Effects of short and long - term nutrition and progesterone supplementation on the success of fixed - time artificial insemination in the ewe

David O Kleemann; Jennifer M Kelly; Kimberley M Foyster; Alyce M Swinbourne; Alice C Weaver; Simon K Walker

doi:10.1016/j.anireprosci.2024.107477

Effects of short and long - term nutrition and progesterone supplementation on the success of fixed - time artificial insemination in the ewe

Anim Reprod Sci. 2024 Apr 18:265:107477. doi: 10.1016/j.anireprosci.2024.107477. Online ahead of print.

Authors

David O Kleemann¹, Jennifer M Kelly², Kimberley M Foyster³, Alyce M Swinbourne⁴, Alice C Weaver⁵, Simon K Walker⁶

Affiliations

¹ Turretfield Research Centre, South Australian Research and Development Institute, Holland Road, Rosedale, South Australia 5350, Australia. Electronic address: dave.kleemann@sa.gov.au.
² Turretfield Research Centre, South Australian Research and Development Institute, Holland Road, Rosedale, South Australia 5350, Australia. Electronic address: jenkelly@internode.on.net.
³ School of Animal and Veterinary Sciences, Roseworthy Campus, The University of Adelaide, Roseworthy, South Australia 5371, Australia. Electronic address: kimmi.foyster@optusnet.com.au.
⁴ Turretfield Research Centre, South Australian Research and Development Institute, Holland Road, Rosedale, South Australia 5350, Australia. Electronic address: alyce.swinbourne@sa.gov.au.
⁵ Turretfield Research Centre, South Australian Research and Development Institute, Holland Road, Rosedale, South Australia 5350, Australia. Electronic address: alice.weaver@sa.gov.au.
⁶ Turretfield Research Centre, South Australian Research and Development Institute, Holland Road, Rosedale, South Australia 5350, Australia. Electronic address: walkersa@adam.com.au.

PMID: 38663150
DOI: 10.1016/j.anireprosci.2024.107477

Abstract

The success of fixed - time artificial insemination (AI) in the ewe is variable due to poor synchrony of estrus. We examined the effects of long-term nutrition (LTN; low, medium, high - 6 months), short-term nutrition (STN; 1.0 M, 1.5 M - 14 days) and progesterone supplementation (P; single pessary, replacement on Day 9) on synchrony and reproductive outcomes. High LTN advanced (P < 0.05) estrus, increased (P = 0.06) pregnancy (range 71.1 - 81.1%) and improved (P < 0.01) litter size (range 1.30 - 1.50). STN increased (P < 0.05) pregnancy (79.0 versus 72.3%) but not litter size or timing of estrus. A LTN x STN interaction (P < 0.01) for time of estrus indicates that the effects of LTN were moderated by STN depending on the level of LTN. Pessary replacement delayed (P < 0.05) the onset of estrus, improved synchrony but did not affect pregnancy or litter size. High LTN increased (P < 0.05) the number of large (≥ 3.8 mm) and medium - size follicles (2.0 - 3.7 mm) but the diameter of large follicles tended to be reduced (P = 0.08) on Day 12. STN did not affect follicle number or size whilst P reduced (P < 0.05) the diameter of large follicles on Day 12 (4.83 versus 5.10 mm) and increased the number of medium - size follicles (3.56 versus 2.74 mm). In conclusion, both LTN and STN are major sources of variability in AI programs whilst pessary replacement has potential to reduce variability.

Keywords: Estrus; Fixed-time artificial insemination; Follicles; Nutrition; Pregnancy; Progesterone.