Aquaculture CRSP 21st Annual Technical Report
Cost Containment Options for Tilapia Production in Central Luzon,
Republic of the Philippines: Alternate Day Feeding Strategy
Tenth Work Plan, Product Diversification Research 2 (10PDVR2)
Christopher L. Brown
Marine Biology Program
Florida International University
North Miami, Florida, USA
Remedios B. Bolivar and Eddie Boy T. Jiminez
Freshwater Aquaculture Center
Central Luzon State University
Science City of Mu–oz, Nueva Ecija, Philippines
The growout efficiency and economics of using alternate day feeding in the pond culture of Nile tilapia (Oreochromis niloticus) was evaluated in an on-farm trial. This feeding strategy was compared with daily feeding to determine the effects on growth rate, survival, yield, and net profit. At harvest, the mean weight of fish in the daily feeding was 167.3 ± 53 g while in alternate day feeding it was 137.8 ± 72 g. The mean survival rates were 55% and 63% for the daily and alternate day feeding groups, respectively. Fish yields were 222 kg from the daily fed group and 200 kg from the alternate day fed group. These apparent
differences in mean weights, survival rates and fish yields from the two feeding schedules were not statistically significant.
The quantity of feeds was 475 kg in the daily feeding schedule and only 208 kg in the alternate day feeding schedule. Feed conversion ratios (FCR) were 2.24 and 1.0, respectively. The amount of feeds and FCR were significantly different between the two feeding schedules. The cost-benefit analysis, taking into account gross sales and fingerling, feeds and fertilizer costs resulted in a negative net return for the daily feeding (-P2,240 ha-1) while the alternate day feeding schedule gave a net return of
P43,095 ha-1. The study indicates that alternate day feeding strategy can provide another cost containment feeding option for tilapia farmers.
The determination of feeding strategies based on mathematical and economic models can be rather complex (Cacho, 1993). It is not known whether the reduction of feed costs without a net reduction in crop yield is a result of more efficient feed consumption (i.e. lack of waste), better feed utilization (increased feed conversion ratio) or both. It has also been argued that optimal feeding levels should be below the level supporting maximal growth on the basis of water quality concernsŃregularly feeding to the point of satiation increases the risk of waste, feed decomposition, and compromised fish health (Hatch and Kinnucan, 1993). The modeling of optimal feeding regimes is based on a mix of observations and assumptions. Most often, decisions about the amount to feed are left to chance, or the instincts of the farmer.
Feeding management strategies have been investigated for several species of fish (Singh and Srivastava, 1984; De
Silva et al., 1986; Srikanth et al., 1989; Diana, 1997). De Silva (1985; 1989) had presented a number of mixed feeding schedules which involved feeding the fish alternately with high and low protein feeds. The results of a study on Nile tilapia reared on some of the mixed feeding schedules (i.e., high protein feed alternated with the low protein feed) indicated comparable growth performance to those reared in entirely high protein feed. A substantial cost saving on feeds was realized and the nitrogen loading of the system reduced in such feeding schedules
(De Silva, 1985; De Silva et al., 1993).
A series of farm trials were concluded on costs and benefits of feeding strategies available to tilapia farmers (Brown et al., 2000; Bolivar et al., 2001; Bolivar et al., 2003). The experiments were designed to test the efficiency of production under conditions of variable feeding intensity. Earlier studies including those of Diana et al. (1996) have raised doubts about the efficacy of pushing the feeding schedule in order to maximize growth. Nevertheless, our studies have shown