Effect of nutrition on the ovulatory response of Coopworth ewes to varying doses of two FSH preparations

J.G.E. Thompson and J.F. Smith

Ruakura Agriculture Centre, Ministry of Agriculture and Fisheries, Hamilton

Proceedings of the New Zealand Society of Animal Production. 1988, 48: 81-86

A 2 x 2 x 4 factorial trial was performed (n=20), N=320) to investigate the effect of 2 levels of nutrition (high protein diet -23% crude protein v low protein diet - 10% crude protein) on the ovarian response to exogenous follicle stimulating hormone (FSH) administration in mixed-age Coopworth ewes. Two preparations of FSH were examined (FSH-P, Burns-Biotec and Folltropin(r), Vetripharm) at 4 different levels (0, 8, 16 and 24 mg equivalents FSH-P).

The ovulation rate of both high and low protein intake ewes increased linearly in response to increasing FSH levels (0 mg = 1.2; 8 mg = 3.2; 16 mg = 7.9; 24 mg = 9.6). There was no difference in response between the 2 sources of FSH. Ewes on a high protein intake had a higher ovulation rate when FSH was not administered (mean ovulation rate ą SE; 1.40 ą 0.1 v 1.0 ą 0.1, P<0.05), but no significant differences were observed when exogenous FSH was administered. These results suggest that the mechanism(s) which cause the protein-induced increase in ovulation rate is masked by the administration of exogenous FSH.

Keywords: NZSAPAB; Coopworth; sheep; nutrition; protein; ovulation rate; superovulation; FSH; CIDR

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