Abstract
The effect of fetal number (single or twin) on plasma concentrations of progesterone, estradiol 17β, cortisol, prolactin, growth hormone, triiodothyronine, thyroxine and insulin around parturition (periparturient period) were studied on ten Alpine × Beetle crossbred goats in their first to third lactation. The hormone profiles were studied on days -20, -15, -10, -5, -4, -3, -2, -1 prior to kidding and on day 0 and +1, +2, +3, +4, +5, +10, +15, +20 days postkidding. Plasma progesterone levels were significantly (p<0.01) higher in twin bearing goats comparison to single bearing goats during all the days of sampling. The decline in progesterone concentration from day 20 to day 1 before kidding was 56% in twin and 42% in single bearing goats. In single bearing goats plasma estradiol 17β was significantly (p<0.01) higher during prekidding days compared to twin bearing goats. The level of estradiol 17β was highest on the day of kidding in both the groups. The plasma prolactin level in twin bearing goats from day 10 to day 1 prepartum was higher as compared to single fetus bearing goats. However there was abrupt increase in prolactin level on the day of kidding in both the groups. The plasma growth hormone levels were significantly (p<0.01) higher in twin compared to single bearing goats. On the day of kidding growth hormone levels were significantly (p<0.01) higher in twin as compared to single bearing goats (1.40 vs. 0.95 ng/ml). In twin bearing goats plasma cortisol values from day 5 till the day of kidding remained elevated and the levels on the day of kidding was significantly highest in both the groups. The levels of triiodothyronine (T3) were significantly higher (p<0.01) during all the periods of sampling in single compared to twin bearing goats. Plasma thyroxine (T4) was significantly (p<0.01) lower in twin compared to single bearing goats. In single bearing goats plasma insulin levels were significantly (p<0.01) higher than twin bearing goats during prepartum period however during post partum period the levels in both the groups remained similar. It can be concluded that number of fetuses is having significant influence on the hormone profile during periparturient period. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 3 : 346-351)
Highlights
The metabolic and functional changes between conceptions to termination of pregnancy is brought about by the interaction of various hormones
48-61 kg were selected from National Dairy Research Institute goat herd
The gestation length ranged from 145-157 days in different goats
Summary
The metabolic and functional changes between conceptions to termination of pregnancy is brought about by the interaction of various hormones. A major amount of mammary development is associated with hormonal stimuli of pregnancy. During prepartum period there is massive development of the mammary gland for lactogenesis and expulsion of fetus at parturition involved a control interaction of different hormones and absence of these stimuli reduces the amount of mammary tissue (Cowie, 1971). The administration of hormones like growth hormone, estrogen, progesterone and prolactin stimulate the growth and development of mammary gland. The presence of more placental tissue in goats due to twinning was related to more placental lactogen secretion to stimulate mammary gland growth (Anderson et al, 1981). An increase number of corpora lutea may contribute more estrogen and progesterone secretion, which leads to stimulation of mammary gland development in goats or sheep bearing twin fetuses. During the placental phase of pregnancy in goats and sheep progesterone and estradiol (Manalu et al, 1996)
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