Growth rate during rearing, which varies depending on provided nutrition, has been related with age at 1st calving (AFC). This study investigated the effect of upgrowth parameters during the rearing period on the reproduction of nulliparous Holstein heifers. The study comprised 77 successively born heifers from the same herd. Growth rate and fertility traits were measured during rearing and fertility parameters were recorded in lactations 1. Growth parameters (body weight, height, heart girth and body length) were measured at the approximate birth time, 270 and 450 d of age. Reproduction data collected included age at 1st breeding, number of services per conception (S/C), pregnancy rate to 1st artificial insemination, AFC. Animals were subsequently divided into 4 AFC groups for analysis: <23 mo, 23∼ 25 mo, 26∼30 mo and >30 mo. The AFC reflected both upgrowth rate and heifer reproduction, with later calving heifers smaller. Increased skeletal growth (at 270 and 450 d) was related with a reduced AFC (p<0.05). Early calving animals (<23 mo) had the best reproduction as nulliparous heifers, with most conceiving at first service (87.5%). Fertility in the first lactation was the worst in the oldest AFC group (>30 mo). In the 1st lactation period, a number of services per conception (3.1±0.3) increased with increasing AFC (>30 mo). Sub-optimal upgrowth related with an increased AFC could be mitigated by improved monitoring of replacement heifers during the rearing period.

The objective of this study was to identify the phenotypic relationships among calving difficulty, calf birth weight and gestation length of Holstein dairy cattle under the environment of Korea. A total of 1,834 calving records collected by Dairy Science Division of National Institute of Animal Science, RDA from 2000 to 2014 was analyzed. General linear multivariate models for calving difficulty scores (CD: 1=no assistance, 2=minor assistance, 3=two to three persons assisted, 4=more than three persons assisted, 5=cesarean section), calf body weight at birth (BW), and gestation length (GL) included fixed effects of year and season (spring, summer, autumn, winter) of births (YS), sex of calves, and parity. For GL and BW, all three fixed effects (YS, sex of calves, parity) were significant (p<0.05). For CD, the effects of YS and sex of calves were significant (p<0.05). Bull calves were born with heavier BW by 3.18 kg, with greater CD by 0.18 point and with longer GL by 0.6 days than heifer calves. The least squares mean of BW was the heaviest at the third parity (44.1 kg) compared to those at the first, the second and the fourth parities or later (41.3-41.9 kg). The least squares mean CD at the first parity was 1.74 point, which was higher than CD at the second and later parities (about 1.68 points). Phenotypic correlation (partial residual correlation) between GL and BW was 0.36. But those between GL and CD and between BW and CD were -0.03 and 0.04, almost zeros. To conclude, we observed higher incidence of calving difficulty in the first calving than in the later ones. Further investigation on the relationships between calf’s birth weight and calving difficulty is needed

케토시스 지표형질에 영향하는 환경요인을 살펴보기 위하여비유단계, 계절 및 착유시간에 대한 생산형질의 변화를 살펴보았다. 유량은 비유일수가 증가할수록 높아지는 추세를 보였고, 유지방 함량, 유단백 함량, 무지고형분 함량은 DIM1(비유초기)에서 가장 높게 나타났다. 계절에 따른 생산형질의 변화를 살펴보면 유량은 봄·겨울에 높게 나타났고, 유지방 함량과유당 함량, Acetone 및 BHBA 모두 가을에 높게 나타났다.또한 유량은 오전 착유시간이 높았고, 유지방 함량 및 유단백함량은 오후 시간대가 높게 나타났다. 환경요인에 따른 생산형질 및 케토시스 지표형질의 함량은 모두 유의적 차이를 보였으며, 분석모형을 설정함에 있어 위의 환경요인은 고려되어야 할 사항이다. 생산형질과 케토시스 지표형질의 상관관계 분석 결과 유량의 경우 Acetone 및 BHBA의 수치가 증가할수록 감소하는추세를 보였고, 유지방 함량은 반대로 Acetone 및 BHBA의수치가 증가할수록 증가하는 경향을 보였다. 비유단계와BHBA의 농도는 음의 상관관계를 보인다는 기존의 결과와 반대로 분석결과 양의 상관관계를 보였다. 유전력은 착유일5 ~ 20일에서 0.03 착유일 21 ~ 40일은 0.05 착유일 41 ~ 60일은 0.04 착유일 61 ~ 80일은 0.08 착유일 81 ~ 100일은 0.04의 유전력을 보였다. 이는 비유 5일째에 준임상형 케토시스의발병률이 가장 높게 나타난다는 기존의 연구결과에 비추어 볼때 유전력이 낮게 추정된 것으로 사료되며, 이는 1산차의 분석 자료수가 충분치 않은 결과로 추정된다. 케토시스 저항성개체 선발을 위한 유전평가모형에 적용가능한 선발지수를 개발하기 위해서는 여러해의 축적된 자료를 이용한 분석이 필요한 것으로 판단된다.

