CASE STUDY: Effects of a supplemental enhanced yeast product on digestion and milk production in dairy cows

Abstract

<h2>ABSTRACT</h2> This research evaluated the effects of an enhanced yeast product (EY) on in sacco and total digestion of nutrients and milk production by lactating cows. For the in sacco study, 4 rumen-cannulated, lactating Holsteins received a common TMR for 1 wk. Thirty grams of EY per day was topdressed daily to 2 of the 4 cows. Corn silage, alfalfa silage, timothy hay, corn grain, and soybean meal were incubated in sacco. Digestion kinetics were calculated. The EY reduced lag to digestion for the corn silage (P < 0.05) and alfalfa silage (P < 0.10). Digestion rates of NDF were greater for corn grain and soybean meal (P < 0.10) with EY. Solubility of DM was greater with EY than control for corn grain and soybean meal. For the digestion trial, 8 lactating Holsteins were divided equally into 2 groups. Thirty grams of EY per day was topdressed after a.m. feeding for the test group, and this group was compared with the control. There were no differences (P > 0.05) in total-tract nutrient digestibility. Urinary N losses were reduced (P < 0.10) by EY. Fourteen on-farm feeding experiments were conducted. In 5 trials in which the control diet contained no yeast, 150-d milk increased in 4, fat percentage increased in 2, and protein percentage increased in 2 trials with EY (P < 0.10). In 9 trials in which EY replaced a yeast product, 150-d milk increased in 6, fat percentage increased in 2 and declined in 2, and protein percentage increased in 1 and declined in 1 study. The EY alters fermentation, which can positively but inconsistently influence milk production.