A Biochemical Study of Fasting, Subfeeding, and Recovery Processes in Yellow‐Legged Gulls
TL;DR: The gulls quickly recovered body mass during the refeeding period, but while some plasma substances quickly reached their initial values, others showed many changes before the end of the experiment, which could reflect a process of metabolic restabilization.
Abstract: An investigation of the effects of fasting, subfeeding, and refeeding on plasma biochemistry was carried out on 22 captive yellow‐legged gulls Larus cachinnans Pallas. These birds showed the same fasting endurance model described in other species, but with an important decrease in glucose plasma concentration and very great differences between individuals when reaching the deterioration limit, suggesting a moderate physiological adaptation to long periods of fasting. A different model was proposed in subfed gulls in relation to fasted gulls, based on lipid and protein use, which could be reflected by changes in nitrogen wastes and triglyceride levels in this experiment. Thus, the subfed gulls might use protein directly from the diet as an energy source, thereby reducing the use of fat stores. The gulls quickly recovered body mass during the refeeding period, but while some plasma substances quickly reached their initial values, others showed many changes before the end of the experiment, which co...
Summary (4 min read)
- Many studies have been developed on the physiological response of birds when enduring food restriction.
- The second phase is a period of steady body mass and metabolism.
- In summary, this study has three objectives: (1) to know whether a seabird, the yellow-legged gull Larus cachinnans Pallas, uses the above-cited classic model of resource allocation during starvation, as shown in other bird species (thus, the authors will analyze differences with respect to the described pattern; Fig. 1).
- Moreover, (2) this species was chosen in order to compare changes during periods of moderate food restriction with periods of absolute fasting.
- These birds were transported to the wildlife recovery center La Cañada de los Pájaros (Huelva, Spain) and were housed in individual cages ( m).
- The study was performed with the per-4 # 4 # 4 mission of the appropriate authorities, avoiding any damage to the birds.
- For 2 wk, sardines (Sardina pilchardus Walbaum) were provided ad lib.
- Variable total body-mass loss was defined as the proportion of body-mass loss regarding weight at the beginning of the experiment.
- Nevertheless, after 8 d, three gulls from the fasting group died on the same day, without symptoms, and their lesser total bodymass loss the day before (15%) was finally established as the final limit before placing the gulls in the recovery period, refeeding them with food ad lib.
Blood Extraction and Weighing Procedures
- Blood samples were taken from the humeral vein (2.5 mL) every 2 d throughout the experiment, always before feeding, at the middle of the day (1100–1500 hours) to avoid any variation in blood chemicals caused by the circadian rhythm (Ferrer This content downloaded on Fri, 15 Feb 2013 07:10:25 AM.
- All use subject to JSTOR Terms and Conditions 1993).
- Winged infusion sets (Valu-Set, Becton Dickinson, Sandy, Utah) were used to prevent damage to the veins, applying them on alternate wings each time.
- Blood sampling was done immediately after capture.
- The gulls were weighed after blood collection with a dynamometer (Pesola; accuracy 5 g).
- Mean values of parameters were tested for differences between groups on the same day or in the same mass-loss rank by the Mann-Whitney U-test for independent samples.
- Within-group variations were tested with Wilcoxon matched pairs signedranks test.
- These nonparametric tests were used as a precaution since, as a result of small sample sizes in some analyses, normal distribution could not be ascertained for all parameters.
- The experiment effects were examined with repeated-measures ANOVA, where the treatment (fasting or subfeeding) was used as a factor (between-subject effect) and the samples obtained from the same bird throughout the experiment were used as repeated measures (within-subject effect).
- Moreover, repeatedmeasures ANOVA was used to analyze changes in mass or biochemical parameters in each group separately.
Initial and Final Values in the Deterioration Period
- That day, there were no differences among the three groups or between sexes (MannWhitney: in all parameters).
- The four birds from theP 1 0.05 control group did not show significant variations in total bodymass loss (repeated-measures ANOVA: , )F p 1.07 P p 0.4110, 30 and plasma biochemical traits (always ) throughout theP 1 0.05 experiment and are not used in the rest of the statistical analyses.
- Urea, uric acid, cholesterol, glucose, and alkaline phosphatase changed in both groups.
- There were no significant differences between these two groups the last day of the deterioration period regarding all the parameters, but inorganic phosphorus, calcium, and magnesium showed a tendency toward higher values in the fasting group (MannWhitney: ).P ! 0.12.
Weight and Biochemical Changes with Respect to the Classic Model
- In order to explain the changes in body mass throughout the deterioration period, the authors analyzed daily body-mass loss and total body-mass loss during the fasting phases according to the classic model (Fig. 2).
- For both variables, data of the first four sampling days from the beginning and, separately, data of the last four sampling days to reach the final limit of the deterioration period were analyzed ( in each group) in order to equil-n p 9 ibrate the sample size between the groups.
- A descent in daily body-mass loss between the second and the fourth day (proposed phase 1) were not significant in either group (Wilcoxon: , in both groups).
- All use subject to JSTOR Terms and Conditions gulls than in the restricted gulls (Mann-Whitney: ,Z p 1.99 ; see Fig. 2).
- P p 0.047 Concerning the biochemical parameters, the authors focused on uric acid and triglycerides as representatives of nitrogen residuals and fat use, respectively, synchronizing newly recorded data with respect to the first and the last day of the deterioration period (in Fig. 3, backward from last day).