Reproductive disorders in cows cause economic loss in livestock farms. Reproductive diseases, such as follicular cyst, luteal cyst, endometritis, pyometra, and repeat breeding cause infertility. Among these diseases, endometritis and pyometra are uterine infections that are leading causes of infertility. This study was performed to investigate the causative agents of uterine diseases using bacterial culture. Bacteria were obtained from the reproductive organs (vagina, uterine cervix, and uterine horn) of dairy cow diagnosed with endometritis or pyometra, and cultured on blood agar. The colonies obtained from cultivation for 24 hours were passaged. To identify the bacteria, the colonies grown in passaged culture Gram stained and applied to an automatic biochemical microbial identification system. Escherichia coli were commonly detected in vagina, uterine cervix, and uterine horn of dairy cows diagnosed to pyometra. The cows having endometritis showed not only Escherichia coli but also Pantoea spp. and Klebsiella spp. strains. Dairy cows that were infected with Escherichia coli in uterus caused mastitis or digestive disease. These results suggest that sanitary feeding and management beforehand are needed to prevent bacterial infections.

Raising replacement heifers is important aspect of dairy farm management that can be characterized as a long-term performance and high-cost production period. This study was investigated the effect of month of age at the first pregnancy on calving difficulty of Holstein heifers. Heifers was inseminated with semen of easy-calving sire and the reproductive performance was compared for the effect of first pregnancy at 12-14 months of age (12 month old), 15-16 months of age (15 month old), 17-19 months of age (17 month old) and > 20 months of age (20 month old) in Holstein heifers. Holstein heifers showed different easy calving score (ECS) depending on their ages; frequency of ECS 1 was 55.2%, 64.9%, 59.4% and 52.0% at 12, 15, 17 and 20 month of age, respectively. Frequency of ECS 4 was 5.2%, 1.8%, 6.3% and 4.8% at 12, 15, 17 and 20 month of age, respectively. The rates of retained placenta postparturition in first pregnancy age category was 12.3% at 12 months of age, 5.3% at 15 months of age, 9.4% at 17 months of age and 19.0% at 20 months of age. When It was evaluated by present results, the reproductive performance like easy calving score (ECS), retained placenta rates, and abortion and stillbirth rates of heifers which was inseminated at 14 months old or less and at 17 months old or more was reduced. Therefore, the first pregnancy age for optimum reproductive performance was 15-16 months.

본 연구의 목적은 육우 송아지 출하월령(3, 6, 9, 12개월) 조건에 따른 채끝등심(m. longissimus lumborum)과 꾸리육(m. tricep brachii)의 이화학적 육질 특성 및 지방산 조성에 미치는 특성을 비교하여 송아지고기의 상품성을 조사해 보고자 수행하였다. 채끝등심육과 꾸리육 모두 출하월령이 증가됨에 따라 수분 함량은 감소하였던(73.20~79.23%) 반면에 단백질(19.51~23.13%) 및 지방(0.76~1.99%) 함량은 증가하였다. 육색의 경우 두 부위 모두 출하월령이 증가됨에 따라 L*값(30.62~43.81)은 감소하는 반면에 a*값과 b*값은 증가하였다 (P<0.05). pH는 채끝등심육은 3개월령(5.96)이 꾸리육은 3개월(5.67) 및 6개월(5.73) 령이 다른 출하월령들 보다 유의적으로 높았다(P<0.05). 미오글로빈 함량은 채끝등심과 꾸리육 모두 출하월령이 증가할수록 증가하였다(P<0.05). 전단력을 측정한 경과 채끝등심육 은 3개월령(5.94 kg)과 12개월령(4.34 kg)이 6개월(9.16kg) 및 9개월령(9.57 kg) 보다 유의적으로 낮았으며, 꾸리육은 3개월령(2.83 kg)이 9개월 (4.47 kg)령 보다 유의적으로 낮았다(P<0.05). 가열감량은 채끝육의 경우 출하월령간에 유의적인 차이가 없었으나 꾸리육은 다른 출하월령들 보다 12개월(28.37%)령이 낮았고 3개월(36.55%)령이 높았다(P<0.05). 한편 채끝등심과 꾸리육은 모두 12개월령이 근절길이가 길었고 보수력이 유의적으로 높았다(P<0.05). 지방산 조성을 분석한 결과 채끝등심육은 3개월령에 C18:2n6, C20:1n9, 총 다가불포화지방산 (PUFA), 포화지방산에 대한 다가불포화지방산의 비율(PUFA/SFA) 및 오메가-6(ω-6) 지방산 함량이 유의적으로 높았고 12개월령에는 C16:1n7, C18:1n9, 총 단가불포화 지방산(MUFA), 총 포화지방산에 대한 총 단가불포화 지방산의 비율(MUFA/SFA) 지방산 함량이 유의적으로 높았다(P<0.05), 꾸리육의 경우 3개월령에 C20:1n9 함량이 높았고 12개월령에는 C14:0, C18:1n9, 총 단가불포화지방산(MUFA) 및 총 포화지방산에 대한 총 단가불포화 지방산의 비율(MUFA/SFA) 함량이 유의적으로 높았다(P<0.05).

