Growth, feed utilization and health of Atlantic salmon Salmo salar L. fed genetically modified compared to non-modified commercial hybrid soybeans

Abstract

The present paper represents a part of a major scientific effort aiming to reveal possible effects, nutritional or health related, of genetically modified (GM) feed ingredients for Atlantic salmon. For 3 months groups of post-smolt Atlantic salmon were treated with diets holding 130 g kg 1 of the protein as soybean, one which contained 800 g kg )1 GM type RR (Roundup Ready ä ), and compared with a standard counterpart (commercial hybrid, not isogenic line) analysed to be non-GM (nGM), and again compared with a standard fishmeal diet without soybean protein. All diets were composed to be within the category Ôcompositional equivalentÕ and held exactly the same proximate compositions, starch and sugar levels, above requirements for methionine and lysine, equal fatty acid profiles, vitamin, mineral and pigment contents. There was, however, a slight difference in levels of antinutrients between the three diets. The various dietary treatments resulted in more than tripling of fish weight in all groups. In addition no significant differences in feed utilization, whole body, liver and muscle proximate compositions, and no significant differences in muscle fatty acid profiles were measured. The diet without soybean of either type resulted in greater retention of lipid, but equal retention of protein (protein productive value). The relative sizes of liver, kidney, head-kidney and brain were the same in all dietary groups, while the relative size of the spleen showed significant differences between fish fed the genetically modified soy diet compared with fish fed the nGM soybeans. Fish fed the soy diets of either type also showed a somewhat reduced mean erythrocyte cell volume. All other haematological values were equal between diet groups. The detoxification system, measured as glutathione peroxidase (GPx) and lysozyme activities, showed equal values for all groups when measured in plasma and liver or head-kidney. The distal part of the intestine showed reduced sizes as an effect of soybean additions, without any differences between the GM and nGM type. Our results showed high growth, no mortality, haematological values within normal ranges, and efficient and equal responses in the detoxification system. This was a first indication that up to 130 g kg )1 RR-soybean protein can safely be used in diets for Atlantic salmon. However, there is still a need to elucidate higher inclusion levels of GM feed ingredients, and why spleen index was reduced, and if this was a long-or short-term effect. KEY WORDS

Utilization of genetically modified soybean meal in Nile tilapia Oreochromis niloticus diets

“…These results are in agreement with previous studies on other species such as catfish [11], Atlantic salmon [12,14,20,21], and rainbow trout [13]. Similar results were also reported in swine [8], rat [22], and broiler [23].…”

“…Feeding experiments with GM soybeans have been conducted in some species of animals including swine [8][9][10], catfish [11], Atlantic salmon [12], and rainbow trout [13]. From those studies, it is concluded that GM SBM is substantially equivalent to non-GM SBM.…”

A nutrigenomic analysis of intestinal response to partial soybean meal replacement in diets for juvenile Atlantic halibut, Hippoglossus hippoglossus, L.

“…This result is in agreement with previous studies with Atlantic salmon (Hemre et al, 1995;Heikkinen et al, 2006;Bakke-McKellep et al, 2007b), cod (Forde-Skjaervik et al, 2006), sea bass (Tibaldi et al, 2006), Egyptian sole (Bonaldo et al, 2006), channel catfish, Ictalurus punctatus (Evans et al, 2005), Japanese flounder (Kikuchi, 1999;Choi et al, 2004), Senegalese sole, Solea senegalensis (Aragão et al, 2003), and turbot, Scophthalmus maximus (Day and Gonzalez, 2000) where no significant changes in growth were detected over the trial periods.…”

Genetically Modified Soybean in Animal Nutrition

“…The authors indicated that GM soy protein intake affected pancreas function, evidenced by the early acute PAP mRNA increased levels and pancreas cellular changes followed by recuperation of acinar cells after 30 days. Evaluating the GM soybean in Atlantic salmon diet, enlarged spleen and possible impaired spleen function as the number of smaller-sized red blood cells simultaneously increased were indicated (Hemre et al, 2005). The same authors (Sagstad et al, 2008) reported lower plasma triacylglycerol levels and a significantly larger spleen somatic index in fish groups fed GM soybean compared to groups fed non-GM soybean.…”