This study was conducted for SNPs in the 5'-regions of estrogen receptor-α(ESR-α), and association with calving interval (CI), service per conception (SPC) and 305 days milk yield in Hanwoo and Holstein dairy cattle. The genet-ic improvement was incurred low reproduction performance. The objective of this study was to investigate connec-tions between single nucleotide polymorphisms (SNP) of Estrogen receptor-α (ESR-α) with reproduction performance (calving interval, service per conception, and 305 d milk yield) in Hanwoo and Holstein dairy cattle. Hanwoo and Holstein blood samples were collected from 183 and 124 dam of breeding farms and DNA was extracted. Primer design was based on NCBI GenBank (Accession No. AY340579). The PCR-RFLP method with Bgl I was used to ge-notype the cattle. The result showed two variants of the ESR-α gene. The Bgl I cut the 492 bp amplification pro- duct into 322 bp and 170 bp fragments for allele G, while allele A remained uncut, resulting in two restriction frag-ments for homozygote G/G and three fragments for heterozygote A/G. We found two of different genotypes in the-se breeds, A/G and G/G. In Hanwoo, the A/G genotype frequency was 0.13, and G/G was 0.87. The CI of A/G was 382.18±10.03 days, and G/G was 381.69±5.22 days. The SPC of A/G was 1.62±0.16, and G/G was 1.32±0.04. While CI showed no significance difference, SPC exhibited significant difference (p<0.05). In Holstein cattle, the frequency of genotype A/G was 0.02 and G/G was 0.98. The 305 days milk yield of A/G was 7,253.00±936.00 kg and of G/G was 8,747.51±204.88 kg, showing no significant difference.

The study aimed to determine the physical characteristics of estrus mucus and conception rates in dairy cattle. Samples of estrus mucus from the cervix were collected from 108 dairy cattle during heat and were examined for color and consistency. Samples were taken from bred animals at starting from day of breeding to the completion of one estrus cycle. The color of the cervical mucus was studied based on its transparency while the consistency was based on the thinness and thickness of the cervical mucus. The dairy cattle were bred and the pregnancy diagnosis was performed at the 60th day post breeding. Findings showed that the estrus mucus of the dairy cattle was transparent in 58.3%, turbid in 31.5% and dirty in 10.2%. It was further observed that the mucus consistency of the dairy cattle was thin in 74.1% and thick in 25.9%. In the pregnant group, 67.3% mucus samples were found transparent, turbid in 23.6% and dirty in 9.1%. However, the corresponding figures for the non-pregnant group had 49.1%, 39.6% and 11.3%. The consistency of cervical mucus was found to be thin in 74.1% and thick in 25.9% of dairy cattle. The conception rates of dairy cattle with thin and thick consistency of cervical mucus were 81.8% and 18.2%, respectively. Pregnant was associated with consistency of cervical mucus (p<0.10). Findings indicated that dairy cattle with thin consistency of cervical mucus and had clear discharge were pregnant cows.

본 연구는 가상의 국내 젖소유전체 데이터를 생성하여 통계분석방법별, 유전력의 크기별, 참조집단 크기에 따라 유전평가의 정확도 변화에 대해 알아보고자 연구를 실시하였다. 모의실험 데이터 생성은 QMSim프로그램을 이용하였으며, 유전력의 크기(0.1, 0.3, 0.5) 및 참조집단의 크기를(420두, 630두, 1,050두) 달리하여 총 9가지 형태의 데이터를 생성하였고 각 형태별 10회 반복 모의실험을 수행하였다. 통계분석방법간 육종가 정확도 비교 결과 표현형정보, 혈통정보 및 유전체 정보를 모두 이용하여 개체의 유전능력을 평가하는 GBLUP이 유전체 정보 없이 분석하는 BLUP방법에 비해 육종가 정확도가 높게 나타났으며, 특히 자신의 표현형 정보를 갖지 않는 검정집단축군에서 통계분석방법간 육종가 정확도의 편차가 크게 나타났다. 검정형질의 유전력에 대한 크기별 육종가 정확도를 비교한 결과 BLUP과 GBLUP에서 모두 유전력이 높을수록 육종가 정확도가 높게 나타났다. 또한 참조집단크기별 육종가 정확도를 비교한 결과 참조집단축군에서 참조집단크기별 차이가 크게 나타나지 않는(0.02 - 0.03) 반면 검정집단축군의 경우 참조집단크기별 육종가 정확도는 0.02 - 0.10로 표현형 정보가 없을 경우 참조집단 크기에 더 크게 영향을 받는 것으로 나타났다. 본 연구결과를 통해 얻어진 결과는 젖소 유전체 선발을 위한 기초자료로 활용될 수 있을 것으로 판단된다.

today's dairy production management systems, reproductive efficiency affects the income of any farm by influencing overall milk production, genetic gain, amount of replacement heifers, and wise cullling decisions. Nutrition, management, and genetics play a major role achieving this maximum herd-reproductive performance. Several reports using trace minerals on the diet of cattle have shown reproductive effects. The main justification for using blocks, to provide deficient nutrients is, therefore, their convenience for packaging, storage, transport and ease of feeding. Dairy cattle are annually exposed to prolonged periods of elevated humidity and heat which reduce feed intake and reproductive performance. The objectives of the present study were to evaluate the effects of mineral on reproductive performance of dairy cows during Summer. The experimental group of cows had access ad libitum to the mineral lick in the following composition : Zn, Fe, Mn, Cu, I, Co, Se. Environmental heat load was described using the THI (temperature humidity index) because thermoregulation in cows is affected by both Temp and RH. The THI was calculated: THI=(0.8×Temp)+[RH×(Temp— 14.4)]+ 46.4. All cows were monitored for estrus twice daily in the morning and late afternoon. And any animal found in estrus was artificially inseminated. Pregnancy diagnosis was performed via ultrasonography at 45 to 70 d after insemination. The visitation and intake of mineral were higher with the maximum THI. The mean intake of mineral block was 23.1 kg in Summer and 17.7 kg in other seasons. The reproductive performance was considerably improved by mineral supplementation. The factors influencing consumption of mineral mixtures include: soil fertility and forage type, available energy and protein, individual requirements, salt content of the water, palatability of mineral mixture, availability of fresh minerals and physical form of minerals. These results show that minerals have a great impact on animal's reproductive physiology.

