The relationships between specific dynamic action, nutrient retention and feed conversion ratio in farmed freshwater Chinook salmon (Oncorhynchus tshawytscha)

Abstract

Improving the feed conversion ratio (FCR; the amount of feed consumed relative to the amount of weight gain) can reduce both production costs and environmental impacts of farmed fish. The aim of this study was to investigate what drives FCR to understand how nutrients are retained, as well as the amount of oxygen consumed for digestion, absorption and assimilation (a metabolic process known as specific dynamic action, SDA). Feed‐efficient and inefficient Chinook salmon (Oncorhynchus tshawytscha) in fresh water were identified using ballotini beads and X‐radiography that tracked individual feed intake across three assessment periods under satiated feeding. This allowed a comparison of physiological traits and body composition between the two FCR phenotypes over two time points as Chinook salmon grew from 305 to 620 g. Fish with higher daily feed intake (DFI) had higher daily weight gain (DWG) as expected. Nonetheless, the relationship between FCR and DFI as well as FCR and DWG was variable between time points. FCR and DWG were not correlated at the first time point and were negatively correlated at the second time point. In contrast, FCR and DFI were positively correlated at the first time point but not the second. Despite this, efficient fish ate smaller meals and retained more protein, lipid and energy in their body tissues. There was no detectable difference in metabolism between the two FCR phenotypes with respect to minimal resting metabolic rate, maximum metabolic rate, aerobic scope, or SDA parameters. In conclusion, FCR is not consistently associated with growth and metabolic differences in freshwater Chinook salmon, but FCR‐efficient fish retain more nutrients and consume smaller meals.

Effects of dietary supplementation with mannan-rich oligosaccharides and solid-state fermented Aspergillus niger on the growth performance of juvenile Asian seabass, Lates calcarifer

“…Additionally, a negative association was found between FCR and ADC, indicating that fish with higher ADC values utilized nutrients more effectively, enhancing growth efficiency (Al-Noor et al 2023). Furthermore, we hypothesize that the significant inverse relationship between FCR and nutrient retention (NR) observed in the present study suggests that feed 40 Effects of dietary supplementation with mannan-rich oligosaccharides and solid-state fermented... additives could increase nutrient assimilation and decrease requisite feed quantities, which Elvy et al (2023) report in their empirical findings on freshwater Chinook salmon (Oncorhynchus tshawytscha (Walbaum)).…”

Dietary Supplementation with R-(+)-Limonene Improves Growth, Metabolism, Stress, and Antioxidant Responses of Silver Catfish Uninfected and Infected with Aeromonas hydrophila

“…The production parameters were evaluated through weight, standard length, weight gain (WG) = (final weight − initial weight), specific growth rate (SGR) = [(ln final weight − ln initial weight)/time] × 100, [39], feed conversion rate (FCR) = (feed intake/weight gain), [40], feed intake (FC) = (percentage of feed consumed per day), [41], hepatosomatic index (HSI) = (liver weight/body weight) × 100, and survival = (final number of fish/initial number of fish) × 100, [42]. The recorded mortality data were used to calculate the relative survival percentage (RSP), RSP = 1 − [(mortality (%) in the treated group)/(mortality (%) in the control group)] × 100 [43].…”