반추위 pH 조정제로서 일반적으로 중조가 많이 사용되고 있으나 사료에 중조의 첨가량을 증가시키는 경우에 기호성을 저하시키는 경향이 있다. 따라서 본 연구에서는 사료의 기호성에 영향을 미치지 않으면서 반추위 완충효과를 나타내도록 개발된 액상형 완충제의 젖소사료 첨가제로서의 이용효과를 구명하기 위하여 수행되었다. 시험축으로 착유 중기 젖소 27두를 공시하였으며, 처리는 대조구와 중조 첨가구, 그리고 액상형 완충제 첨가구로 하여 처리별 9두씩 배치하였다. 대조구는 착유우용 자가배합 TMR 사료를 급여하였으며, 중조 첨가구는 대조 사료에 중조를 두당 1일 150g 추가하여 급여하였고, 액상형 완충제 첨가구는 같은 방식으로 액상형 완충제를 두당 15㎖ 추가하여 사양시험을 수행하였다. 시험결과 산유량은 대조구, 중조 및 액상형 완충제 첨가구의 경우에 각각 23.82, 23.91, 24.91kg으로 대조구에 비하여 액상형 완충제 처리구에서 다소 증가하는 경향이었으나 처리 간에 뚜렷한 유의 있는 결과를 보여주지는 않았다. 처리에 따른 유성분 변화에서는 유단백질 및 무지고형분에서 액상형 완충제를 첨가한 경우에 대조구에 비해 유의 있는 증가(p < 0.05)를 보여주었고, 유지율에서도 대조구에 비하여 처리구가 다소 증가하는 경향을 보였다. 혈액성분 중 포도당과 콜레스테롤은 대조구에 비해 액상형 완충제의 첨가구에서 다소 증가하였으나, 처리 간에 유의 있는 차이를 나타내지는 않았다. 따라서 개발된 액상형 완충제의 추가급여 시 생산성 증대, 특히 유성분 증가 효과가 있어 반추위 pH 조정을 위하여 일반적으로 이용되고 있는 중조를 대체하여 반추동물의 사료첨가제로 이용이 가능할 것으로 평가되었다.

본 연구는 젖소의 분만계절에 비유곡선 모수를 추정하고, 추정된 비유곡선 모수를 이용하여 우리나라 젖소의 비유특성에 대한 기초자료를 제공하고자 실시하였다. 자료는 2009년부터 2011년까지 분만한 1산차 14,189두의 농협중앙회 검정자료를 이용하였으며, 비유곡선 모수는 Wood 모형을 적용하여, SAS 9.2 NLIN Procedure를 이용해 추정하였다. Wood 모형으로 추정 된 비유곡선 함수는 봄, 여름, 가을 및 겨울 분만에 대해 각각 yt=17.1726t0.2074e-0.00243t, yt=17.4108t0.1868e-0.00206t, yt=16.1367t0.2171e-0.00224t 및 yt=15.7759t0.2378e-0.00258t이었다. 봄, 여름, 가을 및 겨울의 분만에 대한 추정최고유량과 최고유량도달시기는 각각 32.55 kg, 84.70일, 31.53 kg, 90.99일, 32.21 kg, 96.51일 및 32.95 kg, 90.20일 이었다. 겨울의 분만이 여름의 분만보다 추정최고유량이 높았다. 또한 봄의 분만이 다른 계절보다 최고유량도달시기가 더 빨랐다.

