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

Abstract

Beef production needs to increase from 60 million to 130 million tons by 2050 to feed a growing world population, and 70% of this production increase is expected from beef industries located in subtropical and tropical regions of the world. Bos indicus-influenced cattle predominate in these regions but are often managed using practices developed for Bos taurus breeds reared in temperate climates. Hence, a fundamental step to meet the increasing global demand for beef is to develop specific management for B. indicus-influenced cattle in tropical or subtropical environments. Bos taurus and B. indicus are different subspecies, and diverge in social and biological functions due to selection pressure caused by complex evolutionary and domestication processes. Bos indicus cattle display different social responses compared with B. taurus counterparts, which must be taken into account by management planning as these traits directly impact cattle performance and welfare. In tropical and subtropical regions, warm-season perennial C4 grasses are the dominant forages, and their availability has a significant influence on the productivity of beef cattle systems. The resilience of C4 grasses under adverse conditions is one of their most important characteristics, even though these forages have reduced nutritive value compared with forages from temperate climates. Accordingly, nutritional planning in tropical and subtropical conditions must include management to optimize the quantity and quality of C4 forages. Nutritional requirements of cattle raised within these conditions also require special attention, including inherent metabolic compromises to cope with environmental constraints and altered energy requirements due to body composition and heat tolerance. Nutritional interventions to enhance beef production need to be specifically tailored and validated in B. indicus-influenced cattle. As an example, supplementation programs during gestation or early life to elicit fetal programming or metabolic imprinting effects, respectively, yield discrepant outcomes between subspecies. Bos indicus-influenced cattle produce carcasses with less marbling than B. taurus cattle, despite recent genetic and management advances. This outcome is mostly related to reduced intramuscular adipocyte volume in B. indicus breeds, suggesting a lesser need for energy stored intramuscularly as a mechanism to improve thermotolerance in tropical and subtropical climates.

Keywords: Bos indicus; behavior; carcass; forage; nutrition; tropical and subtropical environments.

Figure 1.

Distribution of cattle around the world in 2006 using the Gridded Livestock of the World 2 global distribution (https://application.geo-wiki.org/Application/index.php), based on Robinson et al. (2014). The position of the dashed lines for the tropic of Cancer (23°27′N), equator (0°), tropic of Capricorn (23°27′S), and the dotted lines delimiting the subtropical regions are a visual approximation and depicted for illustrative purposes only.

Figure 2.

Simplified cattle phylogenetic tree based on Loftus et al. (1994).

Figure 3.

A nonlinear correlation between HA (kg dry matter/kg of liveweight) and ADG for Mulato and bahiagrass pastures stocked at 4, 8, and 12 heifers/ha (Inyang et al., 2010).

Figure 4.

Conceptual relationship showing three feedback loops (maintenance, growth, intake) of energy partitioning of animals under heat-stressed conditions. The self-reinforcing and self-correcting loops are represented by the positive and negative signs, respectively, with the semicircle arrows. Positive and negative signs at the arrowheads indicate the effect is positively or negatively related to the cause, respectively.

Figure 5.

Probability density functions (PDF) based on Monte Carlo simulation assuming a normal distribution of the coefficients of the NEm of Bos taurus [green; dataset developed by Lofgreen and Garrett (1968)] and B. indicus cattle [purple; dataset developed by Marcondes et al. (2013)]. Panel A used a linear regression of the logarithm of daily HP per metabolic EWB (kcal/kg^0.75) on daily MEI per metabolic EBW (kcal/kg^0.75), and the estimates were 74.93 ± 1.019 and 84.59 ± 1.041 kcal/kg^0.75 (P = 0.0099) for B. indicus and B. taurus, respectively. Panel B used an exponential regression of daily HP per metabolic EWB (kcal/kg^0.75) on daily MEI per metabolic EBW (kcal/kg^0.75), and the estimates were 79.29 ± 1.566 and 86.56 ± 4.038 kcal/kg^0.75 (P = 0.0978) for B. indicus and B. taurus, respectively. The dashed vertical lines represent the averages, and the solid vertical lines represent the 95% quantiles of the PDF.

Figure 6.

Adipocyte volume (pL) and adipocyte metabolism (nmol•2 h^-1•10⁵ cells^-1) for intramuscular (i.m.) and subcutaneous (s.c.) adipose tissues from B. indicus-influenced and B. taurus steers and heifers. Metabolic variables include NADP-MDH, glucose carbon incorporated fatty acids (FA), and acetate carbon incorporated into FA. Means within a trait with different superscripts (a,b,c) differ (P ≤ 0.05). Data derived from Miller et al. (1991).

Figure 7.

Adipocyte volume (pL) and adipocyte metabolism (nmol•2 h^-1•10⁵ cells^-1) for intramuscular (i.m.) and subcutaneous (s.c.) adipose tissues from B. indicus-influenced and B. taurus steers and heifers. Metabolic variables include NADP-MDH, glucose carbon incorporated fatty acids (FA), and acetate carbon incorporated into FA. Means within a trait with different superscripts (a,b,c) differ (P ≤ 0.05). Data derived from Campbell et al. (2016).