In vitro fermentation was conducted to figure out alternative fiber sources for horse feed. For the development of value-added products as a horse feed resource, the pomaces from apple, carrot, grape, and citrus were fermented under solid-state conditions in the presence of 60% soybean meal with 40% of each fruit pomace at 60% of moisture content. Lactobacillus plantarum SK3873, Lactobacillus plantarum SK3893, Weissella cibaria SK3880, and Bacillus subtilis SK3889 were isolated from the fermented fruit pomace by inoculation of horse feces. For the growth of Bacillus subtilis, Saccharomyces cerevisiae, and Lactobacillus plantarum, they were inoculated in 3-step order at 0, 12, and 24 h, respectively. The fruit pomace was fermented for 48 h at 35°C. The pH of the apple, carrot, grape, citrus and all mixed pomaces decreased from 5.45~6.25 to 4.40~4.77. Microbial growth was maintained at 108~109 cfu/g. After 12 and 24 h incubation, dry matter of carrot pomace were highest at 54.84 and 56.66%, respectively (P<0.05) and that of grape pomace was lower than others during fermentation (P<0.05). Dry matter was generally reduced by about 20%. NDF decreased gradually or maintained after 24 h, indicating the fiber degradation. Ash content tended to decrease during fermentation. After 48 hours fermentation, Bacillus, yeast and Lactobacillus showed an excellent growth by using juice by-products. These results suggest that fermented juice pomace has a potential as horse feedstuff with probiotics to maintain beneficial microflora in horse gut.

본 연구는 제주마와 더러브렛을 교잡한 제주산마의 사양 방법에 따른 등심근의 일반 성분과 지방산 조성를 조사하기 위해 수행되었다. 공시축으로 36개월령 이상 제주산마(더러브렛×제주마) 16두를 처리구별 8두씩(개별 사양 8두, 군집 사양 8두) 배치하였다. 농후사료 급여는 말 체중의 2.5%를 일일 4회 나눠서 3개월간 급여하였고, 건초(라이그라스)와 물은 무제한 급여한 후 도축하여 등심근을 분석에 공시하였다. 제주산마 등심근의 일반 성분 조사 결과, 개별 사양을 한 처리구가 군집 사양을 한 처리구보다 수분함량은 낮고(p<0.05) 지방함량이 높았다(p<0.05). 지방산 조성 분석 결과, Palmitic acid와 포화지방산은 개별 사양 처리구가 집단 사양 결과보다 유의적으로 높게 나타났으나(p<0.05) 불포화지방산은 군집 사양 처리구에서 유의적으로 높게 나타났다(p<0.05). 이상의 결과를 종합해보면 말의 사양 방법은 말고기의 일반 성분, 지방산 조성 등에 유의적인 영향을 미치기 때문에 비육마의 경우 목적에 맞는 사양 방법 선택이 필요한 것으로 생각된다.

Spermatozoa viability can be assessed by microscopy, flow cytometry, and other methods using fluorescent stain. Flow cytometry can be used to examine the morphological and functional characteristics of spermatozoa in a short time. The purpose of this study was to compare the viability of cryopreserved spermatozoa in Jeju black cattle by two dual fluorescent stain methods. Semen of Jeju black cattle raised in Subtropical Livestock Research Institute, National Institute of Animal Science, RDA were collected with artificial vaginal technique. Sperm was diluted with Triladyl®-egg yolk diluent and then was performed cryopreservation.There was no significant difference in viability of spermatozoa according to the two dual fluorescent stain methods. However, when the distribution of spermatozoa according to the staining method was compared, the spermatozoa group stained with 6-CFDA/PI was more clearly distinguished than the spermatozoa group stained with calcein AM/PI.