Presently, the first pregnancy age of dairy heifers attended National Dairy Herd Improvement Program (NDHI) in Korea has increased, and more research have been requested to evaluate the possibility of decreasing the first pregnancy age of dairy heifers. Accordingly, this study was investigated the effects of the month of age at the first service and pregnancy on the reproductive efficiency of Holstein heifers. For these, the reproductive performance of heifers was analyzed by evaluating the effects of first insemination service at 12-14 months of age (12 month old), 15-16 months of age (15 month old), 17-19 months of age (17 month old), and > 20 months of age (20 month old) in Holstein heifers. The service numbers per conception in the first insemination months were 1.85±1.22, 1.59±0.77, 1.58±0.72, and 1.76±0.97 times at 12, 15, 17 and 20 months of age, respectively. The conception rates in the first service were 51.2, 57.8, 54.8, and 52.9% at 12, 15, 17 and 20 months of age, respectively. The conception ages were 453.2±78.9, 512.1±75.9, 590.1±98.0, and 713.0±74.5 days in the heifers serviced firstly at 12, 15, 17 and 20 months of age, respectively. There was significantly difference in the conception age among groups (p<0.05). The cumulative conception rates in the heifers serviced firstly at 12, 15, 17 and 20 months of age were 51.21, 57.8, 54.8 and 53.0% by the first service, 29.8, 30.1, 32.3, 23.5% by the second service, and 19.0, 12.1, 12.9 and 23.5% by the third service, respectively. The service numbers per conception in the first pregnancy months were 1.31, 1.55, 2.0, 2.05 times at 12, 15, 17 and 20 months of the first service age, respectively. The service numbers per conception in the 12 and 15 months of age were significantly lower than those in the 17 and 20 months of age (p<0.05). The rates of repeat-breeder were 6.0, 11.3, 22.0, and 41.0% in the heifers serviced firstly at 12, 15, 17 and 20 months of age, respectively. These results demonstrate that first pregnancy of Holstein heifers should be conducted at 15 months of age, because the age at first pregnancy in heifers can be substantially influenced through implementation of reproductive management and performance.

The objective of this study was to estimate genetic parameters for 18 linear conformation traits and overall conformation score in Holstein cattle. A total of 376,606 records for type traits were collected from 2001 to 2011 from Korea Animal Improvement Association. The model of estimation of variance components and correlations among lactations using VCE included both fixed effects (herd-year-season and stage of lactation parity-wise) and random effect (animal additive genetic). The estimated heritabilities (h2) for capacity class, such as stature, chest width, body depth, angularity, and body condition score were 0.32, 0.16, 0.27, 0.12, and 0.19, respectively. Rump angle and width from rump class also showed h2 of 0.31 and 0.17, respectively. The heritabilities in udder class were mostly low to medium; in which traits were fore udder attachment (0.13), rear udder height (0.17), udder support (0.11), udder depth (0.33), front teat placement (0.17), front teat length (0.21), and rear teat placement (0.21). For feet and legs composite class, the estimated heritabilities for rear leg set, foot angle, rear leg rear view, and locomotion were 0.12, 0.07, 0.08, and 0.03, respectively. The h2 estimated for overall conformation score was 0.16 in the study. The genetic and environmental variance components estimated from this study would be helpful to change from single lactation animal models to multiple lactation animal models in the national genetic evaluation system for the improvement of linear type traits. Moreover, The breeding values obtained using these variance components would be able to be used in the calculation of Korean type production index (KTPI), udder composite (UDC) and, feet and legs composite (FLC).

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.

