Pelletier G, Petitclerc D, Lapierre H, Bernier-Cardou M, Morisset J, Gaudreau P, Couture Y, Brazeau P
Agriculture Canada Research Station, Lennoxville, Québec.
J Dairy Sci. 1987 Dec;70(12):2511-7. doi: 10.3168/jds.S0022-0302(87)80319-3.
Eighteen multiparous Holstein cows in the second half of their lactation were used to determine the effect of human growth hormone-releasing factor (1-44)NH2 and a fragment of growth hormone-releasing factor (1-29)NH2 on lactational performance and feed intake. Saline, the 44-amino acid peptide or the 29-amino acid fragment, at the same dose per injection (.2 nmol.kg-1) was injected intravenously at 4-h intervals for 10 d. Average milk yield, milk composition, feed intake, and feed efficiency were compared for the second half of each 10-d preinjection, injection, and post-injection period. Injections of the 44-amino acid peptide and the 29-amino acid fragment increased milk yield 18.6 and 14.6%, respectively. Feed intake was not changed, but feed efficiency was increased 23.9 and 18.8% over control following 44-amino acid peptide and the 29-amino acid fragment injection, respectively. The lactational response was not different between the two peptides for any of the variables measured. This study demonstrates the feasibility of using a growth hormone-releasing factor fragment as an alternative method of elevating milk yield in cattle via somatotropins.
选用18头处于泌乳后期的经产荷斯坦奶牛，以确定人生长激素释放因子（1-44）NH2和生长激素释放因子片段（1-29）NH2对泌乳性能和采食量的影响。以相同剂量（.2 nmol·kg-1）的生理盐水、44个氨基酸的肽或29个氨基酸的片段，每隔4小时静脉注射一次，持续10天。比较每个10天的注射前、注射期和注射后后半期的平均产奶量、乳成分、采食量和饲料效率。注射44个氨基酸的肽和29个氨基酸的片段后，产奶量分别提高了18.6%和14.6%。采食量没有变化，但注射44个氨基酸的肽和29个氨基酸的片段后，饲料效率分别比对照提高了23.9%和18.8%。在所测的任何变量中，两种肽的泌乳反应没有差异。本研究证明了使用生长激素释放因子片段作为通过生长激素提高奶牛产奶量的替代方法的可行性。
