Frutos P, Toral P G, Ramos-Morales E, Shingfield K J, Belenguer A, Hervás G
Instituto de Ganadería de Montaña (CSIC-ULE), Finca Marzanas s/n, 24346 Grulleros, León, Spain.
Instituto de Ganadería de Montaña (CSIC-ULE), Finca Marzanas s/n, 24346 Grulleros, León, Spain.
J Dairy Sci. 2014 Feb;97(2):1036-46. doi: 10.3168/jds.2013-7327. Epub 2013 Dec 6.
Previous investigations have shown that cobalt (Co) modifies milk fat composition in cattle, consistent with an inhibition of stearoyl-coenzyme A desaturase (SCD) activity, but it remains unclear whether other ruminant species are also affected. The present study examined the effects of oral administration of Co acetate on intake, rumen function, and milk production and fatty acid (FA) composition in sheep. Twenty lactating Assaf ewes were allocated into 1 of 4 groups and used in a continuous randomized block design that involved a 15-d adaptation, a 6-d treatment, and a 10-d posttreatment period. During the treatment period, animals received an oral drench supplying 0 (control), 3 (Co3), 6 (Co6), and 9 (Co9) mg of Co/kg of BW per day, administered in 3 equal doses at 8-h intervals. Cobalt acetate had no influence on intake or milk fat and protein concentrations, whereas treatments Co6 and Co9 tended to lower milk yield. Results on rumen parameters showed no effects on rumen fermentation, FA composition, or bacterial community structure. Administration of Co acetate decreased milk concentrations of FA containing a cis-9 double bond and SCD product:substrate ratios, consistent with an inhibition of SCD activity in the ovine mammary gland. Temporal changes in milk fat composition indicated that the effects of treatments were evident within 3d of dosing, with further changes being apparent after 6d and reverting to pretreatment values by d 6 after administration. Effect on milk FA composition did not differ substantially in response to incremental doses of Co acetate. On average, Co decreased milk cis-9 10:1/10:0, cis-9 12:1/12:0, cis-9 14:1/14:0, cis-9 16:1/16:0, cis-9 17:1/17:0, cis-9 18:1/18:0, and cis-9,trans-11 18:2/trans-11 18:1 concentration ratios by 30, 32, 38, 33, 21, 24, and 25%, respectively. Changes in milk fat cis-9 10:1, cis-9 12:1, and cis-9 14:1 concentrations to Co treatment indicated that 51% of cis-9 18:1 and cis-9,trans-11 18:2 secreted in milk originated from Δ(9)-desaturation. In conclusion, results demonstrated the potential of oral Co administration for the estimation of endogenous synthesis of FA containing a cis-9 double bond in the mammary gland of lactating ruminants. Indirect comparisons suggest that the effects of Co differ between sheep and cattle.
先前的研究表明，钴（Co）可改变奶牛的乳脂肪组成，这与硬脂酰辅酶A去饱和酶（SCD）活性受到抑制一致，但其他反刍动物物种是否也受影响仍不清楚。本研究检测了口服醋酸钴对绵羊采食量、瘤胃功能、产奶量及脂肪酸（FA）组成的影响。20只泌乳期的阿萨夫母羊被分为4组中的1组，并采用连续随机区组设计，该设计包括15天的适应期、6天的治疗期和10天的治疗后期。在治疗期，动物接受口服灌服，每天每千克体重分别提供0（对照组）、3（Co3）、6（Co6）和9（Co9）毫克的钴，分3等份，每隔8小时给药一次。醋酸钴对采食量、乳脂肪和蛋白质浓度没有影响，而Co6和Co9处理组的产奶量有降低趋势。瘤胃参数结果显示对瘤胃发酵、FA组成或细菌群落结构没有影响。口服醋酸钴可降低含顺式-9双键的FA的乳浓度以及SCD产物与底物的比率，这与绵羊乳腺中SCD活性受到抑制一致。乳脂肪组成的时间变化表明，给药后3天内治疗效果明显，6天后有进一步变化，给药后第6天恢复到预处理值。醋酸钴剂量增加时，对乳FA组成的影响没有显著差异。平均而言，钴使乳中顺式-9 10:1/10:0、顺式-9 12:1/12:0、顺式-9 14:1/14:0、顺式-9 16:1/16:0、顺式-9 17:1/17:0、顺式-9 18:1/18:0和顺式-9,反式-11 18:2/反式-11 18:1的浓度比分别降低了30%、32%、38%、33%、21%、24%和25%。乳脂肪中顺式-9 10:1、顺式-9 12:1和顺式-9 14:1浓度对钴处理的变化表明，乳中分泌的顺式-9 18:1和顺式-9,反式-11 18:2中有51%源自Δ(9)-去饱和作用。总之，结果表明口服钴在评估泌乳反刍动物乳腺中含顺式-9双键的FA的内源性合成方面具有潜力。间接比较表明，钴对绵羊和奶牛的影响有所不同。
