Effects of Environmental Temperature and Humidity on the Fatty Acid Composition of Milk Fat

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Abstract
Gas chromatographic analysis revealed humidity above 65[degree]F caused marked differences in the fatty acid composition of milk fat from Holstein cows. The proportions of short-chain fatty acids (C6-C12) were lower at the environmental treatment conditions (85[degree]F -70% R. H., 90[degree]F -25% R.H., 95[degree]F -25% R.H.) than at the control (65[degree]F -50% R.H.). No significant difference in the level of myristic acid (C14) at the treatment and control conditions was observed. Palmitic (C16) increased at higher temperature levels. Oleic Acid (C18 [DELTA] 9) decreased while stearic (C18) increased at the treatment conditions. Any combination of high environmental temperature and humidity which results in a rectal temperature of 103[degree] to 105[degree] may cause definite changes in the characteristics of the milk fat. Past evaluations of the effects of specific environmental factors on the fatty acid composition of milk fat have been obscured by lack of control of all conditions surrounding the production of milk. Normally seasonal changes were accompanied by simultaneous changes in feed quality and stages of lactation. In this study only one of these variables was operative at any time''.