본 연구는 농후사료 다량 급여 시 나타나는 산통은 발생하지 않으면서 증체량은 높일 수 있는 적정 농후사료 급여 횟수를 설정하기 위해 수행하였다. 제주산마 13두를 이용하여 12주간 농후사 료 급여 횟수(체중의 2.5%를 2, 3, 4회)를 달리하여 급여하였다. 이때 건초와 물은 무제한 급여하 였다. 번식마의 농후사료 급여 횟수에 따른 산통 발생을 조사한 결과 혈액 내 피브리노겐 함량은 처리구간 유의적 차이가 없었다(p>0.05). 농후사료 급여 횟수별 증체량 조사 결과, 총 증체량은 일 일 4회 급여구에서 높아지는 경향을 보였고, 일당증체량은 8~12주에서 일일 4회 급여구의 경우 높 아지는 경향을 보였으나 유의적인 차이는 없었다(p>0.05). 장내 pH와 직장온도는 모든 처리구에서 정상 범위 내에 있었고, 유의적인 차이가 없었다(p>0.05). 이상의 결과를 종합하면 번식마에게 체 중의 2.5%의 농후사료의 급여 횟수 조절에 따른 산통 발생과 증체에는 차이가 없는 것 판단된다.

제2차 말 산업 육성 5개년 계획의 시행 등 말 산업이 전국적으로 확대됨에 따라 승용마 인공수 정을 원하는 농가도 점차적으로 증가하고 있는 추세이다. 말의 경우 신선·냉장정액 사용 시 적기 수정의 어려움이 있어 동결정액의 중요성이 대두되고 있다. 하지만 국내의 말 동결정액 연구는 미 미한 수준이며, 인공수정을 위한 말 동결정액은 전량 수입하여 사용하고 있는 실정이며, 말 동결 정액의 경우 신선정액이나 액상정액에 비해 활력 및 수태율이 현저히 떨어지는 문제점이 있다. 본 연구에서는 제주산마의 동결정액의 성상 개선을 위하여 펜톡시필린 수준(4mM, 8mM, 16mM)을 설 정하여 정자의 운동성, 생존율, 정자막 온전성을 평가하였다. PDE 억제제인 펜톡시필린 첨가는 정 자의 조기 첨체반응을 방지하고 수정률을 높이며 활성산소를 억제하는 효과가 있다고 보고되었 다. 정액의 동결-융해 30분 후에는 펜톡시필린 4mM(T1)처리구와 펜톡시필린 8mM(T2)처리구에서 Progressive Fast Motility(PFM)가 유의적으로 높게 나타났다. 융해 후 1시간에는 T4와 T8에서 대조 구보다 immotil, Motiltiy, Local Motiltiy에서 유의적으로 높은 결과를 보였다. 또한 생존율에서 T8보 다 T4가 유의적으로 높았으며, 펜톡시필린 16mM(T3) 처리구는 생존율은 대조구와 T4보다 높았으 나 Motiltiy가 다른 처리구보다 유의적으로 낮았다. 이상의 결과를 종합해 볼 때 펜톡시필린 4mM 와 8mM를 처리했을 때 비처리보다 정자의 운동성을 유의적으로 증진시키는 효과가 있었으며 펜 톡시필린 16mM 이상의 처리는 정자에 좋지 않은 영향을 미치는 것으로 나타났다.

