Fertility Traits: Whats in a phenotype? Where we are and Why weve - PDF document

Bob Weaber, Kansas State University June 19, 2019 Overview • Current Evaluations Fertility Traits: • What’s in a phenotype? Where we are and • Why we’ve not made a lot of progress opportunities for • Opportunities for the advancement Bob Weaber, Ph.D. future Professor & Cow-calf Ext. Specialist Kansas State University 785-532-1460 bweaber@k-state.edu What’s the ideal beef cow? Current Evaluations • Many definitions, but here • Angus: Heifer Pregnancy are the musts: • Brangus: Age at 1 st Calving, Heifer Pregnancy, Stayability Don’t forget…she’s a grass harvester – Has minimal maintenance • Gelbvieh: Heifer Preg, 30-month Calving, Stayability requirements, but carries enough first and foremost! body condition to withstand feed • Hereford: Sustained Cow Fertility shortages • Limousin: Stayability – Produces enough milk to raise a good, healthy calf • Red Angus: Heifer Pregnancy, Stayability – Gets pregnant • Shorthorn: Stayability à On Time, Every Time – Has excellent maternal • Simmental: Stayability characteristics What’s in a phenotype? Why haven’t we made a lot progress? • Well a lot it turns out…. • Conception is the result of a whole series of stochastic biological functions • What are we trying to measure? – Binary outcome… you’re either pregnant or not – Pregnancy rate (at an age?) – Influenced by lots of stuff… – Rebreeding • Environment (temperature, feed availability, pest load) – Fertility • Genetics (correlations with other traits, some – Longevity antagonistic, heterosis, recessive conditions) – Days to calving • Management (breeding system, bull fertility, exogenous hormones via synchronization protocols) – Post partum interval Producer Applications Committee, 2019 BIF Symposium, Brookings, S.D. 1

Bob Weaber, Kansas State University June 19, 2019 Why haven’t we made a lot progress? Beef Cow Nutrient Partitioning • What role does longevity play and why Short and Adams, 1988 important? – Seedstock needs to turn generations to sample and capture germplasm • Shorten generation interval • No/limited opportunity to observe longevity – Commercial lengthen generation interval to minimize replacement costs • May shorten to minimize depreciation costs • Optimization Opportunities for the future Opportunities for the future • Use data you already have for • Data Recording-THR, WHR – Calving records and disposal codes – Need exposure date data – Breeding type maybe helpful (code for FTAI with – Need bull cohort data natural cleanup) – Infer reproductive performance – Breeding system (ET and some AI synch really – Survival analysis…sensitive to culling criterion and challenging to get at fertility/repro) censoring (voluntary culling events) • Commercial herd data – Capture information about fertility/productive life in environments where expected to perform • Leverage genomics What should we measure? Days to Calving • Fertility and Longevity (Thallman, 2019) Natural service matings, no exogenous hormone synch. • Fertility as a 0/1 conception to know breeding 1. Joining details of all females season (need bull cohort, turnout date, preg naturally mated within the herd. result) for each parity as a trait 2. Details of all females removed • Days to calving-naturally exposed females, from the herd, particularly those captures differences in PPI and days to breeding present at joining that were no from start of breeding period longer within the herd by the time • Longevity-how many calves did cow produce to of the subsequent calving. some age end point, censored records, survival 3. Details of all calves (dead or alive) analysis, some standardized culling definition for that are born as a result of these skipped calves. joinings. Producer Applications Committee, 2019 BIF Symposium, Brookings, S.D. 2

Bob Weaber, Kansas State University June 19, 2019 Thank you! Questions? Producer Applications Committee, 2019 BIF Symposium, Brookings, S.D. 3