MWE (sorry for the long table, I hadn't anything else at hand):

%%%%%%%%%%%%%%%%%%%%
\definehighlight[emph][style={\em}]
\definehighlight[strong][style={\bf}]

\setupfloat[table][default={here}]

\definereferenceformat[figura][text={Figura~}]
\definereferenceformat[tabla][text={Tabla~}]

\setupcaptions[style={\sans\small},
              width=max,
              prefix=no,
              align={flushleft,nothyphenated},
              way=bytext]
\setupcaption[table][location=top]

\setupthinrules[width=15em] % width of horizontal rules

\setupxtable[frame=off,option=stretch,bodyfont=small,foregroundstyle=sans]
\setupxtable[head][topframe=on,bottomframe=on,foregroundstyle=sansbold]
\setupxtable[body][bottomframe=on]
\setupxtable[foot][bottomframe=on]

\define[1]\fuentent{\start\switchtobodyfont[sans,small]#1\par\stop}
\define[1]\fuente{\start\switchtobodyfont[sans,small]\emph{Fuente:}~#1\par\stop}

\starttext
\reference[tbl:t03]{}%
\startplacetable[title={Composición química y valor energético de recursos
forrajeros de corte en el área de influencia del Subproyecto Carne Bovina
(trópico de altura).}]
\startxtable[option=tight,bodyfont=7pt]
\startxtablehead[head]
\startxrow
\startxcell[align=right,width=.1\textwidth] \strong{Altura\crlf (msnm)}
\stopxcell
\startxcell[align=right,width=.28\textwidth] \strong{Gramíneas forrajeras
de corte} \stopxcell
\startxcell[align=middle,width=.06\textwidth] \strong{Edad (días)}
\stopxcell
\startxcell[align=middle,width=.05\textwidth] \strong{MS
(\letterpercent{})} \stopxcell
\startxcell[align=middle,width=.1\textwidth] \strong{PC\crlf
 (\letterpercent{} MS)} \stopxcell
\startxcell[align=middle,width=.1\textwidth] \strong{FDN\crlf
(\letterpercent{} MS)} \stopxcell
\startxcell[align=middle,width=.1\textwidth] \strong{FDA\crlf
(\letterpercent{} MS)} \stopxcell
\startxcell[align=middle,width=.1\textwidth] \strong{EM\crlf {\bfxx
(Mcal/kg MS)}} \stopxcell
\startxcell[align=middle,width=.1\textwidth] \strong{ENm\crlf {\bfxx
(Mcal/kg MS)}} \stopxcell
\startxcell[align=middle,width=.1\textwidth] \strong{ENg\crlf {\bfxx
(Mcal/kg MS)}} \stopxcell
\startxcell[align=middle,width=.1\textwidth] \strong{ENl\crlf {\bfxx
(Mcal/kg MS)}} \stopxcell
\stopxrow
\stopxtablehead
\startxtablebody[body]
\startxrow
\startxcell[align=right,ny=2] 1800-1860 \stopxcell
\startxcell[align=right,ny=2] \strong{Cuba 22}\crlf (\emph{P. glaucum} x
\emph{P. thyphoides}) \stopxcell
\startxcell[align=middle] 90 \stopxcell
\startxcell[align=middle] 29,0 \stopxcell
\startxcell[align=middle] 10,6 \stopxcell
\startxcell[align=middle] 64,1 \stopxcell
\startxcell[align=middle] 30,8 \stopxcell
\startxcell[align=middle] 1,92 \stopxcell
\startxcell[align=middle] 1,08 \stopxcell
\startxcell[align=middle] 0,52 \stopxcell
\startxcell[align=middle] 1,19 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 210 \stopxcell
\startxcell[align=middle] 27,8 \stopxcell
\startxcell[align=middle] 6,2 \stopxcell
\startxcell[align=middle] 69,1 \stopxcell
\startxcell[align=middle] 33,6 \stopxcell
\startxcell[align=middle] 1,78 \stopxcell
\startxcell[align=middle] 0,94 \stopxcell
\startxcell[align=middle] 0,40 \stopxcell
\startxcell[align=middle] 1,09 \stopxcell
\stopxrow
\startxrow
\startxcell[align=right,ny=3] 1800-2186 \stopxcell
\startxcell[align=right,ny=3] \strong{King Grass} \crlf (\emph{P.
purpureum} x \emph{P. typhoides}) \stopxcell
\startxcell[align=middle] 91 \stopxcell
\startxcell[align=middle] 22,3 \stopxcell
\startxcell[align=middle] 8,7 \stopxcell
\startxcell[align=middle] 65,4 \stopxcell
\startxcell[align=middle] 32,1 \stopxcell
\startxcell[align=middle] 1,86 \stopxcell
\startxcell[align=middle] 1,02 \stopxcell
\startxcell[align=middle] 0,46 \stopxcell
\startxcell[align=middle] 1,14 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 150 \stopxcell
\startxcell[align=middle] 23,6 \stopxcell
\startxcell[align=middle] 7,2 \stopxcell
\startxcell[align=middle] 66,9 \stopxcell