The objective of this study was to determine the growth characteristics of cool (C1) and warm season grasses (C2) in pastures mixed with C1 and C2 at an altitude of 400 m in Jeju island to establishing pasture suitable for grazing horses and to evaluate the effect of pastures mixed with tall and short type grasses on the intake characteristics of horses. C1 used in this study was Kentucky bluegrass, redtop (short type grass) and tall type grasses were orchardgrass and tall fescue, respectively. Treatments of this study were consisted of four groups and the short type grass used in pastures mixed with C1 and C2 was mainly bermudagrass. Four treatment groups were follow as; Treatment 1 (bermudagrass + Kentucky bluegrass + redtop) 2) Treatment 2 (bermudagrass + tall fescue + orchardgrass) 3) Treatment 3 (Kentucky bluegrass + redtop) 4) Treatment 4 (tall fescue + orchardgrass). Bermudagrass was a little winter killing and inhibition of plant growth at an altitude of 400 m. Plant heights in pastures mixed with C1 and C2 were grown better than that in pastures mixed with C1. Especially, plant height in Treatment 4 was higher than other treatments. Dry matter yield was in the following order: Treatment 4> Treatment 3> Treatment 2> Treatment 1. Dry matter yield in pastures mixed with C1 increased as compared with pastures mixed with C1 and C2. Dry matter yield in Treatment 3 was higher than other treatments. In the first investigation regarding vegetation distribution, bermudagrass ratios among grasses in Treatment 1 and Treatment 2 were 11.7 and 13.3%, respectively. The growth of bermudagrass in winter was low due to the cold damage. However the growth of Kentucky bluegrass, redtop, tall fescue and orchardgrass was good. In the second investigation, bermudagrass ratios among grasses in Treatment 1 and Treatment 2 were 5.0 and 11.7%, respectively. Growth of forage in the second investigation was poor as compared to the first investigation. nutritive values(crude protein content, neutral detergent fiber content, acid detergent fiber content, digestibility) were good in pastures mixed with C1 Especially, nutritive values in pastures mixed with tall was higher than those of pastures mixed short grasses. P content among minerals in Treatment 1 was higher than other groups. However, the content of Ca, Mg and Mn were lower. The contents of Ca, K, Mg, Na, Cu, Zn and Fe in Treatment 2 were higher. However, the contents of K, Mg, Na, Cu, Zn and Fe in Treatment 3 were lower. Therefore, we suggest that cool season grasses with short grasses were sowed to establishing pasture suitable for grazing horses at an altitude of 400 m in Jeju island.

본 연구는 농후사료의 급여수준을 달리하여 제주산마 에게 급여하는 경우에 체중 변화, 장내 미생물 조성 및 혈액성상의 변화에 미치는 효과를 구명하기 위하여 수행 되었다. 공시축으로 24-36개월의 제주산마(제주마×더러브 렛) 14두를 공시하였으며, 농후사료의 급여수준을 체중의 1.5%(5두), 2%(4두)와 2.5%(5두)로 급여하여 봄과 겨울 증 체율 및 혈액 특성과 생리적 변화를 조사하였다. 봄에 총 증체량은 1.5%, 2%, 2.5% 급여한 처리구에서 12.6kg, 21.5kg, 29.0kg, 겨울에 총 증체량은 21.6kg, 28.0kg, 42.6kg을 나타냈고, 일당 증체량은 봄에는 0.23kg, 0.39kg, 0.54kg, 겨울에는 0.40kg, 0.52kg, 0.79kg을 나타내어 체중의 2.5%를 섭취한 구에서 높은 경향을 나타내었다. 내독 소는 농후사료 과다 섭취에 의해 그람음성균의 세포벽에 서 방출되는 물질로 봄에 시행한 시험에서 3주차 때 농 후사료를 체중의 2%와 2.5%를 급여한 처리구에서 유의 적으로 낮은 결과를 나타내었으나(p<0.05) 이후에는 점차 모든 처리구에서 수치가 비슷해져 적응하는 경향을 보여 모든 처리구가 농후사료 급여에 적응하는 경향을 보였다. 봄에 실시한 실험에서 8주차에 분 pH는 농후사료를 체 중의 1.5%, 2%, 2.5% 급여한 처리구에서 각각 6.2, 5.8, 5.7로 나타나 농후사료를 체중의 2%와 2.5%를 급여한 처 리구에서 유의적으로 낮은 결과를 나타내었다(p<0.05). 직장온도는 겨울에 실시한 실험에서 8주차에 농후사료를 1.5%, 2%, 2.5%. 급여구에서 각각 37.8℃, 37.9℃, 38.4℃ 를 나타내어 농후사료 2.5% 급여구에서 직장온도가 유의 적으로 높은 수치를 나타내었다(p<0.05). 분내 미생물에 서는 셀룰로오스와 탄수화물(구조 탄수화물) 분해에 관여 하는 미생물로 알려진 Fibrobacter가 체중의 1.5% 급여했 을 경우 총 미생물군에서 2.49%를 차지하였고, 2%와 2.5% 급여구에서는 각각 1.42%와 1.09%를 차지하여 농후 사료 급여량이 증가할수록 유의적으로 감소하는 경향을 보였다. 결론적으로 농후사료 2.5%의 급여가 비육마 사육 방법으로 활용할 수 있을 것으로 사료된다.

