Abstract
The aim of the current study was to evaluate effectiveness of oral administration of Potassium iodide for induction of estrus in postpartum anestrous dairy cows as compared to standard hormonal therapy. A total of 121 cows have been diagnosed with inactive ovary based on rectal examination by having smooth and small ovaries showing no estrus signs for more than 90 days. Selected animals were divided into 6 treatment groups: G1, n=20) treated with I.M injection of 20μg Buserelin-GnRH analogue; G2, n=20) treated by 7gm Potassium iodide orally for 7 successive days; G3, n=20) treated with 7gm Potassium iodide + I.M injection of 20 ml of 14% Phosphorus solution+ 10μg Buserelin; G4, n=15) received single I.M injection of 10mg estradiol benzoate; G5, n=15) received I.M injection of 50mg Progesterone for 4 days and 10mg estradiol benzoate on day 5; G6, n=31) control group- received no treatment. Animals detected in estrus were bred by artificial insemination (A.I) toward end of estrus, pregnancy was confirmed per rectum on day 60 post A.I. Estrus response rate (ERR), treatment-estrus interval, overall conception and pregnancy rates by the end of the experiment (second estrus after treatment) were recorded. ERR was 85%, 80%, 66.67% in G3, G1, and G5 respectively with no significant difference between them (P=0.05). All treated groups were significantly higher than G6-control group (9.68%, 3 out of 31 cows). The interval to first induced estrus was earlier (within 7-10 days) in G1 and G5 cows and was delayed in the other groups (within 14-20 days). Conception rate at first induced estrus in G1, G2, and G3 was 68.75%, 83.33%, 70.58% respectively, and in the steroid treated groups G4, G5 it was 62.50%, 40% respectively. Overall conception rate was non-significantly different (P> 0.05) among all groups with values recorded at 91.66% (11/12), 87.5% (14/16), and 82.34% (14/17) for G2, G1, and G3 respectively. Same pregnancy rate (70%) was obtained in G1 and G3 treated cows that was statistically comparable (P=0.05) to values obtained in G2 (55%), and G5 (40%), but higher than recorded in G4 (33.33%). Pregnancy rate in treated groups was significantly higher than G6-control group (9.68%).
In conclusion, Potassium iodide administration produced good therapeutic effect that is comparable to the standard GnRH and steroid based treatment. Therefore, Potassium iodide could be a cost-effective treatment of inactive ovaries in dairy cows particularly if combined with Phosphorus.

Key words: Inactive ovaries, Dairy cows, Potassium iodide, Phosphorus, GnRH agonist, Estruos cycle, Follicular development, Ovulation, Conception rate