EFFECT OF SUPPLEMENTATION OF CRYSTALLINE LYSINE AND THREONINE ON PERFORMANCE OF WL LAYERS FOR CORN-SOY DIET

Minimizing the cost of production as well as utilizing the correct requirements of amino acids in place of crude protein in commercial layer diet is important to increase the profit and also to minimize the pollution in terms of nitrogen emission. Lysine is considered as an ideal amino acid, and fixing the ratios of other amino acids based on lysine is ideal. In this concept two trials were conducted with objectives of assessment of digestible lysine (d. lysine), digestible threonine (d. threonine) and other d. amino acid ratios with regard to d. lysine for optimum production in WL layers (25-44wks of age). For experiment –I day old pullets (BV-300) were procured and reared up to 25 weeks as per the schedule provided. Five hundred and twenty eight pullets with uniform body weight were taken and fed with 2 protein levels (13.36 and 15.78%) with five concentrations of d. lysine (0.50, 0.55, 0.60, 0.65 and 0.70%) and a control group with 17% CP and 0.70% lysine. A total of 11 treatments, each consisting of 6 replicates with 8 birds were utilized (11x6x8 =528). Birds were maintained under ideal management conditions. Egg production (EP), feed intake (FI), feed intake/egg (FI/E), egg weight(EW), egg mass(EM), feed efficiency ( FE), Mortality, body weight gain, egg shell defects (ESD) were calculated/period (28 days). Two eggs /replicate/period were break opened and analyzed for quality parameters viz. Albumen index (AI), Haugh unit score (HU), Yolk index (YI), yolk color (YC), shell thickness (ST), shell weight percentages. Blood was collected from two birds/replicate, serum was separated and analyzed for immunological and for bio chemical parameters. Economics were calculated based on number of eggs produced, sale price of an egg and feed cost /production of an egg. Intake of amino acids in terms of mg/bird/day was also calculated. Results of the experiment –I revealed that WL layers performance was optimum at 0.65 and0.60 percent d. lysine concentration in terms of hen day egg production (HDEP) and cost economics. Whereas, Feed intake/hen/day (FI/h/d), Feed intake/egg (FI/E), feed intake/Dozen eggs (FI/Dozen eggs), egg shell defects (ESD), mortality, Albumen index(AI), shape index (SI), shell thickness (ST), shell weight (SW), serum biochemical and immunological parameters were not influenced (p >0.05) by the concentration of d. lysine (0.50,0.55,0.60,0.65 and 0.70%) in diet of WL layers. Whereas, HU, YI, YC values were higher at 0.70, 0.50, 0.50 percent d. lysine concentration in low crude protein (LCP) group, but at 0.50, 0.70, 0.50 concentrations of d. lysine in High Crude Protein (HCP) group. Experiment –II. Day old pullets (BV-300) were procured and reared up to 25 weeks as per the schedule provided. Three hundred and ninety pullets with uniform body weight were chosen for the trial. They were fed with two d. lysine concentrations (0.65% and 0.60%) at two different protein level from the experiment –I based on the performance exhibited by the birds. To each lysine concentration, 6 graded concentrations (60, 63, 66, 69, 72 and 75%) of crystalline threonine were added and a control with 17 % CP, 0.70 % lysine and 66% threonine were kept. Thus a total of 13 treatments each with 5 replicates of 6 birds (13x5x6=390). Higher HDEP, EM was observed at 69 and 75 per cent threonine in both the lysine concentrations. FI/h/d, FI/E, FI/dozen eggs, EW, EM, BW, ESD and FE (FI/EM) were not influenced by the concentration of d. threonine in both the group which indicated that 60 percent d. threonine is optimum for production. Whereas, Mortality, AI, YI, ST, SI were not influenced by the concentration of d.threonine at both the lysine levels. However, significantly better YC values and SW percentage were observed at 60 and 63 per cent d.threonine in both the lysine groups. The income through sale of eggs over cost of production is more in 63 percent d.threonine at both the lysine concentrations than control. Increased d.threonine concentrations in diet increased the threonine intake in terms of mg/bird/day. The d. methionine+ Cystine, Trp. , Arg. , Ile. and Val. ratio to d. lysine requirements were assessed based on the performance of WL layers from experiment-I as 86, 19, 114, 72 and 80 per cent, respectively. In conclusion, the d. lysine requirement for optimum performance in WL layers at 25-44 wks of age were 0.65 and 0.60 percent at 13.36 and 15.78 percent crude protein, respectively, or 598.8 and 570 mg/h/d. Whereas the d. threonine requirements were 60 per cent of d.lysine in both the lysine groups i.e 458.3 vs 517.1 mg/h/d respectively. The ratio of other essential amino acids to lysine were assessed as M+C, Trp. , Arg. , Ile and Valine are 86,19,114,72 and 80 percent respectively. This is equivalent to 518.7, 115.2, 678.1, 415.5 and 508.6 Vs 499.1, 112.5, 709.8, 512.3 and 611.5 mg/h/d in WL layers from 25-44 wks of age with 2700 kcal/kg ME in a tropical country like India.