TY - JOUR
T1 - Experimental model of toxin-induced subclinical mastitis and its effect on disruption of follicular function in cows
AU - Furman, Ori
AU - Leitner, Gabriel
AU - Roth, Zvi
AU - Lavon, Yaniv
AU - Jacoby, Shamay
AU - Wolfenson, David
N1 - Publisher Copyright:
© 2014 Elsevier Inc.
PY - 2014/11/1
Y1 - 2014/11/1
N2 - This study establishes an experimental model for subclinical mastitis induced by Gram-positive (G+) exosecretions of Staphylococcus aureus origin or Gram-negative (G-) endotoxin of Escherichia coli origin to examine its effects on follicular growth and steroid concentrations in Holstein dairy cows. Cows were synchronized with the Ovsynch protocol followed by a series of follicular cycles that included GnRH and PGF2α doses administered every 8days. Cows received small intramammary doses of either G+ (10μg, n=10) or G- (0.5μg, n=6) toxin, or saline (n=6; uninfected control) every 48hours for 20days. Follicular fluids were aspirated from preovulatory follicles before (aspiration one: control), at the end of (aspiration two: immediate effect), and 16days after the end of (aspiration three: carryover effect) toxin exposure. During the 3weeks of subclinical mastitis induced by G+ or G-, no local inflammatory signs were detected in the mammary gland and no systemic symptoms were noted: body temperatures of the treated cows did not differ from controls; plasma cortisol and haptoglobin concentrations were not elevated and did not differ among groups. Somatic cell count was higher in the treated groups than in controls, and higher in the G- versus G+ group. For analysis of reproductive responses, cows were further classified as nonaffected or affected based on an more than 20% decline in follicular androstenedione concentration in aspiration two or three relative to the first, control aspiration. Most G- (5/6) and 40% of G+ (4/10) cows were defined as affected by induced mastitis. An immediate decrease in the number of medium-size follicles was recorded on Day 4 of the induced cycle, toward the end of the 20-day mastitis induction, in the affected G+ compared with uninfected control group (1.0±0.5 vs. 3.0±0.4 follicles; P<0.05); the affected G- and nonaffected G+ subgroups exhibited a similar numerical decline in the number of follicles. A carryover (but not immediate) decrease to 51% and 62% in follicular estradiol concentrations in G- affected group and G+ affected group was detected relative to controls (P<0.05). The nonaffected G+ subgroup did not differ from its control counterparts. Based on the current experimental model, subclinical IMI induced by G+ or G- toxin disrupts follicular functions, and it seems that the ovarian pool of early antral follicles is susceptible to subclinical mastitis.
AB - This study establishes an experimental model for subclinical mastitis induced by Gram-positive (G+) exosecretions of Staphylococcus aureus origin or Gram-negative (G-) endotoxin of Escherichia coli origin to examine its effects on follicular growth and steroid concentrations in Holstein dairy cows. Cows were synchronized with the Ovsynch protocol followed by a series of follicular cycles that included GnRH and PGF2α doses administered every 8days. Cows received small intramammary doses of either G+ (10μg, n=10) or G- (0.5μg, n=6) toxin, or saline (n=6; uninfected control) every 48hours for 20days. Follicular fluids were aspirated from preovulatory follicles before (aspiration one: control), at the end of (aspiration two: immediate effect), and 16days after the end of (aspiration three: carryover effect) toxin exposure. During the 3weeks of subclinical mastitis induced by G+ or G-, no local inflammatory signs were detected in the mammary gland and no systemic symptoms were noted: body temperatures of the treated cows did not differ from controls; plasma cortisol and haptoglobin concentrations were not elevated and did not differ among groups. Somatic cell count was higher in the treated groups than in controls, and higher in the G- versus G+ group. For analysis of reproductive responses, cows were further classified as nonaffected or affected based on an more than 20% decline in follicular androstenedione concentration in aspiration two or three relative to the first, control aspiration. Most G- (5/6) and 40% of G+ (4/10) cows were defined as affected by induced mastitis. An immediate decrease in the number of medium-size follicles was recorded on Day 4 of the induced cycle, toward the end of the 20-day mastitis induction, in the affected G+ compared with uninfected control group (1.0±0.5 vs. 3.0±0.4 follicles; P<0.05); the affected G- and nonaffected G+ subgroups exhibited a similar numerical decline in the number of follicles. A carryover (but not immediate) decrease to 51% and 62% in follicular estradiol concentrations in G- affected group and G+ affected group was detected relative to controls (P<0.05). The nonaffected G+ subgroup did not differ from its control counterparts. Based on the current experimental model, subclinical IMI induced by G+ or G- toxin disrupts follicular functions, and it seems that the ovarian pool of early antral follicles is susceptible to subclinical mastitis.
KW - Follicular development
KW - Steroid
KW - Subclinical mastitis
UR - http://www.scopus.com/inward/record.url?scp=84921943541&partnerID=8YFLogxK
U2 - 10.1016/j.theriogenology.2014.08.002
DO - 10.1016/j.theriogenology.2014.08.002
M3 - Article
C2 - 25212394
AN - SCOPUS:84921943541
SN - 0093-691X
VL - 82
SP - 1165
EP - 1172
JO - Theriogenology
JF - Theriogenology
IS - 8
ER -