How Much Does a Ram Lose during the Breeding Season? Assessment of Pre and Post Breeding Reproductive Traits of Rams in a Range Flock in the Pacific Northwest.

Stotts, Meagan

This is a draft schedule. Presentation dates, times and locations may be subject to change.

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How Much Does a Ram Lose during the Breeding Season? Assessment of Pre and Post Breeding Reproductive Traits of Rams in a Range Flock in the Pacific Northwest.

Monday, July 10, 2017

Exhibit Hall (Baltimore Convention Center)

Meagan J Stotts, Department of Animal Sciences, Washington State University, Pullman, WA
McKenzie R. Corpron, Department of Animal Sciences, Washington State University, Pullman, WA
Natasha R Moffitt, Department of Animal Sciences, Washington State University, Pullman, WA
J. L. Mutch, Department of Animal Sciences, Washington State University, Pullman, WA
S M Smith, Department of Animal Sciences, Washington State University, Pullman, WA
Jan R Busboom, Department of Animal Sciences, Washington State University, Pullman, WA
Margaret E. Benson, Department of Animal Sciences, Washington State University, Pullman, WA
Martin G. Maquivar, Department of Animal Sciences, Washington State University, Pullman, WA

The objective of the study was to assess reproductive soundness of rams during two consecutive pre-breeding (PRE) and post-breeding (POST) seasons in a range flock management system in the Pacific Northwest. The present study includes data from two years. 32 animals were evaluated 15 days prior to the beginning of the breeding season (average 6 months of age) and 7 days after the termination of a 120 day breeding season (average 10 months of age). Animals were followed-up during their second year as adult rams at 17 months of age and again at the end of the breeding season (23 months of age). Animals were group mated with a flock of ewes (1:35 male: female), and grazed federal lands during the breeding season. The variables assessed PRE and POST were: body condition score (BCS, using a 1-5 scale), scrotal circumference (SC), and percentage of spermatozoid motility (MOT). Data was analyzed using a mixed model with repeated measures assessing the main effect of season on the variables identified. During the first breeding season, no animals were culled; however, by the end of the second year 34% (11/32) were culled. Over the first breeding season, ram lambs (n=32) lost (P<0.01) on average 0.5 points of BCS, PRE (2.54 ± 0.03 units) to POST (2.04 ± 0.09 units), by the second breeding season the mature rams (n=23) gained on average 0.03 points of BCS, PRE (1.85 ± 0.08 units) to POST (1.86 ± 0.08 units). Similarly, during the first year the ram lambs had a reduced (P<0.01) SC measurement from PRE (38.2 ± 0.3 cm) to POST (35.9 ± 0.5 cm). Values greater than 36 cm were considered exceptional for fertility; during the second year rams decreased (P<0.01) SC from PRE (38.8 ± 0.52 cm) to POST (31.1 ± 1.4 cm). Based on MOT, no differences (P>0.05) were observed between PRE and POST measures (PRE 66.2 ± 5.6% vs. POST 62.1 ± 5.7%) during the first year. MOT decreased (P<0.01) during the second year (PRE 91.9 ± 3.8% vs. 55.8 ± 3.8% 7.8%). It is concluded that in range flock systems the first year of life is critical to manage and maximize the reproductive potential of the rams. Additionally, year-round management is necessary to ensure the reproductive success of sheep flocks and to maximize the productive longevity of rams.

672 How Much Does a Ram Lose during the Breeding Season? Assessment of Pre and Post Breeding Reproductive Traits of Rams in a Range Flock in the Pacific Northwest.

Meeting Information

672
How Much Does a Ram Lose during the Breeding Season? Assessment of Pre and Post Breeding Reproductive Traits of Rams in a Range Flock in the Pacific Northwest.