Paper-Lecture6 - Sheep rumen metabolic development in...

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Sheep rumen metabolic development in response to age and dietary treatments 1,2,3 M. A. Lane* ,4 , R. L. Baldwin VI†, and B. W. Jesse* ,5 *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 ABSTRACT: 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 M U-[ 14 C]-glucose or 10 m M 1- [ 14 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 ( P < .05). The number of ruminal papillae per square centimeter decreased ( P < .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 Introduction Lambs begin to consume solid feed between 2 and 4 wk of age. The fermentation of this feed by ruminal 1 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). 2 This research was supported by the USDA. Received June 24, 1999. Accepted February 9, 2000. 1990 lae/per square centimeter than rumen epithelium from lambs given milk replacer ( P < .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. β -Hydroxybutyr- 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
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This note was uploaded on 09/19/2011 for the course ANS 5446 taught by Professor Brown during the Spring '08 term at University of Florida.

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Paper-Lecture6 - Sheep rumen metabolic development in...

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