Special Considerations for Bos Indicus
Considerations for utilizing reproductive technologies in Bos indicus-influenced cattle.
RUIDOSO, NEW MEXICO (Aug. 29, 2018) — “They are different,” stated University of Missouri animal scientist Jordan Thomas while talking about Bos indicus cattle and the challenges breeders sometimes face when attempting to apply reproductive technologies to herds consisting of indicus-influenced females. Thomas talked about those challenges during the Applied Reproductive Strategies in Beef Cattle workshop hosted Aug. 29-30 in Ruidoso, N.M.
“We don’t have to be content with breeding indicus-influenced females to calve for the first time at 3 years of age,” said Jordan Thomas, University of Missouri. “Research dating back to the 1950s and '60s demonstrated indicus-influenced heifers could be managed to calve as 2-year-olds.”
Thomas reviewed the history of the development of domesticated cattle, explaining Bos indicus breeds were developed in tropical and subtropical environments. The more common Bos taurus breeds were first developed in a more northern, Mediterranean climate. Noting their greater heat and insect tolerance compared to taurus breeds, indicus-influenced cattle have value in many beef cattle operations in the southern United States, said Thomas.
However, indicus-influenced cattle also are different in ways that may hinder implementation of technologies such as synchronized estrus for artificial insemination (AI). Among the potential hindrances Thomas mentioned was greater age at puberty.
“We don’t have to be content with breeding indicus-influenced females to calve for the first time at 3 years of age. Research dating back to the 1950s and '60s demonstrated indicus-influenced heifers could be managed to calve as 2-year-olds,” said Thomas. “Selection pressure for age at puberty has not been as intense for indicus cattle, compared to taurus. I believe there is opportunity to make long-term improvement.”
Thomas said other management strategies to enhance heifer readiness for earlier breeding might focus on nutrition during heifer development to target breeding weights equaling at least 65% of mature weight. He also cited reproductive tract evaluation and scoring as a useful tool. Evidence suggests that more than 50% of breeding heifer candidates should post reproductive tract scores of 4 or 5 on a 5-point scale before heifers are selected for estrous synchronization and AI.
Other challenges Thomas listed included a higher incidence of anestrus at the start of the breeding season. This may be due to greater sensitivity to environmental factors. Indicus-influenced cattle are likely more “seasonal” breeders, and day length may be a contributing factor. Thomas cited ample evidence that indicus cattle can be more susceptible to stress, which could be helped through selection for temperament.
Length of standing estrus also appears to be shorter for indicus females and is more likely to be expressed at night. While that presents a challenge to heat detection, Thomas suggested that it might be addressed through the use of heat-detection aids or synchronization protocols for fixed-time AI.
Thomas also noted that indicus cattle are sensitive to some products commonly used in synchronization protocols.
"Follicular development in Bos indicus cattle is hindered by high-circulating concentrations of progesterone. Therefore, reducing administration of progesterone or limiting endogenous progesterone has been an area of research interest," Jordan explains. "Administration of GnRH is less effective for synchronization of ovarian follicular waves in Bos indicus cattle."
“These animals are different, and that presents challenges, but it should not be an excuse to ignore opportunities to use reproductive technologies in Bos indicus cattle,” concluded Thomas.
For details on Thomas’s presentation — including the proceedings, PowerPoint and video — visit the Newsroom at www.appliedreprostrategies.com.
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