International Journal of Aquaculture, 2016, Vol.6, No.12, 1
-
11
8
Continuing Table 5
6th month
Colour
Smell
Caking condition
Infestation
Coppens
®
Airtight
+
+
+
+
Coppens
®
Open
+ +
+++
+ ++
+*+
Multifeed
®
Airtight
+
+
+ +
+
Multifeed
®
Open
+ +
+ + +
+ ++
+
Vitafeed
®
Airtight
+ +
+ +
+ ++
+*+
Vitafeed
®
Open
+ + +
++
+ ++
+*+
Note: Normal = +, Dull = *, Mouldy = + +, Heavy mould = +++, Rancid = + +, Insect Infestation = +*+, Caking Condition = ++.
Table 6 Number of Insects Infestation and percentage occurrence per Kg of the feeds
Coppens
®
Multifeed
®
Vitafeed
®
Insect species
Tight
Open
Tight
Open
Tight
Open
Delia platura
0(0)
50 (61.73)
0(0)
50 (100)
0(0)
50 (100)
Blattaorientalis
0(0)
0(0)
0(0)
1 (2.4)
0(0)
0(0)
Gryllusasimilis
0(0)
0(0)
0(0)
1 (2.4)
0(0)
0(0)
Dermesteslardarius
0(0)
0(0)
0(0)
0(0)
0(0)
1 (2.3)
Phaeniciasericata
0(0)
0(0)
0(0)
0(0)
0(0)
1 (2.3)
Solenopsis germinate
0(0)
30 (37)
0(0)
0(0)
0(0)
40 (93)
Dermestes maculates
0(0)
1 (1.2)
0(0)
2 (3.7)
0(0)
1 (2.3)
Total no of Insects
0
81
0
54
0
43
The aim of feed storage is to reduce the rapidity at which feed deteriorates hence storage never enhances feed
quality however proper storage is in an effort to maintain the shelf life of feed. Mold growth in stored feeds has
been implicated to reduce nutritional value owing to the loss of dietary lipids, amino acids (especially lysine and
arginine) and vitamins by enzymatic digestion (Jones, 1987). Mold infestation was first noticed in vitalfeed under
open condition compared to other commercial feed (Table 5; Table 7). Thick mold cover on the surface of the feed
was first observed in February and increased till April. This could be attributed to higher relative humidity during
the period (66.38 – 71.53%) recorded in that month of the year (Table 8). Hence, Feed under open condition had
higher chances of mold infestation compared to feed stored in an airtight condition. This is in accordance with
Osuji, (1985) who reported that beyond 70% relative humidity mold infestation is set in. This observation is also
in accordance with Cockrell et al., (1971); NRC, (1981); New, (1987); Effiong and Eyo, (1997); and Eyo, (2001).
The feed under airtight condition had no such problem except for vitalfeed. Vitafeed
®
became damp and musty
with less moldy growth. However, this observation came later than the time of mold infestation recorded for other
opened fish feeds. This could be explained by the influence of factors such as the combination of the feed
ingredients, the chemical composition, and interaction of the feed, also interaction of the above-mentioned factors
may as well be the cause. Moreso the above observation may be explained by the high relative humidity created
within the closed chambers of the storage system (Vitalfeed) thereby increasing dampness and moisture content of
the feed (Figure 9) which in turn created a conducive environment that leads to mold proliferation. However, the
inside of the other feed under airtight condition was noticed to be dry throughout the storage period unlike the
Vitafeed
®
, hence, highlighting the role packaging plays in fish feed preservation. This is in line with the
observations of NRC, (1981).
Seven insects' species were identified to infest the feed, they were;
Gryllus assimilis
,
Blatta orientalis
,
Solenopsis
germinate
,
Delia
plutura
,
Phenicia
sericata
, Damistid bettle and Larder beetle (Table 6). The occurrence and
development of an insect infestation are dependent on many factors such as the source of insect available,
temperature, moisture, air condition of the feed and presence of other organisms, (Chow, 1980). In spite of the
insect infestation of the feed, no weight loss was observed among the feed stored under airtight and open
conditions throughout the storage period. This could be as a result of less number of insect infestations to the feed.
An actively reproducing population of insect can quickly consume a significant amount of feed and deteriorate the
physical quality (Pederson, 2000).The observed nutrition changes and pathogenic content of stored feed
demonstrated in this need to be taken into consideration when feeds are been stored by farmers for long times, the
aftermath effect of feeding fish with such feed need to be investigated to provide information on the performance
