Influence of hypo- or hyperthyroidism on ovarian function in Brahman cows

Journal of Animal Science
G V De MoraesR D Randel

Abstract

Multiparous Brahman cows (n = 21) were randomly assigned during late fall within BW and body condition score (BCS) to receive either 3.0 mL of corn oil (C; n = 7), 3.0 mg/(cow x d) triiodothyronine (T3) s.c. in 3.0 mL of corn oil (HYPER; n = 7), or 4.0 mg/(kg x d) 6-n-propyl-2-thiouracil (PTU; fed with concentrate) plus 3.0 mL/d corn oil (HYPO; n = 7). Water, minerals, and Coastal bermudagrass hay were available free choice, and all cows received 3.2 kg x cow(-1) x d(-1) of 5:1 corn:soybean meal concentrate. The feeding period extended through three normal estrous cycles. Blood samples were collected weekly during the first and second estrous cycle, or until d 42 for anestrous cows, and daily throughout the third cycle. Also, between d 9 and 14 of the third cycle, or after d 35 in anestrous cows, intensive samples were collected at 2-h intervals for 24 h. Serum T3, thyroxine (T4), and progesterone (P4) were measured in weekly and intensive samples, and cortisol, insulin, GH, and thyroid-stimulating hormone (TSH) were measured in intensive samples. The altered thyroid status of HYPER and HYPO cows was evident (P < .001) during the third estrous cycle in mean daily T3, T4, and intensive TSH (P < .001) concentrations. Changes in B...Continue Reading

Citations

May 17, 2018·Biology of Reproduction·Juneo F SilvaRogéria Serakides
Aug 12, 2008·Journal of Veterinary Internal Medicine·R H H TanG B Daniel
May 27, 2004·Journal of Agricultural and Food Chemistry·Qiuqiong ChengTodd A Anderson

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