Reproductive Tract Scoring Brendan Kraus DVM Heifer Selection

Reproductive Tract Scoring Brendan Kraus, DVM

Heifer Selection n Most Cattleman Select Visually n Use Size and Appearance n Cannot evaluate reproductive traits externally

Age at Puberty n n Defined as the age of first behavioral estrus (heat) Age of puberty is highly associated with n n Pregnancy Percentage Percent calving in first 25 days Milk production Heavier progeny weaning weights

Early Conception is the Name of the Game n n Early calving heifers have higher annual lifetime calf production Are more likely to conceive and calve as 3 year olds Wean a bigger calf Can’t afford to have heifers and 2 nd calf heifers drop out of the program

Reproductive Tract Scoring n RTS system estimates pubertal status via rectal palpation of the uterine horns and ovaries n n n RTS 1: RTS 2: RTS 3: RTS 4: RTS 5: Infantile tracts Small uterine horns and ovaries Slight uterine tone Good uterine tone, functional ovaries RTS 4 + palpable corpus luteum

Bovine Reproductive Tract

Bovine Repro Tract

Bovine Ovaries

When to Perform RTS? n The distribution of RTS for a group of heifers depends on when they are examined n n n If before 12 months of age, most heifers will not be cycling If taken too late, most will receive a 4 or 5 The time of exam depends on the desired use of the system and the particular group of heifers

For Instance, n Last minute culling tool n n Selection pressure for age at puberty n n Scoring should occur a month or less before breeding. Immature heifers are culled Evaluate when ½ of heifers are cycling based on age, weight, and estrus observation Heifer development check-up n 30 to 60 days prior to breeding. Nutritional ration can be adjusted according to findings

RTS 3 vs 4 n Heifers scoring 3 at 30 days prior to breeding have up to 20% more opens than heifers scoring 4 or 5 n There is considerable expense developing heifers from weaning to pregnancy exam. It is very costly to have them turn up open at this stage

Effects on RTS n Age of Heifer n Sire genetics n Scrotal size n Weight/Condition Score n Inbreeding

Other Strategies n n Breed heifers one month before the cow herd Minimally develop heifers and use RTS as a tool to select for inherent fertility and lower maintenance cows

Prepare for Breeding n n n MLV vaccine for IBR/BVD Vibrio/Lepto 7 -Way Clostridial Deworm Brand/Ear Tag Pelvic Measure

Pelvic Measure n n n Used as a tool to eliminate small pelvis or those with abnormal shape Used in conjunction with RTS Is not used to select for largest pelvic Utilizes a formula which considers age, weight, and size of calf to deliver Has been shown to allow heifers to deliver 80% unassisted

Questions? * “The Use of Reproductive Tract Scoring in Beef Heifers” Anderson et al CSU Dept of Animal Sciences. Agri-Practice 1991