A systematic literature review of the major factors causing yield gap by affecting growth, feed conversion ratio and survival in Nile tilapia (Oreochromis niloticus)

Abstract

Productivity among small‐ and medium‐scale tilapia farms varies considerably. The difference between the best performers and lower ones (yield gap), is affected by differences in growth rate and feed conversion ratio (FCR). FCR at the farm level is strongly influenced by survival of fish. In this study a systematic literature review of two databases (ASFA and CAB‐Abstracts) identified 1973 potentially relevant articles. Data from 32 articles that met the inclusion criteria were analysed using linear mixed models for the most important factors with significant contributions to growth [investigated through analysis of the thermal growth coefficient (TGC)], survival and FCR of Nile tilapia. Increasing crude protein (CP), dissolved oxygen (DO) and pH significantly decreased FCR and increased TGC. Increasing stocking weight (SW) significantly improved both FCR and survival. Temperature had the largest effect on FCR followed by DO, pH and CP. DO had the largest effect on TGC followed by CP and pH. This study confirms that the optimal rearing temperature for Nile tilapia is between 27 and 32°C. Improving management to optimize DO (> 5 mg/L), stocking density (3–5 fish/m2), SW (> 10 g) and CP (25 − 30%) will improve performance and survival in small‐ and medium‐scale tilapia farming. However, it is hard to influence temperature in ponds and cages while DO is largely influenced by aeration. Since many small‐ and medium‐sized farms do not have aeration, these major tilapia farming systems could benefit from genetically improved strains selected for resilience to highly fluctuating diurnal temperature and DO levels.

Meta‐analysis of genetic parameters of production traits in cultured shrimp species

“…Meta‐analysis studies with cattle, sheep, pig and goat also revealed moderately higher heritability estimates of growth traits (Akanno, Schenkel, Quinton, Friendship, & Robinson, 2013; Jembere et al., 2017; Safari, Fogarty, & Gilmour, 2005). Most of the aquaculture species are raised in the diverse water environments characterized by highly variable aquatic parameters among different ponds or production units, for example variation in temperature, salinity, pH and level of dissolved oxygen, which might greatly affect overall animal production (Mengistu, Mulder, Benzie, & Komen, 2019). Moreover, due to ease in transportation of fertilized eggs and larvae, aquaculture species are disseminated across many locations and experience great variability in rearing conditions.…”

Understanding the Interaction Effects between Dietary Lipid Content and Rearing Temperature on Growth Performance, Feed Utilization, and Fat Deposition of Sea Bass (Dicentrarchus labrax)

“…At the end of the second period (day 100), FCR of Group A (23 to 17 °C) increased while FCR of Group B (17 to 23 °C) decreased, although the differences in FCR between the two groups at day 100 were not statistically significant. The temperature for best feed consumption in many species, such as Nile tilapia ( Oreochromis niloticus ), hapuku ( Polyprionoxygeneios ), and others, is slightly higher than the one for best growth, and the temperature for best FCR is lower that the temperatures for best feed consumption and growth [ 44 , 45 , 46 ] This is in line with our results, as we found higher feed consumption and SGR in Group B (17–23 °C) without an associated improvement in FCR at the end of the trial (day 100).…”

Tilapia On-Farm Welfare Assessment Protocol for Semi-intensive Production Systems

“…For example, the mortality considered here refers to the total percentage recorded over the grow-out cycle, i.e., historical mortality. Rates of mortality vary considerably depending on the production stage and farm management adequacy, with 20-71% mortality reported for tilapia, and is an important tool for the identification of critical welfare points identification (40). However, in addition to the lack of this indicator usually observed on small farms, a low mortality rate does not guarantee the absence of disease (26) or a high degree of welfare (5).…”

“…The economic demand for a short production cycle and fast growth rate was likely related to the high protein levels in the fish diet. However, Mengistu et al (40) showed that tilapia FCR decreased with increasing CP, DO, and pH. Thus, this management may negatively affect fish FCR and their weight gain.…”