Relation of Stage of Cycle and Source of Luteinizing Hormone to Superovulation in Dairy Cattle.

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Abstract
The study included 2 expts. In the 1st, 5 heifers injected with sheep pituitary FSH subcut. and PU or unfractionated sheep gonadotropin (USG) intraven. during the luteal phase of the estrual cycle produced 34 eggs none of which were fertilized. Five treated during the follicular phase produced 43 eggs, of which 74% had cleaved. All 6 heifers treated during the luteal phase, but none of the 6 follicular heifers, had pyometra. In the 2d expt. PMS and USG or PU were used. In both expts. USG produced twice as many corpora lutea as PU. A combination of PMS and HCG may produce satisfactory superovulation and should be studied further. Three of 5 eggs produced by superovulation, fertilized in vivo and transplanted have resulted in pregnancies.