Assessment of the Nutrient Contents of Finished Broiler Starter and Finisher Diets in Nigeria
The study was conducted to assess and compare the proximate composition and amino acid profile of six (6) finished broiler starter and finisher diets with recommendations of National Research Council (NRC) nutrient requirements table for the different physiological age growth stage. Four samples of each feed type were procured from different feed vendors within Abuja metropolis and subjected to proximate composition and amino acid analysis. The dry matter, crude protein, crude fibre, crude fat and ash contents of finished broiler starter and finisher diets were observed to be within the levels of 92.2 – 94.4%, 21.5-24.6%, 4.0 – 8.7%, 5.5 – 8.7% and 7.9 – 12.0% and 91.64- 94.38%, 19.06-22.63%, 4.41-8.77%, 5.37-8.41% and 7.87-11.25%, respectively, and were within the ranges quoted on the labels of the feeds analyzed. The results also showed that there was no significant (P>0.05) difference in the crude protein, arginine, methionine, isoleucine, threonine and valine contents of the finished broiler starter diets compared with the levels in the nutrient tables of NRC. On the other hand, except for methionine+cystein which was lower (P<0.05), most of the finished starter diets had significantly (P<0.05) higher histidine, lysine, proline, phenylalaline, phenylalaline+thyrocine and glycine+serine values than those recommended by NRC for broiler aged 1-3 weeks. Similarly, all test broiler starter diets had superior (P<0.05) CP and amino acids profile compared with the NRC recommendation for broilers aged 3-6 weeks. While crude protein, arginine, isoleucine, methionine, lysine, threonine, methionine+cystein and phenylalanine contents were similar (P>0.05), leucine, valine, phenylalaline+thyrocine and glycine+serine values of the test finisher diets were significantly (P<0.05) different from NRC recommendation for broilers aged 3-6 weeks. Except for arginine, isoleucine and threonine which were similar (P<0.05) to NRC requirement table for broilers aged 6-8 weeks, CP and the other amino acid levels of the test finisher diets were higher (P<0.05). Although, estimated chemical scores of analyzed diets revealed a generally high trend, methionine plus cystine appeared limiting in the broiler starter diets compared with recommended levels for birds aged 1-3 weeks; threonine, valine or isoeucine may be limiting in some broiler finisher diets when compared with requirement for broilers aged 3-6 weeks. It was opined that the limitation has the potential of affecting the performance of birds, especially if not compensated for by other amino acids that were surplus in the diets. Thus, the switch to finisher diets may not be effective for some of the feeds at 3-6 weeks of age without supplementing with synthetic form of the limiting amino acids. However, this would require further studies with live animals. It is advised that beyond indicating the nutrient profile of feed on the labels, age range of broilers that would enjoy optimum growth from the diets could also be indicated.
Keywords: Broiler starter, broiler finisher, finished feeds, proximate composition, amino acid profile