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Effects of feeding supplemental palmitic acid (C16:0) on performance and milk fatty acid profile of lactating dairy cows under summer heat
The objective was to determine performance and milk fatty acid changes of high producing dairy cows in early lactation, under summer heat, by adding a supplemental rumen inert fat in the form of a saturated free fatty acid (856g/kg C16:0/kg of total fatty acids) to the total mixed ration (TMR). Early lactation multiparous Holstein cows in two similar pens of 99 and 115 cows were used in a 2 × 2 Latin Square design experiment with 35 d periods during a period when daily high and low temperatures averaged 34.3 and 15.9 °C, the relative humidity averaged 51% and there were no rain events. The TMR was the same for both groups, consisting of approximately 435 g/kg forage and 565 g/kg concentrate, except that the vitamin/mineral premix had no added fat (control, C) or added fat (C16:0) at a level designed to deliver approximately 450g/cow/d of supplemental fat if cows consumed 26.5 kg/d of dry matter (DM). The two TMR averaged 905 g/kg organic matter (OM), 318 g/kg neutral detergent fiber (aNDF), and 186 g/kg crude protein (CP). The 'C' TMR had 58 g/kg total fatty acids with an estimated net energy for lactation (NE1) of 7.3 MJ/kg (DM), while the C16:0 TMR had 72 g/kg total fatty acids and 7.5 MJ/kg NE1 (DM). Whole tract digestibility of DM, OM, aNDF and CP tended (P<0.10) to increase, and that of fatty acids increased substantially (P<0.01), with C16:0 feeding, whereas, DM intake was not affected. Milk fat content decreased (P<0.01) with C 16:0 feeding (37.5 versus
ISSN : 0377-8401 CODEN : AFSTDH
Animal feed science and technology A. 2008, vol. 140, n° 3-4, pp. 241-257 [17 pages] [bibl. : 1 p.1/4]
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