Pancreatic PYY but not PPY expression is responsive to short-term nutritional state and the pancreas constitutes the major site of PYY mRNA expression in chickens

PP-fold peptides such as peptide YY (PYY) and pancreatic polypeptide (PPY) are known to play key roles in vertebrate energy homeostasis. Until recently, no gene sequence was available for avian PYY and therefore a gap in knowledge of regulation of its expression exists in avian species. Here we further evidence the mRNA sequence for chicken PYY and show that the pancreas is the major site of its mRNA expression, with a secondary peak of expression around the distal jejunum, in contrast to mammals where the large intestine is the major site of PYY expression. We also demonstrate that pancreatic PYY expression is responsive to short-term and long-term nutritional state, increasing within hours of feeding, in contrast to intestinal PYY which does not fluctuate to the same extent, and pancreatic PPY which appears to be primarily determined by long-term energy state. Both pancreatic PYY and PPY expression were found to exhibit ontogeny, being evenly distributed throughout the pancreas in young (2wk) chicks but having a decreasing splenic to duodenal gradient by adolescence (12wk).

Comparative effect of arginine and/or tryptophan in ovo feeding on hatchability percentage, growth performance and economic importance of commercial broiler

In ovo feeding is the administration of exogenous nutrients into the amnion of the late-term avian embryo so that the avian embryo orally consumes the amniotic fluid (primarily water and albumen protein) prior to pipping the air cell. So the study was carried out to find out the effect of in ovo nutrition on post-hatch performances in broilers. Total 700 fertile eggs of Cobb 400 with uniform egg weight were divided into 5 groups: non-injected control, injected control (0.5 ml of 0.9% normal saline), arginine (0.5 ml of 0.5% arginine), tryptophan (0.5 ml of 0.5% tryptophan) and combination (0.25 ml of 0.5% each of arginine and tryptophan); and injected on 18 d of incubation into amnion. On the 21d, 108 chicks were randomly selected from each treatment in total accounting 540 chicks. The hatchability and hatch weight were studied where arginine had shown a highly significant improved hatch weight and placement weight. There was no significant difference in feed efficiency, but cumulative feed intake was higher in tryptophan and combination groups. Body weight and body weight gain had also resulted significantly in arginine fed in ovo groups up to 21d of age. The broiler farm economy index (BFEI) and broiler feed price ratio (BFPR) were best in tryptophan and arginine in ovo fed groups, respectively.

Application of computed tomography to assess the effect of egg yolk ratio on body composition in chickens of different genotype and gender at hatch and during the rearing period

1. Computed tomography was used for the in vivo determination of yolk ratio in 7000 domestic hen eggs, originated from two markedly different genotypes, in order to examine the effect of egg yolk ratio, gender and genotype on the development of hatched chicks. 2. Eggs with extremely low, average and extremely high yolk ratio were chosen for further investigation (n = 350 in each group in both genotypes). After incubating the selected eggs, hatched birds were reared and slaughtered at 11 weeks of age. 3. The yolk ratio of eggs significantly affected the body composition of the chickens at hatching and during rearing to 8-9 weeks of age. 4. Chickens of a genotype selected partly for weight gain had significantly higher live weight from hatching to the end of the rearing period and had better slaughter characteristics than those of the dual purpose TETRA-H genotype. 5. At hatching, only the dry matter content of the body was affected by the gender of the birds. The effect of gender on the live weight and body composition of chickens was evident from the 5th week of age to the time of slaughter. 6. It was concluded that eggs with a low yolk ratio were most beneficial for broiler production, because chickens hatched from these eggs had the highest slaughter weight and muscle index and the lowest fat index for their body mass.

Administration of triiodothyronine and dopamine to broiler chicks increases growth, feed conversion and visceral organ mass

The influences of triiodothyronine (T3) or dopamine (DA) administration on growth, feed conversion, and visceral weights in broiler chicks between the ages of 6 and 12 d posthatch were investigated. In Trial 1, six chicks at age 6 d were randomly administered one of the following treatments: 0.37, 0.74, 1.48, and 2.96 micromol T3/kg BW or 0.07, 0.14, 0.28, and 0.56 micromol DA/kg BW. Both T3 and DA were administered via intraperitoneal injections between the end of sternum and the ends of os pubis, with 0.9% saline as the excepient. In addition, two groups of six birds each were either not injected or injected with excepient only, as controls. Four replications were carried out with a total of 264 chicks. Heart weight as a percentage of feed-deprived body weight (FDBW) of the chicks injected with 2.96 micromol T3/kg BW was heavier than that of controls. Other variables measured were not significantly different between treatments. In trial 2, six chicks at age 6 d were randomly administered, one of the following treatments: 0.56, 1.12, 2.24, and 4.48 micromol T3/kg diet or 0.40, 0.80, 1.60, and 3.20 micromol DA/kg diet as well as a nonsupplemented control. Four replications were carried out with 216 chicks. The results in Trial 2 showed that the effects of T3 (X, micromol/kg diet) on body weight gain (Y1, g) and feed consumption (Y2, g) were linear (Y1 = 310 - 21.5X, R2 = 0.868, P < 0.001 and Y2 = 398 - 22.3X, R2 = 0.765, P < 0.001, respectively). The feed conversion ratio, the weight of liver, the weights of various intestinal segments, the lengths of the duodenum, jejunum and the ileum, as well as weight per centimeter jejunal length, gizzard weight as percentage of FDBW, and the duodenal length per kilogram FDBW all had linear responses (P < 0.05) to the level of dietary supplementation of T3. The effect of dietary supplementation of T3 on the heart weight was quadratic (Y16 = 2.58 + 0.89X - 0.17 X2, R2 = 0.526, P < 0.01). Similarly, the weights of pancreas and gizzard, the heart weight as a percentage of FDBW and the pancreas weight as a percentage of FDBW all had second-order curve responses. Dietary DA supplementation exerted no effect on the variables measured except that the regression of the heart weight as a percentage of FDBW on dietary DA supplementation (X1, micromol/kg diet) existed, namely, Z1 = 0.64 + 0.24 X1 - 0.23 X1(2) + 0.05 X1(3) (R2 = 0.868, P < 0.05).