To control mastitis in dairy cattle, National Mastitis Control Program (NMCP) has been conducted in Korea since early 2000s. Nevertheless, mastitis still remains one of the most important disease in dairy cattle in Korea as other countries worldwide. Under the NMCP, a total of 343,090 lactating cows nationwide were tested for mastitis during 2004～June 2010 based on California Mastitis Test (CMT), and 7.8% (26,782/343,090) and 13.8% (47,335/343,090) of the cows tested were infected with clinical and subclinical mastitis, respectively. Relative frequency of 2,058 bacteria isolated from bovine milk samples with somatic cell count of ≥200,000 cells/㎖ during 2006～2010 were analyzed. The most frequently isolated bacteria were Staphylococcus spp. including Staphylococcus aureus, accounting for over 50% of the total number of isolates. The highest frequency was observed for coagulase-negative staphylococci (CNS), followed by Gram negative bacteria (GNB), S. aureus, Streptococcus spp., and Enterococcus spp. Based on the results of recent studies in Korea, the majority of pathogens isolated from subclinical mastitis in dairy cattle in Korea are environmental minor pathogens. Therefore, more attention should be paid to control of environmental pathogens such as CNS, GNB, and Streptococcus uberis in dairy farms in Korea.

젖소는 분만전후기에 당 및 지방대사를 조절하여 태아와 유선에서 요구하는 영양소를 충족하고자 한다. 이러한 대사적 적응과정에서 중요한 역할을 하는 호르몬으로 insulin을 꼽을 수 있으며, 특 히 지방조직에 작용하여 동물체내 필요한 에너지를 충족시키기 위해 지방산의 재배치를 촉진하고 분만전 말기에 insulin resistance를 야기시킨다. 분만전에 혈중 유리 지방산의 농도가 증가됨에 따라 insulin resistance가 발생하며 이것은 사료섭취량의 감소와 밀접한 관계가 있다. Insulin resistance을 완화시키는 물질로 PPARγ agoinst인 thiazolidinedione (TZD)는 분만전후기에 발 생하는 대사성 질병의 발생을 억제하여 젖소의 건강 및 유생산 증가를 도모할 수 있다고 사료된다.

The present study was carried out to investigate effects of gonadotropin, age of donor, day of estrus cycle gonadotropin injection started and season on embryo production after superovulation in dairy cattles. Embryo collection records were obtained from 177 embryo donor collections from 98 Holstein cows aged from 3 to 9 years during 4 years(1993~1996) at National Livestock Re-search Institute. Superovulation was induced by injections of 3 gonadotropins(FSH-P, FOLLTROPHIN-v* or SUPER-OV*) beginning on days 9 to 14 of the estrus cycle. Em-bryos were collected from donors using a nonsurgical technique on days 6 to 8 after insemi-nation. The results were as follows ;Number of total and freezable embryos per donor cow was affected by gonadotropin(P<0.01). The more number of total and freezable embryos wereobtained by use of FOLLTROPHIN-V (13.2, 7.4) or FSH-P (11.0, 5.7) than SUPER-OV* (5.0, 2.4). Age of donor, the day that gonadotropin was started or season didn't affect total or freezable embryos(P >0.05).

Three fistulated nonlactating Holstein cows were used to examine the change in ruminal characteristics when fed diets of 100% corn silage, 50% corn silage + 50% wet brewers' grain(WBG) and 100% WBG, and also twenty Holstein heifers averaging 156 3.2kg BW

This experiment was conducted to evaluate the grazing performance of dairy cattle for winter rye, sorghum-sudangrass hybrid and oat including of rape in Hwa seong-gun, Kyeonggido, from 1993 to 1994. Each crops were utilized from the stage of 8-leaves to l

Genetic changes from improving female's reproductive rate through in vitro fertilization of large number of oocytes were studied. The breeding scheme employed was multiple ovulation and embryo transfer of juveniles and adults. Both balanced and unbalanced matings were examined for the four closed progeny population sizes, 10, 10, 105, 106. In balanced matings, all selected sires and dams were mated to each other(cross-classified mating) while unbalanced matings allowed selected dams and sires mated partially, eg. unbalanced matings allowed averages of .5 and .25 progeny per each mating. Various numbers of selected sires and dams were also examined in both balanced and unbalanced matings. In all mating schemes, selection of males and females was restricted to he one from each fullsib family to reduce the rate of inbreeding. The model calculations were deterministic and accounted for the effects of selection and inbreeding on loss of the genetic variation in succeeding generations. Balanced rectangular mating schemes, where more donors were selected than sires, resulted in larger selection responses than balanced square mating schemes, where equal numbers of sires and donors were selected, and unbalanced rectangular mating. The first round selection responses from the balanced rectangular matings of juvenile MOET, eg. number of progeny per mating equals 2 with 10 sires selected, were 1.192, 1.406, 1.580 and 1.735 times larger than the first round selection responses from the balanced square mating schemes for the given four progeny population sizes, 10, 10, 105 and 106, respectively. Similar results were obtained in adult MOET breeding schemes. However, balanced square matings gave greater selection responses than the unbalanced rectangular matings.