نوع مقاله : مقالات علمی- پژوهشی
نویسندگان
1 دانشگاه فردوسی مشهد
2 دانشگاه فردوسی
3 گروه علوم دامی، دانشکده کشاورزی، دانشگاه زابل، زابل، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
An experiment was conducted to determine the optimal level of supplemental lysine in a corn-soybean mealcottonseed
meal starter diet. Three hundred and sixty day-old male chicks (Ross 308) were used in a completely
randomized design (15 birds per each pen). A basal diet was formulated to meet or exceed NRC (1994)
recommendations except for lysine. Graded levels of supplemental lysine (0, 0.1, 0.2, 0.3, 0.4, and 0.5% of diet)
were added to the basal diet at the expense of corn starch. At 14d of age, performance and carcass attributes
including body weight gain (BGW), feed conversion ratio (FCR), feed intake (FI), breast meat yield (BMY), and
thigh yield (TY) were assessed. The results showed that lysine supplementation significantly improved BGW,
FCR, FI, BMY, and TY. To determine the optimum level of supplemental lysine, modeling approach was
applied and inflection point in spline models was considered as an optimum point. Using linear broken-line
model, inflection points for BWG, FC, BMY, TY were 0.24, 0.26, 0.35, and 0.22% of diet, respectively. These
values in quadratic broken-line model were 0.39, 0.15, 0.52, and 0.33% of diet, respectively. In conclusion, the
usage of cottonseed meal in starting broiler chicks may increase the needed supplemental lysine in the diet due to
low amino acid digestibility of cottonseed meal. Although the optimum level of supplemental lysine depends on
response criteria and statistical model, required supplemental lysine for BMY was higher than others.
کلیدواژهها [English]
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