Celaya R, Ferreira L M M, García U, Rosa García R, Osoro K
1Área de Sistemas de Producción Animal, Servicio Regional de Investigación y Desarrollo Agroalimentario (SERIDA), PO Box 13 - 33300, Villaviciosa, Asturias, Spain.
Animal. 2011 Aug;5(9):1467-73. doi: 10.1017/S1751731111000449.
As the number of horses is steadily increasing in Cantabrian less-favoured areas, mostly occupied by nutritionally poor heathland communities, the objective of this research was to study and compare diet selection and performance of crossbred horses and beef cattle (Asturiana de los Valles breed) grazing these areas during the summer. A total of 20 cows (seven lactating their calves and thirteen dry) and 20 mares (eight lactating their foals and twelve dry) were managed during 3 years on a heathland area from June to September and October. The proportion of grass (mostly Pseudarrhenatherum longifolium) and heather (Erica umbellata, E. cinerea and Calluna vulgaris) in the diet selected by cows and mares was estimated in two occasions (July and September) each year using the alkane markers. All animals were weighed at the beginning, middle and end of the summer grazing season. Mares selected heath grasses and rejected heather species more than did the cows (P < 0.001), particularly in early summer (0.85 v. 0.65 herbage proportion in July; 0.63 v. 0.55 in September). Lactating state did not affect diet composition. Mares achieved more favourable (P < 0.001) body weight (BW) changes than cows, but there was also an interaction with season (P < 0.001). From June to August, cows lost BW, being the daily changes (in percentage of initial BW) -0.15%/day in lactating and -0.05%/day in dry cows, whereas both lactating and dry mares gained BW (0.16 and 0.12%/day, respectively). From August to October, lactating cows and mares lost more BW (P < 0.01) compared with their non-lactating counterparts (-0.19 v. -0.10%/day in cows, -0.14 v. -0.05%/day in mares). With regard to the offspring, BW gains between June and August were similar in calves and foals (0.83 and 0.90%/day, respectively), but thereafter calves achieved higher (P < 0.05) BW gains than foals (0.37 v. 0.16%/day). It is concluded that the low nutritive quality of these heathlands restricts, both cattle and horse performance, even during short summer grazing season, being more penalized lactating animals, especially the cows. Although calves were able to maintain acceptable growth rates, foals showed reduced ones during the second half of the grazing season. Other plant communities with better nutritive quality should be provided to assure replenishment of body reserves in dams, and enhance offspring gains to maintain sustainable grazing systems with productive herds of cattle and horses in these heathland areas.
随着坎塔布里亚较贫困地区马匹数量稳步增加，这些地区大多为营养贫瘠的石南丛生群落，本研究的目的是研究和比较夏季在这些地区放牧的杂交马和肉牛（阿斯图里亚纳山谷品种）的饮食选择和生产性能。在3年时间里，从6月到9月及10月，在一片石南丛生地区管理了20头母牛（7头带着小牛犊哺乳，13头干奶）和20匹母马（8头带着马驹哺乳，12头干奶）。每年在两个时间点（7月和9月）使用链烷标记物估计母牛和母马所选择饮食中草（主要是长叶假梯牧草）和石南（伞花欧石南、灰毛欧石南和帚石南）的比例。在夏季放牧季节开始、中期和结束时对所有动物进行称重。母马比母牛更倾向选择石南丛生的草并拒绝石南属物种（P<0.001），特别是在初夏（7月草本植物比例为0.85对0.65；9月为0.63对0.55）。泌乳状态不影响饮食组成。母马的体重（BW）变化比母牛更有利（P<0.001），但也存在与季节的交互作用（P<0.001）。从6月到8月，母牛体重下降，泌乳母牛和干奶牛的每日变化（占初始体重的百分比）分别为-0.15%/天和-0.05%/天，而泌乳和干奶母马体重增加（分别为0.16%/天和0.12%/天）。从8月到10月，与非泌乳的同类动物相比，泌乳母牛和母马体重下降更多（P<0.01）（母牛为-0.19对-0.10%/天，母马为-0.14对-0.05%/天）。关于后代，6月至8月小牛和马驹的体重增加相似（分别为0.83和0.90%/天），但此后小牛的体重增加高于马驹（0.37对0.16%/天，P<0.05）。得出的结论是，这些石南丛生地区的低营养质量限制了牛和马的生产性能，即使在夏季短时间放牧季节也是如此，泌乳动物受到的影响更大，尤其是母牛。尽管小牛能够保持可接受的生长速度，但马驹在放牧季节后半段生长速度降低。应提供其他营养质量更好的植物群落，以确保母畜身体储备的补充，并提高后代的生长，从而在这些石南丛生地区维持有生产力的牛群和马群的可持续放牧系统。
