Effect of Substitution of Heat Treated Rock Phosphate With and Without Phytase for Dicalcium Phosphate on Performance and Nutrient Utilization in Egg Type Starters

This investigation was undertaken to study the utilization of heat treated rock phosphate without and with phytase, instead of DCP on performance and nutrient utilization of egg type starters. Three hundred and fifteen, day old White Leghorn chicks (WLH, Babcock BV-300) with identical weights were randomly distributed to 21 replicates of 15 chicks each and were allotted to 7 dietary treatments. In control diet (T₁) DCP was used as a sole source of P. Diets 2, 4 and 6 (T₂, T₄ and T₆) were tested to know the usefulness of using heat-treated rock phosphate (HTRP) replacing DCP @ 60%, 80% and 100% in comparison to T₁. While, diets 3, 5 and 7 (T₃, T₅ and T₇) were similar to T₂, T₄ and T₆ except the addition of phytase enzyme (@1 Phytase unit= 4.0 g of P) in those diets. Experiment was conducted for 0–8 weeks (Starter phase). The cumulative performance of starters indicated that use of HTRP instead of DCP produced better performance in starters. Best performance was noted in chicks assigned 60% HTRP diet. Similarly, in these chicks DM utilization and retention of nutrients (CP, EE, CF, NFE, Ca and P) was higher while cost/kg wt gain was lower. Incorporation of higher levels of HTRP reduced their performance and nutrient utilization. Use of 80% HTRP along with phytase instead of DCP did not influence their performance but led to better utilization of DM and retention of nutrients (CP, EE, NFE, Ca and P). Supplementation of phytase with higher levels (80% and 100%) of HTRP instead of DCP was responsible for better performance (weight gain, feed intake, FER and performance index), increased DM utilization and retention of nutrients in chicks. The serum enzymes (ALT, AST and ALP) and minerals (Ca and P) were not influenced significantly till 60% HTRP was used in the diet. But when it was completely replaced using HTRP, raised the concentration of serum enzymes (ALT, AST and ALP) but reduced the Ca and P concentration. Use of higher levels of HTRP increased the serum F concentration significantly (P<0.05). Use of HTRP along with phytase up to 80% of DCP did not influence their serum AST, ALP and P. However, ALT and Ca concentration reduced significantly when DCP was completely replaced by HTRP supplemented with phytase. Hence, it was concluded that 60% HTRP and 80% HTRP along with phytase was beneficial to replace DCP in the mineral mixture of egg type starters.