Effects of breeder age and egg weight on morphological changes in the small intestine of chicks during the hatch window

Factors influencing the development of gastrointestinal tract and nutrient transporters' function during the embryonic life of chickens-A review

Intestinal morphology and regulation of nutrient transportation genes during the embryonic and early life of chicks influence their body weight and feed conversion ratio through the growing period. The intestine development can be monitored by measuring villus morphology and enzymatic activity and determining the expression of nutrient transporters genes. With the increasing importance of gut development and health in broiler production, considerable research has been directed towards factors affecting intestine development. Thus, this article reviews (1) intestinal development during embryogenesis, and (2) maternal factors, in ovo administration, and incubation conditions that influence intestinal development during embryogenesis. Conclusively, (1) chicks from heavier eggs may have a better-developed intestine than chicks from younger ones, (2) in ovo supplementation with amino acids, minerals, vitamins or a combination of several probiotics and prebiotics stimulates intestine development and increases the expression of intestine mucosal-related genes and (3) the long storage period, improper incubation temperature and imbalanced ventilation can negatively influence intestinal morphology and nutrient transporters gene expression. Finally, understanding the intestine development during embryonic life will enable us to enhance the productivity of broilers.

Data Analytics of Broiler Growth Dynamics and Feed Conversion Ratio of Broilers Raised to 35 d under Commercial Tropical Conditions

Data collection is standard in commercial broiler production; however, growth modeling is still a challenge since this data often lacks an inflection point. This study evaluated body weight (BW) dynamics, feed intake, BW gain, feed conversion ratio (FCR), and mortality of broiler flocks reared under commercial tropical conditions with controlled feeding to optimize FCR. The data analyzed included performance records of 1347 male and 1353 female Ross 308 AP broiler flocks with a total of 95.4 million chickens housed from 2018 to 2020. Decision trees determined high- and low-feed-efficiency groups using FCR at 35 d. Logistic, Gompertz-Laird, and von Bertalanffy growth models were fitted with weekly BW data for each flock within performance groups. The logistic model indicated more accurate estimates with biological meaning. The high-efficiency males and females (p < 0.001) were offered less feed than the low-efficiency group and were consistently more efficient. In conclusion, greater feeding control between the second and the fourth week of age, followed by higher feed allowance during the last week, was associated with better feed efficiency at 35 d in males and females. Additionally, models demonstrated that a reduced growth rate resulted in heavier chickens at 35 d with better feed efficiency and greater BW gain.

Effect of egg weight on composition, embryonic growth, and expression of amino acid transporter genes in yolk sac membranes and small intestines of the domestic pigeon (Columba livia)

The objective of this study was to investigate the effect of egg weight on the composition of the egg, the growth of the embryo, and the expression of amino acid transporter genes in the yolk sac membranes and small intestines of the domestic pigeon (Columba livia). A total of 240 fertilized eggs were collected and divided into two groups based on the weight of the eggs, light (LE) and heavy (HE). The composition of 20 eggs from each group was measured, and the remaining eggs were weighed and placed in an incubator. On embryonic days (E) 9, 11, 13, and 15 and day of hatch (DOH), 15 embryos/hatchlings from each group were measured for embryonic growth, and samples were collected. The HE had heavier yolk and albumen weights than the LE (P < 0.01). Compared with the LE, the HE had heavier yolk-free embryonic body and yolk sac weights from E13 to DOH (P < 0.05). Additionally, the HE had larger yolk sac membrane weights from E13 to E15 (P < 0.05) and had more residual yolk sac content on DOH than those of the LE (P < 0.01). The yolk absorption was greater for the HE than for the LE from E11 to E13 (P < 0.05). Furthermore, the abundance of CAT2 and PepT1 mRNA in the yolk sac membranes was greater in the HE than in the LE on E13 (P < 0.05). Compared with the LE, the gene expression of EAAT2 in the intestine on E13 was greater in the HE, whereas the expression of EAAT3 was lower in the HE (P < 0.05). Taken together, our results suggest that egg weight influenced the composition of the eggs, embryonic development, and expression of amino acid transporter genes in the yolk sac membranes and small intestines of pigeon embryos.

Egg storage duration and hatch window affect gene expression of nutrient transporters and intestine morphological parameters of early hatched broiler chicks

In recent years, researchers have given emphasis on the differences in physiological parameters between early and late hatched chicks within a hatch window. Considering the importance of intestine development in newly hatched chicks, however, changes in gene expression of nutrient transporters in the jejunum of early hatched chicks within a hatch window have not been studied yet. This study was conducted to determine the effects of egg storage duration before incubation and hatch window on intestinal development and expression of PepT1 (H+-dependent peptide transporter) and SGLT1 (sodium-glucose co-transporter) genes in the jejunum of early hatched broiler chicks within a 30 h of hatch window. A total of 1218 eggs obtained from 38-week-old Ross 308 broiler breeder flocks were stored for 3 (ES3) or 14 days (ES14) and incubated at the same conditions. Eggs were checked between 475 and 480 h of incubation and 40 chicks from each egg storage duration were weighed; chick length and rectal temperature were measured. The chicks were sampled to evaluate morphological parameters and PepT1 and SGLT1 expression. The remaining chicks that hatched between 475 and 480 h were placed back in the incubator and the same measurements were conducted with those chicks at the end of hatch window at 510 h of incubation. Chick length, chick dry matter content, rectal temperature and weight of small intestine segments increased, whereas chick weight decreased during the hatch window. The increase in the jejunum length and villus width and area during the hatch window were higher for ES3 than ES14 chicks. PepT1 expression was higher for ES3 chicks compared with ES14. There was a 10.2 and 17.6-fold increase in PepT1 and SGLT1 expression of ES3 chicks at the end of hatch window, whereas it was only 2.3 and 3.3-fold, respectively, for ES14 chicks. These results suggested that egg storage duration affected development of early hatched chicks during 30 h of hatch window. It can be concluded that the ES14 chicks would be less efficiently adapted to absorption process for carbohydrates and protein than those from ES3 at the end of the hatch window.

Physiological status of broiler chicks at pulling time and the relationship to duration of holding period

Newly hatched chicks may be held longer than 48 h and experience long periods of fasting in commercial hatcheries. Limited information is known about the physiological status of chicks in such situations, due to the difficulty of precisely recording time of hatch. This study investigated the effect of the time from hatch to pulling (holding period) on physiological measures/parameters in 109 broiler chicks. Fertile Ross 308 eggs were incubated in a custom built small-scale incubator. The individual hatching time of each focal chick was determined using eggshell temperature monitoring. At 'pulling' (512 h of incubation time), the quality of focal chicks was assessed using the chick scoring method and physiological parameters were measured including BW, organ (heart, liver and stomach) weights, blood values and plasma corticosterone level. The time from hatch to pulling varied from 7.58 to 44.97 h. Egg weight at setting was significantly correlated with chick BW and weight of organs at pulling, but had no effect on chick quality, blood values and plasma corticosterone. Relative BW at pulling was negatively associated with the duration of holding period (P=0.002). However, there was a positive correlation between relative stomach weight and the duration of the holding period (P<0.001). As the holding period duration increased, there was a trend that blood partial pressure of oxygen, haematocrit and haemoglobin also increased, and blood partial pressure of carbon dioxide, total carbon dioxide and bicarbonate decreased (P<0.05). A wide range of plasma corticosterone was observed from chicks that had experienced different durations of holding period. We conclude that shortening the hatch window and minimising the number of chicks that experience a long holding period before pulling may improve chick quality and physiological status, which may be due to unfavourable environmental conditions that include feed and water deprivation.