육종 번식 ; 한우와 샤로례 교잡종 미경산빈우에 있어서 발정기와 임신초기의 혈중호르몬수준 및 체중변화에 관한 연구 = Breeding and Reproduction ; A Study on Changes in Serum Hormone Level and Body Weight During Estrus and Early Pregnancy in Korean Native Heifers and Charolais Crossbred Heifers

다국어 초록 (Multilingual Abstract)

In order to study the changes in serum hormone levels and serum metabolite contents during day 2 before and after estrus and early pregnancy, jugular blood samples were taken from 8 cycling heifers, 4 Korean native cows (K×K) and 4 Charolais crossbreds (C×K). Their average body weight at 1st mating after puberty was 325.8 Kg for purebreds and 416.0 Kg for crossbreds. The live body weights of heifers were measured at monthly intervals from 3 months before 1 st mating to 5 months after mating. Eight heifers were divided into 2 groups according to breed. Serum hormones were assayed by radioimmuhoassay method and serum metabolite contents were analyzed by rapid blood analyser system. The results obtained were as follows: 1. Serum progesterone levels from day-2 to +2 estrus were 0.5-0.9 ng/㎖ for purebreds and 0.6-1.8 ng/㎖ for crossbreds and during the period day 20 to day 60 pregnancy their levels were 7.8-9.1 ng/㎖ for purebreds and 7.7-10.2 ng/㎖ for crossbreds, respectively. There were no significant differences in their levels between 2 breeds, but crossbreds exhibited larger variation among individuals than purebreds. 2. The maximum level of estradiol -17β was 16.9pg/㎖ fer purebreds and 18.4pg/㎖ for crossbreds at day 1 before estrus. These levels decreased at day 2 after estrus. Estradiol -17β levels during 60 days of pregnancy were 7.4-10.1 pg/㎖ for purebreds and 7.0-8.2 pg/㎖ for crossbreds. 3. Serum LH and FSH levels during day 2 before and after estrus and early pregnancy remained below 1.56mIU/ ㎖ and 1.25mIU/㎖ at all the investigated stages, respectively. 4. Serum prolactin levels were highest at the day of estrus in 2 breeds and the maximum level in purebreds and crossbreds were 13.2 ng/㎖ and 13.6ng/㎖, respectively. The stages of elevated serum prolactin level occurred later I days than those of estradiol -17β. Serum prolactin levels during the early pregnancy were 8-11ng/㎖ in 2 breeds and these levels were similar to those of day 2 after estrus. 5. In changes of live body weight during 5 months after mating, the body weight at 5 months of pregnancy increased by 9.1% for purebreds and 10.5% for crossbreds. The weights of crossbreds from 3 months before mating through 5 months of pregnancy were 23-25%~ heavier than those of purebreds. 6. Serum total protein levels during day 2 before and after estrus and early pregnancy were 6.0-6.5 g/㎗ and 5.9-7.0 g/㎗ for purebreds and 7.0-8.8 g/㎗ and 7.0-8.2g/㎗ for crossbreds. There were no significant differences in total protein concentration between 2 breeds and 2 physiological states, although total protein levels of crossbreds were 18-20% higher than those of purebreds. Globulin (G) level in total serum protein was higher than that of albumin (A) at day 2 before estrus and A/G ratio from day 1 before estrus to day 60 of pregnancy ranged 1.08 to 1.16. 7. Serum glucose levels were 43.0 ㎎/㎗ for purebreds and 44.8㎎/㎗ for crossbreds during before and after estrus, and 36.2㎎/㎗ for purebreds and 41.9㎎/㎗ for crossbreds during early pregnancy. Serum GOT levels of purebreds from day 2 before estrus through day 60 of pregnancy were higher than those of crossbreds, but there were not significant between 2 breeds.