Weight Changes in the Recovery Period
- Changes in total body-mass loss during the recovery period were used to explain the return of their gulls to the initial body weight (Fig. 4).
- The values at last day of the deterioration period were significantly higher than the values at the first sampling day of the recovery period (Wilcoxon; fasting group: Z p , ; restricted group: , ).
Changes in Biochemical Variables throughout the Experiment
- The first one was the individual differences in the number of days to attain the deterioration limit (commented on above), which prevents changes from being analyzed with respect to a chronological order.
- With the aim of avoiding these problems, the changes were analyzed using a general linear model (Table 2), which allowed testing of the linear relationship of each biochemical trait with the proportion of total body-mass loss, but not with time.
- All use subject to JSTOR Terms and Conditions 15%–25% ranks as a consequence of the sampling interval.
- The effects of the treatment in this period were significant in triglycerides (cited above), creatinine, and amylase concentrations (see Fig. 5).
- One of the objectives of this study was to test whether the changes during fasting in yellow-legged gulls could be adjusted to the classic model with three periods (see Fig. 1) used by different authors (e.g., Cherel and Le Maho 1985; Boismenu et al.
- Nevertheless, the next two phases were similar to the classic model, with a clear increase in daily bodymass loss the last day (phase 3).
- Changes in triglyceride concentrations in this group were similar to those changes of free fatty acids and b-hydroxybutirate observed in the classic model (Groscolas 1986; Cherel et al.
- F values from variance analysis (general linear model).
- Their results suggest that adult yellow-legged gulls show a moderate adaptation to prolonged fasting, with a biochemical pattern very similar to the classic model but with great differences between individuals.
Strategy of Subfed Gulls
- The second objective of this study was to compare the changes during periods of moderate food restriction with respect to periods of absolute fasting.
- All use subject to JSTOR Terms and Conditions in addition to the product from structural or muscular protein catabolism.
- Triglycerides were also different among the treatments in the deterioration period.
- Some studies have shown a regular maintenance of total protein levels during fasting (Jeffrey et al.
Changes in Other Biochemical Traits throughout the Experiment
- Other substances that were not used to explain the deterioration models could clarify the significance of the exposed results.
- Nevertheless, in this work a regular decline in glycemia occurred in both groups (see Fig. 5).
- In other gull species cholesterol remained stable during fasting, pathological processes, and migration (Jeffrey et al.
- An increment in diet protein produces a rise in the synthesis of cholesterol in the liver and intestines but a reduction in plasma concentration, while a lowprotein diet causes a high plasma cholesterol level, reducing its excretion (Leveille and Sauberlich 1961; Yeh and Leveille 1972; Lewandowski et al. 1986).
- The third objective of their study was to analyze the recovery process in a bird species.
- After this jump, body weight continued to be more or less stable but below the initial level of the experiment.
- In their study, many plasma parameters quickly recovered their initial values after refeeding (see Fig. 5), while other traits showed many changes before the experiment ended (see Fig. 5).
- This could mean that gulls did not reach their prefasting steady metabolism even though they quickly recovered their initial body mass.
- Production of this enzyme decreases during fasting in chickens and increases when food is restored (Kokue and Hayama 1972).
- Yellow-legged gulls showed a moderate physiological adaptation to extended fasting but the same model of biochemical changes in plasma that other more adapted species showed.
- Subfed birds seem to use lipids and proteins in a different way than fasted birds, probably suffering a lesser impact on their health.
- The gulls quickly recovered body mass during the refeeding period, but whereas some plasma substances quickly reached their initial values, others showed many changes before the experiment end, which could reflect a process of metabolic restabilization.
- Some differences in the results reported here with respect to a recent study on fasting in herring gulls can be explained by methodological interferences.
Did you find this useful? Give us your feedback
Cites background from "A Biochemical Study of Fasting, Sub..."
...Future studies may beneWt by selecting plasma as a target tissue; however, lipids must be extracted prior to analysis because 13C-depleted triglycerides are aVected by nutritional restriction (Alonso-Alvarez and Ferrer 2001)....
...Future studies may beneWt by selecting plasma as a target tissue; however, lipids must be extracted prior to analysis because (13)C-depleted triglycerides are aVected by nutritional restriction (Alonso-Alvarez and Ferrer 2001)....
Cites background or methods from "A Biochemical Study of Fasting, Sub..."
...legged gull, the rapid entrance into phase II is met with a decrease in plasma urea (rat and gull) and uric acid (gull) (8, 236)....
...Figure adapted, with permission, from Figure 1 in (8)....
Related Papers (5)
Frequently Asked Questions (2)
Q1. What are the contributions mentioned in the paper "A biochemical study of fasting, subfeeding, and recovery processes in yellow-legged gulls" ?
These results contribute to a better knowledge of fasting, subfeeding, and refeeding processes in birds and can be added to a recent study about fasting in gulls.
Q2. What future works have the authors mentioned in the paper "A biochemical study of fasting, subfeeding, and recovery processes in yellow-legged gulls" ?
Yellow-legged gulls showed a moderate physiological adaptation to extended fasting but the same model of biochemical changes in plasma that other more adapted species showed. Some differences in the results reported here with respect to a recent study on fasting in herring gulls can be explained by methodological interferences.