Effects of feeding systems on rumen environment, degradability and passage kinetics in Ankole × Friesian crossbred steers
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Date
2018
Journal Title
Journal ISSN
Volume Title
Publisher
Livestock Science
Abstract
Natural pastures constitute a large proportion of the feed resource base for meat and milk production in Sub-
Saharan Africa. However, there is increasing use of agro-industrial by-products, especially those that are cerealbased
as supplementary feedstuff to grazing animals and in diets under semi-intensive and intensive production
systems. This study evaluated the influence of feeding systems on rumen environment, degradability and passage
kinetics. Six Ankole x Friesian F1 crossbred steers weighing 339 ± 29 kg (about two years of age), each fitted
with permanent rumen cannula were used in a replicated 3×3 Latin square design (ns =2). Two steers were
allocated per period to one of three feeding systems i.e. (1) sole grazing (control), (2) control plus concentrate
supplement (composition g/kg DM: 375 maize bran, 559 brewer's spent grain, 62.5 molasses and 3.75 NaCl), and
(3) feedlot systems where steers were fed total mixed ration (TMR) comprising g/kg DM: 200 maize stover, 300
maize bran, 447 brewers’ spent grain, 50 molasses and 3 NaCl. Data was collected on rumen pH, ammonianitrogen
(NH3-N), volatile fatty acids (VFA) and degradability of dry matter (DM), crude protein (CP) and
neutral detergent fiber (NDF). Rumen pH was lowest (P < 0.001) at feedlot (5.3) but highest (P < 0.001)
under sole grazing (6.2). Rumen NH3-N ranged between 62.8 and 120 mg/l and was higher (P < 0.001) in sole
grazing than in grazing but supplemented steers and those at the feedlot. Total VFA concentration for sole
grazing steers (124 mmol/Mol) was higher (P < 0.05) than values observed under feedlot (102 mmol/Mol)
while grazing but supplemented steers showed an intermediate value (108 mmol/Mol), not differing significantly
from the two other systems. Molar proportion of acetate was higher (P < 0.001) in grazing steers
compared to values for either grazing but supplemented or those under feedlot while the reverse was true for
propionate. The degradation characteristics of DM, CP and NDF were generally higher in sole grazing steers.
Although, in most cases, the influence of feeding system on degradability was dependent on the type of feedstuff,
feeding systems did not influence total mean retention time. The high extent of DM, CP and fiber degradation in
grazing steers compared to supplemented and feedlot steers demonstrates that forage diversity under grazing
positively influences degradability. However, attention to the nature and fermentation characteristics of proteins
and carbohydrate sources and how they modify rumen environment in different production systems is needed to
improve utilization of supplements and TMR.
Description
Keywords
Agro-industrial by-products, Feed utilization, Feedlot, Supplemented grazing, Tropical pastures
Citation
Asizua, D., Mpairwe, D., Kabi, F., Mutetikka, D., Bareeba, F. B., Hvelplund, T., ... & Madsen, J. (2018). Effects of feeding systems on rumen environment, degradability and passage kinetics in Ankole× Friesian crossbred steers. Livestock Science, 210, 47-54. https://doi.org/10.1016/j.livsci.2018.02.006