Pb0.05 and R-square of 0.6773, which indicated a negative effect of
increased stocking density or harvested density on final weight (Fig. 3b).
4. Discussion
The development of commercial feed formulations based on
alternative ingredients (non marine sources) has progressed for
numerous species. Previous results (Amaya et al., 2007a,b; Davis et al.,
2004; Ray et al., 2010; Roy et al., 2009; Suárez et al., 2009;) and the
present results from our production trials with shrimp stocked at
different densities, confirmed good results with plant based diets in
both pond and tank based systems. Shrimp production of 4612±
1621 kg ha−1(mean±standard deviation) from the pond trial in
this study was comparable to production of shrimp grown at the same
site under the same stocking density; e.g., Zelaya (2005) reported
shrimp production between 4328 and 4398 kg ha−1 for shrimp fed
commercial feed. Similarly, Venero et al. (2007) reported final
production between 5054 and 6482 kg ha−1 for shrimp fed diet
containing 10% fish meal. For the most part production problems
observed in this study were typical for semi-intensive pond systems;
however, four of the ponds had major water quality issues that
compromised production. Water quality problems stemmed from low
alkalinity of two ponds which were infested with surf clams. This
resulted in poor blooms, high TAN levels and wide swings in pH which
lead to poor production. Two additional ponds suffered from blue
green algae blooms followed by algae crashes and low dissolved
oxygen levels resulting in mortality of shrimp. It is typical for the
facility to have some mortality in the production ponds as a result of
low dissolved oxygen. Low dissolved oxygen problems stem from a
combination of algae crashes, high production densities and aeration
failure. Problems with low alkalinity and blue green algae are not
typical albeit, they have been seen at this site. Due to water quality
problems resulting in highmortality, four ponds were excluded from
the data sets. Unfortunately, the problematic ponds were in the two
low density treatments (17 and 26 shrimpm−2) resulting in only two
replicates per treatment.
As would be expected with increasing density, there was a clear
increase in net yield as density increased. As a descriptive tool, this
response was evaluated using regression analyses either as initial or
harvested stocking density using the entire data set. This response
was linear using either initial or final stocking density however, the fit,
as measured by R-square, was considerably lower for initial stocking
density as compared to the final harvest density (0.6556 compare to
0.9297) (Fig. 1a). These results demonstrate that under these
conditions, there was a linear increase in yield with density of the
shrimp. However, there were minimal shifts in final weights, survival
or FCR. Since variable survival could have influenced these results, the
final weights were also regressed against shrimp density at harvest
(number of shrimp m−2) for the entire data set. The R-square was
very poor (0.0033) using all the pond data. However, exclusion of
problematic ponds resulted in an R-square of 0.1832 (Fig. 1b)
indicating a slight decrease in final weights with harvest density.
Additionally, if one looks at the size distributions from the various
treatments, they appear very similar (Fig. 2). Hence, under the
investigated densities, a density dependent growth response was not
clearly apparent under the pond production conditions. Similarly,
there was no trend in the FCR or survival data under pond production
conditions.
Pb0.05 and R-square of 0.6773, which indicated a negative effect of
increased stocking density or harvested density on final weight (Fig. 3b).
4. Discussion
The development of commercial feed formulations based on
alternative ingredients (non marine sources) has progressed for
numerous species. Previous results (Amaya et al., 2007a,b; Davis et al.,
2004; Ray et al., 2010; Roy et al., 2009; Suárez et al., 2009;) and the
present results from our production trials with shrimp stocked at
different densities, confirmed good results with plant based diets in
both pond and tank based systems. Shrimp production of 4612±
1621 kg ha−1(mean±standard deviation) from the pond trial in
this study was comparable to production of shrimp grown at the same
site under the same stocking density; e.g., Zelaya (2005) reported
shrimp production between 4328 and 4398 kg ha−1 for shrimp fed
commercial feed. Similarly, Venero et al. (2007) reported final
production between 5054 and 6482 kg ha−1 for shrimp fed diet
containing 10% fish meal. For the most part production problems
observed in this study were typical for semi-intensive pond systems;
however, four of the ponds had major water quality issues that
compromised production. Water quality problems stemmed from low
alkalinity of two ponds which were infested with surf clams. This
resulted in poor blooms, high TAN levels and wide swings in pH which
lead to poor production. Two additional ponds suffered from blue
green algae blooms followed by algae crashes and low dissolved
oxygen levels resulting in mortality of shrimp. It is typical for the
facility to have some mortality in the production ponds as a result of
low dissolved oxygen. Low dissolved oxygen problems stem from a
combination of algae crashes, high production densities and aeration
failure. Problems with low alkalinity and blue green algae are not
typical albeit, they have been seen at this site. Due to water quality
problems resulting in highmortality, four ponds were excluded from
the data sets. Unfortunately, the problematic ponds were in the two
low density treatments (17 and 26 shrimpm−2) resulting in only two
replicates per treatment.
