CAN REPRODUCTIVE TRACT SCORING
CHANGE YOUR BOTTOM LINE?
Patsy Houghton, PhD, Owner/General Manager | Janet Rippe, Director of Research & Information Transfer | Heartland Cattle Company, McCook, NE
to work from the University of Missouri that shows as many as 35% of all beef heifers remain pre-pubertal at 15 months of age.
Cow herd reproductive performance is the biggest factor related to ranch profitability. More calves produced with less production expense should be a primary goal of every rancher. Selection, management and timing of breeding replacement heifers are important components of total cowherd reproductive efficiency.
Multiple data sets have shown RTS to be highly correlated with first service conception rate and/or seasonal pregnancy rate. For example, data from Heartland Cattle Company’s heifer development program shows the probability that an actively cycling heifer will conceive on her first service is 11% higher than a pre-pubertal heifer; and 32% higher than a heifer with an infantile reproductive tract. Higher first service conception rate translates to higher seasonal pregnancy rate, especially in heifers exposed to a restricted breeding season lasting only 30-45 days.
When heifers are bred at 14 months of age to calve as 2-year-olds they will produce more total calves in their lifetime than heifers that are bred for the first time later in life. Age at puberty and reproductive development can sometimes be a challenge when breeding heifers at 14 months of age. Reproductive tract scoring (RTS) is a quick, low-cost rectal palpation procedure to evaluate ovarian and uterine horn development; ranchers can use this to help identify heifers that have reached puberty, are actively cycling and ready to breed.
The effectiveness of RTS in predicting reproductive performance of yearling heifers depends upon accuracy and timing of the procedure. Data published in “Theriogenology” shows the accuracy and repeatability of RTS performed by trained technicians to be highly correlated to ultrasonography and serum progesterone concentrations for determining the pubertal status of heifers. A number of animal science and veterinary programs throughout the country teach RTS procedures, so the best way to identify a trained technician in your area would be to contact reproductive physiology faculty from these programs.
Various numerical RTS systems have been developed and used throughout the industry, but what each system has in common with the others is to identify normal vs. abnormal reproductive tracts and actively cycling vs. pre-pubertal heifers. In a nutshell, an effective RTS system will identify infantile reproductive tracts due to either age (youth) or hormonal imbalance; pre-pubertal heifers; and normal, actively cycling heifers. Identification of “calf-breds” is another important benefit of RTS. Data from Heartland Cattle Company, from nearly 20,000 heifers over the past five years, shows a normal distribution of 2% infantile tracts and/or free-martins, 25% pre-pubertal heifers and 73% actively cycling heifers at 35 to 45 days pre-breeding. This corresponds
Positive correlations to first service conception and pregnancy rates increase when the timing of RTS is closer to the breeding season. Reproductive tract scoring data collected at Heartland Cattle Company is from 35 to 45 days prior to synchronized breeding date.
Colorado State University RTS System: Single Digit Scoring Reproductive Tract Score
Uterine Horns
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Size and Characteristics of Ovaries Length
Height
Width
Ovarian Structures
Immature <20 mm diameter, no tone
15 mm
10 mm
8 mm
No palpable follicles
2
20-25 mm diameter, no tone
18 mm
12 mm
10 mm
8 mm follicles
3
25-30 mm diameter, slight tone
22 mm
15 mm
10 mm
8-10 mm follicles
4
30 mm diameter, good tone
30 mm
16 mm
12 mm
>10 mm follicles, Corpus luteum possible
5
>30 mm diameter, good tone, erect
>32 mm
20 mm
15 mm
>10 mm follicles, Corpus luteum present
Note: Reproductive tract scores are determined approximately 1 month pre-breeding by rectal palpation Source: Anderson, K.J., D.G. Lefever, J.S. Brinks, and K.G. Odde. 1991. The use of reproductive tract scoring in beef heifers. Agri-Practice 12(4):19.
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