\startxcell[align=middle] 32,8 \stopxcell
\startxcell[align=middle] 1,81 \stopxcell
\startxcell[align=middle] 0,98 \stopxcell
\startxcell[align=middle] 0,42 \stopxcell
\startxcell[align=middle] 1,11 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 182 \stopxcell
\startxcell[align=middle] 27,0 \stopxcell
\startxcell[align=middle] 6,7 \stopxcell
\startxcell[align=middle] 68,8 \stopxcell
\startxcell[align=middle] 35,6 \stopxcell
\startxcell[align=middle] 1,77 \stopxcell
\startxcell[align=middle] 0,93 \stopxcell
\startxcell[align=middle] 0,38 \stopxcell
\startxcell[align=middle] 1,08 \stopxcell
\stopxrow
\startxrow
\startxcell[align=right,ny=3] 1800-1850 \stopxcell
\startxcell[align=right,ny=3] \strong{King Grass morado} \crlf
(\emph{Pennisetum purpureum}) \stopxcell
\startxcell[align=middle] 98 \stopxcell
\startxcell[align=middle] 20,8 \stopxcell
\startxcell[align=middle] 13,1 \stopxcell
\startxcell[align=middle] 62,3 \stopxcell
\startxcell[align=middle] 30,8 \stopxcell
\startxcell[align=middle] 1,99 \stopxcell
\startxcell[align=middle] 1,14 \stopxcell
\startxcell[align=middle] 0,58 \stopxcell
\startxcell[align=middle] 1,23 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 126 \stopxcell
\startxcell[align=middle] 11,9 \stopxcell
\startxcell[align=middle] 10,3 \stopxcell
\startxcell[align=middle] 64,9 \stopxcell
\startxcell[align=middle] 30,8 \stopxcell
\startxcell[align=middle] 1,92 \stopxcell
\startxcell[align=middle] 1,08 \stopxcell
\startxcell[align=middle] 0,52 \stopxcell
\startxcell[align=middle] 1,18 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 154 \stopxcell
\startxcell[align=middle] 16,3 \stopxcell
\startxcell[align=middle] 7,7 \stopxcell
\startxcell[align=middle] 66,9 \stopxcell
\startxcell[align=middle] 33,3 \stopxcell
\startxcell[align=middle] 1,82 \stopxcell
\startxcell[align=middle] 0,98 \stopxcell
\startxcell[align=middle] 0,43 \stopxcell
\startxcell[align=middle] 1,11 \stopxcell
\stopxrow
\startxrow
\startxcell[align=right,ny=4] 1800-2500 \stopxcell
\startxcell[align=right,ny=4] \strong{Pasto Imperial}\crlf \emph{(Axonopus
scoparius)} \stopxcell
\startxcell[align=middle] 42 \stopxcell
\startxcell[align=middle] 15,0 \stopxcell
\startxcell[align=middle] 11,1 \stopxcell
\startxcell[align=middle] 59,5 \stopxcell
\startxcell[align=middle] 27,9 \stopxcell
\startxcell[align=middle] 1,97 \stopxcell
\startxcell[align=middle] 1,12 \stopxcell
\startxcell[align=middle] 0,57 \stopxcell
\startxcell[align=middle] 1,22 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 91 \stopxcell
\startxcell[align=middle] 17,6 \stopxcell
\startxcell[align=middle] 7,0 \stopxcell
\startxcell[align=middle] 61,2 \stopxcell
\startxcell[align=middle] 28,8 \stopxcell
\startxcell[align=middle] 1,84 \stopxcell
\startxcell[align=middle] 1,00 \stopxcell
\startxcell[align=middle] 0,45 \stopxcell
\startxcell[align=middle] 1,13 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 119 \stopxcell
\startxcell[align=middle] 17,6 \stopxcell
\startxcell[align=middle] 5,4 \stopxcell
\startxcell[align=middle] 61,4 \stopxcell
\startxcell[align=middle] 30,4 \stopxcell
\startxcell[align=middle] 1,79 \stopxcell
\startxcell[align=middle] 0,94 \stopxcell
\startxcell[align=middle] 0,40 \stopxcell
\startxcell[align=middle] 1,10 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 150 \stopxcell
\startxcell[align=middle] 21,5 \stopxcell
\startxcell[align=middle] 4,5 \stopxcell
\startxcell[align=middle] 61,7 \stopxcell
\startxcell[align=middle] 31,6 \stopxcell
\startxcell[align=middle] 1,75 \stopxcell
\startxcell[align=middle] 0,91 \stopxcell
\startxcell[align=middle] 0,37 \stopxcell
\startxcell[align=middle] 1,07 \stopxcell
\stopxrow
\startxrow
\startxcell[align=right,ny=2] 1800 \stopxcell
\startxcell[align=right,ny=2] \strong{Pasto Guatemala}\crlf
\emph{(Tripsacum dactyloides)} \stopxcell
\startxcell[align=middle] 126 \stopxcell
\startxcell[align=middle] 15,2 \stopxcell
\startxcell[align=middle] 6,6 \stopxcell
