Methionine levels in whiteleg shrimp How do dietary methionine sources and feeding frequency impact the post feed hemolymph methionine levels in whiteleg shrimp?
A
by Dr Karthik Masagounder, Head Aqua and Swine Research, Evonik Nutrition and Care GmbH, Germany and Dr D Allen Davis, Professor, Auburn University, USA n in-vitro study based on the enzymes extracted from shrimp hepatopancreas showed that shrimp are able to completely cleave the four available isomers of DL-methionyl-DL-methionine (AQUAVI® Met-Met) but at different rates. This allows delayed liberation and absorption of D- and
L- Methionine (Met) in the digestive tract. However, no in-vivo data was published showing changes in the postprandial profile of Met in the hemolymph – a fluid analogous to the blood in vertebrates – of shrimp fed different Met sources. We therefore instigated a study to investigate and compare postprandial Met levels in relation to other amino acids in the hemolymph of whiteleg shrimp fed diets supplemented with AQUAVI® Met-Met or DL-Met. The effects of different sources on the Met levels of shrimp hemolymph were evaluated under
Table 1: Dietary and nutritional composition of the experiment diets used in the study Ingredients (%)
Basal
DL-Met
Met-Met
Analysed nutrients %
Basal
DL-Met
Met-Met
Soybean meal
49.10
49.10
49.10
Dry matter
91.18
91.19
90.39
Fish meal
5.00
5.00
5.00
GE (MJ/kg)*
20.00
20.00
20.00
Wheat
25.00
25.00
25.00
Crude lipid*
8.00
8.00
8.00 37.41
Gelatin
7.00
7.00
7.00
Crude protein
38.65
37.11
Corn starch
1.83
1.83
1.82
Lys
1.96
1.89
1.90
Ca-P-dibasic
2.20
2.20
2.20
Met
0.52
0.84
0.83
Fish oil
5.89
5.89
5.89
Met+Cys
0.97
1.26
1.25
Trace minerals
0.50
0.50
0.50
Thr
1.26
1.22
1.22
Vitamin premix
1.80
1.80
1.80
Arg
2.63
2.53
2.55
Choline chloride
0.20
0.20
0.20
Ile
1.40
1.35
1.35
Stay C
0.10
0.10
0.10
Leu
2.44
2.38
2.38
Lecithin
1.00
1.00
1.00
Val
1.58
1.53
1.54
Cholesterol
0.08
0.08
0.08
His
0.82
0.80
0.80
DL-Met
0.00
0.30
0.00
Phe
1.64
1.59
1.60
AQUAVI® Met-Met
0.00
0.00
0.31
Met_free
0.01
0.29
0.03
Glycine
0.30
0.00
0.00
Met- Met_free
<0.02
<0.02
0.28
*calculated values.
26 | August 2020 - International Aquafeed