본 연구결과 조농비가 다른 사료를 각각 급여한 젖소에 서 임신초기의 유방 크기는 HF군이 LF군 보다 2.4배 가량 유의하게 컸으나, 임신중기와 착유기 동안에는 두 군 간에 차이가 없었다. Estradiol의 혈중농도는 두 군 모두 사춘기 부터 서서히 증가하여 임신기간 동안 사춘기의 2~3.5배가 량이 되었으며, 두 군간 유의한 차이는 나타나지 않았다. 착유기 전 기간에 걸쳐서도 estradiol의 농도는 두 군간 차 이가 없었다. Progesterone의 혈중 농도는 사춘기부터 증가 하기 시작하여 임신중기까지 두 군 모두 비슷한 농도로 유지되었으며, 시험 전 기간에 걸쳐 두 군간 유의한 차이는 없었다. 산유량 4% FCM은 두 군 모두 분만 후 증가하다 LF군은 분만 100일, HF군은 150일을 기점으로 감소하였다. 그러나, 분만 후 50일까지를 제외하고 그 후 전 기간에 걸 쳐 양질 조사료 함량이 높은 사료를 급여한 HF군의 젖소 에서 산유량이 유의하게 높았으며, 분만 250일 까지도 높 은 산유량을 유지하였다. 우유 내 체세포 수는 분만초기를 제외하고 착유기 전 기간 동안 HF군에서 유의하게 감소하 였다. 유지율은 분만 후 비유 초기에 LF군에서 다소 높게 나타났으나, 그 이후부터는 두 군간 차이가 없었으며, 그 밖에 우유 내 단백율, 고형율, MUN 모두 두 군간 차이는 관찰되지 않았다. 산유량과 체세포 수 및 유지율을 기초로 계산한 유대에 있어 HF군이 LF군에 비하여 최고 141.5% 증대되었다. 본 연구결과로부터 젖소의 양질 조사료의 함 량을 적당 수준으로 증가시킴으로써 유방의 크기나 관련 호르몬의 변화 없이 우유의 생산량을 증대시키고 우유의 질을 높일 수 있을 것으로 평가되었다.

본 연구는 사료 내 총NDF 수준과 조사료에서 기인된 NDF 수준(fNDF)이 착유우에서의 영양소 섭취량과 유생산 성에 미치는 영향을 평가하기 위하여 실시하였다. 분만우 36두를 대상으로 6개의 처리구를 나누어 2×3 요인실험으로 설계를 하였고, 각 처리구별 사료는 건물기준 NDF 38%에 1) fNDF 18%, 2) fNDF 15%, 3) fNDF 12% 와 건물기준 NDF 34%에 4) fNDF 18%, 5) fNDF 15%, 6) fNDF 12%로 구분하여 분만 후 3주부터 20주까지 급여하였으며 결과의 처리는 분만 4주부터 영양소 섭취량 및 산유성적을 분석하 였다. 사료 내 총 NDF 함량과 fNDF 함량이 감소함에 따라 건물섭취량, NEl 섭취량 그리고 비구조탄수화물 섭취량이 유의적으로(p<0.01) 증가하였고, 통계적인 유의성은 없었으 나 유생산량 또한 다소 증가하는 경향이었으며 유지방율은 감소하였다(p<0.01). 건물섭취량의 증가에 따른 NEl 섭취 량의 증가가 유발되었고, NDF 섭취량은 감소하였음에도 불구하고 NDF 함량이 낮은 처리구와 높은 처리구간의 비 교에서 유지방율에 대한 유의적인 차이를 나타내지는 않았 다. 총 NDF와 조사료유래 NDF의 사료 내 함량변화는 유 단백질율과 무지유고형분 함량에는 영향을 미치지 않았지 만, 유단백질 함량과 무지유고형분 생산량에 있어서는 유 량 증가에 의한 영향으로 증가하는 경향을 나타내었다. 조 사료유래 NDF 섭취량과 유지방율 간의 상관관계는 저수준 NDF 함량에서 고수준 NDF 함량보다 높게 나타났으며 유 량과 영양소 섭취량간의 상관관계 또한 저수준의 NDF 처 리구에서 고수준 처리구보다 높게 나타났다.

