Effect of saturated fatty acid supplementation on production and metabolism indices in heat-stressed mid-lactation dairy cows.
Experimental objectives were to determine the effects of supplemental saturated fatty acids on production, body temperature indices, and some aspects of metabolism in mid-lactation dairy cows experiencing heat stress. Forty-eight heat-stressed Holstein cows were allocated into 3 groups (n=16/group) according to a completely randomized block design. Three treatment diets consisted of supplemental saturated fatty acids (SFA) at 0 (SFA0), 1.5 (SFA1.5), or 3.0% (SFA3) of dry matter (DM) for 10 wk. Diets were isonitrogenous (crude protein=16.8%) and contained 1.42, 1.46, and 1.49 Mcal of net energy for lactation/kg of DM for the SFA0, SFA1.5 and SFA3 diets, respectively. The average temperature-humidity index at 0700, 1400 and 2200 h was 72.2, 84.3, and 76.6, respectively. Rectal temperatures at 1400 h were decreased with fat supplementation. Treatment did not affect dry matter intake (20.1+/-0.02 kg/d), body condition score (2.72+/-0.04), body weight (627+/-16.1 kg), or calculated energy balance (1.32+/-0.83 Mcal/d). Saturated fatty acid supplementation increased milk yield, milk fat content, and total milk solids. Increasing fat supplementation decreased plasma nonesterified fatty acids (8%) but had no effect on other energetic metabolites or hormones. In summary, supplemental SFA improved milk yield and milk fat content and yield and reduced peak rectal temperatures in mid-lactation heat-stressed dairy cows. This demonstrates the remarkable amount of metabolic heat that is "saved" by energetically replacing fermentable carbohydrates with supplemental SFA.
Wang
J P
JP
State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy Agricultural Sciences, Beijing 100393, PR China.
Bu
D P
DP
Wang
J Q
JQ
Huo
X K
XK
Guo
T J
TJ
Wei
H Y
HY
Zhou
L Y
LY
Rastani
R R
RR
Baumgard
L H
LH
Li
F D
FD
D000818:Animals; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D002417:Cattle / Q000378:metabolism / Q000502:physiology*; D019587:Dietary Supplements; D004435:Eating / Q000187:drug effects / Q000502:physiology; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D005227:Fatty Acids / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D018869:Heat-Shock Response / Q000187:drug effects / Q000502:physiology; D007774:Lactation / Q000187:drug effects / Q000502:physiology; D008892:Milk / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*
D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified