Comparative growth and development of the digestive organs and of some enzymes in broiler and egg type chicks after hatching

Abstract

1. Body weight, the weight of digestive organs and activities of some digestive enzymes were determined from hatching to 14 d of age in meat- and egg-type chickens. 2. Relative daily food intake and growth rate were much higher in meat- than in egg-type chickens. Relative daily food intake peaked at 30% of body weight at 3 d of age in meat-type, and at 20% of body weight at 6 d of age in egg-type chickens and then decreased gradually. The corresponding values for growth rate were 20 and 14%. 3. Allometric growth of the small intestine, intestinal contents and liver was greater in meat-type chickens, but the growth of the pancreas attained a higher value in the egg-type birds. Diminution of the vitelline residue was similar in the two breeds. 4. Pancreatic digestive enzyme activities were similar between stocks, but activities in the small intestinal contents were lower in meat-type chickens. 5. The secretion of digestive enzymes in the newly-hatched meat-type chicken could be a limiting factor in digestion and, consequently, in food intake and growth.

Effect of age and exogenous amylase and protease on development of the digestive tract, pancreatic enzyme activities and digestibility of nutrients in young meat-type chicks

“…Development of the GIT in the present experiment was consistent with that described in n earlier studies, ie a decrease in the relative weight of digestive organs from a peak observed at 7-10 d and a gradual increase in the activity of pancreatic enzymes (Nitsan ef al, 1991 a; Nir et al, 1993). The reduction of fat digestibility and metabolizability of the diet during week 2 and its subsequent increase is in accord with the reports of Zelenka (1968,1973) and Murakami et al (1988Murakami et al ( , 1992.…”

“…The above was confirmed when stocks selected for high body weight were compared with those selected for low body weight (Barbato et al, 1984). In another study, Nir et al (1993) (Dunnington and Siegel, 1985). In this case HW chicks had higher enzymatic activities in their intestinal contents than LW ones.…”

“…Gastrointestinal tract (GIT) development during the post-hatching growth period has been widely investigated in birds (Dror et al, 1977;Lilja, 1983;Katanbaf et al, 1988;Nitsan et al, 1991 a, b;Sell et al, 1991;Nir et al, 1993). All of these studies emphasize the major role of the GIT in inducing growth during the early post-hatching period.…”

Breeding for efficiency in the broiler chicken: A review

“…Selection for higher growth rate has led to a lower degree of maturity at slaughter and this affects the size of different organs at any given age with some organs, such as those that make up the digestive tract, being genetically predisposed to maturing sooner than others (Katanbaf et al 1988;Mitchell and Smith 1991;Nitsan et al 1991;Nir et al 1993). Despite the digestive system maturing more quickly in modern breeds compared to old-type ones, the digestive system has reduced in size relative to body weight at a comparable age.…”

“…Poultry rely on enzymatic digestion, more so than other livestock, as their colons are relatively short and largely lack the bacteria that aid other species in digestion. Nir et al (1993) claimed digestive enzyme production to be the limiting factor in improving broiler digestion, particularly in young birds. Differences in enzyme production between high and low body weight lines have been reported in chickens at the same chronological age (Nir et al 1987;O'Sullivan et al 1992a).…”