regimen (group 1: fed twice daily at 8:00 and 18:00 for 28 days followed by 5 days of fasting; group 2: fed twice daily at 8:00 and 18:00 for 28 days and then fed once daily at 8:00 for 5 days; and group 3: fed twice daily at 8:00 and 18:00 for 33 days) on the circadian rhythms of the RNA/DNA ratio in the liver and muscle of the loach Misgurnus anguillicaudatus. The experiment was carried out with a photoperiod of 14 hr (light):10 hr (dark), with light from 07:30 to 21:30, followed by sampling. Cosine rhythm analysis and parametric analysis revealed obvious diurnal variation regularity in all three groups. The amplitude and phase of diurnal regularity in the RNA/DNA ratios increased after feeding. The highest value in group 2 was higher than that in group 3. Correlation analysis showed a correlation coefficient between the RNA/DNA ratios of the two tissues of 0.85. The coefficients of variation in the maximum RNA/DNA ratio and two cycles of chi‐square values in liver tissue were lower than those in muscle tissue, but the stability of the ratio was more reliable and representative in liver than in muscle. These results suggest the occurrence of some altered circadian rhythms of the RNA/DNA ratios in the liver and muscle of the loach M. anguillicaudatus and that the best sampling time was after 4 hr of daily feeding.