As would be expected with increasing density, there was a clear
increase in net yield as density increased. As a descriptive tool, this
response was evaluated using regression analyses either as initial or
harvested stocking density using the entire data set. This response
was linear using either initial or final stocking density however, the fit,
as measured by R-square, was considerably lower for initial stocking
density as compared to the final harvest density (0.6556 compare to
0.9297) (Fig. 1a). These results demonstrate that under these
conditions, there was a linear increase in yield with density of the
shrimp. However, there were minimal shifts in final weights, survival
or FCR. Since variable survival could have influenced these results, the
final weights were also regressed against shrimp density at harvest
(number of shrimp m−2) for the entire data set. The R-square was
very poor (0.0033) using all the pond data. However, exclusion of
problematic ponds resulted in an R-square of 0.1832 (Fig. 1b)
indicating a slight decrease in final weights with harvest density.
Additionally, if one looks at the size distributions from the various
treatments, they appear very similar (Fig. 2). Hence, under the
investigated densities, a density dependent growth response was not
clearly apparent under the pond production conditions. Similarly,
there was no trend in the FCR or survival data under pond production
conditions.
การแปล กรุณารอสักครู่..
และ pb0.05 r-square ของ 0.6773 ซึ่งชี้ให้เห็นผลกระทบของ
เพิ่มความหนาแน่นหรือเก็บเกี่ยวที่มีต่อน้ำหนักสุดท้าย ( รูปที่ 3B )
4 การอภิปรายการพัฒนาสูตรอาหาร
โฆษณาขึ้นอยู่กับส่วนผสมทางเลือก ( ไม่ใช่ทะเลแหล่ง ) มีขึ้นสำหรับ
ชนิดต่าง ๆ ผลลัพธ์ก่อนหน้า ( Amaya et al . , 2007a , B ; Davis et al . ,
2004 ; เรย์ et al . , 2010 ; รอย et al . , 2009ซู ซัวเรซ et al . , 2009 ; ) และนำเสนอผลจากการทดลองการผลิตของเรา
กุ้งเลี้ยงที่ความหนาแน่นต่างกัน ยืนยันผลลัพธ์ที่ดีกับโรงงานที่ใช้อาหารในบ่อและถังตาม
ทั้งระบบ การผลิตกุ้งของ 4612 ±
1537 กกฮา− 1 ( ค่าเฉลี่ยส่วนเบี่ยงเบนมาตรฐาน± ) จากบ่อทดลอง
การศึกษาเปรียบการผลิตกุ้งโตพร้อมกัน
เว็บไซต์ภายใต้ความหนาแน่นเดียวกัน เช่นg., Zelaya (2005) reported
shrimp production between 4328 and 4398 kg ha−1 for shrimp fed
commercial feed. Similarly, Venero et al. (2007) reported final
production between 5054 and 6482 kg ha−1 for shrimp fed diet
containing 10% fish meal. For the most part production problems
observed in this study were typical for semi-intensive pond systems;
however, four of the ponds had major water quality issues that
compromised production. Water quality problems stemmed from low
alkalinity of two ponds which were infested with surf clams. This
resulted in poor blooms, high TAN levels and wide swings in pH which
lead to poor production. Two additional ponds suffered from blue
green algae blooms followed by algae crashes and low dissolved
การแปล กรุณารอสักครู่..