The objective of this study is to clarify the present situation and trend in the management of horse-breeding farms in the Hidaka region. As a method, we carried out questionnaire surveys with 12 farms and referred to the statistical data. As the results, approximately 70% of farms have fewer than 10 broodmares due to managerial difficulties and the absence of successors. These problems induce give-up-farming. Moreover, we discovered the new management type of these farms with more appropriate classification than previous studies from the results of our questionnaire surveys.

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馬の血漿リポタンパク構成成分と構成比を明らかにするため, 密度勾配遠心法による分析によって種牡馬19頭 (6-20歳), 16頭 (5-20歳), 2歳牡馬および2歳牝馬の各6頭を用いて雌雄ならびに成馬と若馬の間における年齢構成比を調べた. その結果, 密度勾配遠心法によるリポタンパクは, 高比重側から, HDL, VLDLおよびCMの3つの分画に分離された.
雌雄ならびに成馬と若馬の間の年齢構成比を調べたところ,
1) 血漿脂質では, 牡馬より牝馬の方が総コレステロール (TC) は有意に高かった.
2) 高密度リポタンパク (HDL) は最大の分画で, その構成脂質はPLが約65%, TCが約30%をしめ, 牡馬及び牝馬でほぼ一定していた.
3) 低密度リポタンパク (LDL) の構成脂質のうちTC, リン脂質 (PL) および総脂質 (TL) は牡馬より牝馬の方が有意に高値を示した. 種牡馬では, に比較して, LDL中のPL/TC比の有意な低値 (0.59), TC比率の有意な高値 (57.6%) が認められた.
4) 超低密度リポタンバクおよびカイロミクロン (VLDLおよびCM) のPLおよびTC濃度は各約10%とほぼ一定で, この分画はTGを主体とするものと判断された.
したがって, 牝馬で, 牡馬より血漿TCが高いのは, 牝馬でLDL分画中TC濃度の増大によると考えられた. また, 種牡馬では, LDLのTLは低いものの, TC比率の高値, PL/TCの低値を示すことから, LDLの構成になんらかの変動要因があったものと考えられた.

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This paper analyzes the structure of “overproduction” in light-breed horses in Japan. By analyzing both aspects of the breeding structure from the aspect of supply and the stable of situation from the aspect of demand, it is the intention of this paper to clarify the charac teristics “overproduction” in light-breed horses in the 1990's. As the 1st horse racing boom before and after 1970 brought on the 1st overproduction in the latter part of the 1970's, the 2nd horse racing boom in the latter part of the 1980's brought about the 2nd overproduction into the 1990's. However, “overproduction” in the 1990's fundamentally differed from that of the 1970's on the following points. First, the bubble economy in the latter part of the 1980's caused an abnormal expansion of purchasing power where the number of foals purchased greatly exceeded the demand. In other words, this brought about a breakdown of coordination in supply. As the bubble economy was of such an extensive scale, the rebound was likewise devastating in which the increase of the number bred was far greater than the previous “overproduction period.” Second, into the 1980's, as the foals and yearlings were dispersed and kept at the stud farms, the yearling training farms in the breeding area, the yearling training farms in and around the training centers, it gave the impression that a certain degree of the “overproduction” had been absorbed. But, the “overproduction” this time was so grave that even this absorbing function would no longer work. Third, the “overproduction” this time was an “overproduction” of only Thoroughbreds. There was a difference in scope with the previous overproduction in that there was an “over production” of both Thoroughbreds and Anglo-Arabs. This was because during this period, light-breed horse breeding continued to specialize on Thoroughbreds. At the present, there is no “overproduction” of Anglo-Arabs. However, depending on the subscription Anglo-Arab horse problem in National Racing and the degree of recession in Regional Public Racing, it isbelieved that eventually the recession in Anglo-Arabs will become a problem. At such a time, if Anglo-Arab horse management was forced to convert, even in a partial way, to Thoroughbred horse management, the “overproduction” of Thoroughbreds will probably become more serious. Fourth, during this period, the light-breed horse management as a principal occupation and specialization have further increased creating a Thoroughbred-inclined structure. For this reason, conversion to other forms of agriculture industry is difficult and countermeasures against “overproduction” become more difficult, both in management and regionally. For these reasons, demands may be forthcoming for drastic “countermeasures against overproduction.”

