The effects of fructooligosaccharide (FOS) on growth performance, immunity and predominant autochthonous intestinal microbiota of shrimp (Litopenaeus vannamei) fed diets with fish meal (FM) partially replaced by soybean meal (SBM) were evaluated. After acclimation, shrimps (1.82 ± 0.01 g/kg) were allocated into 15 tanks (25 shrimps per tank) and fed five different diets including positive control diet (C0, containing 250 g/kg FM and 285 g/kg SBM), control diet (C, containing 125 g/kg FM, 439 g/kg SBM) and three experimental diets supplemented with 1.0 g/kg FOS (T1), 2.0 g/kg FOS (T2) and 4.0 g/kg FOS (T3) to control diet (C) respectively. Shrimps were fed diets to apparent satiation three times per day, and 15 shrimps from each aquarium were randomly sampled and analysed at the end of the 6-week feeding trial. The results showed that FBW, WGR, SGR and SR decreased, while FCR and FI increased significantly in control (C) compared with positive control (C0). Besides, significantly decreased trypsase and lipase activities, and SOD, AKP and ACP activities were recorded in control (C) compared with positive control (C0). On the other hand, significantly improved SGR and decreased FCR were observed in groups T1, T2 and T3 compared with control (C). Moreover, lipase and amylase activities enhanced significantly in group T3 compared with the control (C), while GOT and GPT activities dropped significantly with the increment supplementation of FOS in diets. Compared with the control (C), SOD activity enhanced significantly and MDA level decreased significantly in groups T2 and T3, and improved AKP and ACP activities were observed in group T3. In addition, dietary FOS improved the microbial diversity, and suppressed several potential pathogens, such as Vibrio tubiashii, Vibrio parahaemolyticus and Photobacterium damselae-like strains in the intestine of shrimp. Overall, these results proved FOS could relieve the side effects induced by SBM and supported the use of 2.0-4.0 g/kg FOS in shrimp diets with FM partially replaced by SBM. K E Y W O R D S Fructooligosaccharide, growth performance, immunity, intestinal microbiota, Litopenaeus vannamei | 195 HU et al.

Thirty growing yaks Bos grunniens or Poephagus grunniens, 1·0-3·5 years and 50 -230 kg, from their native altitudes (3000 -4000 m), were used to study the basal metabolism in this species and to evaluate the effects of high altitude and season on the energy metabolism. Fasting heat production (FHP) was measured at altitudes of 2260, 3250 and 4270 m on the Tibetan plateau in both the summer and the winter, after a 90 d adaptation period at each experimental site. Gas exchanges of the whole animals were determined continuously for 3 d (4 -5 times per d, 10 -12 min each time) after a 96 h starvation period, using closed-circuit respiratory masks. Increasing altitude at similar ambient temperature (Ta) did not affect (P. 0·10) FHP in the summer, but decreased (P, 0·05) it at different Ta in the winter. However, the decrease of FHP in the winter was mainly due to the decrease of Ta instead of the increase of altitude. In the summer, the respiratory rate, heart rate and body temperature were unaffected by altitude, except for a decrease (P, 0·05) in body temperature at 4270 m; in the winter, they were decreased (P,0·05) by increasing altitude. In both seasons, the RER was decreased (P, 0·05) by increasing altitude. At all altitudes for all groups, the daily FHP was higher (P, 0·05) in the summer (Ta 6-248C) than in the winter (Ta 0 to 2308C), and the Ta-corrected FHP averaged on 920 kJ/kg body weight 0·52 at Ta 8 -148C and on 704 kJ/kg body weight 0·52 at Ta 2 158C respectively. We conclude that in the yak high altitude has no effect on the energy metabolism, whereas the cold ambient temperature has a significant depressing effect. The results confirm that the yak has an excellent adaptation to both high altitude and extremely cold environments.

No abstract

Four steers, average body weight 260p15 kg, fitted with portal catheters were used in a 4i4 Latin Square design to evaluate the influence of dietary protein degradability in the rumen on peptide and amino acid fluxes across the gastrointestinal tract. Dietary protein degradability was regulated by using different protein sources and the diets were calculated to contain 130 g CP\kg and 9n62 MJ ME per kg DM. Plasma concentrations of amino acids were analysed before and after acid hydrolysis of samples first subjected to chemical deproteinization and physical ultrafiltration, and peptide amino acids (PAA) were calculated as the difference between total and free amino acids (FAA). Portal blood flow and arterial concentrations of FAA and PAA were not affected by protein degradability or by diet. Venoarterial concentration difference and net portal flux of FAA tended to increase (P 0n10) with increase of degradable protein intake. Portal-arterial concentration difference (P 0n05) and net portal flux (P 0n10) of PAA increased linearly as dietary protein degradability increased. The proportion of PAA in total amino acid (FAAjPAA) net flux was not modified by dietary protein degradability or by diet, and the mean value as a proportion was 0n32. The major PAA absorbed were glutamate, leucine, aspartate and lysine for all diets, accounting in total for 0n50 of PAA flux. The results demonstrate that PAA may contribute significantly to AA flux across the portal-drained viscera (PDV) of steers, and both FAA and PAA net fluxes can be affected by degradable protein intake.

Growing yellow cattle (Bos taurus, n 30, 1·0 -3·5 years old and 75 -240 kg) from their native altitude (2000-2800 m) were used to evaluate the effects of altitude, ambient temperature (Ta) and solar radiation on the basal energy metabolism in this large mammal. Fasting heat production (FHP) was measured at altitudes of 2260, 3250 and 4270 m on the Tibetan plateau both in the summer and winter respectively, after a 90 d adaptation period at each experimental site. The gas exchanges of the whole animal were determined continuously for 3 (2260 and 3250 m) or 2 (4270 m) d after a 96 (2260 and 3250 m) or 48 (4270 m) h starvation period, using closed-circuit respiratory masks. Increasing altitude from 2260 to 3250 m at similar Ta in the summer significantly elevated FHP for all animals (P, 0·01), and from 3250 to 4270 m for young cattle (P,0·05); increasing altitude from 2260 to 3250 m in the winter also significantly elevated FHP (P,0·05), but the increase was mainly due to the decrease of Ta and the increase in wind speed. No results were obtained at 4270 m in the winter, due to the problems of the animals, adaptating to the altitude. The magnitude of FHP elevation caused by increasing altitude was greater with summer sunshine or winter wind than without them. Increase of Ta from 10·0 to 22·08C, in the presence of solar radiation, slightly (2260 m) or significantly (3250 and 4270 m, P, 0·01) elevated FHP, but slightly reduced it in the absence of solar radiation; decrease of Ta from 0·0 to 2 30·08C linearly increased FHP. At 3250 and 4270 m, FHP at the same Ta was higher with summer sunshine or winter wind (3250 m) than without them, but this did not occur at 2260 m. In conclusion, high altitude elevates FHP in yellow cattle in the warm season, and the summer solar radiation and winter wind at high altitude significantly increase metabolic rate. It may be also concluded that the effects of solar radiation on metabolic rate depend on the altitude and the environmental temperature.