title: Feed efficiency of mid-lactation dairy cows fed yeast culture during summer.
abstract: Thirty-eight Holstein cows (26 multiparous and 12 primiparous), that averaged 105 d postpartum at the start of the experiment, were used to evaluate the feeding of yeast culture (60 g/cow daily of Diamond V XP) on production efficiency during hot summer weather. From early June until early September and after a 2-wk covariate period, cows were fed a control diet without or with 60 g of yeast culture/cow daily for 12 wk. Weekly daytime high temperatures in the free-stall barn during the 12-wk period averaged 33 degrees C (28 to 39 degrees C). Total mixed diets on a dry matter (DM) basis consisted of corn silage (28%), alfalfa hay (21%), and a concentrate mix (51%) without or with the yeast culture added to the total mixed ration at the time of feeding. Milk production (34.9 and 35.4 kg/d, for control and yeast culture treatment, respectively), 4% fat-corrected milk (31.2 and 32.0 kg/d), energy-corrected milk (ECM; 33.4 and 34.2 kg/d), and DM intake (23.1 and 22.1 kg/d) were similar for cows fed control and yeast culture diets. Percentages of milk fat (3.34 and 3.41) and true protein (2.85 and 2.87) were similar for both diets. Feed efficiency defined as kilogram of ECM/kilogram of DM intake was improved by 7% for cows fed the yeast culture. Body weights and body condition scores were similar for both groups. The results suggest that the yeast culture can improve feed efficiency of heat stressed dairy cows in midlactation.
authors.affiliation: Dairy Science Department, South Dakota State University, Brookings 57007-0647, USA. david.schingoethe@sdstate.edu
authors.forename: D J
authors.initials: DJ
authors.lastname: Schingoethe
authors.forename: K N
authors.initials: KN
authors.lastname: Linke
authors.forename: K F
authors.initials: KF
authors.lastname: Kalscheur
authors.forename: A R
authors.initials: AR
authors.lastname: Hippen
authors.forename: D R
authors.initials: DR
authors.lastname: Rennich
authors.forename: I
authors.initials: I
authors.lastname: Yoon
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001824:Body Constitution; D002417:Cattle / Q000502:physiology*; D004435:Eating; D002149:Energy Intake; D005260:Female; D006358:Hot Temperature; D007774:Lactation / Q000378:metabolism* / Q000502:physiology; D000455:Medicago sativa; D008892:Milk / Q000737:chemistry / Q000378:metabolism*; D009751:Nutritional Requirements; D012621:Seasons; D012820:Silage; D015003:Yeasts; D003313:Zea mays