Preliminary study for phenotypic description of vertebral abnormalities in triploid trout subjected to prolonged deficiency in phosphorus

Abstract

Summary In trout farmed in freshwater, the use of low phosphorus diet and other concurrent changes in food formulations could affect the normal growth of the skeleton and enhance the occurrence of vertebral abnormalities. Hence, it is important to refine diagnostic of malformations to quickly detect signs of P deficiency during production. Two practical diets consisting of P‐deficient (0.5% total P) and P‐sufficient (0.9% total P) were formulated. Experiments were conducted on all‐female juvenile triploid rainbow trout (initial mass ~60 g) until fish fed continuously with P‐sufficient diet reached <850 g (241 days; 12°C; 18:6 D:L). The choice of using practical diets as well as triploid trout were made in order to adapt to the context of production. Early P‐deficient and P‐sufficient trout were fed continuously (starting at day 0 for 241 days) with the respective diets while late P‐deficient trout only started feeding on P‐deficient diet at day 134 of the experiment. Growth performance were used to assess P deficiency and induced vertebral abnormalities were count and described using the classification suggested by Witten et al. () for Atlantic salmon. Our results showed that P deficient diet impaired vertebral mineralization and growth performance. The P deficient vertebrae showed increasing evidence with time of compression and reduction of intervertebral spaces (vertebrae showing pronounced biconcave end plates ‐ type 11 have evolved into platyspondyly; type 1, 2, 3 and 4). As P deficiency seems to affect all vertebrae along the vertebral column, examination of the caudal region alone could enable to increase the resolution of x‐rays and minimize time‐consuming efforts for analyses. The dimensions of rearing tanks might be responsible of high frequency of post‐cranial vertebrae precluding conclusion on the intensity of the effect of P deficiency.

Effect of dietary phosphorus levels on growth and body composition of crucian carp, Carassius auratusunder indoor and outdoor experiments

“…The research found that P deficiency decreased final length and weight significantly, and increased feed conversion in early P-deficient when compared to P-sufficient trout. However, 107 days of late P deficiency did not affect final length and weight significantly (Deschamps et al 2014). The initial body weight in the present study was about 40~45 g, while in many of the previous studies, fish used in the experiments were less than 10 g (Roy & Lall 2003;Mai et al 2006;Zhang et al 2006;Shao et al 2008;Sukumaran et al 2009;Luo et al 2010;Xie et al 2011;Yuan et al 2011;Liang et al 2012;Yu et al 2013), which should be more sensitive to P supplement.…”

A primary phosphorus‐deficient skeletal phenotype in juvenile Atlantic salmon Salmo salar: the uncoupling of bone formation and mineralization

“…The increased P demand of S. salar after smoltification is well documented (Albrektsen et al , ; Fjelldal et al , ), and several types of skeletal deformities, diagnosed on radiographs, have been related to dietary P deficiency: vertebral body compression, abnormal softness and structural distortion (Baeverfjord et al , ; Sullivan et al , 2007 a , b ; Fjelldal et al , ). Deschamps et al () observed on X‐rays from P‐deficient rainbow trout Oncorhynchus mykiss (Walbaum 1792) decreased intervertebral spaces, homogenous compression of vertebral bodies, a combination of abnormalities, irregular compression and undersized vertebral bodies. Also, hyper radio‐dense vertebral bodies have been linked to mineral deficiency due to the development of ectopic cartilage in bone marrow spaces (Helland et al , ).…”

“…The increased efficiency in P use must, of course, not come at the expense of animal health and welfare. Thus, there is a growing demand to increase the digestibility of P in fish diets (Sullivan et al , 2007 a ) and to determine the quantity of dietary P content that is required for healthy growth and healthy skeletal development in farmed fishes (Åsgård & Shearer, ; Roy et al , ; Deschamps et al , ). Greater knowledge of the mechanisms by which P deficiency causes skeletal malformations can contribute to improve the management of P resources in aquaculture.…”

Responses of different body compartments to acute dietary phosphorus deficiency in juvenile triploid rainbow trout (Oncorhynchus mykiss , Walbaum)

“…Trout were starved 2 days prior to all sampling events. Diet compositions (Table ) were adapted from an open formulation previously developed at Guelph University and successfully tested in our laboratory (Koko et al., ; Deschamps et al., ; Poirier Stewart et al., ).…”

“…8 × 10 in., Lot 366018, Kodak Industry, France). As post‐cranial and ural vertebrae can develop abnormalities irrespective to their nutritional condition (Deschamps et al., , ), we focused on caudal vertebrae (V31‐44) using the regionalization proposed by Kacem et al. ().…”