Sheep rumen metabolic development in response to age
and dietary treatments
M. A. Lane*
, R. L. Baldwin VI†, and B. W. Jesse*
*Department of Animal Sciences, Rutgers-The State University of New Jersey, New Brunswick, 08903 and
†Nutrient Conservation and Metabolism Laboratory, USDA/ARS, Beltsville, MD 02705
This study examined the time course of
rumen metabolic development in the absence of solid
feed consumption and the effect of delayed solid feed
consumption on sheep rumen development. Twenty-
seven lambs consumed milk replacer until slaughter at
nine ages from 1 to 84 d (milk group). Three additional
lambs consumed milk replacer from 1 to 48 d. From 49
d until slaughter at 84 d, these lambs were weaned
onto solid feed (fed group). At slaughter, rumen con-
tents were removed for VFA analysis and rumen epithe-
lium was preserved for morphological examination. Ru-
men epithelial cells were isolated and incubated in me-
dia containing 2.5 m
C]-glucose or 10 m
C]-butyrate. Rumen VFA concentrations did not
change with age in lambs given milk replacer. At 84 d
of age, intraruminal VFA concentrations were elevated
in lambs consuming solid feed compared to 84-d-old
lambs given milk replacer (
.05). The number of
ruminal papillae per square centimeter decreased (
.05) while papillae length and width did not change
signi±cantly with age in rumen epithelium from lambs
given milk replacer. At 84 d of age, rumen epithelium
from lambs in the fed group had fewer and larger papil-
Key Words: Ketogenesis, Metabolism, Rumen, Sheep, Substrates, Volatile Fatty Acids
2000 American Society of Animal Science. All rights reserved.
J. Anim. Sci. 2000. 78:1990–1996
Lambs begin to consume solid feed between 2 and 4
wk of age. The fermentation of this feed by ruminal
Selected data in this paper were reported at the Experimental
Biology 1995 Mtg., Washington, DC (M. A. Lane, R. L. Baldwin and
B. W. Jesse. 1995. Metabolic development of rumen epithelium does
not occur in the absence of solid feed consumption. FASEB J.
9:A1017), and at the American Dairy Science Association 1995 Mtg.,
Ithaca, NY (M. A. Lane, R. L. Baldwin and B. W. Jesse. 1995. Sheep
rumen metabolic development in response to different dietary treat-
ments. J. Dairy Sci. 78:310).
This research was supported by the USDA.
Received June 24, 1999.
Accepted February 9, 2000.
lae/per square centimeter than rumen epithelium from
lambs given milk replacer (
.05). Rates of glucose
and butyrate oxidation and acetoacetate and lactate
production by rumen cells isolated from lambs given
milk replacer did not change with age.
ate (BHBA) production was undetectable before 42 d
of age in lambs given milk replacer and increased to
levels found in conventionally raised adults by 84 d. At
84 d there were no differences in rates of glucose and
butyrate oxidation or acetoacetate and lactate produc-
tion by rumen cells between the two treatment groups.
Thus, the change in substrate oxidation from glucose