CHANGES IN PARENCHYMA AND STROMA OF GOAT UDDERS DURING PREGNANCY, LACTATION AND INVOLUTION

被引:9
作者
ANDERSON, RR
WAHAB, IM
机构
[1] Department of Dairy Science, University of Missouri-Columbia, S139 Animal Science Research Center, Columbia
关键词
D O I
10.1016/0921-4488(90)90055-B
中图分类号
S8 [畜牧、 动物医学、狩猎、蚕、蜂];
学科分类号
0905 ;
摘要
Sixty-five mammary glands (udders) were obtained from dairy goats representing four breeds (30 Toggenburgs, 21 Nubians, 10 Saanens, and four French Alpines) at 13 stages of pregnancy, lactation and involution to determine growth patterns. Emphasized was the difference in growth rates between parenchyma (milk secreting tissue) and stroma (supportive tissue). The thirteen groups of five goats each included virgins (19 months old) and day 1 of pregnancy in goats with two or more previous pregnancies and lactations. Other groups included days 95, 120, 145 and 149 of pregnancy, days 1, 5, 10, 15, 30 and 90 of lactation, and day 30 of involution following 90 days of lactation in goats with one previous pregnancy and lactation. Measurements included body weight, untrimmed and trimmed udder weight, dry fat-free trimmed weight (DFFT), protein, collagen, glycans and nucleic acids. Collagen was estimated using a colorimetric measure of hydroxyproline. Stroma was estimated by adding collagen and glycans together. Parenchyma was estimated by subtracting stroma from DFFT. Parenchymal growth rate increased much faster than stroma during pregnancy. The exponential rate for parenchymal growth was 0.0205/day and the rate for stroma was 0.0105/day. Parenchymal growth peaked the day before kidding, while growth of stroma peaked 10 to 15 days later in early lactation. Rate of involution or disappearance of parenchyma in lactation and 30 days in dry period after lactation was 0.0124/day and that for stroma was 0.0088/day. After 30 days involution, the udder had regressed almost to the level of the virgin goats. A parabolic model based upon a quadratic regression equation described changes in udder supportive tissue as % of total weight throughout pregnancy, lactation and involution: Y, % stroma=60.8-0.450X+0.0015 X2, where X are days post conception, days 151 to 240 represent the lactation period and days 241 to 270 are the period of udder involution. Stroma represented 60% of udder weight in early pregnancy but only 24% in late pregnancy, while parenchyma was 40% of the gland in early pregnancy and 76% at 145 days of pregnancy. Stroma continued to increase in absolute and percentage terms for the first 15 days of lactation which is a significant new finding. Estimates of structural support needed for milk weight load in the udder may be derived from these data and enable reduction of udder support problems. © 1990.
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页码:605 / 615
页数:11
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