Effect of feeding frequency on the daily rhythms of acidic digestion in a teleost fish (gilthead seabream)

Abstract

Gilthead seabream is a fish species of great importance in Mediterranean aquaculture, attracting many studies on nutrition and chronobiology, although nothing is known about the effect of feeding frequency on the daily rhythms of the gastric digestion process. In this article, we investigated daily rhythms in stomach fullness, gastric and intestine pH, as well as pepsin activity and expression of pepsinogen and proton pump in juvenile fish under three different feeding protocols: (A) one daily meal at 9:00, (B) two daily meals at 9:00 and 17:00 and (C) continuous feeding during the daytime. The results revealed that feeding protocol affected significantly the rhythm of gastric pH and the pepsin activity pattern. The gastric pH exhibited significant daily rhythms in the three cases with the acrophase located at night in the regimes A and B and during daytime, in the regime C. In the regimes A and B, the pepsin activity peaked few hours after the meals, although the afternoon meal in B produced a higher peak. In the regime C, the peak occurred in the middle of the feeding period. Lowest total pepsin activity was observed in regime A, and the highest activity with the regime C. In contrast, the pepsinogen gene expression remained low along the daily cycle, with an expression peak just before or after the morning meal in regimes A and C, respectively. The proton pump gene expression was also practically constant with a peak right after the morning meal in the regime C. On the other hand, intestinal pH showed a postprandial increase after the first morning meal in all the three treatments, recovering the resting values in the dark period. Two meals and continuous feeding allowed a better and prolonged gastric digestion and consequently the juveniles exhibited better growth with the same daily ration of food. In short, while the gastric digestion pattern is mainly driven by pH changes induced by the time of food ingestion, the regulation of the intestinal digestion seems to be more independent of the feeding protocol.

Effect of increased rearing temperature on digestive function in cobia early juvenile

“…Contrary to this, the pancreatic trypsin activity exhibited a daily cycle with the expected increase associated with the intestinal alkalization when the chyme is released from the stomach. Such daily pattern has been already reported in other fish species (Rosero, 2013;Yúfera et al, 2014). It is also interesting to note that the proteolytic activity in the stomach was much higher than in the intestine.…”

“…A similar effect on the intestinal pH was described at increased temperature in channel catfish Ictalurus punctatus (Page et al, 1976). The same effect in the anterior intestine was also detected in other species when feed only one meal (Bucking and Hood, 2009;Rosero, 2013;Yúfera et al, 2014). A decrease of the intestinal pH has been reported for different freshwater species associated to seasonal increased temperatures (Solovyev et al, 2018).…”

“…In our study we considered two meals according to the customary use in hatcheries for this species in this region (Nguyen, 2013). With this feeding protocol we found more realistic overview of the digestive function but with additional complications to interpret results because fish may change the feeding behavior and daily digestive patterns when have the possibility to choose among different daily meals (Montoya et al, 2010;Yúfera et al, 2014).…”

Estimating the effect of different factors on the digestive bioaccessibility of protein by the Senegalese sole ( Solea senegalensis ); combination of response surface methodology and in vitro assays

“…Gut transit time is other critical factor that determines how long the food is being digested under given luminal conditions and that may change among species (Nikolopoulou et al, 2011). In addition, while in the present case, the pH was considered a fixed factor, in other cases it may be considered an additional variable, considering that each species has a particular acidification strategy modulated by the feeding regime (Papastamatiou et al, 2007;Yúfera et al, 2012Yúfera et al, , 2014Hlophe et al, 2014). It is deduced that the use of this approach in other species should require adaptation to the specific features of their digestion process.…”

Effects of different feeding frequencies on growth, feed utilisation, digestive enzyme activities and plasma biochemistry of gilthead sea bream (Sparus aurata) fed with different fishmeal and fish oil dietary levels

“…Most of these studies have been performed on juvenile fish, which is consistent with the high metabolic and feeding demand at this stage where incorrect feeding frequency can have critical consequences on growth and survival (Lee et al, 2016). At this stage, different feeding frequencies were associated with growth, feeding behaviour, feed utilisation, digestive physiology, gastric evacuation, blood biochemistry, antioxidant status, immune response, fish welfare and water quality (Booth et al, 2008;Xie et al, 2011;Yúfera et al, 2014;Guo et al, 2018;Imsland et al, 2019;Pedrosa et al, 2019).…”