کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8501483 | 1553841 | 2018 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Plasma glucose and nonesterified fatty acids response to epinephrine challenges in dairy cows during a 670-d lactation
ترجمه فارسی عنوان
پاسخ گلوکز پلاسما و اسیدهای چرب غیراسترید شده به چالش های اپی نفرین در گاوهای شیری طی شیردهی 670 دقیقه
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کلمات کلیدی
طولانی شدن شیردهی بسیج چربی، پراکندگی مواد مغذی،
موضوعات مرتبط
علوم زیستی و بیوفناوری
علوم کشاورزی و بیولوژیک
علوم دامی و جانورشناسی
چکیده انگلیسی
This experiment investigated the metabolic response to a 2-dose epinephrine challenge of dairy cows undergoing an extended lactation. Twelve multiparous Holstein-Friesian cows that calved in late winter in a seasonally calving pasture-based dairying system were managed for a 670-d lactation by delaying rebreeding. In each of four 40-d experimental periods commencing at 73, 217, 422, and 520 (±9.1) d in milk (DIM), cows were offered a diet of perennial ryegrass (73 and 422 DIM) or pasture hay and silage (217 and 520 DIM), supplemented with 1 (CON; n = 6) or 6 kg of grain (GRN; n = 6) as a ration. Daily energy intake was approximately 160 and 215 MJ of metabolizable energy/cow for the CON and GRN treatments, respectively. At all other times, cows were managed as a single herd and grazed pasture supplemented with grain to an estimated daily total intake of 180 MJ of metabolizable energy/cow. Cows were fitted with a jugular catheter during the final week of each experimental period. Two doses of epinephrine (0.1 and 1.6 µg/kg of body weight) were infused via the catheter 2 h apart to each cow at approximately 100, 250, 460, and 560 DIM. Blood plasma concentrations of glucose and nonesterified fatty acids (NEFA) were measured before and after infusions. Cows in the GRN treatment had greater milk yield, milk fat and protein yields, and body weight than cows in the CON treatment. The maximum plasma glucose concentration was observed at 100 DIM for both the low and high doses of epinephrine. Thus, sensitivity and responsiveness to exogenous epinephrine were greater during early lactation, coinciding with increased priority of milk synthesis. Both the sensitivity and responsiveness to epinephrine decreased with decreasing milk yield, as measured by the acute appearance of NEFA in the plasma. Increased plasma glucose and NEFA clearance rates before 300 DIM indicated greater uptake of these substrates by the mammary gland for milk synthesis in early and mid lactation. These results support previous findings that major changes occur in terms of adipose tissue metabolism during extended lactations. Overall, sensitivity to epinephrine was not affected by diet, but responsiveness was greater in cows fed the GRN diet. The endocrine regulation of nutrient partitioning throughout traditional and extended lactations is complex, with many interactions between stage of lactation, diet, and milk yield potential.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Dairy Science - Volume 101, Issue 4, April 2018, Pages 3501-3513
Journal: Journal of Dairy Science - Volume 101, Issue 4, April 2018, Pages 3501-3513
نویسندگان
L.C. Marett, M.J. Auldist, W.J. Wales, K.L. Macmillan, F.R. Dunshea, B.J. Leury,