Submitted to: Journal of Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 12, 1999
Publication Date: N/A
Interpretive Summary: The impact of disease stress can be appreciated by observing how severely an animal reacts to the disease or stress or how quickly its activities return to normal. An animal's response to an encounter with a disease is determined by two factors: (1) how immunologically resistant the animal is to the invading pathogen and (2) how dramatically it needs to change its metabolic processes to fight off the disease and restore good health. A goal of the present research is to identify strategies to minimize how severely animals react to the presence of a disease pathogen and whether strategies that are readily implementable in the cattle industry can be identified that shorten the animal's recovery time. We identified properties beneficial to animal health for an estrogen and progesterome implant approved by the FDA for use as a growth promoter in cattle. We tested the ability for the common use of this implant to affect the recovery time of steers treated with a bacterial extract (endotoxin) to mimic a disease stress without the need to actually infect them with a disease. We discoveres that this estrogen and progesterone implant appeared to stabilize the host response to the introduction of the bacterial toxin, minimize changes in some hormones needed for growth, and shorten the time for animals to return to full feed. The cost of use of these implants is readily offset by the reduction in production losses associated with severe animal response to disease.
The objectives of this study were to determine whether a gonadal steroid implant (20 mg estrogen and 200 mg progesterone) given to endotoxic steers would: (1) reduce hyperglycemia, hypoglycemia and insulin resistance, (2) reduce changes in concentrations of GH and IGF-I, (3) reduce inappetence, NEFA and BUN, and (4) reduce fever and plasma concentrations of TNF and cortisol. Holstein steers were assigned within a 2 x 2 factorial to steroid and LPS treatments. Steers were implanted at 20 weeks of age and serial blood samples (15 min intervals) were collected on day 14 for 8 hours with vehicle or LPS (.001 mg/kg, i.v.) after 2 hours. Intravenous glucose tolerance tests (100 mg glucose/kg BW) were carried out at 6 and 24 hours. Hyperglycemia was 67% lower (P<.05) in steroid-treated steers after LPS, although hypoglycemia and insulin resistance was greater in the steroid- treated steers. Concentrations of IGF-I were restored earlier with steroid treatment and appetite and intake were greater after LPS with the steroid treatment. Steroid did not affect the concentrations of cortisol or TNF after LPS. It is concluded that gonadal steroids reduce the severity of some endocrine and metabolic parameters associated with endotoxemia. However, it is unlikely that gonadal steroids acted via anti-inflammatory and immunosuppressive actions of glucocorticoids or reducing concentrations of cytokines.