\startxcell[align=middle] 67,7 \stopxcell
\startxcell[align=middle] 32,8 \stopxcell
\startxcell[align=middle] 1,79 \stopxcell
\startxcell[align=middle] 0,96 \stopxcell
\startxcell[align=middle] 0,40 \stopxcell
\startxcell[align=middle] 1,10 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 147 \stopxcell
\startxcell[align=middle] 17,8 \stopxcell
\startxcell[align=middle] 6,0 \stopxcell
\startxcell[align=middle] 70,1 \stopxcell
\startxcell[align=middle] 35,2 \stopxcell
\startxcell[align=middle] 1,75 \stopxcell
\startxcell[align=middle] 0,91 \stopxcell
\startxcell[align=middle] 0,37 \stopxcell
\startxcell[align=middle] 1,07 \stopxcell
\stopxrow
\startxrow
\startxcell[align=right,ny=2] 1800-1976 \stopxcell
\startxcell[align=right,ny=2] \strong{Maralfalfa}\crlf \emph{(Pennisetum
hybridum)} \stopxcell
\startxcell[align=middle] 63 \stopxcell
\startxcell[align=middle] 20,8 \stopxcell
\startxcell[align=middle] 10,0 \stopxcell
\startxcell[align=middle] 65,8 \stopxcell
\startxcell[align=middle] 31,6 \stopxcell
\startxcell[align=middle] 1,90 \stopxcell
\startxcell[align=middle] 1,08 \stopxcell
\startxcell[align=middle] 0,50 \stopxcell
\startxcell[align=middle] 1,17 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 84 \stopxcell
\startxcell[align=middle] 33,1 \stopxcell
\startxcell[align=middle] 7,0 \stopxcell
\startxcell[align=middle] 71,8 \stopxcell
\startxcell[align=middle] 38,3 \stopxcell
\startxcell[align=middle] 1,75 \stopxcell
\startxcell[align=middle] 0,91 \stopxcell
\startxcell[align=middle] 0,37 \stopxcell
\startxcell[align=middle] 1,07 \stopxcell
\stopxrow
\startxrow
\startxcell[align=right,ny=2] 2167-2500 \stopxcell
\startxcell[align=right,ny=2] \strong{Pasto elefante}\crlf
(\emph{Pennisetum purpureum} cv. Merker) \stopxcell
\startxcell[align=middle] $>$~140 \stopxcell
\startxcell[align=middle] 21,0 \stopxcell
\startxcell[align=middle] 7,9 \stopxcell
\startxcell[align=middle] 64,5 \stopxcell
\startxcell[align=middle] 31,8 \stopxcell
\startxcell[align=middle] 1,84 \stopxcell
\startxcell[align=middle] 1,00 \stopxcell
\startxcell[align=middle] 0,45 \stopxcell
\startxcell[align=middle] 1,13 \stopxcell
\stopxrow
\startxrow
\startxcell[align=middle] 70 \stopxcell
\startxcell[align=middle] 19,9 \stopxcell
\startxcell[align=middle] 16,3 \stopxcell
\startxcell[align=middle] 58,2 \stopxcell
\startxcell[align=middle] 25,4 \stopxcell
\startxcell[align=middle] 2,13 \stopxcell
\startxcell[align=middle] 1,27 \stopxcell
\startxcell[align=middle] 0,70 \stopxcell
\startxcell[align=middle] 1,33 \stopxcell
\stopxrow
\stopxtablebody
\stopxtable
\fuentent{\emph{Nota:} En el cuadro se muestran los resultados de materia
seca (MS), proteína cruda (PC), fibra en detergente neutro (FDN), fibra en
detergente ácido (FDA), energía metabolizable (EM), energía neta de
mantenimiento (ENm), energía neta de ganancia (ENg), y energía neta de
lactancia (ENl).\crlf Los resultados del análisis son mostrados en
porcentajes (\letterpercent{}) sobre la materia seca (MS) del ingrediente.}
\fuente{Equipo CTA-2, Subproyecto Carne Bovina (2018).}
\stopplacetable

\input knuth
\stoptext

%%%%%%%%%%%%%%%%%%%%%%%%%%%%

-- 
Andrés Conrado Montoya
Andi Kú
andresconrado@gmail.com
http://sesentaycuatro.com
http://messier87.com
http://chiquitico.org
----------------------------------------
Los fines no justifican los medios, porque la medida verdadera de nuestro
carácter está dada por los medios que estamos dispuestos a utilizar, no por
los fines que proclamamos.
----------------------------------------

“You develop an instant global consciousness, a people orientation, an
intense dissatisfaction with the state of the world, and a compulsion to do
something about it. From out there on the moon, international politics look
so petty. You want to grab a politician by the scruff of the neck and drag
him a quarter of a million miles out and say, ‘Look at that, you son of a
bitch.’” — Apollo 14 astronaut Edgar Mitchell