Dietary phosphorous and protein supplementation enhances seawater growth and reduces severity of vertebral malformation in triploid Atlantic salmon (Salmo salar L.)

Abstract

Diploid (2N) and triploid (3N) sibling post-smolts were divided between six sea pens and fed: a standard nutrient package diet (2 x 2N SP, 2 x 3N SP), or an iso-energetic nutrient boosted package (2 x 3N BP) until market size. 3N groups initially grew significantly faster than 2N, and by harvest, 3N BP weighed significantly more (3210 ± 87g) than 2N SP or 3N SP (3007± 64g; 2965 ± 88g), while there was no significant difference in weight between ploidy in SP diet. Higher visible vertebral (9.6 ± 0.4%) and jaw deformities (10.6 ± 1.2%) were observed in 3N compared to 2N (0.9 ± 0.1%; 1.3 ± 0.5%).However, x-ray radiography revealed that 3N BP and 2N SP had comparable levels of severely affected individuals to that at time of sea transfer, while 3N SP showed a 3 fold increase in the severity of malformed individuals. The tail region (R3) in 3N SP fish had both the lowest vertebral strength and stiffness and the highest number of deformed vertebrae. Fillet quality attributes were comparable between diet and ploidy. These findings showed that triploid growth rate can be sustained until harvest throughout the seawater phase by using a nutrient boosted diet, and furthermore, the progression of spinal deformity beyond that at sea transfer can be stabilised by increasing dietary P during the marine phase. The study generates new data on dietary requirements of triploid Atlantic salmon that provides a significant improvement in farmed triploid welfare, allowing exploitation of faster growth rates and highlights the need to develop "triploid specific" aquafeeds rather than the use of conventional diploid diets.We look forward to receiving your feedback. Cover Letter  Triploid Atlantic salmon growth rate can be sustained during marine rearing using nutrient boosted diets  Progression of skeletal malformation development can be prevented during marine rearing of triploid Atlantic salmon by increasing dietary phosphorous  The occurrence of skeletal malformation in triploid Atlantic salmon must be addressed during freshwater rearing in the first instance Highlights (for review)This study demonstrates that triploid Atlantic salmon have higher dietary requirements than their diploid siblings and that supplementing dietary phosphorous can prevent further progression of deformity during marine rearing. Tailored triploid specific aquafeeds must be formulated to support growth and prevent deformity in order to minimise welfare implications and allow exploitation of faster growth potential of triploid salmon within industry. were observed in 3N compared to 2N (0.9 ± 0.1%; 1.3 ± 0.5%). However, x-ray radiography 7 revealed that 3N BP and 2N SP had comparable levels of severely affected individuals to that comparable between diet and ploidy. These findings showed that triploid growth rate can be 12 sustained until harvest throughout the seawater phase by using a nutrient boosted diet, and 13 furthermore, the progression of spinal deformity beyond that at sea transfer can be stabilised 14 by increasing dietary P during the m...

Concurrence of lower jaw skeletal anomalies in triploid Atlantic salmon (Salmo salar L.) and the effect on growth in freshwater

“…; Smedley et al . ). Overall in Atlantic salmon, the development of lower jaw skeletal anomalies has been associated with several factors such as genetic predisposition especially in triploids (Sadler et al .…”

“…However, LJD has been linked to a lack of dietary phosphorus (Roberts, Hardy & Sugiura 2001;Fjelldal et al 2016). The findings of Fjelldal et al (2016) suggest that LJD may occur anytime in early development when fish are not supplied with an appropriate amount of dietary P. Furthermore, it has been shown that triploids have a higher dietary P requirement than diploids (Fjelldal et al 2016;Smedley et al 2016). Overall in Atlantic salmon, the development of lower jaw skeletal anomalies has been associated with several factors such as genetic predisposition especially in triploids (Sadler et al 2001), a deficiency in dietary elements (Sadler et al 2001), high growth rates (King & Lee 1993;Taylor et al 2014;Fraser et al 2015), high incubation temperatures (Fraser et al 2015) and the different requirements for phosphorus in triploids (Fjelldal et al 2016).…”

Mineral nutrition and bone health in salmonids

“…The prevalence of deformed vertebrae in triploid salmon fed low P diet (1%, total P) was threefold higher compared with diploids (Smedley et al . ). Increasing the level of dietary phosphorus (1.2–1.4%, total P) effectively reduced the incidence of these anomalies in triploid salmon (Fjelldal et al .…”

“…; Smedley et al . ). Correlation regression analysis of literature data revealed that the relation between dietary P and skeletal deformities is to a greater extent significant in triploids, than diploids, although the variation was high within triploids (Fig.…”

“…The tail region of the vertebrae (Smedley et al . ) and lower jaw (Fjelldal et al . ) are reported to be more susceptible to low dietary P‐induced deformities in triploids.…”