泌乳奶牛通常在每个季度用抗生素输注治疗,以治愈和预防致病性乳房内感染,这仍然是奶牛群最常见的疾病。这种方法被称为毯子干牛疗法,通常对预防和治疗感染有效,但已被证明可能有助于抗生素抗性细菌菌株的出现和传播。探索非抗生素治疗与选择性干牛治疗相结合的使用对于降低抗生素耐药性和对牛奶微生物组平衡的潜在干扰的风险是必要的。需要仔细评估选择性干牛治疗对生理乳微生物组的影响。在这个小规模的试验中,五个健康的(没有侏儒,对SCC<200,000个细胞mL-1)从干燥到产卵后5天的第二胎次母牛进行采样。对于每一头母牛来说,每个季度接受不同的处理:(I)硝酸铋(内部乳头密封剂,OrbSeal®,Zoetis,意大利),右前四分之一;(ii)二水头孢铵(Cepravin®,MSD,意大利),右后四分之一;(iii)苄星氯唑西林(干氯沙林,Ati,意大利),左后四分之一。对用作实验对照的剩余四分之一(左前)不进行处理。对于16SrRNA基因测序,从5毫升牛奶样品中提取细菌DNA,使用V3-V4高变区的引物进行扩增,并在一个MiSeq(Illumina)运行中以2×250个碱基的双端读数进行测序。细菌学结果证实,这些季度都是健康的。门变形杆菌,Firmicutes,放线菌在所有三个时间点的所有治疗和对照中都是最丰富的,占整个牛奶微生物群组成的80%以上。在主要α和β多样性指数方面,处理和对照之间没有发现显着差异,揭示了抗生素,和非抗生素治疗的选择性干牛治疗并没有显着改变奶牛的牛奶微生物组。牛奶的微生物群组成显示出在整个泌乳周期中的明显演变,在整个泌乳周期中,牛奶微生物群多样性的总体变化主要与治疗无关。
Lactating cows are routinely treated at dry-off with antibiotic infusions in each quarter for the cure and prevention of pathogenic intramammary infection, which remains the most common disease in dairy herds. This approach is known as blanket dry-cow therapy, usually effective for the prevention and cure of infections, but has been shown to potentially contribute to the emergence and spreading of antibiotic resistant bacterial strains. Exploring the use of non-antibiotic treatments coupled with selective dry-cow therapy is necessary to reduce the risk of antibiotic resistance and potential interference with milk microbiome balance. The impact of selective dry-cow therapy on the physiological milk microbiome needs to be carefully evaluated. In this small-scale
trial, five healthy (no mastits, SCC <200,000 cells mL-1) second-parity cows from dry-off to 5 days after calving were sampled. For every cow, each quarter received a different treatment: (i) bismuth salnitrate (internal teat sealant, OrbSeal®, Zoetis, Italy), front right quarter; (ii) cephalonium dihydrate (Cepravin®, MSD, Italy), rear right quarter; (iii) benzathine cloxacillin (Cloxalene dry, Ati, Italy), rear left quarter. No treatment was applied to the remaining quarter (front left) which served as experimental control. For 16S rRNA gene sequencing, bacterial DNA was extracted from 5 ml of milk samples, amplified using the primers for the V3-V4 hypervariable regions and sequenced in one MiSeq (Illumina) run with 2 × 250-base paired-end reads. Bacteriological results confirmed that the quarters were all healthy. The phyla Proteobacteria, Firmicutes, and Actinobacteria were the most abundant for all treatments and controls at all three timepoints, accounting for over 80% of the entire milk microbiota composition. No significant differences were found between treatments and controls in terms of the major alpha and beta diversity indexes, revealing that antibiotic, and non-antibiotic treatments for selective dry-cow therapy did not alter significantly the milk microbiome of dairy cows. The milk microbiota composition showed a clear evolution over the lactation cycle, and the overall changes in the milk microbiota diversity over the lactation cycle were mainly independent of treatments.