This study was conducted to investigate the effects of the slaughtering age on carcass characteristics and economic efficiency of Holstein steers. The Holstein steers (n=27, 4 months old, average body weight 160 ㎏) were divided into 3 groups and raised with TMR feeding formulation until 18, 20 and 22 months old, respectively. In the result, final body weights were 703, 768 and 804 ㎏, and average daily gains were 1.32, 1.32 and 1.27 ㎏, respectively. Dry matter intakes (DMI) were 8.62, 8.94 and 9.24 ㎏. Feed conversion ratio was 6.53, 6.77 and 7.28 for 18, 20 and 22 months old groups. Feed conversion ratio was increased as the fattening periods increased. In yield traits, carcass weight was significantly lower in 18 months old group compared to other groups (p<0.05). The back fat thickness were 8.4, 7.3 and 7.8 ㎜, rib eye area were 70.6, 73.4 and 73.84 ㎠, and the meat yield index was 62.9, 62.5 and 62.1 when slaughtered at 18, 20 and 22 months old, respectively. In the frequency of the yield grade (A:B:C, %), grade B was highest at 20 months old group as 0:75:25. In the quality traits, marbling score, texture and maturity were not different among slaughtering age groups. However, marbling score tended to be increased at 22 months old group. Meat color and fat color were higher at 22 months old group compare to other groups (p<0.05). In the frequency of the quality grade (1+:1:2:3,%), 22 months-old group was the greatest as 12:0:50:38. The income was highest for 20 months old group as 279 thousand wons among the 3 groups. Therefore, the slaughtering ages of Holstein steers may be appropriate at 20 months old.

지구 온난화에 따른 외기온도의 지속적인 상승은 젖소의 유질저하를 초래하는 것으로 알려져 있다. 현재 우리나라에서는 원유의 유지방함량, 체세포수 및 세균수를 기준으로 유대가격을 산정하고 있어 궁극적으로 여름철 온도의 상승은 젖소농가의 수익성에 악영향을 미치게 된다. 본 연구에서는 경북지역을 중심으로 외기온도와 상대습도을 조사하고 외기온도와 상대습도에 따른 온습도지수 (THI)를 도출하여 유질에 미치는 영향을 상관관계와 회귀분석 방법을 이용하여 분석하였다. 유지방 함량은 겨울철 4.0-4.1%에서 여름철로 접어들면서 3.6-3.7%로 저하하였고 동시에 온도와 THI가 상승하였다. 체세포수 1등급 출현율은 4-9월이 다른 달에 비해 낮은 것으로 나타났다. THI는 유지방 함량과는 r=-0.8914, 체세포수 1등급 출현율과는 r=-0.6067의 상관관계를 보였으나, 세균수 1등급 출현율과는 통계적으로 유의한 상관관계을 보이지 않았다. THI에 따른 유지방함량 및 체세포수 1등급 출현율을 예측할 수 있는 공식을 단순회귀분석법을 이용하여 도출하였다. 본 연구의 결과을 종합하면, 온도 및 상대습도를 이용하여 도출한 THI는 젖소의 고온스트레스를 분석하는 지표로 사용될 수 있을 것으로 사료된다.

This study was conducted to investigate the effects of supplementing additional sucrose, in the form of black sugar (BS), into the diet of Holstein dairy cows on dry matter intake (DMI), milk yield, and milk composition. Eight Holstein dairy cows (741 ± 65.8 kg body weight) were divided into two groups, including the control and BS groups. Animals in the control group were offered a total mixed ration (TMR) ad libitum, and the BS group was offered TMR with 300 g of BS/head/d. After two weeks of adaptation period, the animal performance, including DMI, milk yield and milk composition, was measured. Cows supplemented with BS appeared to consume more feed than that by the controls (i.e., 17.08 and 18.28 kg/d for the control and BS groups, respectively). However, there were no significant differences between treatments. Milk yield or milk composition, such as milk fat, milk protein, lactose, solids-non-fat, total solids and pH, did not differ between treatments. However, there was a significant difference (p<0.05) in the concentration of milk urea nitrogen (MUN). The MUN concentration of the BS group was approximately 15% lower than that of the control group (i.e., 18.75 vs. 16.05 mg/dL for the control and BS groups, respectively), which suggests improved nitrogen metabolism in the animals. The somatic cell count was numerically lower in the cows of the BS group compared to those in the control group. However, a significant difference was not noted due to the substantial amount of variation among cows. In terms of the trace mineral composition for milk, the concentration of Cu from BS animals was higher (p<0.05) than that of the control animals. In summary, supplementing the diets of dairy cows with BS marginally affected animal performance and improved nitrogen metabolism. The level of supplementation and other factors, such as animal variation were discussed.