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The purpose of this paper is to clarify how the horse-breeding industry was changed by inter-war policy concerning the maintenance of military horses, particularly noting the desire of farmers carrying out horse breeding as a secondary activity to improve their income. Through analysis of data for the Tohoku region, the main horse-breeding area in Japan, this study makes clear the following three points. 1) In the 1920s, farmers chose to breed farm horses instead of military horses. As the demand for military horses decreased with armaments reduction after World War One, the risk of breeding those horses increased. Consequently, farmers attempted to stabilize their income by breeding farm horses, which were sold at a lower price but for which there was a large market. Nevertheless, these attempts were not successful as the maintenance of stallions for breeding was difficult both institutionally and economically, leading some to suspend horse breeding entirely. Such farmers increased the use of their mares in their own farming, offsetting the idle horse-breeding section. 2) In the 1930s, farmers were terribly weakened by the Showa depression and disastrously cold weather. Consequently, they requested the Ministry of Agriculture to cover a part of their breeding expenses to reduce the risk inherent in the horse-breeding business. The Ministry recognized the situation as a military and industrial crisis, and immediately enacted relief policies for farmers. These policies succeeded in increasing their motivation for horse breeding, but such temporary subsidies could not fundamentally improve their economic situation. 3) Further to the above point, farmers also requested the Army to increase purchases of military horses in the colt market, expecting this to raise the price of horses and increase farmers' incomes. However, the Army purchased mainly older horses for immediate use in Manchuria, as a result of which the desired outcome was not achieved.

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平成20年の4月と5月，青森県の同一地域内で25日齢のサラブレッド種の子馬2頭が急死した． 両子馬ともに肝臓に病変が認められ，病理組織学的に多発性巣状壊死が特徴的であった． ワーチンスターリー染色で壊死巣周辺の肝細胞内に長桿菌が確認された． 抗Clostridium piliformeポリクローナル抗体を用いた免疫染色では長桿菌に一致して陽性抗原が検出された． 透過型電子顕微鏡検査で肝細胞内の桿菌体に周毛性鞭毛の密生が観察された． C. piliforme特異プライマーを用いたリアルタイムPCR検査では肝臓で陽性反応が認められた． 以上の所見からティザー病と診断された． を対象に間接蛍光抗体法による抗体検査を実施した結果，大部分の個体が抗体を保有していることが判明し，本菌が広く浸潤している可能性が示唆された．

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In recent years, the economic problems facing farming families in the Urakawa area have mounted. Causes include the liberalization of farm product markets, a slump in the market for dry field products, government-imposed cutbacks in rice production, and increased competition in the production of light breed horses (in the Hidaka area). Given these conditions, the importance of scrutinizing the various limiting factors affecting crop and product choices for farmers who are aiming for maximum efficiency of agricultural land use can be argued. Bearing these conditions in mind, this paper will examine statistically changes in agriculture and agricultural land use patterns in Urakuwa since 1982. The following conclusions were reached.
1) Within the areas under the jurisdiction of the Hidaka administrative offices, the effects of the cutbacks in rice production continue to be felt in the 1990s. Because of this, the relative importance of light breed horse production has increased, resulting as well in a significant increase in the mumber of thoroughgreds and a gradual decrease in the number of Anglo-Arabian breeds. However, in Urakawa, the percentages in both directions have decreased, indicating that light breed horse production has peaked out.
2) While the number of head of Anglo-Arabians has decreased in the Urakawa area, the increase in the number of thoroughbreds has been greater than that of the Ogifushi area. In Ogifushi, the decrease in the number of Anglo-Arabians has been less than that of Urakawa.
3) In Urakawa, the number of farming households has decreased since 1981, while the average amount of cultivated land per household has increased. This is because of the reduction of paddy land and the increased amount of land used for feed grasses. This conversion from paddy land to feed grass land has been more pronounced in Urakawa than in Ogifushi. This tendency marks a reversal of that found in the previous survey.
4) In the area of the lower reaches of the Motoura River, more light breed horse farms are located in gravelly alluvial areas than in peat bog areas. Moreover, the transition from paddy land to pasture land has reached its limits.

