Ganda E K, Bisinotto R S, Vasquez A K, Teixeira A G V, Machado V S, Foditsch C, Bicalho M, Lima F S, Stephens L, Gomes M S, Dias J M, Bicalho R C
Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
J Dairy Sci. 2016 Sep;99(9):7319-7329. doi: 10.3168/jds.2016-10989. Epub 2016 Jun 16.
Objectives of this clinical trial were to evaluate the effects of injectable trace mineral supplementation (ITMS) on somatic cell count (SCC), linear score (LS), milk yield, milk fat and protein contents, subclinical mastitis cure, and incidence of clinical mastitis in cows with elevated SCC. Holstein cows from a commercial dairy farm in New York were evaluated for subclinical mastitis, defined as SCC ≥200×10(3) cells/mL on the test day preceding enrollment. Cows with a history of treatment for clinical mastitis in the current lactation and those pregnant for more than 150d were not eligible for enrollment. Cows fitting inclusion criteria were randomly allocated to 1 of 2 treatment groups. Cows assigned to ITMS (n=306) received 1 subcutaneous injection containing zinc (300mg), manganese (50mg), selenium (25mg), and copper (75mg) at enrollment (d 0). Control cows (CTRL; n=314) received 1 subcutaneous injection of sterile saline solution. Following treatment, visual assessment of milk was performed daily, and cows with abnormal milk (i.e., presence of flakes, clots, or serous milk) were diagnosed with clinical mastitis (CM). Chronic clinical mastitis was defined as cows with 3 or more cases of CM. Milk yield, milk fat and protein contents, SCC, and LS were evaluated once monthly. Additionally, randomly selected animals were sampled to test serum concentrations of selected minerals on d0 and 30 (n=30 cows/treatment). Treatment did not affect serum concentrations of calcium, magnesium, phosphorus, potassium, copper, iron, manganese, selenium, and zinc on d30. Injectable supplementation with trace minerals did not improve overall cure of subclinical mastitis (CTRL=42.8 vs. ITMS=46.5%), although a tendency was observed in cows with 3 or more lactations (CTRL=27.1 vs. ITMS=40.0%). Supplementation did not reduce treatment incidence of CM (CTRL=48.2 vs. ITMS=41.7%); however, it tended to reduce the proportion of cows diagnosed with chronic CM (CTRL=16.9 vs. ITMS=12.0%), particularly among first-lactation cows (CTRL=18.4 vs. ITMS=7.6%). Cure of subclinical mastitis was associated with higher serum concentrations of phosphorus and selenium on d30. Supplementing trace minerals to cows with elevated SCC had no effect on milk yield, milk fat and protein contents, SCC, and LS.
本临床试验的目的是评估注射用微量矿物质补充剂（ITMS）对体细胞计数（SCC）、线性评分（LS）、产奶量、乳脂和蛋白质含量、亚临床乳腺炎治愈率以及SCC升高的奶牛临床乳腺炎发病率的影响。对来自纽约一家商业奶牛场的荷斯坦奶牛进行亚临床乳腺炎评估，在入组前一天的检测日，将SCC≥200×10³个细胞/mL定义为亚临床乳腺炎。当前泌乳期有临床乳腺炎治疗史的奶牛以及怀孕超过150天的奶牛不符合入组条件。符合纳入标准的奶牛被随机分配到2个治疗组中的1组。分配到ITMS组（n = 306）的奶牛在入组时（第0天）接受1次皮下注射，注射剂含有锌（300mg）、锰（50mg）、硒（25mg）和铜（75mg）。对照组奶牛（CTRL；n = 314）接受1次皮下注射无菌生理盐水溶液。治疗后，每天对牛奶进行视觉评估，牛奶异常（即有薄片、凝块或浆液性牛奶）的奶牛被诊断为临床乳腺炎（CM）。慢性临床乳腺炎定义为患有3例或更多例CM的奶牛。每月评估一次产奶量、乳脂和蛋白质含量、SCC和LS。此外，在第0天和第30天随机选取动物进行采样，以检测所选矿物质的血清浓度（每个治疗组n = 30头奶牛）。治疗对第30天的钙、镁、磷、钾、铜、铁、锰、硒和锌的血清浓度没有影响。注射补充微量矿物质并没有提高亚临床乳腺炎的总体治愈率（CTRL = 42.8% vs. ITMS = 46.5%），尽管在有3次或更多泌乳的奶牛中观察到一种趋势（CTRL = 27.1% vs. ITMS = 40.0%）。补充剂并没有降低CM的治疗发病率（CTRL = 48.2% vs. ITMS = 41.7%）；然而，它倾向于降低被诊断为慢性CM的奶牛比例（CTRL = 16.9% vs. ITMS = 12.0%），特别是在头胎奶牛中（CTRL = 18.4% vs. ITMS = 7.6%）。亚临床乳腺炎的治愈与第30天较高的磷和硒血清浓度有关。向SCC升高的奶牛补充微量矿物质对产奶量、乳脂和蛋白质含量、SCC和LS没有影响。