The objective of this study was to analyze the accuracy of estrus detection of heat detector and analysis of estrus behavior (mounting and mounted), and the evaluation of conditions required for improving reproductive efficiency in Holstein dairy cows fitted with a estrous detector. The heat detection system consists of estrous detector based on wireless sensor and an electric bulletin board displayed estrus behavior data. When cow mounting other cows, the accuracy of estrus behavior displayed an electric bulletin board were 87.5% (mounting other cows only), 100% (mounting other cows but not standing), 80.0% (mounting other cows with standing for 1∼4 seconds), 90.0% (mounting other cows but not standing for 1∼4 seconds), 80% (mounting other cows with standing for more than 5 seconds) and 90.0% (mounting other cows but not standing for more than 5 seconds). When cow mounted other cows, the accuracy of estrus behavior displayed an electric bulletin board were 100% (mounted other cows but not standing), 100% (mounted other cows with standing for 1∼4 seconds), 100% (mounted other cows but not standing for 1∼4 seconds) and 100% (mounted other cows with standing for more than 5 seconds). Circadian distribution of first observed in estrus were 59.1% (am 8∼pm 6) and 40.9% (pm 6∼am 8). Distribution for the number of estrus behavior were 40.9% (less than 3 times), 36.4% (4∼6 times) and 22.7% (more than 4 times). The conception rates relative to interval from first estrus behavior to insemination for estrus periods were 23.1% (less than 11 hours) and 55.6% (12∼20 hours).

This study aimed to improve the reproductive efficiency of dairy herds by comparison and analyzing estrous appearance rate, conception and non-conception rate according to the stage of lactation using the lactation and reproductive records of average (less than 10,000 liters milk in 305 days) and high yielding (more than 10,000 liters milk in 305 days) Holstein cows (n=102). Milk production and reproduction data were collected between January 2010 and December 2012 from Holstein cows kept in the commercial dairy farms. Average (n=32) and high yielding (n=24) Holstein cows used to analyze the relationship between milk yield and reproductive performance. Our results showed that estrous appearance rate according to the stage of lactation was 25.0% (30∼59d), 40.6% (60∼ 89d), 25% (90∼110d) and 9.4% (>111d) in average yielding cows and 16.7% (30∼59d), 20.8% (60∼89d), 12.5% (90 ∼110d) and 50.0% (>111d) in high yielding cows, respectively. Conception rate according to the stage of lactation was 87.5% (30∼59d), 61.5% (60∼ 89d), 75.0% (90∼110d) and 66.7% (>111d) in average yielding cows and 25.0% (30∼59d), 0% (60∼89d), 33.3% (90∼ 110d) and 50.0% (>111d) in high yielding cows, respectively. Days between parturition and conception was 23.7% (<149d), 0% (150∼209d) and 0% (>210 d) in average yielding cows and 69.0% (<149 d), 77.8% (150∼209d) and 38.9% (>210d) in high yielding cows, respectively. Conception rate from 110 days postpartum in high yielding cows was 41.7% (110∼150d), 50.0% (151∼180d) and 50.0% (>181d). Body condition score (BCS) in 120 days postpartum was 2.64±0.1 in average yielding cows and 2.28±0.1 in high yielding cows, respectively.

This study was conducted to investigate the effects of different levels of soybean curd residue as an ingredient of TMR on growth performance and carcass characteristics of Holstein steers. Twenty four Holstein steers of 7 months age(average body weight 274.6 kg) were randomly allocated to 3 experimental groups, which contained 8animals per group during 15-months feeding trial. The treatments composed of the group fed concentrate and rice straw separately (Control), the group fed TMR containing low levels of soybean curd (T1), the group fed TMR containing high levels of soybean curd residue (T2). Body weight and average daily gain were not significantly different among the treatment groups during the feeding trial periods. Feed intake was not differ among treatment groups, but feed conversion ratio was significantly higher in T2 group compared to T1 group during late fattening stage (p<0.05). However, it was not different in overall average. According to the yield traits, carcass weight of control, T1 and T2 were 466.4, 451.1 and 460.1 kg, respectively. Back fat thickness, rib eye area and yield index were not different among the groups. The marbling score, meat color, texture and maturity in quality traits were not different among the treatment groups, but fat color was significantly higher in T2 group compared to T1 group (p<0.05). The quality grade (1+:1:2:3, NO.) tended to be higher for T1(0:2:1:5) and T2 (0:1:4:3) compared with the control (0:0:3:5). Therefore, these results indicated that TMR with soybean curd residue may be appropriate the growth performance and carcass characteristics of Holstein steers.