Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: May 15, 2002
Publication Date: July 15, 2002
Citation: BALDWIN, R.L., CAPUCO, A.V., MCLEOD, K. EFFECT OF STAGE OF LACTATION ON VISCERAL TISSUE MASS AND INTESTINAL PROLIFERATION. JOURNAL OF DAIRY SCIENCE. 2002.
Twenty dairy cows were used to assess the impact of stage of lactation on visceral tissue mass. Cows were slaughtered at four stages of lactation: 14 d, 90 d, 120 d and 240 d of lactation. Following exsanguination, visceral organs were separated and weighed, lengths determined, and composition analyzed. Duodenal mucosa was obtained and incubated to assess proliferative activity. Dry matter intake increased with stage of lactation through 120 d with intake at 90 d and 240 d being similar. Conversely, empty body wt. (EBW) declined with stage of lactation through 120 d and by 240 d was not different from 14 d cows. As a percentage of EBW , hepatic, ruminal and small intestinal weights were increased with increasing stage of lactation through 120 d, and then either declined (liver) or remained the same through 240 d. However, stage of lactation did not have a measurable affect on Reticular, Omasal, Abomasal, or large intestinal weights as a percentage of EBW. Visceral adipose tissue mass as a percentage of EBW declined with stage of lactation to a minimum at 120 d and was not different from 14 d by 240 d. Duodenal incorporation of tritiated-thymidine was greatest at 90 and 120 d of lactation with rates of incorporation being similar 14 and 240 d of lactation. These data demonstrate that dairy cattle visceral tissues increase in mass, as a percentage of EBW, in order to meet the energetic demands of lactation.