The objective of this study was to determine the growth characteristics of cool (C1) and warm season grasses (C2) in pastures mixed with C1 and C2 suitable for grazing horses and effect of pastures mixed with tall and short grasses on the intake characteristics of horses. C1 used in this study was Kentucky bluegrass, Redtop (short type grass) and tall type grasses were orchardgrass and tall fescue, respectively. The short type grass used as C2 was Bermudagrass. This study had the following four treatment groups: 1) Treatment 1 (Bermudagrass + Kentucky bluegrass + Redtop) 2) Treatment 2 (Bermudagrass + tall fescue + orchardgrass) 3) Treatment 3 (Kentucky bluegrass + Redtop) 4) Treatment 4 (tall fescue + orchardgrass). There was no winterkilling or lodging problem at an altitude of 200 m. Plant heights in mixed pasture of Treatment 1, 2, 3, and 4 were 53.9, 58.2, 57.5, and 78.1 cm, respectively. Plant height was the highest in Treatment 4. Dry matter yield was in the following order : Treatment 4 > Treatment 3 > Treatment 2 > Treatment 1. In the first investigation regarding vegetation distribution, Bermudagrass ratios among grasses in Treatment 1 and Treatment 2 were 70% and 66.7%, respectively. Overall, other grasses showed poor growth. In the second investigation of vegetation distribution, Bermudagrass ratios among grasses in Treatment 1 and Treatment 2 were 80% and 60.7%, respectively. Crude protein content, neutral detergent fiber content, acid detergent fiber content, digestibility value, and nutritive values were the lowest in Treatment 4, followed by those in Treatment 1, Treatment 2 and Treatment 3.

