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Abstract
Economic benefits of raising birds sex separate vs. straight-run has been a paradigm for the broiler industry over the years. Three experiments were conducted to evaluate the effects of raising birds straight-run vs. sex separate (Experiment 1), and determine optimum digestible lysine (dLys maintaining the amino acid ratio) levels for net returns (NRML) for the starter (Experiment 2) and grower phases (Experiment 3) for each system. For each of the 3 experiments an economic simulation of net returns of feed cost over whole carcass or cut-up part weights was made for different market weights considering a 1.8 million broiler complex. Experiment 1 revealed economic advantages of sex separation, on 1,344 broilers chicks of two genetic strains processed at 1.7, 2.7, and 3.7 kg MW, of $99,000 for Ross 308, and $254,700 for Ross 708. In addition, bird uniformity was increased in sex separate treatments when compared to straight-run. In experiment 2, 3,240 Ross 708 chicks were fed starter diets (0 to 25d) with 6 dLys levels (1.05% to 1.80% of dLys). A 1.6 kg projected market weight was considered to be sold as whole carcass. Females, males and straight-run birds had 1.07, 1.05, and 1.05 % NRML of dLys respectively. Sex separation was not economically viable (-$13,058) for the light market weight after the cost of sexing chicks was deducted from the returns. Experiment 3 had 2,160 Ross 708 chicks fed grower diets (14 to 32d) with 6 dLys levels (0.90% to 1.30% of dLys). There were 2 projected market weights: 1.7 kg (whole carcass females and straight-run birds) and 2.9 kg (cut-ups males and straight-run birds). For the whole carcass, 0.90 and 1.01% were NRML of dLys for females and straight-run birds. The cut-up market had NRML of dLys set at 1.30 and 1.14 % for males and straight-run birds. When combining the two market weights for the complex, sex separation resulted in $112,341 of extra returns. In conclusion, sex separation was shown to result in increased profitability, and NRML of dLys to be dependent on market target weight.