An experiment was conducted using ninety-six, day old broiler chicks to study the effect of inclusion of heat-treated rock phosphate (HTRP) instead of dicalcium phosphate (DCP) on performance of broilers. Total four diets were tested. Control diet (T1) was prepared using maize 54.08 %, soybean meal 25.73 %, deoiled rice polish 9.19 %, fishmeal 8.00 %, mineral mixture (MM) 3.0 % and vitamin supplements. All the diets were isonitrogenous and isocaloric (22% CP and 2800 kcal ME/kg).In T1, dicalcium phosphate (DCP) was exclusively used as phosphorus supplement. While, in other three diets, dicalcium phosphate (DCP) was replaced using HTRP @ 60, 80 and 100% (T2, T3, and T4). Inclusion of HTRP significantly increased the weight gain of broilers. Maximum gain was observed in broilers assigned T3 diet. Conversely, significant (P<0.05)>
Increase in the level of HTRP also reduced the feed intake significantly. As a result of which there was significant improvement in FER as well as PI in broilers with HTRP diets. There was also reduction in the cost of feeding and increase in the net return over feed cost due to incorporation of HTRP. Maximum net return over feed cost was noted in broilers assigned T3 diet. Hence, it was concluded that 80% HTRP can be incorporated instead of dicalcium phosphate (DCP) in broiler diets economically.
INTRODUCTION
In broiler farming, feed accounts to about 65-70 % of total cost of production.Beside cereals and protein supplements, next important input in broiler ration is mineral mixture. Phosphorus is a critical and expensive mineral used for preparing mineral mixture. Dicalcium phosphate (DCP) is used traditionally as phosphorus supplement in poultry diet.
However, due I to high demand and scarce availability, its cost is steeply increasing. Therefore, to reduce the cost of mineral mixture, it has become imperative to use alternate and economical phosphorus supplements.
One of the alternates is rock phosphate (RP), which is available in plenty at much lower cost. But on account of high level of fluorine in it10, its use is limited. To reduce the fluorine content of rock phosphate usually it is heat-treated. The heat-treated rock phosphate (HTRP) also contains fluorine but at much lower level than RP.
Therefore, present study was planned to see the utilization of heat-treated rock phosphate instead of dicalcium phosphate (DCP) in broilers.
MATERIALS AND METHODS
The experiment was conducted using ninety-six, day old broilers chicks randomly allotted to 12 replicates. Total four diets were used in the study. All the diets were iso-nitrogenous and iso-caloric containing 22% CP and 2800 kcal ME/kg as per BIS3.Feed ingredients used for diet formulation were maize, soybean meal, fish meal, deoiled rice polish, minerals and vitamins supplements. The ingredients were analysed for proximate constituents, energy, calcium and phosphorus content. Control diet was formulated using maize, 54.08 %, soybean meal, 25.73 %, DORP, 9.19 %, fish meal, 8.00 %, mineral mixture (MM), 3.0 % and vitamin supplements.
All the diets were same except the change in phosphorus supplement. Mineral mixture as reported in the Iiterature6 was used @ 3% in control diet. Diet I had only dicalcium phosphate (DCP) as phosphorus supplement. Whereas, in other diets, DCP was replaced using HTRP @ 60, 80 and 100% (T2, T3, and T4). The fluorine content of HTRP was only 1.81 %. Each diet was randomly allotted to three replicates of 8 chicks each.
The experiment was conducted for a period of 6 weeks. During the experiment, weekly body weight, feed intake and left over feed was recorded and weight gain and feed efficiency ratio (FER) was calculated. Feed samples were analyzed for proximate constituents1. While calcium and phosphorus contents were estimated by titrimetric method9. The energy content of the samples was estimated using titrimetric method5.
The performance of birds was measured in terms of weight gain, feed intake, feed efficiency ratio, performance index and economics of feeding. The performance index (PI) was calculated as detailed by Bird2. The data obtained during the study were analysed7 and significance between the treatments were tested using
RESULTS AND DISCUSSION
The performance of broilers in terms of body weight gain, feed intake, FER and PI for 0-4 and 4-6 weeks is presented in Table 1 and 2 while including cost of feeding as well as net return over feed cost for 0-6 weeks is presented in Table 3.Table 1. Performance of broilers on MM containing HTRP instead of dicalcium phosphate (DCP) (0-4 week)
Increase in HTRP above 60% reduced the weight gain significantly. Among HTRP groups, minimum weight was attained by those receiving D4 diet.Feed intake also increased due to incorporation of HTRP. Maximum intake recorded in broilers assigned T3 diet was comparable to those allotted T2 diet. While, minimum feed intake was registered in broilers offered T4 diet. Conversely, FER was maximum and significantly higher in broilers assigned T4 diet. FER of broilers assigned T2 diet was although bit lower but statistically comparable to those assigned T4 diet. Minimum FER was registered in broilers assigned T1 diet.
The PI was maximum and significantly (P
Minimum feed intake was noted in broilers assigned T4 diet. FER improved significantly (P<0.05)>
Table 2. Performance of broilers on MM containing HTRP instead of dicalcium phosphate (DCP) (4-6 weeks)
The cumulative performance for 0-6 weeks (Table 3) also revealed that inclusion of HTRP instead of DCP up to 80% level, increased the weight gain significantly.However, complete replacement of dicalcium phosphate (DCP) reduced it significantly.
Studies revealed that inclusion of HTRP instead of dicalcium phosphate (DCP) increased the weight gains of broilers significantly, however, it was true only up to inclusion of 80% HTRP. Complete replacement of DCP led to significant (P<0.05)->
As it was heat treated rock phosphate, it has low levels of fluorine (1.81%) and probably phosphorus was more available hence it improved the weight gain of broilers. The amount of fluorine ranged from 79.5 ppm in D2, 106.0 ppm in D3 and 132.5 ppm in D4. While the maximum and safe dietary level of fluorine in broilers is 300 ppm8. Thus, in all the groups fluorine level was within the tolerable limit.
Feed intake reduced due to inclusion of HTRP. It was minimum and significantly lower in broilers assigned T4 diet. As a result of it, FER improved significantly in HTRP groups but among these groups, differences were not significant (P>0.05). As like FER, PI also improved significantly due to use of HTRP. On account of higher weight gain and lower feed intake besides lower cost of HTRP, replacement of DCP led to significant reduction in the feeding cost of broilers.
However, among HTRP groups (T2, T3 and T 4) differences were non significant. The net return over feed cost also increased due to use of HTRP. It was higher and statistically similar in groups assigned T2 and T3 diets containing 60% and 80% HTRP instead of DCP. Hence, it was concluded that up to 80%, HTRP can be used instead of DCP in the mineral mixture of broilers economically.
Table 3: Performance of broilers on MM containing HTRP instead of DCP (0- 6week).
