title: Why are dairy cows not able to cope with the subacute ruminal acidosis?
abstract: One of the largest challenges for the dairy industry is to provide cows with a diet which is highly energetic but does not negatively affect their rumens' functions. In highly productive dairy cows, feeding diets rich in readily fermentable carbohydrates provides energy precursors needed for maximum milk production, but simultaneously decreases ruminal pH, leading to a widespread prevalence of subacute ruminal acidosis. Maximizing milk production without triggering rumen acidosis still challenges dairy farmers, who try to prevent prolonged bouts of low ruminal pH mainly by proper nutrition and management practices. The animals try to avoid overeating fermentable feeds, as it causes negative consequences by disturbing digestive processes. The results of several experiments show that ruminants, including sheep and beef cattle, are able to modify some aspects of feeding behaviour in order to adjust nutrient intake to their needs and simultaneously prevent physiological disturbances. Particularly, such changes (e.g., increased preference for fibrous feeds, reduced intake of concentrates) were observed in animals, which were trying to prevent the excessive drop of rumen fluid pH. Thanks to a specific mechanism called "the postingestive feedback", animals should be able to work out such a balance in intake, so they do not suffer either from hunger or from negative effects of over-ingesting the fermentable carbohydrates. This way, an acidosis should not be a frequent problem in ruminants. However, prolonged periods of excessively decreased rumen pH are still a concern in dairy cows. It raises a question, why the regulation of feed intake by postingestive feedback does not help to maintain stable rumen environment in dairy cows?
authors.affiliation: Department of Animal Improvement, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzebiec, Postepu 36A, 05-552 Magdalenka, Poland. a.brzozowska@ighz.pl
authors.forename: A M
authors.initials: AM
authors.lastname: Brzozowska
authors.affiliation: Department of Animal Improvement, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzebiec, Postepu 36A, 05-552 Magdalenka, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Sloniewski
authors.affiliation: Department of Animal Improvement, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzebiec, Postepu 36A, 05-552 Magdalenka, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Oprzadek
authors.affiliation: Department of Internal Medicine, Faculty of Veterinary Medicine, University of Warmia and Mazury, Olsztyn, Oczapowskiego 14, 10-957 Olsztyn.
authors.forename: P
authors.initials: P
authors.lastname: Sobiech
authors.affiliation: Department of Animal Nutrition, University of Agriculture in Krakow, Al. Mickiewicza 24/28, 30-059 Krakow, Poland.
authors.forename: Z M
authors.initials: ZM
authors.lastname: Kowalski
mesh_terms: D000138:Acidosis / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000473:pathology*; D005260:Female; D012417:Rumen / Q000473:pathology*; D013272:Stomach Diseases / Q000473:pathology / Q000662:veterinary*