2024-06-11 ペンシルベニア州立大学(PennState)
◆経済的な課題に直面する酪農家が、ホルスタイン牛と肉牛品種の交配を進めている中、ペンシルベニア州立大学の研究者たちは約4万頭の牛を対象に分析を行い、肉牛交配の大きな子牛を運ぶことが酪農牛の健康に悪影響を与えないことを確認しました。この研究は「Journal of Dairy Science」に掲載され、2010年から2023年にかけて10の酪農場のホルスタイン牛を対象としています。
◆研究によると、肉牛交配の子牛の出産はホルスタイン牛と同様に安全であり、産後の健康状態や初乳の終了も差がありませんでした。また、肉牛交配の子牛を持つ牛の妊娠期間は長くなりますが、乳量や乳質には影響がありませんでした。これにより、米国の牛乳生産における肉牛交配の安全性が示されました。
＜関連情報＞
- https://www.psu.edu/news/research/story/study-suggests-holstein-dairy-cows-not-harmed-producing-beef-crossbred-calves/
- https://www.journalofdairyscience.org/article/S0022-0302(23)00794-4/fulltext
肉牛×乳牛の子牛を産む牛の難産、死産、妊娠期間、健康状態、および泌乳成績に及ぼす肉牛種の影響 The impact of beef sire breed on dystocia, stillbirth, gestation length, health, and lactation performance of cows that carry beef × dairy calves
B.L. Basiel,A.A. Barragan,T.L. Felix,C.D. Dechow
Dairy Science Published:November 08, 2023
DOI:https://doi.org/10.3168/jds.2023-24112
ABSTRACT
In the United States, it is becoming common for dairy herds to mate a portion of cows to beef semen to create a value-added calf. The objectives of this study were to determine if dystocia risk, stillbirth (SB) risk, gestation length (GL), probability of early-lactation clinical disease events, early-lactation culling risk, or subsequent milk production differ between cows that carried calves sired by different beef breeds and those that carried Holstein-sired calves. Records from 10 herds contained 75,256 lactations from 39,249 cows that had calves with known Holstein or beef breed sires from the years 2010 to 2023. Calf sire breeds with ≥150 records included in analyses were Holstein, Angus, Simmental, Limousin, crossbred beef, and Charolais. Additional beef sire breeds that existed in lower frequency (n < 150 records) were condensed together and classified as “other.” Because GL is a continuous variable, sire breed inclusion criteria were reduced to n ≥ 100 records; thus, Wagyu sires were included as their own breed group. Some records did not contain all variables of interest, thus models included fewer lactations depending on variable. Binomial generalized mixed models evaluated dystocia risk (defined as calving ease score ≥4 or calving ease score ≥3), SB risk, clinical health event risk (defined as lameness, mastitis, metabolic, reproductive, other, or any health events occurring within 60 d in milk [DIM]), and early culling risk (defined as death or culling within 60 DIM). Gestation length and test-date milk, fat, and protein yields were evaluated with mixed models. Calves sired by crossbred beef bulls had a greater probability of being stillborn (5%; 95% confidence interval lower = 2.9% upper = 9.0%) than those sired by Holstein bulls (2%; 95% confidence interval lower = 1.5%, upper = 2.7%). All beef-sired calves increased GL from that of Holstein-sired calves (277 ± 0.15 d) with Limousin (282 ± 0.81 d) and Wagyu-sired calves (285 d ± 0.79) resulting in the longest GL. The risk of dystocia, clinical health events, and early-lactation culling did not differ by calf sire breed nor did subsequent milk and component yield. Generally, carrying a calf sired by the beef breeds included in this study did not negatively affect the dairy cow.
