Effects of altering the energy and protein supply to dairy cows during the dry period. 2. Metabolic and hormonal responses.
J Dairy Sci
; 83(8): 1795-805, 2000 Aug.
Article
in En
| MEDLINE
| ID: mdl-10984156
ABSTRACT
We offered 48 multiparous Holstein-Friesian cows one of three different dry-period diets for 6 wk before predicted calving A) a grass silage and barley straw mix (6040 on a dry-matter basis), with a low protein content; B) grass silage only (medium protein); or C) grass silage plus 0.5 kg of high protein corn gluten meal (high protein)/d. A standard grass silage-based diet was offered to all cows following calving. All animals were blood sampled at weekly intervals during the dry period, and at wk 1, 3, 5, 7, 13, 17, and 21 of lactation. Nitrogen balance was measured in a subset of 12 cows (four per treatment) at 3 wk before calving, and at wk 8 and 18 of lactation. Nitrogen balance in the dry period increased significantly as dietary protein supply increased [9, 34, and 50 g of N/d (SED 8.8) for the three diets, respectively]. We measured no residual effects of dry-period treatment on N balance during lactation. Plasma concentrations of growth hormone became significantly higher in the late dry period in cows offered the silage and straw diet, although treatment differences disappeared after calving. Insulin concentrations were significantly affected by treatment throughout the dry period and indicated inadequate nutrient supplies from the low protein diet, leading to losses in body reserves of energy and protein. The results indicate that animals offered the low protein diet accumulated less N per day than is required for fetal development, suggesting that protein must have been repartitioned from maternal tissues.
Search on Google
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Energy Intake
/
Labor, Obstetric
/
Lactation
/
Cattle
/
Dietary Proteins
/
Nitrogen
Type of study:
Prognostic_studies
Limits:
Animals
/
Pregnancy
Language:
En
Journal:
J Dairy Sci
Year:
2000
Document type:
Article
Affiliation country:
United kingdom