Abstract
Aim:To study the impact of deficiency of second line limiting amino acids (SLAA; valine, isoleucine and tryptophan) on the production performance and carcass characteristics of commercial broilers.Materials and Methods:A control (T1) corn-soy diet was formulated to contain all essential AA on standardized ileal digestible basis; While in T2-a ‘moderate SLAA deficit’ diet was formulated by replacement of soybean meal with 6% rapeseed meal and T3-a ‘high SLAA deficit’ diet was formulated by replacement of soybean meal with 6% de-oiled rice bran. Each of these treatments was allotted to six replicates of ten chicks each. During the 42 days experimental period, growth performance, carcass parameters and intake of metabolizable energy (ME), crude protein (CP) and AA were studied.Results:The cumulative body weight gain, feed conversion ratio, carcass cut weights and yields of carcass, breast and thighs were decreased (p<0.05) in T3 compared to T1. The absolute intake of ME, lysine, methionine + cysteine and threonine were not affected while intake of CP and all SLAA were reduced in SLAA deficit diets. The relative intake of ME, lysine, methionine + cysteine, threonine and SLAA reduced in T3 in comparison to T1. The relative weights of internal organs were not affected by treatments while the abdominal fat percentage was increased linearly to the magnitude of SLAA deficiency.Conclusion:The deficiency of SLAA decreased performance, carcass yields and impaired utilization of ME, CP and AA linearly to the magnitude of the deficiency.
Highlights
Protein is un-debatably an important nutrient for poultry and should be an integral part of the diet
The results imply that deficiency of valine was much larger than that of isoleucine and tryptophan in that order during pre-starter and starter phase while it was almost similar during finisher phase
The body weight gain (BWG) of birds was significantly reduced by second line limiting amino acids (SLAA) deficiency at all stages of life, which is a clear reflection of impact of treatments on the input of critical nutrients channeled through feed intake and it was found that the bids eat to satisfy the need for a limiting nutrient, and in this attempt the birds might have failed as a result of bulkiness of the feed or the inability of birds to lose sufficient heat to remain in thermal balance, which follows the principles of the Theory of food intake and growth proposed by Emmans [14,15]
Summary
Protein is un-debatably an important nutrient for poultry and should be an integral part of the diet. Protein rich ingredients accounts for 30-40% of the ration yet play an imperative role in determining the feed cost. It is universally accepted that, birds as such do not have a need for crude protein (CP) rather there is a need for amino acids (AA). In commercial poultry feed formulations, the first line of limiting AA are supplemented extensively as DL-methionine, L-lysine and L-threonine to rationalize the AA levels and to economize feed cost on corn soy diets. Reduction of protein through inclusion of locally available feed ingredients such as rape seed meal (RSM) and de oiled rice bran (DORB) can be thought of as an alternative solution
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