Effects of wheat quality on digestion differ between the D+ and D- chicken lines selected for divergent digestion capacity

Abstract

The aim of the experiment was to study the effects of 2 wheat cultivars (Baltimor and Scipion) with different hardness values (75 and 5, respectively) on 2 divergent lines (D+ and D-) of broiler chickens selected on the basis of their digestion ability assessed by AME(n). Wheat was incorporated at 54.6% in diets. The other main ingredients were soybean meal (35.3%) and rapeseed oil (5.5%). Diets were given as pellets from 7 to 26 d. The experimental design was a 2 x 2 factorial design testing 2 wheat cultivars (soft or hard) on 2 selected lines of broiler chickens (high AME(n) or low AME(n)). From 7 to 16 d, D+ line showed lower (P < 0.0001) feed intake and feed:gain ratio than the D- line. At 3 wk of age, the D+ chickens resulted in increased digestibility values (P < 0.01) and 9% increased AME(n) value (P < 0.0001) compared with D-. Wheat cultivar effects on feed efficiency and AME(n) differed between lines. In the D+ line, their values were about 6% higher (P < 0.05) with soft than with hard wheat, whereas they did not differ in the D- line. However, wheat cultivar effect on starch digestibility did not differ between lines; soft instead of hard wheat resulted in about 6% improvement (P < 0.0001) in both lines. In the D- line, soft instead of hard wheat tended to reduce lipid and protein digestibilities, which explained why the starch digestibility improvement due to soft wheat was not converted into a significant AME(n) improvement in D birds. Study of digestive organ size revealed that increased proventriculus and gizzard weight (P < 0.05) could be one of the causes for the better digestion capacity of the D+ line. The pancreas was bigger (P < 0.01) in D- than in D+ birds, which probably came from an adaptation to a digestive disorder in D- birds.

Breeding for efficiency in the broiler chicken: A review

“…Differences in resource allocation to digestive organs, observed between the broilers bred for high body weight (Katanbaf et al 1988;Mitchell and Smith 1991) and for high digestive efficiency specifically (Péron et al 2006), suggest selecting for digestive efficiency may actually compromise other traits which are incorporated into modern breeding programs and vice versa (Pym et al 2004). Contrasting correlations in relative organ sizes have been discovered between lines selected for commercial objectives and high digestive efficiency (Carré et al 2005;Péron et al 2006;Rougière and Carré 2010;de Verdal et al 2010).…”

“…Contrasting correlations in relative organ sizes have been discovered between lines selected for commercial objectives and high digestive efficiency (Carré et al 2005;Péron et al 2006;Rougière and Carré 2010;de Verdal et al 2010). For instance, Mussini (2012) showed that the gizzard is significantly smaller, and the pancreas similar, in modern commercial breeds when compared to old-type breeds fed on the same diet.…”

“…For instance, Mussini (2012) showed that the gizzard is significantly smaller, and the pancreas similar, in modern commercial breeds when compared to old-type breeds fed on the same diet. On the other hand, Péron et al (2006) found that the gizzard was much larger (correlation = +0.27, +0.82 and −0.05 with protein, starch and lipid digestibility, respectively) and the pancreas much smaller (correlation = −0.22, −0.20 and −0.29 with protein, starch and lipid digestibility, respectively) in the birds selected specifically for high digestive efficiency compared to birds from a control line on the same diet. These observations in organ sizes between the lines indicate that selecting for the maximum energy digestive efficiency generally may not be compatible with selection for highperformance traits.…”

“…The morphometries of the internal structures, in particular the organs that comprise the digestive system, are significantly different between high digestive efficiency lines and birds bred for high commercial performance (Carré et al 2005;Péron et al 2006;Rougière and Carré 2010). Selecting for high digestive efficiency may conflict with performance traits and this probably goes part way to explaining why the genetic change witnessed in broilers does not appear to have delivered their full digestive efficiency potential, at least not to the extent it could have had digestive efficiency been the only trait of interest in breeding programs.…”

Opportunities to improve nutrient efficiency in pigs and poultry through breeding

“…Correlations between this and other performance traits, such as body weight (BW) gain and FCR were either low or negligible; suggesting that selection for P bioavailability will not affect adversely the performance (Zhang et al, 2003). The attempts of Carré et al (2008;Mignon-Grasteau et al, 2004;Pé ron et al, 2006) to select for overall digestive efficiency in broiler chickens have been more promising, as they reported relatively high heritabilities (0.33 to 0.47) for energy, lipid, starch and protein digestion efficiencies for 3-week-old broilers fed on a wheat-based diet in birds selected for digestive efficiency (Mignon-Grasteau et al, 2004). Interestingly, these differences had disappeared by 8 weeks of age and were affected greatly by diet type (Pé ron et al, 2006;Carré et al, 2008).…”