SULONG, AHMAD HANAFI (2022) CHARACTERIZING THE IMPACT OF PRENATAL THERMAL AND AUDITORY STIMULATION ON BROILER CHICKENS. Doctoral thesis, University Putra Malaysia.
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Abstract
Five experiments were conducted to investigate the effects of prenatal manipulation with different stimulation episodes during embryonic development on physiological stress response and their roles in stress tolerance parameters such as serum levels of acute phase proteins (APPs), corticosterone (CORT), heat shock protein 70 (HSP70), stress-related genes expressions as well as cecal microflora in broiler chickens. In experiment I, a study was conducted to determine the presence and circulating levels of APPs, namely, serum levels of ceruloplasmin (CPN) and serum levels of alpha-1- acid-glycoprotein (AGP), in embryos and neonates. Under normal incubation settings, APPs were detected in the blood of chicken embryos and neonates for the first time, and the levels varied according to the development stage. Experiment II was conducted to investigate further the functional roles of APPs, CORT and HSP 70 following thermal stress. Hatching eggs were subjected to three thermal treatments; (i) standard optimum temperature throughout (SS: 37.8 °C and 56 % RH), (ii) heat stress for 12 h daily (HS: 40.0 °C and 56 % RH), and (iii) cold stress for 12 h daily (CS: 30.2 °C and 56 % RH). The heat and cold stress treatments were imposed from the 10th to the 18th day of incubation (ED). The results suggest that heat-stressed treatment elevated AGP, CPN and CORT. On the contrary, cold-stressed embryos had reduced AGP, CPN and CORT. The HSP70 were upregulated throughout the experimental period in both prenatal heat and cold treatment. The results suggest that the modifications of APPs, CORT and HSP70 reactions are crucial to coping with thermal stress. In order to gain more evidence on the circulating reactions of APPs and other blood biochemistry due to different stressful stimulation episodes, hatching eggs were subjected to different prenatal auditory stimulation (PAS), which are prerecorded noise and music stimulation in Experiment III. Chicken embryos were exposed to pre-recorded noise and music at 90 dB for 20 min/h for 24-h starting from ED 12 to hatching. The results showed that both MUSIC and NOISE treatments significantly elevated CPN, AGP and CORT during embryonic development. The MUSIC but not NOISE treatment enhances the ability of embryos at ED 18 and neonatal chicks to express HSP70. The alterations of these analytes could be significant in developing embryos and newly hatched chicks to cope with stress attributed to auditory stimulation. Experiment IV was conducted to gain more insights into PAS effect following to different chick placement (PL) in day old chicks. Following hatching, chicks were divided into two different placements: early placement (EAR) and 24-h delayed placement (DEL). Reduction in body weights of DEL chicks was noted at d 7 and 14. Irrespective of PL, NOISE was detrimental to feed intake and concomitant body weights. There were significant PAS x PL interactions for HSP70 and telomere length (TL). Following DEL, the NOISE chicks had reduced HSP70, but the converse was noted for the Control and MUSIC chicks at d 7. A similar trend was noted for messenger RNA (mRNA) expression of HSP70. The NOISEexposed embryos subjected to DEL had reduced TL compared to Control and MUSIC counterparts. Longer TL was noted in MUSIC-exposed embryos compared to the Control. It is interesting to note that irrespective of PL, the NOISE-exposed chicks had lower CPN, AGP and CORT than Control chicks. Subjecting the hatching eggs to NOISE has modified the ability of chicks to cope with the stress attributed to delayed placement. The NOISE may have triggered significant and sustained epigenetic changes during embryogenesis, leading to a better ability to withstand noxious stimuli later in life. The last experiment (Experiment V) was conducted to investigate the long-term impact of PAS on different feeding regimens (FR) at the market age. An equal number of chicks were subjected to one of the FR; ad libitum (Control) or 30-h feed restriction at d 42. As measured by AGP and CORT, the NOISE chicks showed improved coping ability when feed deprived for 30-h. The reduced physiological distress following feed deprivation in the NOISE chicks compared to Control and MUSIC groups is associated with an enhanced ability to elicit HSP70 response at protein and gene levels. The phenomenon could be associated with higher glucocorticoid receptor (GR) expression available in NOISE chicks to reduce corticosterone release into the bloodstream. However, stress attributed to NOISE stimulation had detrimental effects on TL attrition. Besides, results demonstrated that subjecting the chicks to a 30-h feed restriction had reduced the cecal population of Lactobacillus. Based on these findings, prenatal auditory stimulation can reduce the detrimental effects of feed deprivation at market age. These findings are essential in formulating strategies to improve the welfare of feed-restricted broiler breeders. This may offer a potentially practical approach to ameliorate the stressfulness of chronic hunger in feed-restricted broiler breeders.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Subjects: | Agriculture > Agriculture (General) |
| Depositing User: | ENCIK SAIFUL FADZLY JAMALUDIN |
| Date Deposited: | 31 Jul 2026 07:32 |
| Last Modified: | 31 Jul 2026 07:32 |
| URI: | https://repositori.mohe.gov.my/id/eprint/383 |
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