Abstract
ABSTRACT A total of 810 one-day-old, straight-run broilers were used to evaluate the effects of dietary nutrient density and feed additives included in the starter diet on their performance, intestinal microbiota, gut morphology, and immune response. A 3×3 factorial arrangement with three nutrient densities (100, 103.75 and 107.5%, as recommended) and three feed additives (no additives, 0.5 g/kg diet Maxi-Gen, and Maxi-Gen + Superzyme + Bio-Phytase at the rate of 0.5, 0.25 and 0.1 g/kg diet, respectively), fed from 1 to 10 d of age. Similar commercial corn-soy grower and finisher diets fed to all birds from 10-24 and 24-42 d of age, respectively. There was higher (p<0.05) body weight gain and lower (p<0.05) feed conversion ratio in chicks fed starter diet with 107.5% nutrient density and Maxi-Gen with or without exogenous enzymes compared with those fed control diet at 10 and 42 d of age. Lactobacilli and Bifidobacteria counts in the cecal content were increased linearly as dietary nutrient density increased in 10-d-old birds (p<0.05). Higher duodenal and jejunal villus height and villus height to crypt depth ratio (p<0.05) were measured in the birds fed the starter diets with 103.75% and 107.5% nutrient density at 5 and 10 d of age. Total anti-SRBC and IgM titers were significantly higher in the broilers fed the 107.5% nutrient density diet containing feed additives at 35 day of age. It is concluded that higher nutrient density and the inclusion of feed additives in the starter diet may improve the growth performance, gut morphology, and immune response of broiler chickens.
Highlights
The same dietary nutrient specifications for starter Ross 308 broilers were established in 2014 and 2015
The chicks fed starter diet supplemented with both feed additives presented higher (p
The starter diet containing the combination of feed additives improved (p
Summary
The same dietary nutrient specifications for starter Ross 308 broilers were established in 2014 and 2015. Nutrient requirements may be higher to promote a good start due to the high growth capacity of broilers during this period. Their feed intake is relatively low (Kidd et al, 2004), and pancreatic and biliary secretions, required especially for protein and fat digestion, may be insufficient in the first week of post hatch (Noy & Sklan, 1997). Otherwise, feed presents lower digestibility, resulting in a high proportion of undigested in the excreta (Noy & Uni, 2010). Higher densities of critical nutrients and the inclusion of exogenous enzymes have been driven by the idea that nutrient requirements for maximum growth rate may be higher than the current recommendations, as well as that newly-hatched chicks may present poor dietary nutrient utilization due to their undeveloped digestive tract and insufficient digestive enzyme secretion
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