소에서 저수태 발생율은 5∼35%로 지역, 조사방법 및 연구자 등에 따라 다양하게 보고 되고 있다(Purohit, 2008). 저수태의 원인으로서는 비정상적인 번식기관, 자궁 내 감염, 호 르몬 이상, 사양관리 부적합, 복합적 요인 등이 관여하고 있는데(Singh 등, 2008), 이 중에 서도 자궁 내 감염의 요인이 2.4∼20.0%로 비교적 높게 보고되고 있다(Rao, 1981). 자궁질 환을 가진 대부분의 암소들은 황체단계가 연장됨에 따라 무발정형태로 나타나게 되므로 적극적인 대처가 요구된다는 점에서, 호르몬 투여방법을 포함하여 PGF2α나 estradiol의 투 여 그리고 항생물질이나 povidone-iodine(PVP-I)의 자궁 내 주입과 같은 많은 치료방법이 적용되고 있다. 그러나 호르몬 잔류, 항생제 내성균 및 처리 중단시기 등의 문제점들을 가 지고 있다. PVP-I는 처리 중단시기가 필요하지 않고, 과도한 투여의 경우를 제외하고는 우유로 전이되지 않으며, 구입이 쉽고, 저렴하며, 투여하기가 용이하다는 실용성을 가지고 있기 때문에 매우 고무적인 방법이라고 할 수 있다(Rayos 등, 2002). 또한 자궁내막의 환 경을 개선하고, 암소의 자궁수촉을 촉진시키기 때문에 PGF2α를 생산하는 역할이 빨리 회 복된다(Ahmed와 Elsheikh, 2014). 그러나 PVP-I는 농도가 중요한데, 농도가 너무 높으면 자궁벽을 자극할 수 있고 문제를 더 키울 수 있는 반면에, 농도가 너무 약하면 효과가 나 타나지 않거나, 어떤 유형의 미생물이 제거되는 대신에 다른 기회적 미생물이 점유하기에 적합한 환경을 제공할 수가 있다(Rayos 등, 2002). 자궁내막염을 가진 암소의 경우에는 자 궁 내에 존재하는 화농과 유기물의 잔재가 PVP-I 용액의 살균효과를 저해할 수 있다는 부정적인 견해도 있으나(Nakao 등, 1988), 대부분의 연구자들은 1% 및 2% PVP-I 용액이 번식효율을 향상시키는데 매우 효과적이라고 보고하였다(Mido 등, 2016; Ahmed와 Nour, 2015; Ahmed 등, 2013; Knutti 등, 2000; Edwell 등, 2000; Rayos 등, 2002; Koujanz 등, 1996). 본 연구에서는 2% PVP-I 용액을 저수태우의 자궁 내에 주입하여, 발정발현 및 수 태율에 미치는 영향을 구명하고자 수행하였다. 저수태우에 2% PVP-I 용액을 50mL 자궁 내에 주입하여 자연발정 비율, 유기발정(PGF2α)에 의한 발정발현율, 자연 및 유기발정에 의한 수태율, 황체중기 및 황체중기 이외의 단계에 따른 자연발정 발현율을 조사하였다. PVP-I 처리 후 자연발정 비율은 27.3%(3/11두)였고, 유기발정에 의한 발정발현율은 87.5%(7/8두)였으며, 자연 및 유기발정에 의한 수태율은 63.6%(7/11두)였다. 황체중기(발정 주기 5∼10일) PVP-I 처리에 따른 자연발정 발현율은 60%(3/5두)였고, 황체중기 이외에 PVP-I 용액을 처리한 경우의 자연발정 발현율은 0%(0/6두)였다.

본 연구는 오차드그라스와 톨 페스큐 혼파초지에서 비축 시기별(8월 1일, 15일, 30일) 으로 처리하여 11월 중순경(11.10∼11.12)에 수확할 때 목초의 비축시기에 따른 생산량과 목초의 사료 가치 등을 비교하기 위해 수행하였다. 목초 비축시기에 따른 오차드그라스와 톨 페스큐 혼파초지(동량 혼파초지)의 건물수량은 8월하순구가 2,983.0kg/ha으로 가장 높은 경향을 보였다. 목초의 비축시기가 늦어짐에 따라 목초의 생산량도 증가하였으나 유의성이 인정되지는 않았다. 조사료의 조단백질은 16.5∼18.16%으로 목초 비축시기별로 일정한 경향을 나타내지 않았다. NDF와 TDN는 비축시기가 늦을수록 증가하는 경향을 나타내었으나 유의성이 인정되지는 않았다. 반면에 ADF 비율은 목초 비축시기가 감소함에 따라 점차 감소하는 것으로 나타내었으나 유의성이 인정되지는 않았다. 무기물의 변화는 비축 기간이 증가할수록 P, Ca, Mg, Na, Zn이 증가하였고 반면에 Mn, Cu는 감소하는 경향을 나타내었다. 결과적으로 8월 초순부터 초지를 비축할 경우 고온으로 인한 생육 위축으로 목초의 수량증가는 기대하기 어렵다. 따라서 제주도에서 가을철에 활용하기 위한 초지를 비축할 경우에는 8월 하순 이후에 시작하는 것이 바람직할 것으로 사료된다.

