Yan T, Mayne C S, Keady T W J, Agnew R E
The Agricultural Research Institute of Northern Ireland, Hillsborough, BT26 6DR, UK.
J Dairy Sci. 2006 Mar;89(3):1031-42. doi: 10.3168/jds.S0022-0302(06)72170-1.
The data used in the present study were derived from a 2 (genotype) x 2 (plane of nutrition) factorial design production study using Holstein-Friesian (n = 32) and Norwegian (n = 32) first-lactation dairy cattle offered grass silage-based diets from 1 to 44 wk of lactation. The high nutrition diet had concentrate inclusions (g/kg of dry matter) of 600, 500, and 400 for lactation days of < 101, 101 to 200, and > 200, respectively, and the low nutrition diet included concentrates at 300, 200, and 100 for the same periods. Dietary metabolizable energy (ME) concentrations were measured in calorimetric chambers at lactation d 80, 160, and 240 respectively, and then applied to production data to calculate ME intake. From wk 1 to 44 of lactation, Holstein-Friesian cows had a consistently lower accumulated live weight gain and body condition score, and a consistently higher ME intake and milk energy output than Norwegian cows, irrespective of the plane of nutrition. Compared with Norwegian cows using mean data derived from the 2 planes of nutrition, Holstein-Friesian cows produced a significantly higher proportion of milk energy output over ME intake in early and mid lactation, although this increase was not significant in late lactation. In contrast, Holstein-Friesian cows partitioned a significantly lower proportion of ME intake into body tissue than Norwegian cows in early lactation, although the differences were not significant in mid or late lactation. When ME intake and energy used for maintenance, milk, and body tissue were taken into account, the efficiency of ME use for lactation was similar between the 2 genotypes offered the high or low concentrate diet during the whole lactation. It is concluded that Holstein-Friesian cows can produce more milk energy than Norwegian cows, mainly as a result of higher ME intake and because of a greater ability to partition more energy into milk and less into body tissue. The effect on energy partitioning mainly occurs in early and midlactation and is particularly evident with high concentrate diets.
本研究中使用的数据来自一项2（基因型）×2（营养水平）析因设计生产研究，该研究使用了荷斯坦-弗里生奶牛（n = 32头）和挪威奶牛（n = 32头），在泌乳1至44周期间，为其提供以青贮草为基础的日粮。高营养日粮中，泌乳天数<101天、101至200天、>200天时，精料添加量（g/kg干物质）分别为600、500和400；低营养日粮在相同泌乳阶段的精料添加量分别为300、200和100。分别在泌乳第80天、160天和240天，在量热室中测定日粮的代谢能（ME）浓度，然后将其应用于生产数据以计算ME摄入量。从泌乳第1周到44周，无论营养水平如何，荷斯坦-弗里生奶牛的累积体重增加和体况评分始终低于挪威奶牛，而ME摄入量和牛奶能量输出始终高于挪威奶牛。与使用来自两种营养水平的平均数据的挪威奶牛相比，荷斯坦-弗里生奶牛在泌乳早期和中期，牛奶能量输出占ME摄入量的比例显著更高，尽管在泌乳后期这种增加并不显著。相反，在泌乳早期，荷斯坦-弗里生奶牛将ME摄入量分配到身体组织中的比例显著低于挪威奶牛，尽管在泌乳中期或后期差异不显著。当考虑到ME摄入量以及用于维持、产奶和身体组织的能量时，在整个泌乳期，两种基因型的奶牛在提供高或低精料日粮时，ME用于产奶的效率相似。研究得出结论，荷斯坦-弗里生奶牛比挪威奶牛能产生更多的牛奶能量，这主要是由于较高的ME摄入量，以及将更多能量分配到牛奶中、更少分配到身体组织中的能力更强。对能量分配的影响主要发生在泌乳早期和中期，在高精料日粮中尤为明显。
