The aim of this study was to determine the coefficients of the Goettingen model for Redbro birds and estimate the digestible lysine requirements. To determine the model parameters, three nitrogen balance trials were performed in Periods I (14–28 days), II (42–56 days) and III (70–84 days), using 42 birds per trial. The birds were individually housed and subjected to six diets with increasing levels of nitrogen, with lysine as the limiting amino acid (deficient by 20% in relation to other amino acids). Dietary nitrogen concentrations were 8, 16, 24, 32, 40 and 48 g/kg. A control diet was added to confirm lysine as the first limiting amino acid. Nitrogen balance trials were divided into 5 days of adaptation and two periods of excreta collection, each one of 5 days. The response of the birds to a control diet confirmed that lysine was the first limiting amino acid. The adjustment of the exponential functions between nitrogen retention or excretion and nitrogen intake allowed estimation of parameters of the Goettingen model. The maximum potential for nitrogen retention was 3276, 2585 and 2603 mg/BWkg0.67.day, nitrogen maintenance requirement was 225, 135 and 122 mg/BWkg0.67.day and efficiency of nitrogen utilisation was 313 × 10−6, 406 × 10−6 and 415 × 10−6 in the phases of 14–28, 42–56 and 70–84 days. The digestible lysine intake for Periods I, II and III, based on 60% of the maximum potential for nitrogen retention, was 711, 989 and 1272 mg/day (1.225%, 1.137% and 1.09% of lysine in the diet for a daily feed intake of 58, 87and 117 g/day), respectively.
This study evaluated the digestibility of cottonseed meal with or without addition of enzymes (phytase and protease) for growing pigs. It was used 18 barrows, housed in metabolism cages, distributed in a completely randomized design, standardizing body weight (bw) with average of 25.8 ± 3.6 kg, with three treatments and six repetitions. The treatments consisted of a reference diet based on corn and soybean meal, the second treatment with replacement of 30% of the reference diet by cottonseed meal without enzymes, and the third with 30% of the reference diet replaced by cottonseed meal with added enzymes. Was determined the digestible protein, digestible energy, digestibility of dry matter, energy and protein. It was also registered the balance of nitrogen and phosphorus. The use of cottonseed meal with the addition of enzymes in diets for growing pigs has no effect on the digestibility of dry matter, gross energy and crude protein, but improved the absorption of phosphorus, consequently reducing its excretion in the feces. There was no improvement in nitrogen balance in the diets containing cottonseed meal with enzymes.
Two experiments were conducted with pigs in the growth phase (30–50 kg). Experiment I consisted of a digestibility trial to determine the nutritional value of cottonseed cake with and without addition of an enzyme complex through the method of total collection of excreta. Twenty barrows were used and housed in metabolic cages to collect the total collection of feces and urine. Four treatments and five replications randomized the experimental design completely. Two reference diets and two test diets were experimental (70% reference diet and 30% cottonseed cake), with and without the addition of an enzyme complex. The evaluated variables were: apparent digestibility coefficient of dry matter, of crude protein, of Gross energy, of phosphorus and the values of digestible dry matter, digestible protein, digestible phosphorus, digestible energy and metabolizable energy of cottonseed cake with and without enzymes. The addition of enzymes increased the levels of digestible protein to 0.302–0.313 kg/kg and digestible energy to 2,538–2,894 kcal/kg. Experiment II was conducted to assess barrow performance when they were fed diets containing increasing levels of cottonseed cake protein (0, 20, 40 and 60%), which replaced protein from soybean meal, with the enzyme complex. The design was a randomized block design consisting of four treatments and five replications. The performance, carcass characteristics and biochemical parameters of the blood were evaluated. These results indicate that the protein from soybean meal can be replaced up to 60% by the cottonseed cake protein with enzyme complex in diets for pigs in the growth phase, without sacrificing performance or carcass characteristics
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