Morphological and functional development of the rumen
in the calf: influence of the time of weaning. 1. Morphological development
of rumen mucosa.
Zitnan R, Voigt J, Wegner J, Breves G, Schroder B, Winckler C, Levkut M,
Kokardova M, Schonhusen U, Kuhla S, Hagemeister H, Sommer A
Research Institute of Animal Production Nitra, Division Kosice, Slovak
Republic.
The objective of this study was to determine whether the nutritional regimen
of rearing calves would influence the morphometric and histological
development of rumen mucosa. Twelve male Holstein calves 7 d of age were
assigned to three groups of 4 animals each: milk group (I), early weaned (6
weeks) group (II) and late weaned (9 weeks) group (III). All animals
received additional solid feed. Animals of group I were slaughtered after 6
weeks of age, whereas those in groups II and III were slaughtered after 9
weeks of age. At slaughter, the ruminal digesta amounted to 2035 g (milk
group), 3092 g (late weaned group) and 5374 g (early weaned group). The
differences in the ruminal molar percentage of SCFA were not significant.
There was a trend for lower pH and higher SCFA concentrations in the order
late weaned, early weaned and milk fed animals (pH: 6.4, 6.6 and 6.7,
respectively; SCFA: 96, 87 and 77 mmol/l, respectively). The mean length
(1.07 mm in milk group, 1.45 mm in late weaned group and 1.87 mm in early
weaned group), width (0.43, 0.58 and 0.71 mm, respectively) and surface of
papillae (190, 232 and 241 mm2/cm2 mucosa, respectively) increased with both
the age of the animals and the elevated intake of solid feed, whereas the
number of papillae (210, 140 and 92 per cm2 mucosa, respectively) decreased.
In both milk-fed groups type A and B corneal cells were present in the
Stratum corneum, whereas in the earlier weaned calves type C-cells could be
also seen. These findings indicate a more advanced stage of development of
the rumen epithelium in the earlier weaned calves fed higher amounts of
concentrate and hay.