Cattle adapted to tropical and subtropical environments: genetic and reproductive considerations

Abstract

Efforts to understand biological functions and develop management schemes specific to Bos indicus-influenced cattle raised in tropical and subtropical environments are critical to meet the increasing global demand for protein. In the United States, B. indicus breeds are mostly used to generate B. indicus × B. taurus crosses with increased thermal and parasite tolerance, while retaining some productive characteristics of B. taurus cattle. Although crossbreeding represents a proven strategy to improve cattle adaptation almost immediately, research has also attempted to identify B. taurus genetics that can withstand subtropical and tropical climates. Reduced milk production and delayed reproductive maturation appear to be related with tropical adaptation of B. taurus breeds, as a means to conserve energy under stressful conditions and limited nutrition. Moreover, longevity may be the ultimate adaptation response to unfavorable environments, and retention of bulls and heifers from proven cows is the recommended strategy to improve longevity in B. indicus-influenced herds. Besides selection for longevity, other aspects should be considered when planning reproductive management in tropical and subtropical regions. Bos indicus and B. taurus breeds have multiple differences pertaining to reproductive function, including age at puberty, ovarian dynamics, and pregnancy development. Nutritional strategies such as the stair-step regimen, and use of exogenous progesterone (P4) inserts are options to hasten puberty attainment of late-maturing B. indicus-influenced heifers. Yet, limited pharmacological alternatives are available for reproductive management of B. indicus-influenced females in the United States, which rely on GnRH-based protocols not specifically designed to the reproductive function of B. indicus breeds. In contrast, hormonal protocols based on exogenous P4, estradiol esters, and equine chorionic gonadotropin are available for use in B. indicus females in South America. These include protocols tailored to prepubertal heifers, anestrous cows, and cycling nulliparous or parous females, which often yield pregnancy rates of 50% to fixed-time artificial insemination. The global dairy industry also faces similar challenges in increasing demand and production as the beef industry. Selection of cows capable of sustaining optimal milk yield, reproductive success, and health status in hot and humid conditions is essential for optimal dairy production in subtropical and tropical regions.

Identification of Reference Genes for Expression Studies in the Whole-Blood from Three Cattle Breeds under Two States of Livestock Weather Safety

“…The Temperature–Humidity Index has been widely used to alert cattle producers of potential weather-based heat stress; for example, some recommendations for mitigating heat stress are based on estimating THI values [ 20 , 37 , 38 ]. In the present study, two states of heat stress (alert THI = 70–80 and emergency THI ≥ 84) in cattle were chosen for blood sample collection due to the expected cellular stress responses in these states [ 5 , 17 , 37 , 39 ].…”

“…Additionally, heat stress decreases pregnancy rates and embryonic development in embryos produced in vivo and in vitro [ 4 ]. Due to heat stress effects, humans have reevaluated management decisions regarding which animals to use for food production [ 5 ]. In this way, breeds that originated in warm climates such as African zebu ( Bos primigenius indicus ) and African taurus ( Bos taurus africanus ) show adaptive advantages to heat stress compared with breeds that originated in temperate areas such as European taurus ( Bos taurus taurus ) [ 5 , 6 ].…”

Omega-6 Fatty Acids: A Sustainable Alternative to Improve Beef Production Efficiency

“…Supplementing omega-6 FA upregulated mRNA expression of IFN-τ by the conceptus and ISG in the whole blood, but did not increase conceptus length (11.3 vs. 11.4 cm for CSSO and CON, respectively) and mRNA expression of prostaglandin Our initial efforts in characterizing the benefits of omega-6 FA to cattle reproduction were conducted with B. indicus cows reared in tropical conditions [15,16,18,20]. Pregnancy establishment and overall reproductive physiology differ between B. indicus and B. taurus females [25], and FA composition differs between tropical and temperate feed ingredients. Hence, Brandão et al [26] conducted two trials evaluating omega-6 FA supplementation via CSSO to B. taurus cows in temperate conditions.…”

Cattle adapted to tropical and subtropical environments: social, nutritional, and carcass quality considerations

“…This manuscript provides a review of historical and contemporary research focusing on social, nutritional, and carcass quality considerations related to the production of B. indicus-influenced cattle within the planet's subtropics. A similar review focusing on genetic aspects and reproductive parameters is presented by the companion manuscript (Cooke et al, 2020).…”