Effects of nutritional management on production performance and rumen fermentation in dairy cows during calving transition

• Author / Creator

  Shi, Weina

• Dairy cows usually experience negative energy balance during the calving transition period (3 weeks before to 3 weeks after parturition) due to the rapid increase in nutrient demands for milk production. In order to compensate for the energy deficits, diets rich in highly fermentable carbohydrates are commonly fed to dairy cows after calving. However, the increase in dietary fermentable carbohydrate does not guarantee an increase in energy intake and is likely to decrease rumen pH and increase the risk of sub-acute acidosis (SARA) in dairy cows after calving. The overall objective of this research was to evaluate the effects of nutritional management during the calving transition period on production performance and rumen fermentation in early-lactation dairy cows. The first study (Chapter 2 and 3) evaluated the effects of Saccharomyces cerevisiae fermentation product (SCFP) supplementation during the periparturient period on production performance and rumen fermentation of dairy cows fed fresh diets differing in starch content were evaluated. One-hundred seventeen Holstein dairy cows, including 18 ruminally cannulated cows, were fed diets with SCFP (SCFP) or without (CON) from day (d) 28 prior to expected calving date to d 44 after calving. A common basal low-energy diet was fed to all cows during the close-up period. Cows within each treatment (CON or SCFP) were fed either a low-(LS; 22.1% starch) or high-starch (HS; 28.3%) diet during the fresh period (d 1 to 23 after cavling). All cows were fed the HS diets during the post-fresh early lactation period (d 24 to 44 after calving). In Chapter 2, it was found that starch content of fresh diets did not affect dry matter intake (DMI), but LS cows had greater milk yield and tended to lose more body condition during the fresh period compared with HS cows. Supplementation of SCFP transiently increased DMI on d 1 and 5 after calving and increased feed efficiency (3.5% fat-corrected milk yield/DMI) during the post-fresh early lactation period. In Chapter 3, rumen pH data were collected from the eighteen ruminally cannulated cows. Rumen pH was measured over a 3-d period from d -10 relative to expected calving date and from d -3, 1, 7, and 21 relative to actual calving date. As expected, minimum rumen pH tended to be higher for LS cows than HS cows on d 1 after calving. However, rumen pH was not affected by dietary starch content during the other periods after calving. Supplementation of SCFP tended to increase mean rumen pH on d -3 before calving and tended to increase minimum rumen pH and reduce the duration of pH below 5.8 on d 21 after calving. Based on the effects of feeding LS diets on increasing rumen pH during the fresh period, I hypothesized that the negative effect of feeding a low-starch close-up diet on increasing the risk of rumen pH depression may occur only during the immediate postpartum period. Therefore, the effects of prepartum dietary starch content on rumen fermentation and responses of dairy cows to grain-induced SARA were evaluated in the second study (Chapter 4). Rumen pH was monitored over a 3-d period from d -10 relative to expected calving date and was measured during the grain challenge. Feeding a low-starch diet (14.0% starch) before calving reduced the duration and area of pH below 5.8 on d -10 before calving compared with a high-starch diet (26.1% starch). Contrary to the hypothesis, feeding a low-starch prepartum diet tended to reduce the duration and area of pH below 5.8 during a grain challenge on d 7, possibly because of reduced inflammation and less rumen epithelial damage as indicated by a lower serum amyloid A concentration. However, rumen pH was not different betwwen treatments during a grain challenge on d 21 after calving. In summary, these findings suggest that 1) feeding low-starch diets during the fresh period can increase milk production of dairy cows fed a low-energy close-up diet and reduce the decrease in rumen pH during the immediate postpartum period, 2) supplementation of SCFP may increase feed intake around calving and feed efficiency in post-transition early lactation period and can help to reduce the duration of pH below 5.8 by the end of the calving transition, and 3) feeding a high-starch close-up diet may increase the rumen pH depression after calving.

• Subjects / Keywords

  • Saccharomyces cerevisiae
  • Rumen fermentation
  • Transition cow
  • Production performance

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-qhkg-tt58

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.