246 FISH HATCHF.RY MANAGEMENT 



A simplified method to calculate the amount of daily feed is based on 

 monthly percent gain in fish weight. In conjunction with past records that 

 establish both growth in inches and conversion, Table 27 can be used to 

 project daily feed requirements on a monthly basis. To calculate the 

 amount of feed required for a one month period two values must be deter- 

 mined: (l) the gain in weight for the month; and (2) the percent gain for 

 the month. 



(1) Gain in weight = weight of lot on hand at the end of the 



month minus the weight of lot on 

 hand the start of the month. 



.s „ monthly gain in weight x 100 



(2) Percent gain = f-^ ^ ; 



weight at start of month 



The feed requirement during the month of July for 100,000 fish averag- 

 ing 100 pounds per 1,000 fish, or 6.30 inches, on July 1st can be calculated 

 in the following manner. The expected growth for the month of July is 

 0.60 inches and the feed conversion is 1.3 pounds of feed per pound of 

 growth. 



Length, July 1st 6.30 inches (lOO pounds/1,000 fish) 



Expected growth, July 0.60 



Length, July 31st 6.90 inches (132 pounds/1,000 fish) 



100,000 fish X 100 pounds/1,000 = 10,000 pounds July 1st 



100,000 fish X 132 pounds/1,000 = 13,200 pounds July 31st 



Expected gain in fish weight, July = 3,200 pounds 



The expected gain in fish weight, multiplied by the food conversion 

 determines the required pounds of feed for the month. 



Pounds of feed required for July = 3,200 pounds gain x 1.3 conversion 



= 4,160 pounds 



„ 3,200 pounds gain „„„, 



Percent gain=  ^ , ^ , ^ , = 32% 



10,000 pounds on hand July 1 



Table 27 shows that at the 30% rate of gain, fish should be fed 2.91% of 

 the monthly feed total per day during the first 8 days; 3.13% during the 

 second 8 days; 3.34% during the third 8 days; and 3.57% per day the 

 remaining days of the month. 



