Changes in egg production rate induced by progesterone injection in broiler breeder hens

Abstract

A polycystic ovarian follicle (PCOF) syndrome associated with high baseline concentrations of progesterone (P4) without preovulatory luteinizing hormone (LH) surges has been reported in turkey hens. The PCOF syndrome could be induced in turkey hens by injecting P4 (0.33 mg/kg per d) daily early in the reproductive period for 10 to 12 d and then waiting 3 wk for the syndrome to develop. It was hypothesized that an arrest in laying associated with the PCOF syndrome could be induced by daily injection of P4 in restricted-fed broiler breeder hens. Hens were divided into 5 treatment groups and were injected subcutaneously daily with P4 in canola oil at dosages of 0, 0.17, 0.33, 0.5, and 1.5 mg/kg per d for 13 d, at 14 wk of egg production when they were 41 wk of age. Blood samples were collected on d 7 and 13 immediately before P4 injection. Oviductal and ovarian morphologies were measured at necropsy 1 d after the last P4 injection. Egg production rate was reduced by injection of P4 at dosages < 0.17 mg/kg per d. At dosages of 0.5 and 1.5 mg/kg per d, ovarian hierarchical follicles had regressed. None of the broiler breeder hens had the PCOF syndrome at necropsy, but a high incidence of hens holding hard-shelled uterine eggs for several days was observed. Concentrations of LH decreased with P4 injection at > 0.17 mg/kg per d, and P4 concentrations were increased with P4 injection at > 0.5 mg/kg per d. Estradiol-17beta (E2) concentrations were decreased at all P4 dosages. It was concluded that egg production rate was reduced by daily injection of P4 at dosages > 0.17 mg/kg per d, and egg production ceased and ovarian follicles and the oviduct regressed at dosages > 0.50 mg/kg per d. The PCOF syndrome, however, was not induced in restricted-fed broiler breeder hens by P4 injection.

Effects of progesterone injection on performance, plasma hormones and ovarian morphology of ad libitum and restricted fed broiler breeder hens

“…The lower concentration of E 2 may thus lead to regression of the oviduct and impaired follicles development after P 4 injection. Similar to our results, Liu and Bacon (2005) observed a depression in plasma E 2 along with regressed ovary after injection of P 4 in broiler breeder hens. Lower E 2 concentration of ad libitum fed hens compared to restricted fed hens observed in this research is in agreement with Onagbesan et al (2006).…”

“…Taken together, these data suggest that P 4 treatment has a strong negative effect on egg production rate and hierarchical follicular maintenance and development. Liu and Bacon (2005) came to similar conclusion.…”

“…Inability of oviduct to direct all ovulated follicles resulted in higher incidence of soft shell and double yolk eggs. Liu and Bacon (2005) observed higher incidence of soft shell egg after P 4 injections in broiler breeder. Similar to results obtained in the current study, egg production decreased after P 4 injection in turkey , broiler breeder (Liu and Bacon, 2005) and in Japanese quail (Tell et al, 1999;Liu and Bacon, 2004).…”

“…Plasma concentrations of E 2 are increased after follicle stimulating hormone (FSH) injection in laying hens late in the reproductive period (Palmer and Bahr, 1992), suggesting that the secretion of FSH is also decreased after P 4 injection. Liu and Bacon (2005) reported a decline in LH concentration after P 4 injection. Taken together, these data suggest P 4 injection may have negative effect on secretion of GnRH.…”

“…High baseline concentrations of P 4 in arrested hens might negatively feedback on the ability of the hypothalamus to secret surges of GnRH and subsequently surges of LH, or on the ability of the pituitary to respond to surges of GnRH secretion if they occur (Liu et al, 2001b;Bacon and Liu, 2004;Liu and Bacon, 2005).…”