Live performance, carcass composition, and blood metabolite responses to dietary nutrient density in two distinct broiler breeds of male chickens

Abstract

A study was conducted to evaluate the effects of varying nutrient density with constant ME:CP ratio on growing performance, carcass characteristics, and blood responses in 2 distinct broiler breeds of male chickens (Arbor Acres, a commercial line, and Beijing-You, a Chinese nonimproved line). Experimental diets were formulated with high, medium, or low nutrient densities for 3 growing phases. Starter diets (1 to 21 d) contained 23, 21, and 19% CP with 3,059, 2,793, and 2,527 kcal/kg of ME; grower diets (22 to 35 d) contained 21, 19, and 17% CP with 3,150, 2,850, and 2,550 kcal/kg of ME; and finisher diets (36 to 42 d for Arbor Acres and 36 to 91 d for Beijing-You) had 19, 17, and 15% CP with 3,230, 2,890, and 2,550 kcal/kg of ME. Male hatchlings (216 of each breed) were randomly assigned to 6 replicates of 12 birds in each treatment. Arbor Acres broilers had better (P < 0.001) BW gain, feed conversion ratio (FCR), and carcass yield, but had greater (P < 0.001) abdominal and carcass fat deposition. In both breeds, the higher nutrient density increased (P < 0.05) BW gain, protein efficiency ratio, and energy efficiency ratio while decreasing (P < 0.05) feed intake and FCR. The breed differences were increased for FCR, protein efficiency ratio, and energy efficiency ratio in the starter period and decreased for carcass chemical composition, respectively, by higher nutrient density. These findings indicate that 1) genetic improvement has a significant effect on broiler responses to dietary nutrient density, 2) performance differences between breeds are lessened with diets of low nutrient density, 3) carcass quality differences are less when birds were fed diets of high nutrient density, 4) carcass composition is hardly modified by nutrient density and both breeds exhibit similar metabolite responses to dietary concentrations, and 5) optimal diets are deduced for these breeds for the 3 growing phases.

Cool perch availability improves the performance and welfare status of broiler chickens in hot weather

“…It is more difficult to modify carcass composition than to alter growth rate (Quentin et al, 2003;Zhao et al, 2009), but in the present study, increased weight gain induced by cool perches reflected the differences in processing yield. In support of previous findings , broilers subjected to cool perches showed more breast (F 2, 24 = 3.31, P = 0.0539) and thigh muscle deposition and lower abdominal fat percentage.…”

Effect of dietary protein regime on meat quality traits and carcase nutrient content of broilers from two commercial genotypes

“…Dietary protein may influence meat quality by altering carcase composition, increasing meat yield and muscle pH decline (Karlsson et al, 1993;Tesseraud et al, 2003;Sterling et al, 2006). A significant decrease in fat deposition due to dietary high protein or amino acid regime has been reported (Jones, 1986;Tesseraud et al, 1996;Wijtten et al, 2004;Zhao et al, 2009). Karlsson et al (1993) found lower muscle pH and less tender meat in pigs fed a high protein diet compared to pigs fed a low protein diet.…”

Effect of dietary nutrient density and vitamin premix withdrawal on performance and meat quality of broiler chickens

“…Dietary nutrient density is of the most important nutritional factors which have a significant effect on walking ability, growth performance and carcass quality of broiler chickens. Increasing dietary nutrient density increases feed cost, nitrogen excretion, fat deposition and metabolic disorders in poultry production.…”