Feeding systems can play an important role, not only in beef farm profitability but also in animal health and performance.
Fourteen Avileña-Negra Ibérica bulls, with an initial weight of 270 kg (SE 22.6 kg) and aged 223 d (SE 16.2) were used
to study the effect of two feeding systems on ruminal pH and temperature and animal performance when calves were
kept in loose housing conditions. Feeding systems were barley ( Hordeum vulgare
L.) grain-based concentrate plus barley
straw (CONC) and maize ( Zea mays
L.) silage-based total mixed ration (TMR). Internal wireless boluses were used to
collect pH and temperature values every 10 min throughout the measurement period (15 d). Diet did not modify (P >
0.10) average daily gain, carcass weight, dressing percentage, ruminal mucosa color, or papilla counts. Papilla width
and papilla width/lamina propria thickness were significantly lower (P < 0.05) in TMR than in CONC animals. Time
spent below ruminal pH thresholds of 7.0, 6.6, 6.2, and 5.8 and the corresponding areas under the curve were higher (P
< 0.05) for animals fed under the TMR system. No significant changes were observed between experimental treatments
in parameters related to ruminal temperature or estimated number of times that the animals were drinking during the day
(P > 0.10). Although animal performance is not affected, feeding fattening calves on a concentrate plus barley straw diet
can result in better rumen conditions than using maize silage-based TMR.