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2012年12月に北海道日高管内の1サラブレッド生産牧場にてLawsonia intracellularis（Li）感染症の発生が認められたことから，臨床・病原・免疫学的に検討した．当該牧場の当歳馬8頭中4頭で発熱，食欲低下，浮腫，白血球増多，下痢などの症状が認められたが，テトラサイクリン系抗菌薬により治癒した．発症馬4頭中2頭の糞便からLi特異遺伝子が検出された．一方，非発症馬の1頭からも検出されたことや，全頭からLi特異抗体が検出されたことから，当該牧場内では不顕性感染も含め当歳馬全頭が感染していたと考えられた．血清総蛋白は発症馬が最も低値を呈したが，非発症馬も2010年度・2011年度の同牧場の当歳馬の平均値と比較し有意に低かった．

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種牡馬の死亡原因や発生状況等に関して詳細に調査・解析した報告は見あたらない．そこで過去45年間に死亡したサラブレッド種牡馬53例の死亡状況について回顧的な調査を実施した．死亡状況としては突然死が16例と最も多く，消化器疾患による急性腹症死が13例，骨折等の運動器損傷後の安楽殺が11例と続いた．突然死の発生は1月と12月がそれぞれ4例と3例，3～6月は各月2例であった．またその発生場所は，運動場と種付場がそれぞれ5例と4例，厩󠄃舎が7例であった．突然死例の死因は，心筋の出血，線維化あるいは梗塞に伴う心不全が7例，大動脈起始部破裂による心不全が4例，腹腔内の大血管破裂による失血死が2例であった．一方，3例では死因が特定されなかった．このように種牡馬の突然死の主因は心臓・血管系の異常であり，冬期から繁殖供用期間に多く発生していた．

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18歳11カ月齢, サラブレッド種のが長期にわたる両前蹄の蹄癌を罹患した。両前蹄の白帯及び蹄壁から悪臭ある浸出液及び刷毛状の灰白色贅成物が増生した。その贅成物の母体は蹄壁の角質層及び真皮であった。病理組織所見は角質層の角化不全, 水腫と壊死, 真皮での著しい炎症性変化と水腫が特徴であった。特に, 角質層を形成する胚芽層の核濃縮扁平化と角質細胞の風船状に膨化及びケラトヒアリン様物質の消失を示した。角質に栄養を与える真皮は水腫, 細胞浸潤, 中～小動脈壁の水腫性粗鬆化と内膜肥厚, 血管狭窄が散在した。このことから角質形成の母体となる真皮の慢性的水腫による循環障害が角質層の角化不全に関するひとつの要因と成りえることが推察された。

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The purpose of this paper is to clarify the influence of the horse improvement policy in horse-producing area. Former studies of the horse industry in the modern age have treated mainly the using aspect -how farmers used or kept horses-, and not treated the producing aspect sufficiently. However, the characteristics of the industry are that the horse improvement policy was carried out rapidly to satisfy the military demand, and that most of Japanese horses were interbred with foreign ones as a result. Therefore, the analysis of producing is indispensable for that of using because horse producing was directly connected with the policy. As to the research period this paper focuses on the late Meiji and the Taisho era in which the horse improvement was most developed, and as to the research area on Kamikita county Aomori prefecture that was a typical horse-producing area at that time. By examining concrete means to carry out the policy-stallion system and purchase at auction market-and comparing them with the grazing land policy, this study clarifies the following two points: First, in former producing area, the horse improvement couldn't be carried out without restricting the number of horses produced, because of the grazing land shortage. Second, the horse improvement policy encouraged large-scale producers who could produce horses demanded from the military, and obliged small-scale producers who couldn't to decrease their production consequently.

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