Casper's Calf Ranch, 4890 West Lily Creek Road, Freeport, IL 61032; Department of Animal Sciences, North Carolina A&T State University, Greensboro 27411.
Hubbard Feeds, 111 West Cherry St., Suite 500, Mankato, MN 56001.
J Dairy Sci. 2021 Oct;104(10):10669-10677. doi: 10.3168/jds.2021-20252. Epub 2021 Jul 30.
Cobalt lactate is a highly soluble ruminal Co source. Prior research evaluating higher Co feeding rates demonstrated increased ruminal fiber digestion. Feeding high-forage (>70%) rations to late-lactation dairy cows to enhance income over feed cost could potentially benefit from higher ruminal-soluble Co inclusion rates to enhance ruminal fiber and nutrient digestibility. Twenty-four late-lactation [238 ± 68.8 d in milk (DIM) and 36.4 ± 5.4 kg/d milk] Holstein dairy cows (10 primiparous and 14 multiparous) were blocked by milk yield, DIM, and parity, and randomly assigned to 1 of 2 treatments. Treatments were (1) control, CoCO total mixed ration (TMR) containing 12.5 mg/cow per day of cobalt (cobalt carbonate), and (2) cobalt lactate (Co-LAC), same CoCO TMR but containing an additional 50 mg/cow per day of Co, via a 1% cobalt lactate product (CoMax, Ralco Inc.). The basal TMR was 70% forage [60% alfalfa baleage and 40% corn silage on a dry matter (DM) basis] and 30% of the respective experimental grain mix on a DM basis. Cows were fed the CoCO TMR during the 7-d covariate period, followed by 4 wk of data collection when CoCO and Co-LAC TMR were fed. Milk production (26.2 and 25.8 kg/d for CoCO and Co-LAC, respectively) and dry matter intake (DMI; 22.9 and 23.1 kg/d) were similar for cows fed both Co treatments. Production of milk fat (1.02 and 1.09 kg/d), milk protein (0.87 and 0.91 kg/d), and lactose (1.17 and 1.26 kg/d) were similar for cows fed both treatments. Body weights (684 and 674 kg) were similar for cows fed both treatments. Rumen ammonia concentrations (15.8 and 12.3 mg/dL) were lower for cows fed Co-LAC compared with cows fed CoCO (15.8 mg/dL). Ruminal molar acetate concentrations (59.5 and 61.1%) were greater for cows fed Co-LAC compared with cows fed CoCO. Feeding additional Co as cobalt lactate in the TMR did not enhance lactational performance (milk production, composition, DMI, or body weight changes) when fed a high-forage TMR but altered ruminal fermentation with decreased ruminal ammonia and increased ruminal acetate concentrations.
乳酸钴是一种高度可溶性的瘤胃钴源。先前的研究评估了更高的钴喂养率，表明瘤胃纤维消化增加。为了提高饲料成本的收入，给泌乳后期（泌乳期 238 ± 68.8 天，产奶量 36.4 ± 5.4 kg/d）的奶牛饲喂高粗饲料（>70%）日粮，可以通过提高瘤胃可溶性钴的添加率来提高瘤胃纤维和养分消化率。24 头泌乳后期（泌乳期 238 ± 68.8 天，产奶量 36.4 ± 5.4 kg/d）荷斯坦奶牛（10 头初产和 14 头经产）根据产奶量、泌乳天数和胎次进行分组，然后随机分配到 2 种处理中的 1 种。处理方法为：（1）对照组，钴碳酸钴总混合日粮（TMR），每天每头奶牛含钴 12.5mg；（2）乳酸钴（Co-LAC），与对照组相同的钴碳酸钴 TMR，但每天每头奶牛额外添加 50mg 钴，通过 1%的乳酸钴产品（CoMax，Ralco Inc.）添加。基础 TMR 为 70%的粗饲料[干物质（DM）基础上 60%的苜蓿干草捆和 40%的玉米青贮]和 30%的各自的实验谷物混合物。奶牛在 7 天协变量期间饲喂钴碳酸钴 TMR，然后在饲喂钴碳酸钴和 Co-LAC TMR 的 4 周数据收集期间进行饲喂。两组奶牛的产奶量（钴碳酸钴组为 26.2kg/d 和 Co-LAC 组为 25.8kg/d）和干物质采食量（钴碳酸钴组为 22.9kg/d 和 Co-LAC 组为 23.1kg/d）相似。两组奶牛的乳脂产量（1.02kg/d 和 1.09kg/d）、乳蛋白产量（0.87kg/d 和 0.91kg/d）和乳糖产量（1.17kg/d 和 1.26kg/d）相似。两组奶牛的体重（684kg 和 674kg）相似。与钴碳酸钴组相比，饲喂 Co-LAC 的奶牛的瘤胃氨浓度（15.8mg/dL 和 12.3mg/dL）较低。与钴碳酸钴组相比，饲喂 Co-LAC 的奶牛的瘤胃乙酸摩尔浓度（59.5%和 61.1%）较高。当饲喂高粗饲料 TMR 时，瘤胃中额外添加乳酸钴作为钴源并不会提高泌乳性能（产奶量、组成、干物质采食量或体重变化），但改变了瘤胃发酵，降低了瘤胃氨浓度，增加了瘤胃乙酸浓度。
