| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
* Département des Sciences Animales, Université Laval, Québec, Québec, Canada G1K 7P4
Agriculture and Agri-Food Canada, Québec, Québec, Canada G1V 2J3
Département de Phytologie, Université Laval, Québec, Québec, Canada G1K 7P4
1 Corresponding author: edith.charbonneau{at}fsaa.ulaval.ca
Timothy grass has a lower dietary cation-anion difference [DCAD = (Na + K) – (Cl + S)] than other cool-season grass species. Growing timothy on low-K soils and fertilizing it with CaCl2 could further decrease its DCAD. The objective of this study was to evaluate the effects of feeding low-DCAD timothy hay on dry dairy cows. Six nonpregnant and nonlactating cows were used in a replicated 3 x 3 Latin square. Treatments were as follows: 1) control diet (control; DCAD = 296 mEq/kg of dry matter); 2) low-DCAD diet based on low-DCAD timothy hay (L-HAY; DCAD = – 24 mEq/kg of dry matter); and 3) low-DCAD diet using HCl (L-HCl; DCAD = – 19 mEq/kg of dry matter). Decreasing DCAD with L-HAY had no effect on dry matter intake (11.8 kg/d) or dry matter digestibility (71.5%). Urine pH decreased from 8.21 to 5.89 when L-HAY was fed instead of the control. Blood parameters that decreased with L-HAY were base excess (– 0.4 vs. 3.8 mM) and HCO3– (23 vs. 27 mM), and blood parameters that increased were Ca2+ (5.3 vs. 5.1 mg/dL), Cl– (30.5 vs. 29.5 mg/dL), and Na+ (60.8 vs. 60.1 mg/dL). Compared with the control, L-HAY resulted in more Ca in urine (13.4 vs. 1.2 g/d). Comparing L-HAY with L-HCl, cow dry matter intake tended to be higher (11.5 vs. 9.8 kg/d), and blood pH was higher (7.37 vs. 7.31). Urine pH; total dry matter; Ca, K, P, and Mg apparent absorption; and Ca, K, Na, Cl, S, P, and Mg apparent retention were similar. Absorption as a percentage of intake of Na and Cl was lower for L-HAY as compared with L-HCl. In an EDTA-challenge test, cows fed L-HAY regained their initial level of blood Ca2+ twice as quickly as the control treatment (339 vs. 708 min); there were no differences between L-HAY and L-HCl. This experiment confirms that feeding low-DCAD hay is an effective means of decreasing the DCAD of rations and obtaining a metabolic response in dry dairy cows.
Key Words: dietary cation-anion difference • nonlactating cow • hay • blood calcium
This article has been cited by other articles:
|
|
 |
|
  E. Charbonneau, P. Y. Chouinard, G. F. Tremblay, G. Allard, and D. Pellerin Timothy silage with low dietary cation-anion difference fed to nonlactating cows J Dairy Sci, May 1, 2009; 92(5): 2067 - 2077. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. S. Heron, G. F. Tremblay, and M. Oba Timothy hays differing in dietary cation-anion difference affect the capability of dairy cows to maintain their calcium homeostasis J Dairy Sci, January 1, 2009; 92(1): 238 - 246. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. B. Penner, G. F. Tremblay, T. Dow, and M. Oba Timothy Hay with a Low Dietary Cation-Anion Difference Improves Calcium Homeostasis in Periparturient Holstein Cows J Dairy Sci, May 1, 2008; 91(5): 1959 - 1968. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
