J. Paul Thaxton

Ascorbic Acid in Poultry: a Review

All species of poultry are capable of AA synthesis and dietary supplementation with AA is not necessary when the animal is managed properly. However, when the birds are subjected to stressful condi...

Demasculinization of male Japanese quail by prenatal estrogen treatment

Abstract Genetic male Japanese quail were administered sex hormones or the oil vehicle on Day 10 of incubation and were caponized 3 weeks after hatching. As adults, the capons were injected with testosterone propionate daily for 2 weeks and then were tested for masculine sexual behavior in response to sexually receptive females. Males that had received as little as 2 μg of estradiol-17β in ovo failed to exhibit the head grabbing and mounting typical of the normal masculine sexual response to females. In a second experiment, this demasculinization was produced by prenatal treatment with 2 μg of estradiol-17α, estrone, estriol, or diethylstilbestrol, but not by this quantity of testosterone. These data suggest that an estrogen is the agent of behavioral demasculinization in the normal female, and that endogenous testosterone poses no difficulty for proper sexual development in the normal male.

Humoral immunity in the chicken as affected by mercury.

An evaluation was made of the effects of chronic and acute mercury (Hg) treatments on humoral immunity in the chicken. Three treatments were examined,i.e., chronic, acute high, and acute low Hg treatments. Although chronic dietary treatment with 300 ppm of Hg in the drinking water was growth inhibitory, acute high and low Hg treatments given by IM injections were not growth inhibitory. Chronically-treated birds showed suppressed primary and secondary responses to challenge with sheep red blood cells (SRBC). Additionally, immunoglobulin M levels were reduced to a greater extent than immunoglobulin G levels in chronically-treated birds. These effects did not occur in birds that received acute high and low Hg treatments. Immune suppression by growth inhibitory Hg treatment agrees with published reports and the differential effect on specific immunoglobulin levels is a new finding. Primary responses toBrucella abortus (BA) in chronically-treated birds were also suppressed, but secondary responses were enhanced. These data further clarify the role of Hg on immune responsiveness in chickens.

Mercury toxicity as compared to adrenocorticotropin-induced physiological stress in the chicken

Broiler cockerels (Gallus domesticus) received mercury (Hg) in the form of HgCl2via drinking water from hatching through five weeks of age. Adrenocorticotropin (ACTH) was administered IM on each of five consecutive days beginning at four weeks of age. Hg inhibited growth, increased relative adrenal weights, decreased adrenal cholesterol and corticosteroids, and decreased relative weights of the bursa of Fabricius. ACTH decreased body weight gain, increased blood cholesterol and protein levels, decreased adrenal cholesterol, and decreased relative weights of the bursa. Additionally, Hg and ACTH interacted significantly or caused numerical changes in adrenal cholesterol, relative weights of the adrenal glands and the bursa. All treatments resulted in extensive involution and histological discontinuity of the bursa. Chickens attempt to adapt to Hg toxicity by exhibiting classic physiological stress.

Abnormal Mating Behavior and Reproductive Dysfunction Caused by Mercury in Japanese Quail

Summary The results of this study support previous findings that Hg does reduce the reproductive potential of the female of avian species (3, 4). Additionally, the dangers of Hg are not relegated entirely to the female, but rather it is concluded that Hg exerts an equally adverse effect on the reproductive potential of the avian male. The loss of reproductive efficiency which is caused by Hg in both male and female quail may be correlated directly to a diminution in their normal mating behavior.

Immunological responsiveness of the pigeon (Columbalivia) following neonatal bursectomy

Pigeon squabs in two separate experiments were surgically bursectomized ( BSX ), surgically sham bursectomized ( SBSX ), or maintained as non-surgical controls (CON). Surgical procedures were performed within 2 hr of hatching. Primary and secondary hemagglutinin (HA) responses, as well as mercaptoethanol sensitive (ME-S) and resistant (ME-R) levels, to sheep red blood cells (SRBC) were quantitated. BSX did not reduce HA responses, nor ME-S and ME-R levels.