Effect of feeding Yucca schidigera extract on performance of lactating dairy cows and ruminal fermentation parameters in steers

Two experiments were conducted to determine the effects of Yucca schidigera extract (YE) on firstly, dry matter intake (DMI), milk production and milk composition in lactating Holstein Friesian cows and secondly on DMI and GEI and rumen fermentation parameters of ruminally fistulated Holstein Friesian steers. Three levels of YE supplementation were studied in both experiments. In Experiment 1, 33 early lactating dairy cows that were 69 days in milk (S.D. +/- 39) at cornmencement of the trial were fed YE at either 0, 25 or 50 g/head/day in a randomised block design while in Experiment 2, the three fistulated steers were fed YE at 0, 15 and 28 g/head/day within a latin square design. The lower levels of YE supplementation fed in Experiment 2 were designed to provide similar inclusion rates within the diet as in Experiment 1 after allowing for the higher DMI within Experiment 1. All animals in both trials were offered ad libitum a total mixed ration (TMR) supplemented with concentrates containing the YE, The dairy cows were group housed by diet, however when milk and intake measurements were conducted (days 12 to 18 and days 54 to 60 post commencement of the feeding of the experimental diets) the animals were housed in individual tie up stalls, whereas for Experiment 2 all animals were individually stall fed for the duration of the trial. Feeding YE had no effect on milk yield or composition, however DMI decreased linearly (P < 0.06) in response to increasing YE dietary inclusion within Experiment 1. No effects of YE supplementation on total tract digestibility were identified in either experiment, however comparisons between treatments revealed that total volatile fatty acid (VFA) concentration in rumen fluid were lower at for both YE25 and YE50 relative to the control, and rumen protozoa numbers were also linearly (P < 0.01) reduced. Although feeding YE to early lactation Holstein Friesian cows had no effect on milk production or digestibility and had only elicited limited responses in rumen fermentation characteristics it would appear to lead to an increase in the efficiency of converting feedstuffs to milk (as comparisons between individual treatments revealed a significant increase following YE supplementation relative to YE0) due to a reduction in voluntary DMI. (c) 2005 Elsevier B.V. All rights reserved.