This study was conducted to evaluate the chemical composition and physico-chemical meat quality properties for Jeju-horse (Jeju-horse×Thoroughbred) with different fattening periods (4-, 8- and 13.5-month). In chemical composition, the moisture contents were decreased as the fattening periods increased. The fat contents were 3.78% at 4-months and they were decreased such as 70∼76% at 13.5-months whereas the protein contents increased as the fattening period increased. The cooking loss was highest (33.41%) at 4-months group and decreased after that periods, however, there was no significant difference among 3 fattening period groups. The Warner-Bratzler shear force (WBS) values were lowest at 4-months group and tended to increase as the fattening period increased. In mineral contents, the contents of Fe, Na, Zn were significantly higher for 4-month group than 8- and 13.5-month group whereas the contents of Mg were significantly lower for 4-month group than 8- and 13.5-month group (p＜0.05). The results of the amino acid composition analysis showed that cystein, methionine, threonine, serine, glutamic acid, alanine, valine, lysine, histidine, arginine contents were significantly increased and tyrosine contents were significantly decreased as the fattening period increased (p<0.05). The contents of palmitic acid (C16:0) were highest at 4-month group and they decreased as the fattening period increased (p＜0.05). The contents of oleic acid (C18:ln9) were highest at 8-month group and they were lowest at 13.5-month group. The total contents of unsaturated fatty acids were significantly higher for 13.5-month group than those for 4-month groups (p＜0.05). In conclusions, the fat contents were decreased whereas the protein, Fe, Mg contents and WHC increased as the fattening periods increased. Overall contents of amino acids increased only except several amino acids. The total contents of unsaturated fatty acids were increased as the fattening period increased, however they were not significantly different when those were fattened more than 8-month. These results indicated that longer fattening period could be more effective to enhance horse meat quality.

Horse leg bone has been used as a traditional folk medicine for the sick and weak. Bone primarily contains collagen, a key building block of cells for bones, cartilage, and ligaments. In our previous study, horse leg bone hydrolysates showed anti-oxidation and skin protection effects against UV light. The aim of this study was to evaluate the quality of jelly containing Jeju crossbred horse leg bone hydrolysates at 0.3 (HLBH 0.3), 0.5 (HLBH 0.5) and 1.0% (HLBH 1.0). The HLBH 1.0 showed the highest pH and Brix values compare to control. Lightness (L*) and redness (a*) of HLBH 1.0 showed the lowest value compare to other treatments. However, yellowness (b*) of HLBH 0.3 and 0.5% was increased significantly with increasing levels of Jeju crossbred horse leg bone hydrolysates (p<0.05), while HLBH 0.5 and HLBH 1.0 showed no significant difference. Hardness and chewiness of jelly was decreased with increase of HLBH up to 0.5%, whereas no significant difference was found between HLBH 0.5 and 1.0. In sensory evaluation, panels did not tell the difference of jelly with different level of HLBH in all sensory factors likely color, appearance, flavor, chewiness, taste, and overall acceptability. This result suggests that Jeju crossbred horse leg bone hydrolysates can be used up to 1% without any significant bad influence on quality and sensory characteristics of jelly.

Horses are non-ruminant and monogastric animal. If concentrates are fed plentifully at a time, undigested starch reaches large intestine and it activates amyloytic bacteria. Finally, it lowers a pH level and causes colic. Therefore, standard feed of concentrates and period of feed are important factors to fat up horses. This study was conducted to evaluate the productivity and carcass quality, quantity grade for Jeju horse (24 month old) with different fattening periods (4-, 8- and 13.5-month). The body weights were increased as the fattening periods increased and the increase rate was highest at 4-month group. The daily weight gain was decreased as the fattening periods increased such as 0.46 kg for 4-month group, 0.39 kg for 8-month group and 0.34 kg for 13.5-month groups. The daily intake was increased as the fattening periods increased such as 4.42 kg for 4-month group, 5.00 kg for 8-month group and 5.26 kg for 13.5-month groups. The daily feed conversion was increased as the fattening periods increased such as 11.71% for 4-month group, 17.69% for 8-month group and 18.53% for 13.5-month group. The backfat thicknesses and loin-eye areas were 3.50 mm, 83.50 ㎠ and increased to 4.20 mm, 94.00 ㎠ until they were fattening up for 8-month then they were decreased to 4.00 mm, 89.40 ㎠ when they were fattening up to 13.5-month. There was no significant difference in the meat color among 3 fattening groups, however, the a-values (redness) of meat color and b-values of fat color were highest (5.0 and 3.80, respectively) for 13.5-month group. The texture was not significantly different among 3 fattening groups. The maturity levels were in the 3.8∼4.5. All horses used in the experiment had the quality grade 2 and the horses for 13.5-month group had the quantity grade A, whereas the horses for 4-month group had the quantity grade B or C. Jeju horse had the low quality grade (quality grade 2) although the carcass yield increased when they were fattened from 24 month to 37.5 month.

