Pineal Gland and Ocular Influences on Turkey Breeder Hens

Abstract

Yearling Large White turkey breeder hens underwent pinealectomy (PX), bilateral ocular enucleation (EX), or both and were then photo-induced into reproductive activity. During the subsequent 20-week reproductive period, data were recorded for body weight, change in body weight, feed intake, egg weight, eggshell thickness, and percent settable eggs. A significant interaction between PX and EX treatments did not occur for any of the parameters of this study. Absolute body weight, feed intake, shell thickness, and percent settable eggs were not significantly affected by PX during the study, but PX significantly increased egg weights. Feed intake was significantly reduced by EX, but other parameters were not affected. Both PX and EX reduced body weight losses typically observed in breeder hens during an in-season egg laying cycle. It was concluded that the pineal gland and the eyes can influence body weight changes, egg size, or feed intake in breeder turkey hens during a reproductive cycle.

Diurnal Rhythm of Plasma Melatonin Concentration in the Domestic Turkey and Its Regulation by Light and Endogenous Oscillators

“…The daily and seasonal changes in the photoperiod duration are the most important factors controlling melatonin (MLT) secretion by the pineal gland. Day-night rhythmic MLT secretion regulates in birds, among others, the diurnal rhythm of locomotor activity and feed intake [1][2][3][4]; body weight [2]; reproductive system functions [2,[5][6][7][8]; immune system activity [9][10][11][12]; seasonal singing, migration, and spatial orientation during flight [8,13]; thermal homeostasis [14][15][16]; and energy metabolism [1,17]. MLT is also an important component of the antioxidative defense system [18].…”

“…MLT supplementation and/or properly set lighting schedules resulted in a reduction in the incidence of sudden death syndrome [19], activity-related heat production [16,17], and isolation distress [20], in chickens. The better use of feed [2], the influence on growth of the ovaries and egg production [2,5], the improvement of male reproduction [21], and the acceleration of development of the cellular and humoral immune responses [10,11] have been described as the effects of such treatment in turkeys.…”

Roles of Direct Photoreception and the Internal Circadian Oscillator in the Regulation of Melatonin Secretion in the Pineal Organ of the Domestic Turkey: A Novel In Vitro Clock and Calendar Model

“…The turkey pineal organ retains a tubule-follicular structure up to the age one year and possess highly developed rudimentary-receptor pinealocytes, which lead to the hypothesis that direct photoreception plays a primary role in the regulation of MLT secretion in this organ [45]. Second, the turkey is a poultry species with high economic significance and knowledge about its circadian physiology may be important from a practical point of view [49,50,51].…”

Fusaric acid in Fusarium moniliforme cultures, corn, and feeds toxic to livestock and the neurochemical effects in the brain and pineal gland of rats

“…In turkey breeder hens, the pineal influences body weight changes, egg size, or feed intake during a reproductive cycle, as well as influences plasma prolactin during ovarian development, and thus can influence certain reproductive parameters [Siopes, 1987;Siopes and Underwood, 1987;Siopes and Halawani, 19891. Consequently, an alteration of these mechanisms by fusaric acids in birds and mammals may alter MEL synthesis, circadian rhythms, and ultimately affect production.…”