Shigeru Morita

Distribution of radioactive cesium in edible parts of cattle

After the disastrous incident of the Fukushima Daiichi Nuclear Power Station, various agricultural, livestock and fishery products have been inspected for radioactive contamination with cesium in Japan. In this study, radioactive cesium was measured in various edible parts of cattle to verify the current inspection method for cattle, in which the neck tissues are generally used as samples. Radioactive cesium concentration in the short plate, diaphragm, liver, lung, omasum, abomasum and small intestine were lower and sirloin, tenderloin, top round meat and tongue were higher than that in the neck. There was no significant difference between the other organs (heart, kidney, lumen and reticulum) and the neck. Ninety-five percent upper tolerance limits of the relative concentration to the neck were 1.88 for sirloin, 1.74 for tenderloin, 1.87 for top round and 1.45 for tongue. These results suggest that a safety factor of 2 is recommended for the radioactivity inspection of cattle to prevent a marketing of meat with higher cesium than the legal limit. Re-inspection should be conducted using another part of muscle, for example, top round, when suspicious levels of 50-100 Bq/kg are detected in the neck.

Hair cortisol levels of lactating dairy cows in cold- and warm-temperate regions in Japan

We compared the hair cortisol levels of lactating dairy cows in a cold- and a warm-temperate region out of four climatic zones in Japan. We simultaneously investigated the effects of calving number, lactation period and month of hair sampling. Hair of nine Holstein lactating cows chosen from each region (i.e. 18 cows per sampling) was sampled in March, June, September and December. Number of calvings (1, 2, ≥3) and lactation duration (early: <100, middle: 101-200, and late: >201xa0days) were balanced between regions. Cortisol was extracted from hair by methanol, and its level was determined with a cortisol immunoassay kit. A multi-way analysis of variance revealed that the effects of month of hair sampling (Pxa0<xa00.001) and its combination with region (Pxa0<xa00.05) were significant. In a multiple comparison test, significant differences (Pxa0<xa00.01) in hair cortisol level (pg/mg of hair) were found between June (13.0xa0±xa01.0) and the other 3 months, and between September (1.6xa0±xa00.2) and December (4.5xa0±xa00.3). The rise in cortisol level from March to June was more intense in the cold-temperate region. These results demonstrate the necessity of considering seasonal variations in each climatic region when we use hair cortisol level as an indicator of stress.

On-line Near-infrared Spectroscopic Sensing Techniques for Assessing Milk Quality in Automatic Milking Systems

We constructed an on-line near-infrared (NIR) spectroscopic sensing system on an nexperimental basis. The sensing system enables NIR spectra of unhomogenized milk to be obtained nin automatic milking systems over a wavelength range of 600 nm to 1050 nm. Calibration models for ndetermining three major milk constituents (fat, protein and lactose), somatic cell count (SCC) and nmilk urea nitrogen (MUN) of unhomogenized milk were developed, and the precision and accuracy of nthe models were validated. The coefficient of determination (r2) and standard error of prediction n(SEP) of the validation set for fat were 0.95 and 0.27%, respectively. The values of r2 and SEP for nprotein were 0.72 and 0.15%, those for lactose were 0.85 and 0.18%, those for SCC were 0.62 and n0.32 log SCC/mL, and those for MUN were 0.68 and 2.08 mg/dL, respectively. These results indicate nthat the NIR sensing system developed in this study could be used to assess milk quality in real time nin automatic milking systems. The system can provide dairy farmers with information on milk quality nand physiological condition of individual cows and therefore give them feedback control for noptimizing dairy farm management. By using the system dairy farmers will be able to produce highquality nmilk and dairy precision farming will be realized.

Definition of Hay Eating and Rumination Period and Analysis of Relationship between Eating and Rumination Activities in Steers Fed Hay ad libitum

ホルスタイン種去勢牛(試験開始時体重約200kg)16頭を供試し,以下の実験を行なった.給与飼料には,市販のペレット状配合飼料およびイネ科主体1番刈乾草を用いた.配合飼料の乾物給与日量は代謝体重kg当り75gとし,乾草は自由採食させた.いずれの飼料も,1日2回8:20および17:20に給与した.試験期間は11日間とし,その最終日にテレビカメラにより採食行動を調査した.同時に,咬筋の筋電図から反芻時間を調査した.代謝体重当りの乾草乾物採食量は,約28g/日となった.採食バウトおよび採食バウト間隔の持続時間分布から,前後に4分を超える採食活動の休止期が認められた場合に,その採食活動を採食期と定義した.反芻バウトおよび反芻バウト間隔の持続時間分布から,15分を超える期間,反芻活動の休止が認められた場合,反芻期と定義した.1日当りの採食時間(採食期の合計時間)は約4時間,反芻時間は約7時間となった.飼料給与後反芻開始までの時間は,約3時間であった.飼料給与3時間以降の期間では,前の採食終了後,次の採食開始までの時間が長いほど,次の採食期の持続時間は長くなることが示された.飼料給与後3時間以内の期間においては,前の採食時間の延長によりその後の反芻時間が延長するのに対し,3時間以降の期間では,反芻時間の長さによりその後の採食時間が影響を受けることが示された.

Efficiency of Energy Utilization by Growing Calves on Realimentation After Fasting

絶食後2および5週間の飼料給与時における子牛のエネルギー利用効率について検討した.5カ月齢のホルスタイソ種去勢雄子勢8頭を用い,飼料給与水準を乾物で,70g/kg0.75•dayとして,2回のエネルギー出納試験を行なった.最初の試験は,絶食から2週間後(第1期),2回目は,5週間後(第2期)に実施し,以下のような結果を得た.1. 出納試験期間中の日増体量は,第1期で0.41kgと第2期の0.58kgより低い傾向にあったが,有意な差は認められなかった.2. エネルギーの消化率および代謝率は,第1期で低くなる領向にあったが,有意ではなく,代謝率が,約0.6程度であった.3. 発育に要する代謝エネルギーの正味利用効率は,第1期で第2期より低くなる傾向にあったが,有意ではなかった.両期間をプールした正味利用効率は,0.446であった,また,維持に要する代謝エネルギー量は,528kJ/kg0.75•dayと算定した.4. 絶食後の発育時のエネルギー代謝測定は,個体変動を考慮すれば,絶食から5週間後が望ましいといえる.5. 既報の絶食時代謝量と本試験の結果から,維持に要する代謝エネルギーの正味利用効率は,0.73と推定された.

Determination of Metabolizable Energy Required for fhe Maintenance of Growing Calves at 4 and 6 Months of Age

同一個体におけるエネルギーの維持要求量の月齢による違いを検討する目的で,6週齢で離乳したホルスタイン種去勢雄子牛10頭を供試した.濃厚飼料6:1番刈乾草4の割合で混合した2種類の,等蛋白質,等エネルギー含量の混合飼料を維持水準で,4および6ヵ月齢に3週間給与しエネルギー出納試験を実施して以下の結果を得た.1) 試験期間の最後の1週間の体重変化は,4および6ヵ月齢でそれぞれ,-0.059および0.62kgであった.2) エネルギーの消化率および代謝率は,飼料による有意な違いはなく,6ヵ月齢において4ヵ月齢に比べ有意に高くなった.可消化エネルギーに占める代謝エネルギーの割合は,飼料,月齢に関係なく0.85となった.月齢による消化率の違いは,繊維分画の消化率の寄与の差によるものであり,代謝率の違いは,消化率の差が反映したと推察した.3) 代謝エネルギー摂取量(MEI)は,飼料による有意な差は認められず,4および6ヵ月齢でそれぞれ,508および554kJ/kg0.75となった.熱産生量は,飼料および月齢による相違は認められず520kJ/kg0.75前後であった.エネルギー蓄積量(ER)は,4ヵ月齢で負,6ヵ月齢で正となった.各月齢のMEIおよびERとそれらに対応する既報の絶食時の値により回帰分析を行ない,ER=0.747(±0.018)MEI-390(se=±4.9,r=0.994)なる式を得た.これにより,4および6ヵ月齢の子牛の維持に要する代謝エネルギー量は,月齢による差はなく,522kJ/kg0.75,代謝エネルギーの正味利用効率は,0.75前後と結論した.