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.

A study was performed to investigate the effect of reseeding rates of Italian ryegrass (IRG)〔Lolium multiflorum L.〕on its nutritive value and productivity in native grasssland of Jeju region from Oct. 2011 to Jul. 2012. IRG was sown at reseeding rates (0 30, 40 and 50 kg/ha) in native grassland. When IRG was sown, there was no draught and lodging damage. Plant height in treatment 30 kg/ha of reseeding IRG was the tallest at all harvest stages (p<0.05). DM yield in treatment of 30 kg/ha of reseeding IRG was 12,790 kg/ha and increased 2.7 folds as compared to control. However, there was no significant difference among the treatments. The content of neutral detergent fiber (NDF) significantly decreased in treatment of reseeding, compared to control (p<0.05). In general, the content of NDF in second harvest stage was lower than that of control in first harvest stage. The content of acid detergent fiber (ADF) also showed simliar trend as content of NDF. The content of total digestible nutrients (TDN) in treatments of 30 kg/ha and 50 kg/ha of reseeding were approximately 45.2% each. The content of TDN in treatments of 30 kg/ha and 50kg/ha of reseeding increased as compared to 40 kg/ha and control of reseeding (p<0.05). Therefore, it is conclued that reseeding rate of IRG may improve the yield and nutritive values of IRG at 30 kg/ha.

‘다한’은 추위에 강해 충청지역에서도 월동이 가능하면서 수량이 많은 귀리 품종 개발을 목표로 2011년 농촌진흥청 국립식량과학원에서 육성되었다. 잡종은 1999년에 Sprinter/ 73625의 F1을 모본, 귀리26호를 부본으로 인공교배하여 작성되었으며, 집단 및 계통 선발에 의해 내한성이 강하고 초형이 우수한 ‘SO99027-GB-B-113-4-4-3’ 계통을 선발하였다. 이 계통은 2005년부터 2008년까지 4개년에 걸쳐 생산력검정시험을 실시하였으며, 내한성이 강하고 수량이 많아 ‘귀리75호’로 계통 이름을 부여하고 2009년부터 2011년까지 3년간 충남 예산, 전북 김제와 익산, 제주 등 4개 지역에서 지역적응시험을 실시하였다. 이 계통은 2011년 11월 신품종으로 선정되었으며, 그 특성은 다음과 같다. 귀리 신품종 ‘다한’은 중간 크기의 농록색 잎, 황백색 줄기, 황갈색의 종실을 가졌다. 출수기는 전국 평균 5월 13일로 표준품종인 ‘삼한’과 비슷하였으며, 내한성은 ‘삼한’과 대등하였고, 도복에 강하였다. 건물수량은 ha당 평균 15.6톤으로 14.1톤인 ‘삼한’에 비해 11% 많았다. ‘다한’의 조단백질 함량은 8.4 %로 ‘삼한’의 9.9 %에 비해 다소 낮았으나 TDN은 60.8 %, TDN 수량은 ha당 9.5톤으로 59.3 %와 8.4톤인 ‘삼한’보다 높았다. ‘다한’의 적응지역은 1월 최저평균기온이 －7℃ 이상인 지역이면 전국 어느 곳에서나 재배가 가능하다.