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)...
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Veröffentlicht in: | Journal of dairy science 2010-09, Vol.93 (9), p.4121-4127 |
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Sprache: | eng |
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Zusammenfassung: | 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 2200h was 72.2, 84.3, and 76.6, respectively. Rectal temperatures at 1400h were decreased with fat supplementation. Treatment did not affect dry matter intake (20.1±0.02kg/d), body condition score (2.72±0.04), body weight (627±16.1kg), or calculated energy balance (1.32±0.83Mcal/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. |
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ISSN: | 0022-0302 1525-3198 |
DOI: | 10.3168/jds.2009-2635 |