乳牛の生殖機能を維持するためのアミノ酸サプリメント(Amino acid supplement key to reproductive health in dairy cows)

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2022-09-19 イリノイ大学アーバナ・シャンペーン校

リジンは乳牛にとって必須アミノ酸であり、適切なレベルで食事に加えると乳量の増加に役立ちます。イリノイ大学の新しい研究では、第一胃で保護されたリジンが移行期に与えられた場合、子宮の健康を改善できることが示されています.
研究チームは、第一胃で保護されたリジン製品を総合混合飼料(TMR)に 0.54% 添加し、分娩前の 28 日間にわたって投与した。分娩後、リジンは 0.4% で 28 日間追加された。牛は分娩前か分娩後、またはその両方にリジンを添加し、対照群にはどちらの時期にもリジンを補給しないようにした。
子宮の炎症性タンパク質の産生に関与する遺伝子が、ルーメンで保護されたリジ ンを摂取することで、特に分娩前後に摂取した牛で減少することがわかった。また、子宮を清潔に保つことに関与する遺伝子は、より活発に働いていた。
研究チームは、産後初めて卵巣の卵胞が成長する周期も追跡した。リジンは初排卵までの期間(全群平均18日)にも、排卵時の卵胞径にも影響を与えなかった。

<関連情報>

乳牛の分娩後の子宮の健康に対する移行期の第 1 胃保護リジン給餌の影響 Effect of feeding rumen-protected lysine through the transition period on postpartum uterine health of dairy cows

A.R. Guadagnin,L.K. Fehlberg,B. Thomas,Y. Sugimoto,I. Shinzato,F.C. Cardoso
Journal of Dairy Science  Published:August 05, 2022
DOI:https://doi.org/10.3168/jds.2022-21934

ABSTRACT

Feeding rumen-protected methionine as an indispensable amino acid source has been shown to improve reproductive performance in dairy cows, but the effect of feeding rumen-protected lysine (RPL) during the peripartum period on reproductive performance is not well explored. Therefore, we aimed to determine the effects of feeding RPL (AjiPro-L Generation 3, Ajinomoto Heartland Inc.) prepartum, postpartum, or both on follicular dynamics, uterine health, and mRNA gene expression of the endometrium. Seventy-five multiparous Holstein cows were assigned to 1 of 2 dietary treatments with or without RPL in a randomized, complete block design. A 2 × 2 factorial arrangement of treatments was used. Prepartum (–28 d to calving), animals were fed a diet (68% of dietary DM from forage) with RPL [PRE-L; 0.54% RPL of dietary dry matter intake] or without RPL (PRE-C). After calving, half of the cows from each prepartum treatment group were assigned to a diet (56% forage) with RPL (PRE-L POST-L; PRE-C POST-L; 0.40% RPL of dietary dry matter intake) or without RPL (PRE-C POST-C; PRE-L POST-C) until 28 d in milk (DIM). Vaginal discharge was detected with a Metricheck device (Simcro) to detect metritis, and at 28 DIM polymorphonuclear leukocytes were evaluated as a percentage of the epithelial cells using a cytology brush (Andwin Scientific) and an endometrial tissue biopsy was collected for mRNA expression and histology. The first postpartum follicular growth cycle was monitored at 7, 10, 11, 13, 15, 17, 19, 21, 23, 25, 27, and 28 DIM via transrectal ultrasonography. Time to first ovulation did not differ between treatments and averaged 18 ± 1.6 DIM. Follicular diameter at first ovulation was not affected by the treatments, but the growth rate of dominant follicle before first ovulation tended to be lower for cows in POST-L in comparison with cows in POST-C. Prevalence of fetid vaginal discharge and metritis did not differ between treatments. Cows in PRE-L POST-L had lower polymorphonuclear leukocytes percentage at 15 and 28 DIM than cows in PRE-L POST-C, PRE-C POST-L, and PRE-C POST-C. Feeding RPL prepartum downregulates the expression of TLR4, SLC7A6, EHMT2, and tends to downregulate the expression of PTGES3 in uterine tissues at 28 DIM. Additionally, it upregulates the expression of APOL3 and NFKB1, and tends to upregulate the expression of AHCY and MAT2A. In conclusion, feeding RPL pre- and postpartum improved indicators of uterine immune status, but did not change days to first ovulation postpartum.

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